v1.4.0

this change is backwards-incompatible

.gitignore

@@ -15,4 +15,4 @@ spec/reports
 test/tmp
 test/version_tmp
 tmp
-build_tests_run
+build_test_run

README.md

@@ -2,15 +2,17 @@
 
 Software construction library inspired by SCons and implemented in Ruby
 
+[![Gem Version](https://badge.fury.io/rb/rscons.png)](http://badge.fury.io/rb/rscons)
+
 ## Installation
 
 Add this line to your application's Gemfile:
 
-    gem 'rscons'
+    gem "rscons"
 
 And then execute:
 
-    $ bundle
+    $ bundle install
 
 Or install it yourself as:
 
@@ -18,20 +20,346 @@ Or install it yourself as:
 
 ## Usage
 
-    RScons::Environment.new do |env|
+Rscons is a Ruby library.
-      env.Program('program', Dir['*.c'])
+It can be called from a standalone Ruby script or it can be used with rake and
-    end
+called from your Rakefile.
 
-    main_env = RScons::Environment.new do |env|
+### Example: Building a C Program
-      env.build_dir('src', 'build/main')
-      env.Program('program', Dir['src/**/*.cc'])
-    end
 
-    debug_env = main_env.clone do |env|
+```ruby
-      env.build_dir('src', 'build/debug')
+Rscons::Environment.new do |env|
-      env['CFLAGS'] = ['-g', '-O0']
+  env["CFLAGS"] << "-Wall"
-      env.Program('program-debug', Dir['src/**/*.cc'])
+  env.Program("program", Dir["**/*.c"])
+end
+```
+
+### Example: Building a D Program
+
+```ruby
+Rscons::Environment.new do |env|
+  env["DFLAGS"] << "-Wall"
+  env.Program("program", Dir["**/*.d"])
+end
+```
+
+### Example: Cloning an Environment
+
+```ruby
+main_env = Rscons::Environment.new do |env|
+  # Store object files from sources under "src" in "build/main"
+  env.build_dir("src", "build/main")
+  env["CFLAGS"] = ["-DSOME_DEFINE", "-O3"]
+  env["LIBS"] = ["SDL"]
+  env.Program("program", Dir["src/**/*.cc"])
+end
+
+debug_env = main_env.clone do |env|
+  # Store object files from sources under "src" in "build/debug"
+  env.build_dir("src", "build/debug")
+  env["CFLAGS"] -= ["-O3"]
+  env["CFLAGS"] += ["-g", "-O0"]
+  env.Program("program-debug", Dir["src/**/*.cc"])
+end
+```
+
+### Example: Custom Builder
+
+Custom builders are implemented as classes which extend from `Rscons::Builder`.
+The builder must have a `run` method which is called to invoke the builder.
+The `run` method should return the name of the target built on success, and
+`false` on failure.
+
+```ruby
+class GenerateFoo < Rscons::Builder
+  def run(target, sources, cache, env, vars)
+    cache.mkdir_p(File.dirname(target))
+    File.open(target, "w") do |fh|
+      fh.puts <<EOF
+#define GENERATED 42
+EOF
     end
+    target
+  end
+end
+
+Rscons::Environment.new do |env|
+  env.add_builder(GenerateFoo.new)
+  env.GenerateFoo("foo.h", [])
+  env.Program("a.out", Dir["*.c"])
+end
+```
+
+### Example: Custom Builder That Only Regenerates When Necessary
+
+```ruby
+class CmdBuilder < Rscons::Builder
+  def run(target, sources, cache, env, vars)
+    cmd = ["cmd", "-i", sources.first, "-o", target]
+    unless cache.up_to_date?(target, cmd, sources, env)
+      cache.mkdir_p(File.dirname(target))
+      system(cmd)
+      cache.register_build(target, cmd, sources, env)
+    end
+    target
+  end
+end
+
+Rscons::Environment.new do |env|
+  env.add_builder(CmdBuilder.new)
+  env.CmdBuilder("foo.gen", "foo_gen.cfg")
+end
+```
+
+### Example: Custom Builder That Generates Multiple Output Files
+
+```ruby
+class CModuleGenerator < Rscons::Builder
+  def run(target, sources, cache, env, vars)
+    c_fname = target
+    h_fname = target.sub(/\.c$/, ".h")
+    cmd = ["generate_c_and_h", sources.first, c_fname, h_fname]
+    unless cache.up_to_date?([c_fname, h_fname], cmd, sources, env)
+      cache.mkdir_p(File.dirname(target))
+      system(cmd)
+      cache.register_build([c_fname, h_fname], cmd, sources, env)
+    end
+    target
+  end
+end
+
+Rscons::Environment.new do |env|
+  env.add_builder(CModuleGenerator.new)
+  env.CModuleGenerator("build/foo.c", "foo_gen.cfg")
+end
+```
+
+### Example: Custom Builder Using Builder#standard_build()
+
+The `standard_build` method from the `Rscons::Builder` base class can be used
+when the builder needs to execute a system command to produce the target file.
+The `standard_build` method will return the correct value so its return value
+can be used as the return value from the `run` method.
+
+```ruby
+class CmdBuilder < Rscons::Builder
+  def run(target, sources, cache, env, vars)
+    cmd = ["cmd", "-i", sources.first, "-o", target]
+    standard_build("CmdBld #{target}", target, cmd, sources, env, cache)
+  end
+end
+
+Rscons::Environment.new do |env|
+  env.add_builder(CmdBuilder.new)
+  env.CmdBuilder("foo.gen", "foo_gen.cfg")
+end
+```
+
+### Example: Using different compilation flags for some sources
+
+```ruby
+Rscons::Environment.new do |env|
+  env["CFLAGS"] = ["-O3", "-Wall", "-DDEFINE"]
+  env.add_build_hook do |build_op|
+    if build_op[:target] =~ %r{build/third-party}
+      build_op[:vars]["CFLAGS"] -= ["-Wall"]
+    end
+  end
+  env.build_dir("src", "build")
+  env.Program("program", Dir["**/*.cc"])
+end
+```
+
+Each build hook block will be invoked for every build operation, so the block
+should test the target or sources if its action should only apply to some
+subset of build targets or source files.
+
+The `build_op` parameter to the build hook block is a Hash describing the
+build operation with the following keys:
+* `:builder` - `Builder` instance in use
+* `:env` - `Environment` calling the build hook; note that this may be
+  different from the Environment that the build hook was added to in the case
+  that the original Environment was cloned with build hooks!
+* `:target` - `String` name of the target file
+* `:sources` - `Array` of the source files
+* `:vars` - `Rscons::VarSet` containing the construction variables to use.
+  The build hook can overwrite entries in `build_op[:vars]` to alter the
+  construction variables in use for this specific build operation.
+
+### Example: Creating a static library
+
+```ruby
+Rscons::Environment.new do |env|
+  env.Library("mylib.a", Dir["src/**/*.c"])
+end
+```
+
+### Example: Creating a C++ parser source from a Yacc/Bison input file
+
+```ruby
+Rscons::Environment.new do |env|
+  env.CFile("#{env.build_root}/parser.tab.cc", "parser.yy")
+end
+```
+
+## Details
+
+### Builders
+
+Rscons ships with a number of builders:
+
+* CFile, which builds a C or C++ source file from a lex or yacc input file
+* Disassemble, which disassembles an object file to a disassembly listing
+* Library, which collects object files into a static library archive file
+* Object, which compiles source files to produce an object file
+* Preprocess, which invokes the C/C++ preprocessor on a source file
+* Program, which links object files to produce an executable
+
+If you want to create an Environment that does not contain any builders,
+you can use the `exclude_builders` key to the Environment constructor.
+
+#### CFile
+
+```ruby
+env.CFile(target, source)
+# Example
+env.CFile("parser.c", "parser.y")
+```
+
+The CFile builder will generate a C or C++ source file from a lex (.l, .ll)
+or yacc (.y, .yy) input file.
+
+#### Disassemble
+
+```ruby
+env.Disassemble(target, source)
+# Example
+env.Disassemble("module.dis", "module.o")
+```
+
+The Disassemble builder generates a disassembly listing using objdump from
+and object file.
+
+#### Library
+
+```ruby
+env.Library(target, sources)
+# Example
+env.Library("lib.a", Dir["src/**/*.c"])
+```
+
+The Library builder creates a static library archive from the given source
+files.
+
+#### Object
+
+```ruby
+env.Object(target, sources)
+# Example
+env.Object("module.o", "module.c")
+```
+
+The Object builder compiles the given sources to an object file.
+
+#### Preprocess
+
+```ruby
+env.Preprocess(target, source)
+# Example
+env.Preprocess("module-preprocessed.cc", "module.cc")
+```
+
+The Preprocess builder invokes either ${CC} or ${CXX} (depending on if the
+source contains an extension in ${CXXSUFFIX} or not) and writes the
+preprocessed output to the target file.
+
+#### Program
+
+```ruby
+env.Program(target, sources)
+# Example
+env.Program("myprog", Dir["src/**/*.cc"])
+```
+
+The Program builder compiles and links the given sources to an executable file.
+Object files or source files can be given as `sources`.
+
+### Managing Environments
+
+An Rscons::Environment consists of:
+
+* a collection of construction variables
+* a collection of builders
+* a mapping of build directories from source directories
+* a default build root to apply if no build directories are matched
+* a collection of targets to build
+* a collection of build hooks
+
+When cloning an environment, by default the construction variables and builders
+are cloned, but the new environment does not inherit any of the targets, build
+hooks, build directories, or the build root from the source environment.
+
+The set of environment attributes that are cloned is controllable via the
+`:clone` option to the `#clone` method.
+For example, `env.clone(clone: :all)` will include construction variables,
+builders, build hooks, build directories, and the build root.
+
+The set of pending targets is never cloned.
+
+Cloned environments contain "deep copies" of construction variables.
+For example, in:
+
+```ruby
+base_env = Rscons::Environment.new
+base_env["CPPPATH"] = ["one", "two"]
+cloned_env = base_env.clone
+cloned_env["CPPPATH"] << "three"
+```
+
+`base_env["CPPPATH"]` will not include "three".
+
+### Construction Variable Naming
+
+* uppercase strings - the default construction variables that Rscons uses
+* symbols, lowercase strings - reserved as user-defined construction variables
+
+### API documentation
+
+Documentation for the complete Rscons API can be found at
+http://rubydoc.info/github/holtrop/rscons/frames.
+
+## Release Notes
+
+### v1.4.0
+
+- add CFile builder
+- add Disassemble builder
+- add Preprocess builder
+- pass the Environment object to build hooks in the :env key of the build_op parameter
+- expand target/source paths beginning with "^/" to be relative to the Environment's build root
+- many performance improvements, including:
+  - use JSON instead of YAML for the cache to improve loading speed (Issue #7)
+  - store a hash of the build command instead of the full command contents in the cache
+  - implement copy-on-write semantics for construction variables when cloning Environments
+  - only load the cache once instead of on each Environment#process
+  - only write the cache when something has changed
+- fix Cache#mkdir_p to handle relative paths (Issue #5)
+- flush the cache to disk if a builder raises an exception (Issue #4)
+
+### v1.3.0
+
+- change Environment#execute() options parameter to accept the following options keys:
+  - :env to pass an environment Hash to Kernel#system
+  - :options to pass an options Hash to Kernel#system
+
+### v1.2.0
+
+- add :clone option to Environment#clone to control exactly which Environment attributes are cloned
+- allow nil to be passed in to Environment#build_root=
+
+### v1.1.0
+
+- Change Cache#up_to_date?() and #register_build() to accept a single target
+  file or an array of target file names
 
 ## Contributing
 

Rakefile.rb

@@ -7,11 +7,8 @@ end
 
 require "bundler/gem_tasks"
 require "rspec/core/rake_task"
-require "rake/clean"
 require "yard"
 
-CLEAN.include 'build_tests_run'
-
 RSpec::Core::RakeTask.new(:spec)
 
 YARD::Rake::YardocTask.new do |yard|
@@ -19,3 +16,11 @@ YARD::Rake::YardocTask.new do |yard|
 end
 
 task :default => :spec
+
+task :clean do
+  FileUtils.rm_rf(["build_test_run", "doc", "coverage"])
+end
+
+task :clobber => :clean do
+  FileUtils.rm_rf(["pkg"])
+end

build_tests/build_dir/build.rb

@@ -1,5 +0,0 @@
-Rscons::Environment.new do |env|
-  env.append('CPPPATH' => Dir['src/**/*/'])
-  env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
-  env.Program('build_dir', Dir['src/**/*.c'])
-end

build_tests/build_dir/tweaker_build.rb

@@ -1,12 +0,0 @@
-Rscons::Environment.new do |env|
-  env.append('CPPPATH' => Dir['src/**/*/'])
-  env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
-  env.add_tweaker do |build_op|
-    if build_op[:target] =~ %r{build_one/.*\.o}
-      build_op[:vars]["CFLAGS"] << "-O1"
-    elsif build_op[:target] =~ %r{build_two/.*\.o}
-      build_op[:vars]["CFLAGS"] << "-O2"
-    end
-  end
-  env.Program('tweaker', Dir['src/**/*.c'])
-end

build_tests/clone_env/build.rb

@@ -1,11 +0,0 @@
-debug = Rscons::Environment.new do |env|
-  env.build_dir('src', 'debug')
-  env['CFLAGS'] = '-O2'
-  env['CPPFLAGS'] = '-DSTRING="Debug Version"'
-  env.Program('program-debug', Dir['src/*.c'])
-end
-
-release = debug.clone('CPPFLAGS' => '-DSTRING="Release Version"') do |env|
-  env.build_dir('src', 'release')
-  env.Program('program-release', Dir['src/*.c'])
-end

build_tests/custom_builder/build.rb

@@ -1,15 +0,0 @@
-class MySource < Rscons::Builder
-  def run(target, sources, cache, env, vars = {})
-    File.open(target, 'w') do |fh|
-      fh.puts <<EOF
-#define THE_VALUE 5678
-EOF
-    end
-    target
-  end
-end
-
-Rscons::Environment.new(echo: :short, builders: [MySource.new]) do |env|
-  env.MySource('inc.h', [])
-  env.Program('program', Dir['*.c'])
-end

build_tests/d/main.d

@@ -0,0 +1,6 @@
+import std.stdio;
+
+void main()
+{
+    writeln("Hello from D!");
+}

build_tests/header/build.rb

@@ -1,3 +0,0 @@
-Rscons::Environment.new(echo: :short) do |env|
-  env.Program('header', Dir['*.c'])
-end

build_tests/library/build.rb

@@ -1,4 +0,0 @@
-Rscons::Environment.new(echo: :command) do |env|
-  env.Program('library', ['lib.a', 'three.c'])
-  env.Library("lib.a", ['one.c', 'two.c'], 'CPPFLAGS' => ['-Dmake_lib'])
-end

build_tests/simple/build.rb

@@ -1,4 +0,0 @@
-Rscons::Environment.new do |env|
-  # CHANGE FLAGS
-  env.Program('simple', Dir['*.c'])
-end

build_tests/simple_cc/build.rb

@@ -1,4 +0,0 @@
-Rscons::Environment.new do |env|
-  # CHANGE FLAGS
-  env.Program('simple', Dir['*.cc'])
-end

build_tests/two_sources/build.rb

@@ -1,4 +0,0 @@
-Rscons::Environment.new(echo: :command) do |env|
-  env.Object("one.o", "one.c", 'CPPFLAGS' => ['-DONE'])
-  env.Program('two_sources', ['one.o', 'two.c'])
-end

lib/rscons.rb

@@ -1,31 +1,33 @@
-require "rscons/builder"
+require_relative "rscons/builder"
-require "rscons/cache"
+require_relative "rscons/cache"
-require "rscons/environment"
+require_relative "rscons/environment"
-require "rscons/varset"
+require_relative "rscons/varset"
-require "rscons/version"
+require_relative "rscons/version"
-
-require "rscons/monkey/module"
-require "rscons/monkey/string"
 
 # default builders
-require "rscons/builders/library"
+require_relative "rscons/builders/cfile"
-require "rscons/builders/object"
+require_relative "rscons/builders/disassemble"
-require "rscons/builders/program"
+require_relative "rscons/builders/library"
+require_relative "rscons/builders/object"
+require_relative "rscons/builders/preprocess"
+require_relative "rscons/builders/program"
 
 # Namespace module for rscons classes
 module Rscons
   DEFAULT_BUILDERS = [
-    Library,
+    :CFile,
-    Object,
+    :Disassemble,
-    Program,
+    :Library,
+    :Object,
+    :Preprocess,
+    :Program,
   ]
 
-  class BuildError < Exception
+  class BuildError < RuntimeError; end
-  end
 
   # Remove all generated files
   def self.clean
-    cache = Cache.new
+    cache = Cache.instance
     # remove all built files
     cache.targets.each do |target|
       FileUtils.rm_f(target)
@@ -37,6 +39,19 @@ module Rscons
         Dir.rmdir(directory) rescue nil
       end
     end
-    Cache.clear
+    cache.clear
+  end
+
+  # Return whether the given path is an absolute filesystem path or not
+  # @param path [String] the path to examine
+  def self.absolute_path?(path)
+    path =~ %r{^(/|\w:[\\/])}
+  end
+
+  # Return a new path by changing the suffix in path to suffix.
+  # @param path [String] the path to alter
+  # @param suffix [String] the new filename suffix
+  def self.set_suffix(path, suffix)
+    path.sub(/\.[^.]*$/, suffix)
   end
 end

lib/rscons/builder.rb

@@ -1,8 +1,17 @@
 require "fileutils"
 
 module Rscons
+  # Namespace module in which to store builders for convenient grouping
+  module Builders; end
+
   # Class to hold an object that knows how to build a certain type of file.
   class Builder
+    # Return the name of the builder.
+    # If not overridden this defaults to the last component of the class name.
+    def name
+      self.class.name.split(":").last
+    end
+
     # Return a set of default variable values for the Environment to use
     # unless the user overrides any.
     # @param env [Environment] The Environment.
@@ -23,11 +32,11 @@ module Rscons
     # build command.
     # Return the name of the target or false on failure.
     def standard_build(short_cmd_string, target, command, sources, env, cache)
-      unless cache.up_to_date?(target, command, sources)
+      unless cache.up_to_date?(target, command, sources, env)
         cache.mkdir_p(File.dirname(target))
         FileUtils.rm_f(target)
         return false unless env.execute(short_cmd_string, command)
-        cache.register_build(target, command, sources)
+        cache.register_build(target, command, sources, env)
       end
       target
     end

lib/rscons/builders/cfile.rb

@@ -0,0 +1,40 @@
+module Rscons
+  module Builders
+    # Build a C or C++ source file given a lex (.l, .ll) or yacc (.y, .yy)
+    # input file.
+    #
+    # Examples::
+    #   env.CFile("parser.tab.cc", "parser.yy")
+    #   env.CFile("lex.yy.cc", "parser.ll")
+    class CFile < Builder
+      def default_variables(env)
+        {
+          "YACC" => "bison",
+          "YACC_FLAGS" => ["-d"],
+          "YACC_CMD" => ["${YACC}", "${YACC_FLAGS}", "-o", "${_TARGET}", "${_SOURCES}"],
+          "LEX" => "flex",
+          "LEX_FLAGS" => [],
+          "LEX_CMD" => ["${LEX}", "${LEX_FLAGS}", "-o", "${_TARGET}", "${_SOURCES}"],
+        }
+      end
+
+      def run(target, sources, cache, env, vars)
+        vars = vars.merge({
+          "_TARGET" => target,
+          "_SOURCES" => sources,
+        })
+        cmd =
+          case
+          when sources.first.end_with?(".l", ".ll")
+            "LEX"
+          when sources.first.end_with?(".y", ".yy")
+            "YACC"
+          else
+            raise "Unknown source file #{sources.first.inspect} for CFile builder"
+          end
+        command = env.build_command(env["#{cmd}_CMD"], vars)
+        standard_build("#{cmd} #{target}", target, command, sources, env, cache)
+      end
+    end
+  end
+end

lib/rscons/builders/disassemble.rb

@@ -0,0 +1,25 @@
+module Rscons
+  module Builders
+    # The Disassemble builder produces a disassembly listing of a source file.
+    class Disassemble < Builder
+      def default_variables(env)
+        {
+          "OBJDUMP" => "objdump",
+          "DISASM_CMD" => ["${OBJDUMP}", "${DISASM_FLAGS}", "${_SOURCES}"],
+          "DISASM_FLAGS" => ["--disassemble", "--source"],
+        }
+      end
+
+      def run(target, sources, cache, env, vars)
+        vars = vars.merge("_SOURCES" => sources)
+        command = env.build_command(env["DISASM_CMD"], vars)
+        unless cache.up_to_date?(target, command, sources, env)
+          cache.mkdir_p(File.dirname(target))
+          return false unless env.execute("Disassemble #{target}", command, options: {out: target})
+          cache.register_build(target, command, sources, env)
+        end
+        target
+      end
+    end
+  end
+end

lib/rscons/builders/library.rb

@@ -1,18 +1,17 @@
-require 'fileutils'
-
 module Rscons
-  # A default RScons builder that produces a static library archive.
+  module Builders
+    # A default Rscons builder that produces a static library archive.
     class Library < Builder
       def default_variables(env)
         {
           'AR' => 'ar',
           'LIBSUFFIX' => '.a',
           'ARFLAGS' => [],
-        'ARCOM' => ['$AR', 'rcs', '$ARFLAGS', '$_TARGET', '$_SOURCES']
+          'ARCMD' => ['${AR}', 'rcs', '${ARFLAGS}', '${_TARGET}', '${_SOURCES}']
         }
       end
 
-    def run(target, sources, cache, env, vars = {})
+      def run(target, sources, cache, env, vars)
         # build sources to linkable objects
         objects = env.build_sources(sources, [env['OBJSUFFIX'], env['LIBSUFFIX']].flatten, cache, vars)
         if objects
@@ -20,9 +19,10 @@ module Rscons
             '_TARGET' => target,
             '_SOURCES' => objects,
           })
-        command = env.build_command(env['ARCOM'], vars)
+          command = env.build_command(env['ARCMD'], vars)
           standard_build("AR #{target}", target, command, objects, env, cache)
         end
       end
     end
+  end
 end

lib/rscons/builders/object.rb

@@ -1,18 +1,26 @@
 module Rscons
-  # A default RScons builder which knows how to produce an object file from
+  module Builders
+    # A default Rscons builder which knows how to produce an object file from
     # various types of source files.
     class Object < Builder
+      KNOWN_SUFFIXES = {
+        "AS" => "ASSUFFIX",
+        "CC" => "CSUFFIX",
+        "CXX" => "CXXSUFFIX",
+        "DC" => "DSUFFIX",
+      }
+
       def default_variables(env)
         {
           'OBJSUFFIX' => '.o',
 
-        'AS' => '$CC',
+          'AS' => '${CC}',
           'ASFLAGS' => [],
           'ASSUFFIX' => '.S',
-        'ASPPPATH' => '$CPPPATH',
+          'ASPPPATH' => '${CPPPATH}',
-        'ASPPFLAGS' => '$CPPFLAGS',
+          'ASPPFLAGS' => '${CPPFLAGS}',
-        'ASDEPGEN' => ['-MMD', '-MF', '$_DEPFILE'],
+          'ASDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'ASCOM' => ['$AS', '-c', '-o', '$_TARGET', '$ASDEPGEN', '-I$[ASPPPATH]', '$ASPPFLAGS', '$ASFLAGS', '$_SOURCES'],
+          'ASCMD' => ['${AS}', '-c', '-o', '${_TARGET}', '${ASDEPGEN}', '-I${ASPPPATH}', '${ASPPFLAGS}', '${ASFLAGS}', '${_SOURCES}'],
 
           'CPPFLAGS' => [],
           'CPPPATH' => [],
@@ -20,61 +28,54 @@ module Rscons
           'CC' => 'gcc',
           'CFLAGS' => [],
           'CSUFFIX' => '.c',
-        'CCDEPGEN' => ['-MMD', '-MF', '$_DEPFILE'],
+          'CCDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'CCCOM' => ['$CC', '-c', '-o', '$_TARGET', '$CCDEPGEN', '-I$[CPPPATH]', '$CPPFLAGS', '$CFLAGS', '$_SOURCES'],
+          'CCCMD' => ['${CC}', '-c', '-o', '${_TARGET}', '${CCDEPGEN}', '-I${CPPPATH}', '${CPPFLAGS}', '${CFLAGS}', '${_SOURCES}'],
 
           'CXX' => 'g++',
           'CXXFLAGS' => [],
           'CXXSUFFIX' => '.cc',
-        'CXXDEPGEN' => ['-MMD', '-MF', '$_DEPFILE'],
+          'CXXDEPGEN' => ['-MMD', '-MF', '${_DEPFILE}'],
-        'CXXCOM' =>['$CXX', '-c', '-o', '$_TARGET', '$CXXDEPGEN', '-I$[CPPPATH]', '$CPPFLAGS', '$CXXFLAGS', '$_SOURCES'],
+          'CXXCMD' =>['${CXX}', '-c', '-o', '${_TARGET}', '${CXXDEPGEN}', '-I${CPPPATH}', '${CPPFLAGS}', '${CXXFLAGS}', '${_SOURCES}'],
 
           'DC' => 'gdc',
           'DFLAGS' => [],
           'DSUFFIX' => '.d',
           'D_IMPORT_PATH' => [],
-        'DCCOM' => ['$DC', '-c', '-o', '$_TARGET', '-I$[D_IMPORT_PATH]', '$DFLAGS', '$_SOURCES'],
+          'DCCMD' => ['${DC}', '-c', '-o', '${_TARGET}', '-I${D_IMPORT_PATH}', '${DFLAGS}', '${_SOURCES}'],
         }
       end
 
       def produces?(target, source, env)
-      target.has_suffix?(env['OBJSUFFIX']) and (
+        target.end_with?(*env['OBJSUFFIX']) and KNOWN_SUFFIXES.find do |compiler, suffix_var|
-        source.has_suffix?(env['ASSUFFIX']) or
+          source.end_with?(*env[suffix_var])
-        source.has_suffix?(env['CSUFFIX']) or
+        end
-        source.has_suffix?(env['CXXSUFFIX']) or
-        source.has_suffix?(env['DSUFFIX']))
       end
 
-    def run(target, sources, cache, env, vars = {})
+      def run(target, sources, cache, env, vars)
         vars = vars.merge({
           '_TARGET' => target,
           '_SOURCES' => sources,
-        '_DEPFILE' => target.set_suffix('.mf'),
+          '_DEPFILE' => Rscons.set_suffix(target, '.mf'),
         })
-      com_prefix = if sources.first.has_suffix?(env['ASSUFFIX'])
+        com_prefix = KNOWN_SUFFIXES.find do |compiler, suffix_var|
-                     'AS'
+          sources.first.end_with?(*env[suffix_var])
-                   elsif sources.first.has_suffix?(env['CSUFFIX'])
+        end.tap do |v|
-                     'CC'
+          v.nil? and raise "Error: unknown input file type: #{sources.first.inspect}"
-                   elsif sources.first.has_suffix?(env['CXXSUFFIX'])
+        end.first
-                     'CXX'
+        command = env.build_command(env["#{com_prefix}CMD"], vars)
-                   elsif sources.first.has_suffix?(env['DSUFFIX'])
+        unless cache.up_to_date?(target, command, sources, env)
-                     'DC'
-                   else
-                     raise "Error: unknown input file type: #{sources.first.inspect}"
-                   end
-      command = env.build_command(env["#{com_prefix}COM"], vars)
-      unless cache.up_to_date?(target, command, sources)
           cache.mkdir_p(File.dirname(target))
           FileUtils.rm_f(target)
           return false unless env.execute("#{com_prefix} #{target}", command)
           deps = sources
           if File.exists?(vars['_DEPFILE'])
-          deps += env.parse_makefile_deps(vars['_DEPFILE'], target)
+            deps += Environment.parse_makefile_deps(vars['_DEPFILE'], target)
             FileUtils.rm_f(vars['_DEPFILE'])
           end
-        cache.register_build(target, command, deps.uniq)
+          cache.register_build(target, command, deps.uniq, env)
         end
         target
       end
     end
+  end
 end

lib/rscons/builders/preprocess.rb

@@ -0,0 +1,25 @@
+module Rscons
+  module Builders
+    # The Preprocess builder invokes the C preprocessor
+    class Preprocess < Builder
+      def default_variables(env)
+        {
+          "CPP_CMD" => ["${_PREPROCESS_CC}", "-E", "-o", "${_TARGET}", "-I${CPPPATH}", "${CPPFLAGS}", "${CFLAGS}", "${_SOURCES}"],
+        }
+      end
+
+      def run(target, sources, cache, env, vars)
+        pp_cc = if sources.find {|s| s.end_with?(*env["CXXSUFFIX"])}
+                  env["CXX"]
+                else
+                  env["CC"]
+                end
+        vars = vars.merge("_PREPROCESS_CC" => pp_cc,
+                          "_TARGET" => target,
+                          "_SOURCES" => sources)
+        command = env.build_command(env["CPP_CMD"], vars)
+        standard_build("Preprocess #{target}", target, command, sources, env, cache)
+      end
+    end
+  end
+end

lib/rscons/builders/program.rb

@@ -1,5 +1,6 @@
 module Rscons
-  # A default RScons builder that knows how to link object files into an
+  module Builders
+    # A default Rscons builder that knows how to link object files into an
     # executable program.
     class Program < Builder
       def default_variables(env)
@@ -10,19 +11,19 @@ module Rscons
           'LDFLAGS' => [],
           'LIBPATH' => [],
           'LIBS' => [],
-        'LDCOM' => ['$LD', '-o', '$_TARGET', '$LDFLAGS', '$_SOURCES', '-L$[LIBPATH]', '-l$[LIBS]']
+          'LDCMD' => ['${LD}', '-o', '${_TARGET}', '${LDFLAGS}', '${_SOURCES}', '-L${LIBPATH}', '-l${LIBS}']
         }
       end
 
-    def run(target, sources, cache, env, vars = {})
+      def run(target, sources, cache, env, vars)
         # build sources to linkable objects
         objects = env.build_sources(sources, [env['OBJSUFFIX'], env['LIBSUFFIX']].flatten, cache, vars)
-      if objects
+        return false unless objects
         ld = if env["LD"]
                env["LD"]
-             elsif sources.find {|s| s.has_suffix?(env["DSUFFIX"])}
+             elsif sources.find {|s| s.end_with?(*env["DSUFFIX"])}
                env["DC"]
-             elsif sources.find {|s| s.has_suffix?(env["CXXSUFFIX"])}
+             elsif sources.find {|s| s.end_with?(*env["CXXSUFFIX"])}
                env["CXX"]
              else
                env["CC"]
@@ -32,7 +33,7 @@ module Rscons
           '_SOURCES' => objects,
           'LD' => ld,
         })
-        command = env.build_command(env['LDCOM'], vars)
+        command = env.build_command(env['LDCMD'], vars)
         standard_build("LD #{target}", target, command, objects, env, cache)
       end
     end

lib/rscons/cache.rb

@@ -1,92 +1,101 @@
-require 'yaml'
+require "digest/md5"
-require 'fileutils'
+require "fileutils"
-require 'digest/md5'
+require "json"
-require 'set'
+require "set"
-require 'rscons/version'
+require "singleton"
+require "rscons/version"
 
 module Rscons
   # The Cache class keeps track of file checksums, build target commands and
-  # dependencies in a YAML file which persists from one invocation to the next.
+  # dependencies in a JSON file which persists from one invocation to the next.
   # Example cache:
   #   {
-  #     version: '1.2.3',
+  #     "version" => "1.2.3",
-  #     targets: {
+  #     "targets" => {
-  #       'program' => {
+  #       "program" => {
-  #         'checksum' => 'A1B2C3D4',
+  #         "checksum" => "A1B2C3D4",
-  #         'command' => ['gcc', '-o', 'program', 'program.o'],
+  #         "command" => "13543518FE",
-  #         'deps' => [
+  #         "deps" => [
   #           {
-  #             'fname' => 'program.o',
+  #             "fname" => "program.o",
-  #             'checksum' => '87654321',
+  #             "checksum" => "87654321",
-  #           }
+  #           },
   #         ],
-  #       }
+  #         "user_deps" => [
-  #       'program.o' => {
-  #         'checksum' => '87654321',
-  #         'command' => ['gcc', '-c', '-o', 'program.o', 'program.c'],
-  #         'deps' => [
   #           {
-  #             'fname' => 'program.c',
+  #             "fname" => "lscript.ld",
-  #             'checksum' => '456789ABC',
+  #             "checksum" => "77551133",
+  #           },
+  #         ],
+  #       },
+  #       "program.o" => {
+  #         "checksum" => "87654321",
+  #         "command" => "98765ABCD",
+  #         "deps" => [
+  #           {
+  #             "fname" => "program.c",
+  #             "checksum" => "456789ABC",
   #           },
   #           {
-  #             'fname' => 'program.h',
+  #             "fname" => "program.h",
-  #             'checksum' => '7979764643',
+  #             "checksum" => "7979764643",
-  #           }
+  #           },
-  #         ]
+  #         ],
-  #       }
+  #         "user_deps" => [],
-  #     }
-  #     directories: {
-  #       'build' => true,
-  #       'build/one' => true,
-  #       'build/two' => true,
   #       }
+  #     },
+  #     "directories" => {
+  #       "build" => true,
+  #       "build/one" => true,
+  #       "build/two" => true,
+  #     },
   #   }
   class Cache
-    #### Constants
+    include Singleton
 
     # Name of the file to store cache information in
-    CACHE_FILE = '.rsconscache'
+    CACHE_FILE = ".rsconscache"
-
-    #### Class Methods
-
-    # Remove the cache file
-    def self.clear
-      FileUtils.rm_f(CACHE_FILE)
-    end
-
-    #### Instance Methods
 
     # Create a Cache object and load in the previous contents from the cache
     # file.
     def initialize
-      @cache = YAML.load(File.read(CACHE_FILE)) rescue {}
+      initialize!
-      unless @cache.is_a?(Hash)
-        $stderr.puts "Warning: #{CACHE_FILE} was corrupt. Contents:\n#{@cache.inspect}"
-        @cache = {}
     end
-      @cache[:targets] ||= {}
+
-      @cache[:directories] ||= {}
+    # Remove the cache file.
-      @cache[:version] ||= VERSION
+    def clear
+      FileUtils.rm_f(CACHE_FILE)
+      initialize!
+    end
+
+    # Clear the cached file checksums.
+    def clear_checksum_cache!
       @lookup_checksums = {}
     end
 
     # Write the cache to disk to be loaded next time.
     def write
-      File.open(CACHE_FILE, 'w') do |fh|
+      if @dirty || (@cache["version"] != VERSION)
-        fh.puts(YAML.dump(@cache))
+        @cache["version"] = VERSION
+        File.open(CACHE_FILE, "w") do |fh|
+          fh.puts(JSON.dump(@cache))
         end
       end
+      @dirty = false
+    end
 
-    # Check if a target is up to date
+    # Check if target(s) are up to date
-    # @param target [String] The name of the target file.
+    # @param targets [String, Array] The name(s) of the target file(s).
-    # @param command [Array] The command used to build the target.
+    # @param command [String, Array] The command used to build the target.
     # @param deps [Array] List of the target's dependency files.
-    # @param options [Hash] Optional options. Can contain the following keys:
+    # @param env [Environment] The Rscons::Environment.
-    #   :strict_deps::
+    # @param options [Hash] Optional options.
+    # @option options [Boolean] :strict_deps
     #   Only consider a target up to date if its list of dependencies is
     #   exactly equal (including order) to the cached list of dependencies
-    # @return true value if the target is up to date, meaning that:
+    # @return [Boolean]
+    #   True value if the targets are all up to date, meaning that,
+    #   for each target:
     #   - the target exists on disk
     #   - the cache has information for the target
     #   - the target's checksum matches its checksum when it was last built
@@ -96,79 +105,113 @@ module Rscons
     #     exactly equal to those cached
     #   - each cached dependency file's current checksum matches the checksum
     #     stored in the cache file
-    def up_to_date?(target, command, deps, options = {})
+    def up_to_date?(targets, command, deps, env, options = {})
+      Array(targets).each do |target|
         # target file must exist on disk
         return false unless File.exists?(target)
 
         # target must be registered in the cache
-      return false unless @cache[:targets].has_key?(target)
+        return false unless @cache["targets"].has_key?(target)
 
         # target must have the same checksum as when it was built last
-      return false unless @cache[:targets][target][:checksum] == lookup_checksum(target)
+        return false unless @cache["targets"][target]["checksum"] == lookup_checksum(target)
 
         # command used to build target must be identical
-      return false unless @cache[:targets][target][:command] == command
+        return false unless @cache["targets"][target]["command"] == Digest::MD5.hexdigest(command.inspect)
 
-      cached_deps = @cache[:targets][target][:deps].map { |dc| dc[:fname] }
+        cached_deps = @cache["targets"][target]["deps"] || []
+        cached_deps_fnames = cached_deps.map { |dc| dc["fname"] }
         if options[:strict_deps]
           # depedencies passed in must exactly equal those in the cache
-        return false unless deps == cached_deps
+          return false unless deps == cached_deps_fnames
         else
           # all dependencies passed in must exist in cache (but cache may have more)
-        return false unless (Set.new(deps) - Set.new(cached_deps)).empty?
+          return false unless (Set.new(deps) - Set.new(cached_deps_fnames)).empty?
         end
 
+        # set of user dependencies must match
+        user_deps = env.get_user_deps(target) || []
+        cached_user_deps = @cache["targets"][target]["user_deps"] || []
+        cached_user_deps_fnames = cached_user_deps.map { |dc| dc["fname"] }
+        return false unless user_deps == cached_user_deps_fnames
+
         # all cached dependencies must have their checksums match
-      @cache[:targets][target][:deps].map do |dep_cache|
+        (cached_deps + cached_user_deps).each do |dep_cache|
-        dep_cache[:checksum] == lookup_checksum(dep_cache[:fname])
+          return false unless dep_cache["checksum"] == lookup_checksum(dep_cache["fname"])
-      end.all?
+        end
       end
 
-    # Store cache information about a target built by a builder
+      true
-    # @param target [String] The name of the target.
-    # @param command [Array] The command used to build the target.
-    # @param deps [Array] List of dependencies for the target.
-    def register_build(target, command, deps)
-      @cache[:targets][target.encode(__ENCODING__)] = {
-        command: command,
-        checksum: calculate_checksum(target),
-        deps: deps.map do |dep|
-          {
-            fname: dep.encode(__ENCODING__),
-            checksum: lookup_checksum(dep),
-          }
     end
+
+    # Store cache information about target(s) built by a builder
+    # @param targets [String, Array] The name of the target(s) built.
+    # @param command [String, Array] The command used to build the target.
+    # @param deps [Array] List of dependencies for the target.
+    # @param env [Environment] The {Rscons::Environment}.
+    def register_build(targets, command, deps, env)
+      Array(targets).each do |target|
+        @cache["targets"][target] = {
+          "command" => Digest::MD5.hexdigest(command.inspect),
+          "checksum" => calculate_checksum(target),
+          "deps" => deps.map do |dep|
+            {
+              "fname" => dep,
+              "checksum" => lookup_checksum(dep),
             }
+          end,
+          "user_deps" => (env.get_user_deps(target) || []).map do |dep|
+            {
+              "fname" => dep,
+              "checksum" => lookup_checksum(dep),
+            }
+          end,
+        }
+        @dirty = true
+      end
     end
 
     # Return a list of targets that have been built
     def targets
-      @cache[:targets].keys
+      @cache["targets"].keys
     end
 
     # Make any needed directories and record the ones that are created for
     # removal upon a "clean" operation.
     def mkdir_p(path)
       parts = path.split(/[\\\/]/)
-      (0..parts.size).each do |i|
+      parts.each_index do |i|
-        subpath = File.join(*parts[0, i + 1]).encode(__ENCODING__)
+        next if parts[i] == ""
+        subpath = File.join(*parts[0, i + 1])
         unless File.exists?(subpath)
           FileUtils.mkdir(subpath)
-          unless @cache[:directories].include?(subpath)
+          @cache["directories"][subpath] = true
-            @cache[:directories][subpath] = true
+          @dirty = true
-          end
         end
       end
     end
 
     # Return a list of directories which were created as a part of the build
     def directories
-      @cache[:directories].keys
+      @cache["directories"].keys
     end
 
-    # Private Instance Methods
     private
 
+    # Create a Cache object and load in the previous contents from the cache
+    # file.
+    def initialize!
+      @cache = JSON.load(File.read(CACHE_FILE)) rescue {}
+      unless @cache.is_a?(Hash)
+        $stderr.puts "Warning: #{CACHE_FILE} was corrupt. Contents:\n#{@cache.inspect}"
+        @cache = {}
+      end
+      @cache["targets"] ||= {}
+      @cache["directories"] ||= {}
+      @lookup_checksums = {}
+      @dirty = false
+    end
+
     # Return a file's checksum, or the previously calculated checksum for
     # the same file
     # @param file [String] The file name.
@@ -179,7 +222,7 @@ module Rscons
     # Calculate and return a file's checksum
     # @param file [String] The file name.
     def calculate_checksum(file)
-      @lookup_checksums[file] = Digest::MD5.hexdigest(File.read(file, {mode: 'rb'})).encode(__ENCODING__) rescue ''
+      @lookup_checksums[file] = Digest::MD5.hexdigest(File.read(file, mode: "rb")) rescue ""
     end
   end
 end

lib/rscons/environment.rb

@@ -2,40 +2,47 @@ require 'set'
 require 'fileutils'
 
 module Rscons
-  # The Environment class is the main programmatic interface to RScons. It
+  # The Environment class is the main programmatic interface to Rscons. It
   # contains a collection of construction variables, options, builders, and
   # rules for building targets.
   class Environment
-    # [Hash] of {"builder_name" => builder_object} pairs.
+    # Hash of +{"builder_name" => builder_object}+ pairs.
     attr_reader :builders
 
+    # :command, :short, or :off
+    attr_accessor :echo
+
+    # String or +nil+
+    attr_reader :build_root
+    def build_root=(build_root)
+      @build_root = build_root
+      @build_root.gsub!('\\', '/') if @build_root
+    end
+
     # Create an Environment object.
-    # @param variables [Hash]
+    # @param options [Hash]
-    #   The variables hash can contain construction variables, which are
+    # Possible options keys:
-    #   uppercase strings (such as "CC" or "LDFLAGS"), user variables, which
+    #   :echo => :command, :short, or :off (default :short)
-    #   are lowercase strings (such as "sources"), and RScons options, which
+    #   :build_root => String specifying build root directory (default nil)
-    #   are lowercase symbols (such as :echo).
+    #   :exclude_builders => true to omit adding default builders (default false)
     # If a block is given, the Environment object is yielded to the block and
     # when the block returns, the {#process} method is automatically called.
-    def initialize(variables = {})
+    def initialize(options = {})
-      @varset = VarSet.new(variables)
+      @varset = VarSet.new
       @targets = {}
+      @user_deps = {}
       @builders = {}
       @build_dirs = []
-      @tweakers = []
+      @build_hooks = []
-      @varset[:exclude_builders] ||= []
+      unless options[:exclude_builders]
-      unless @varset[:exclude_builders] == :all
+        DEFAULT_BUILDERS.each do |builder_class_name|
-        exclude_builders = Set.new(@varset[:exclude_builders] || [])
+          builder_class = Builders.const_get(builder_class_name)
-        DEFAULT_BUILDERS.each do |builder_class|
+          builder_class or raise "Could not find builder class #{builder_class_name}"
-          unless exclude_builders.include?(builder_class.short_name)
           add_builder(builder_class.new)
         end
       end
-      end
+      @echo = options[:echo] || :short
-      (@varset[:builders] || []).each do |builder|
+      @build_root = options[:build_root]
-        add_builder(builder)
-      end
-      @varset[:echo] ||= :command
 
       if block_given?
         yield self
@@ -44,18 +51,53 @@ module Rscons
     end
 
     # Make a copy of the Environment object.
-    # The cloned environment will contain a copy of all environment options,
+    #
-    # construction variables, builders, and build directories. It will not
+    # By default, a cloned environment will contain a copy of all environment
-    # contain a copy of the targets or tweakers.
+    # options, construction variables, and builders, but not a copy of the
+    # targets, build hooks, build directories, or the build root.
+    #
+    # Exactly which items are cloned are controllable via the optional :clone
+    # parameter, which can be :none, :all, or a set or array of any of the
+    # following:
+    # - :variables to clone construction variables (on by default)
+    # - :builders to clone the builders (on by default)
+    # - :build_root to clone the build root (off by default)
+    # - :build_dirs to clone the build directories (off by default)
+    # - :build_hooks to clone the build hooks (off by default)
+    #
     # If a block is given, the Environment object is yielded to the block and
     # when the block returns, the {#process} method is automatically called.
-    def clone(variables = {})
+    #
-      env = Environment.new()
+    # Any options that #initialize receives can also be specified here.
+    #
+    # @return a new {Environment} object.
+    def clone(options = {})
+      clone = options[:clone] || Set[:variables, :builders]
+      clone = Set[:variables, :builders, :build_root, :build_dirs, :build_hooks] if clone == :all
+      clone = Set[] if clone == :none
+      clone = Set.new(clone) if clone.is_a?(Array)
+      clone.delete(:builders) if options[:exclude_builders]
+      env = self.class.new(
+        echo: options[:echo] || @echo,
+        build_root: options[:build_root],
+        exclude_builders: true)
+      if clone.include?(:builders)
         @builders.each do |builder_name, builder|
           env.add_builder(builder)
         end
-      env.append(@varset.clone)
+      end
-      env.append(variables)
+      env.append(@varset) if clone.include?(:variables)
+      env.build_root = @build_root if clone.include?(:build_root)
+      if clone.include?(:build_dirs)
+        @build_dirs.each do |src_dir, obj_dir|
+          env.build_dir(src_dir, obj_dir)
+        end
+      end
+      if clone.include?(:build_hooks)
+        @build_hooks.each do |build_hook_block|
+          env.add_build_hook(&build_hook_block)
+        end
+      end
 
       if block_given?
         yield env
@@ -66,7 +108,7 @@ module Rscons
 
     # Add a {Builder} object to the Environment.
     def add_builder(builder)
-      @builders[builder.class.short_name] = builder
+      @builders[builder.name] = builder
       var_defs = builder.default_variables(self)
       if var_defs
         var_defs.each_pair do |var, val|
@@ -75,9 +117,9 @@ module Rscons
       end
     end
 
-    # Add a tweaker block to the Environment.
+    # Add a build hook to the Environment.
-    def add_tweaker(&block)
+    def add_build_hook(&block)
-      @tweakers << block
+      @build_hooks << block
     end
 
     # Specify a build directory for this Environment.
@@ -89,18 +131,21 @@ module Rscons
 
     # Return the file name to be built from source_fname with suffix suffix.
     # This method takes into account the Environment's build directories.
-    # It also creates any parent directories needed to be able to open and
-    # write to the output file.
     def get_build_fname(source_fname, suffix)
-      build_fname = source_fname.set_suffix(suffix).gsub('\\', '/')
+      build_fname = Rscons.set_suffix(source_fname, suffix).gsub('\\', '/')
-      @build_dirs.each do |src_dir, obj_dir|
+      found_match = @build_dirs.find do |src_dir, obj_dir|
         if src_dir.is_a?(Regexp)
           build_fname.sub!(src_dir, obj_dir)
         else
           build_fname.sub!(%r{^#{src_dir}/}, "#{obj_dir}/")
         end
-        build_fname.gsub!('\\', '/')
       end
+      if @build_root and not found_match
+        unless Rscons.absolute_path?(source_fname) or build_fname.start_with?("#{@build_root}/")
+          build_fname = "#{@build_root}/#{build_fname}"
+        end
+      end
+      build_fname.gsub!('\\', '/')
       build_fname
     end
 
@@ -119,47 +164,50 @@ module Rscons
     # Add a set of construction variables or environment options.
     # @see VarSet#append
     def append(*args)
-      @varset.send(:append, *args)
+      @varset.append(*args)
-    end
-
-    # Return a list of target file names
-    def targets
-      @targets.keys
-    end
-
-    # Return a list of sources needed to build target target.
-    def target_sources(target)
-      @targets[target][:source] rescue nil
     end
 
     # Build all target specified in the Environment.
     # When a block is passed to Environment.new, this method is automatically
     # called after the block returns.
     def process
-      cache = Cache.new
+      unless @targets.empty?
-      targets_processed = Set.new
+        clean_target_paths!
+        cache = Cache.instance
+        cache.clear_checksum_cache!
+        targets_processed = {}
         process_target = proc do |target|
-        if @targets[target][:source].map do |src|
+          targets_processed[target] ||= begin
-          targets_processed.include?(src) or not @targets.include?(src) or process_target.call(src)
+            @targets[target][:sources].each do |src|
-        end.all?
+              if @targets.include?(src) and not targets_processed.include?(src)
-          run_builder(@targets[target][:builder],
+                process_target.call(src)
+              end
+            end
+            result = run_builder(@targets[target][:builder],
                                  target,
-                      @targets[target][:source],
+                                 @targets[target][:sources],
                                  cache,
                                  @targets[target][:vars] || {})
-        else
+            unless result
-          false
-        end
-      end
-      @targets.each do |target, info|
-        next if targets_processed.include?(target)
-        unless process_target.call(target)
-          cache.write
               raise BuildError.new("Failed to build #{target}")
             end
+            result
           end
+        end
+        begin
+          @targets.each do |target, target_params|
+            process_target.call(target)
+          end
+        ensure
           cache.write
         end
+      end
+    end
+
+    # Clear all targets registered for the Environment.
+    def clear_targets
+      @targets = {}
+    end
 
     # Build a command line from the given template, resolving references to
     # variables using the Environment's construction variables and any extra
@@ -173,82 +221,83 @@ module Rscons
       @varset.merge(extra_vars).expand_varref(command_template)
     end
 
+    # Expand a construction variable reference (String or Array)
+    def expand_varref(varref)
+      @varset.expand_varref(varref)
+    end
+
     # Execute a builder command
-    # @param short_desc [String] Message to print if the Environment's :echo
+    # @param short_desc [String] Message to print if the Environment's echo
     #   mode is set to :short
     # @param command [Array] The command to execute.
-    # @param options [Hash] Optional options to pass to {Kernel#system}.
+    # @param options [Hash] Optional options, possible keys:
+    #   - :env - environment Hash to pass to Kernel#system.
+    #   - :options - options Hash to pass to Kernel#system.
     def execute(short_desc, command, options = {})
       print_command = proc do
         puts command.map { |c| c =~ /\s/ ? "'#{c}'" : c }.join(' ')
       end
-      if @varset[:echo] == :command
+      if @echo == :command
         print_command.call
-      elsif @varset[:echo] == :short
+      elsif @echo == :short
         puts short_desc
       end
-      system(*command, options).tap do |result|
+      env_args = options[:env] ? [options[:env]] : []
-        unless result or @varset[:echo] == :command
+      options_args = options[:options] ? [options[:options]] : []
+      system(*env_args, *command, *options_args).tap do |result|
+        unless result or @echo == :command
           $stdout.write "Failed command was: "
           print_command.call
         end
       end
     end
 
-    alias_method :orig_method_missing, :method_missing
     def method_missing(method, *args)
       if @builders.has_key?(method.to_s)
-        target, source, vars, *rest = args
+        target, sources, vars, *rest = args
         unless vars.nil? or vars.is_a?(Hash) or vars.is_a?(VarSet)
           raise "Unexpected construction variable set: #{vars.inspect}"
         end
-        source = [source] unless source.is_a?(Array)
+        sources = [sources] unless sources.is_a?(Array)
-        @targets[target] = {
+        add_target(target, @builders[method.to_s], sources, vars, rest)
-          builder: @builders[method.to_s],
-          source: source,
-          vars: vars,
-          args: rest,
-        }
       else
-        orig_method_missing(method, *args)
+        super
       end
     end
 
-    # Parse dependencies for a given target from a Makefile.
+    def add_target(target, builder, sources, vars, args)
-    # This method is used internally by RScons builders.
+      @targets[target] = {
-    # @param mf_fname [String] File name of the Makefile to read.
+        builder: builder,
-    # @param target [String] Name of the target to gather dependencies for.
+        sources: sources,
-    def parse_makefile_deps(mf_fname, target)
+        vars: vars,
-      deps = []
+        args: args,
-      buildup = ''
+      }
-      File.read(mf_fname).each_line do |line|
-        if line =~ /^(.*)\\\s*$/
-          buildup += ' ' + $1
-        else
-          buildup += ' ' + line
-          if buildup =~ /^(.*): (.*)$/
-            mf_target, mf_deps = $1.strip, $2
-            if mf_target == target
-              deps += mf_deps.split(' ').map(&:strip)
     end
+
+    # Manually record a given target as depending on the specified
+    # dependency files.
+    def depends(target, *user_deps)
+      @user_deps[target] ||= []
+      @user_deps[target] = (@user_deps[target] + user_deps).uniq
     end
-          buildup = ''
+
-        end
+    # Return the list of user dependencies for a given target, or +nil+ for
-      end
+    # none.
-      deps
+    def get_user_deps(target)
+      @user_deps[target]
     end
 
     # Build a list of source files into files containing one of the suffixes
     # given by suffixes.
-    # This method is used internally by RScons builders.
+    # This method is used internally by Rscons builders.
     # @param sources [Array] List of source files to build.
     # @param suffixes [Array] List of suffixes to try to convert source files into.
     # @param cache [Cache] The Cache.
     # @param vars [Hash] Extra variables to pass to the builder.
     # Return a list of the converted file names.
-    def build_sources(sources, suffixes, cache, vars = {})
+    def build_sources(sources, suffixes, cache, vars)
       sources.map do |source|
-        if source.has_suffix?(suffixes)
+        if source.end_with?(*suffixes)
           source
         else
           converted = nil
@@ -275,16 +324,62 @@ module Rscons
     # Return the result of the builder's run() method.
     def run_builder(builder, target, sources, cache, vars)
       vars = @varset.merge(vars)
-      @tweakers.each do |tweaker_block|
+      @build_hooks.each do |build_hook_block|
         build_operation = {
           builder: builder,
           target: target,
           sources: sources,
           vars: vars,
+          env: self,
         }
-        tweaker_block.call(build_operation)
+        build_hook_block.call(build_operation)
       end
       builder.run(target, sources, cache, self, vars)
     end
+
+    private
+
+    # Expand all target paths that begin with ^/ to be relative to the
+    # Environment's build root, if present
+    def clean_target_paths!
+      if @build_root
+        expand = lambda do |path|
+          path.sub(%r{^\^(?=[\\/])}, @build_root)
+        end
+
+        new_targets = {}
+        @targets.each_pair do |target, target_params|
+          target_params[:sources].map! do |source|
+            expand[source]
+          end
+          new_targets[expand[target]] = target_params
+        end
+        @targets = new_targets
+      end
+    end
+
+    # Parse dependencies for a given target from a Makefile.
+    # This method is used internally by Rscons builders.
+    # @param mf_fname [String] File name of the Makefile to read.
+    # @param target [String] Name of the target to gather dependencies for.
+    def self.parse_makefile_deps(mf_fname, target)
+      deps = []
+      buildup = ''
+      File.read(mf_fname).each_line do |line|
+        if line =~ /^(.*)\\\s*$/
+          buildup += ' ' + $1
+        else
+          buildup += ' ' + line
+          if buildup =~ /^(.*): (.*)$/
+            mf_target, mf_deps = $1.strip, $2
+            if mf_target == target
+              deps += mf_deps.split(' ').map(&:strip)
+            end
+          end
+          buildup = ''
+        end
+      end
+      deps
+    end
   end
 end

lib/rscons/monkey/module.rb

@@ -1,7 +0,0 @@
-# Standard Ruby Module class.
-class Module
-  # @return the base module name (not the fully qualified name)
-  def short_name
-    name.split(':').last
-  end
-end

lib/rscons/monkey/string.rb

@@ -1,20 +0,0 @@
-# Standard Ruby String class.
-class String
-  # Check if the given string ends with any of the supplied suffixes
-  # @param suffix [String, Array] The suffix to look for.
-  # @return a true value if the string ends with one of the suffixes given.
-  def has_suffix?(suffix)
-    if suffix
-      suffix = [suffix] if suffix.is_a?(String)
-      suffix = suffix.flatten
-      suffix.find {|s| self.end_with?(s)}
-    end
-  end
-
-  # Return a new string with the suffix (dot character and extension) changed
-  # to the given suffix.
-  # @param suffix [String] The new suffix.
-  def set_suffix(suffix = '')
-    sub(/\.[^.]*$/, suffix)
-  end
-end

lib/rscons/varset.rb

@@ -1,57 +1,73 @@
 module Rscons
   # This class represents a collection of variables which can be accessed
-  # as certain types
+  # as certain types.
+  # Only nil, strings, arrays, and hashes should be stored in a VarSet.
   class VarSet
-    # The underlying hash
+    # Create a VarSet.
-    attr_reader :vars
-
-    # Create a VarSet
     # @param vars [Hash] Optional initial variables.
     def initialize(vars = {})
-      if vars.is_a?(VarSet)
+      @my_vars = {}
-        @vars = vars.clone.vars
+      @coa_vars = []
-      else
+      append(vars)
-        @vars = vars
-      end
     end
 
     # Access the value of variable as a particular type
     # @param key [String, Symbol] The variable name.
-    # @param type [Symbol, nil] Optional specification of the type desired.
+    # @return [Object] The variable's value.
-    #   If the variable is a String and type is :array, a 1-element array with
+    def [](key)
-    #   the variable value will be returned. If the variable is an Array and
+      if @my_vars.include?(key)
-    #   type is :string, the first element from the variable value will be
+        @my_vars[key]
-    #   returned.
-    def [](key, type = nil)
-      val = @vars[key]
-      if type == :array and not val.is_a?(Array)
-        [val]
-      elsif type == :scalar and val.is_a?(Array)
-        val.first
       else
-        val
+        @coa_vars.each do |coa_vars|
+          if coa_vars.include?(key)
+            @my_vars[key] = deep_dup(coa_vars[key])
+            return @my_vars[key]
+          end
+        end
+        nil
       end
     end
 
     # Assign a value to a variable.
     # @param key [String, Symbol] The variable name.
-    # @param val [Object] The value.
+    # @param val [Object] The value to set.
     def []=(key, val)
-      @vars[key] = val
+      @my_vars[key] = val
+    end
+
+    # Check if the VarSet contains a variable.
+    # @param key [String, Symbol] The variable name.
+    # @return [true, false] Whether the VarSet contains a variable.
+    def include?(key)
+      if @my_vars.include?(key)
+        true
+      else
+        @coa_vars.find do |coa_vars|
+          coa_vars.include?(key)
+        end
+      end
     end
 
     # Add or overwrite a set of variables
     # @param values [VarSet, Hash] New set of variables.
     def append(values)
-      values = values.vars if values.is_a?(VarSet)
+      coa!
-      @vars.merge!(Marshal.load(Marshal.dump(values)))
+      if values.is_a?(VarSet)
+        values.send(:coa!)
+        @coa_vars = values.instance_variable_get(:@coa_vars) + @coa_vars
+      else
+        @my_vars = deep_dup(values)
+      end
       self
     end
 
     # Create a new VarSet object based on the first merged with other.
     # @param other [VarSet, Hash] Other variables to add or overwrite.
     def merge(other = {})
-      VarSet.new(Marshal.load(Marshal.dump(@vars))).append(other)
+      coa!
+      varset = self.class.new
+      varset.instance_variable_set(:@coa_vars, @coa_vars.dup)
+      varset.append(other)
     end
     alias_method :clone, :merge
 
@@ -64,24 +80,49 @@ module Rscons
           expand_varref(ent)
         end.flatten
       else
-        if varref =~ /^(.*)\$\[(\w+)\](.*)$/
+        if varref =~ /^(.*)\$\{([^}]+)\}(.*)$/
-          # expand array with given prefix, suffix
           prefix, varname, suffix = $1, $2, $3
-          varval = expand_varref(@vars[varname])
+          varval = expand_varref(self[varname])
-          unless varval.is_a?(Array)
+          if varval.is_a?(String)
-            raise "Array expected for $#{varname}"
+            expand_varref("#{prefix}#{varval}#{suffix}")
+          elsif varval.is_a?(Array)
+            varval.map {|vv| expand_varref("#{prefix}#{vv}#{suffix}")}.flatten
+          else
+            raise "I do not know how to expand a variable reference to a #{varval.class.name} (from #{varname.inspect} => #{self[varname].inspect})"
           end
-          varval.map {|e| "#{prefix}#{e}#{suffix}"}
-        elsif varref =~ /^\$(.*)$/
-          # expand a single variable reference
-          varname = $1
-          varval = expand_varref(@vars[varname])
-          varval or raise "Could not find variable #{varname.inspect}"
-          expand_varref(varval)
         else
           varref
         end
       end
     end
+
+    private
+
+    # Move all VarSet variables into the copy-on-access list.
+    def coa!
+      unless @my_vars.empty?
+        @coa_vars.unshift(@my_vars)
+        @my_vars = {}
+      end
+    end
+
+    # Create a deep copy of an object.
+    # @param obj [nil, String, Array, Hash] Object to deep copy.
+    # @return [nil, String, Array, Hash] Deep copied value.
+    def deep_dup(obj)
+      obj_class = obj.class
+      if obj_class == Hash
+        obj.reduce({}) do |result, (k, v)|
+          result[k] = deep_dup(v)
+          result
+        end
+      elsif obj_class == Array
+        obj.map { |v| deep_dup(v) }
+      elsif obj_class == String
+        obj.dup
+      else
+        obj
+      end
+    end
   end
 end

lib/rscons/version.rb

@@ -1,4 +1,4 @@
 module Rscons
   # gem version
-  VERSION = "0.0.14"
+  VERSION = "1.4.0"
 end

spec/build_tests_spec.rb

@@ -1,45 +1,40 @@
 require 'fileutils'
 
+class Dir
+  class << self
+    alias_method :orig_bracket, :[]
+  end
+  def self.[](*args)
+    orig_bracket(*args).sort
+  end
+end
+
 describe Rscons do
+  BUILD_TEST_RUN_DIR = "build_test_run"
+
   before(:all) do
-    FileUtils.rm_rf('build_tests_run')
+    FileUtils.rm_rf(BUILD_TEST_RUN_DIR)
     @owd = Dir.pwd
   end
 
+  before(:each) do
+    @output = ""
+    $stdout.stub(:write) do |content|
+      @output += content
+    end
+    $stderr.stub(:write) do |content|
+      @output += content
+    end
+  end
+
   after(:each) do
     Dir.chdir(@owd)
-    FileUtils.rm_rf('build_tests_run')
+    FileUtils.rm_rf(BUILD_TEST_RUN_DIR)
   end
 
-  def build_testdir(build_script = "build.rb")
+  def test_dir(build_test_directory)
-    if File.exists?(build_script)
+    FileUtils.cp_r("build_tests/#{build_test_directory}", BUILD_TEST_RUN_DIR)
-      build_rb = File.read(build_script)
+    Dir.chdir(BUILD_TEST_RUN_DIR)
-      File.open(build_script, "w") do |fh|
-        fh.puts(<<EOF + build_rb)
-require "simplecov"
-
-SimpleCov.start do
-  root("#{@owd}")
-  command_name("build_test_#{@build_test_name}")
-  add_filter("spec")
-end
-
-require "rscons"
-EOF
-      end
-      IO.popen(%{ruby -I #{@owd}/lib #{build_script}}) do |io|
-        io.readlines.reject do |line|
-          line =~ /^Coverage report/
-        end
-      end.map(&:strip)
-    end
-  end
-
-  def test_dir(build_test_directory, build_script = "build.rb")
-    @build_test_name = build_test_directory
-    FileUtils.cp_r("build_tests/#{build_test_directory}", 'build_tests_run')
-    Dir.chdir("build_tests_run")
-    build_testdir(build_script)
   end
 
   def file_sub(fname)
@@ -53,18 +48,31 @@ EOF
     end
   end
 
+  def lines
+    @output.lines.map(&:rstrip).tap do |v|
+      @output = ""
+    end
+  end
+
   ###########################################################################
   # Tests
   ###########################################################################
 
   it 'builds a C program with one source file' do
     test_dir('simple')
+    Rscons::Environment.new do |env|
+      env.Program('simple', Dir['*.c'])
+    end
     File.exists?('simple.o').should be_true
     `./simple`.should == "This is a simple C program\n"
   end
 
   it 'prints commands as they are executed' do
-    lines = test_dir('simple')
+    test_dir('simple')
+    Rscons::Environment.new(echo: :command) do |env|
+      env["LD"] = "gcc"
+      env.Program('simple', Dir['*.c'])
+    end
     lines.should == [
       'gcc -c -o simple.o -MMD -MF simple.mf simple.c',
       'gcc -o simple simple.o',
@@ -72,7 +80,10 @@ EOF
   end
 
   it 'prints short representations of the commands being executed' do
-    lines = test_dir('header')
+    test_dir('header')
+    Rscons::Environment.new do |env|
+      env.Program('header', Dir['*.c'])
+    end
     lines.should == [
       'CC header.o',
       'LD header',
@@ -81,61 +92,127 @@ EOF
 
   it 'builds a C program with one source file and one header file' do
     test_dir('header')
+    Rscons::Environment.new do |env|
+      env.Program('header', Dir['*.c'])
+    end
     File.exists?('header.o').should be_true
     `./header`.should == "The value is 2\n"
   end
 
   it 'rebuilds a C module when a header it depends on changes' do
     test_dir('header')
+    env = Rscons::Environment.new do |env|
+      env.Program('header', Dir['*.c'])
+    end
     `./header`.should == "The value is 2\n"
     file_sub('header.h') {|line| line.sub(/2/, '5')}
-    build_testdir
+    env.process
     `./header`.should == "The value is 5\n"
   end
 
   it 'does not rebuild a C module when its dependencies have not changed' do
-    lines = test_dir('header')
+    test_dir('header')
+    env = Rscons::Environment.new do |env|
+      env.Program('header', Dir['*.c'])
+    end
     `./header`.should == "The value is 2\n"
     lines.should == [
       'CC header.o',
       'LD header',
     ]
-    lines = build_testdir
+    env.process
     lines.should == []
   end
 
   it "does not rebuild a C module when only the file's timestampe has changed" do
-    lines = test_dir('header')
+    test_dir('header')
+    env = Rscons::Environment.new do |env|
+      env.Program('header', Dir['*.c'])
+    end
     `./header`.should == "The value is 2\n"
     lines.should == [
       'CC header.o',
       'LD header',
     ]
     file_sub('header.c') {|line| line}
-    lines = build_testdir
+    env.process
     lines.should == []
   end
 
   it 're-links a program when the link flags have changed' do
-    lines = test_dir('simple')
+    test_dir('simple')
+    Rscons::Environment.new(echo: :command) do |env|
+      env.Program('simple', Dir['*.c'])
+    end
     lines.should == [
       'gcc -c -o simple.o -MMD -MF simple.mf simple.c',
       'gcc -o simple simple.o',
     ]
-    file_sub('build.rb') {|line| line.sub(/.*CHANGE.FLAGS.*/, '  env["LIBS"] += ["c"]')}
+    Rscons::Environment.new(echo: :command) do |env|
-    lines = build_testdir
+      env["LIBS"] += ["c"]
+      env.Program('simple', Dir['*.c'])
+    end
     lines.should == ['gcc -o simple simple.o -lc']
   end
 
   it 'builds object files in a different build directory' do
-    lines = test_dir('build_dir')
+    test_dir('build_dir')
+    Rscons::Environment.new do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
+      env.Program('build_dir', Dir['src/**/*.c'])
+    end
     `./build_dir`.should == "Hello from two()\n"
     File.exists?('build_one/one.o').should be_true
     File.exists?('build_two/two.o').should be_true
   end
 
+  it 'uses build directories before build root' do
+    test_dir('build_dir')
+    Rscons::Environment.new do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_dir("src", "build")
+      env.build_root = "build_root"
+      env.Program('build_dir', Dir['src/**/*.c'])
+    end
+    lines.should == ["CC build/one/one.o", "CC build/two/two.o", "LD build_dir"]
+  end
+
+  it 'uses build_root if no build directories match' do
+    test_dir('build_dir')
+    Rscons::Environment.new do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_dir("src2", "build")
+      env.build_root = "build_root"
+      env.Program('build_dir', Dir['src/**/*.c'])
+    end
+    lines.should == ["CC build_root/src/one/one.o", "CC build_root/src/two/two.o", "LD build_dir"]
+  end
+
+  it "expands target and source paths starting with ^/ to be relative to the build root" do
+    test_dir('build_dir')
+    Rscons::Environment.new(echo: :command) do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_root = "build_root"
+      FileUtils.mkdir_p(env.build_root)
+      FileUtils.mv("src/one/one.c", "build_root")
+      env.Object("^/one.o", "^/one.c")
+      env.Program('build_dir', Dir['src/**/*.c'] + ["^/one.o"])
+    end
+    lines.should == [
+      %q{gcc -c -o build_root/one.o -MMD -MF build_root/one.mf -Isrc/one/ -Isrc/two/ build_root/one.c},
+      %q{gcc -c -o build_root/src/two/two.o -MMD -MF build_root/src/two/two.mf -Isrc/one/ -Isrc/two/ src/two/two.c},
+      %q{gcc -o build_dir build_root/src/two/two.o build_root/one.o},
+    ]
+  end
+
   it 'cleans built files' do
-    lines = test_dir('build_dir')
+    test_dir('build_dir')
+    Rscons::Environment.new do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
+      env.Program('build_dir', Dir['src/**/*.c'])
+    end
     `./build_dir`.should == "Hello from two()\n"
     File.exists?('build_one/one.o').should be_true
     File.exists?('build_two/two.o').should be_true
@@ -148,7 +225,12 @@ EOF
   end
 
   it 'does not clean created directories if other non-rscons-generated files reside there' do
-    lines = test_dir('build_dir')
+    test_dir('build_dir')
+    Rscons::Environment.new do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
+      env.Program('build_dir', Dir['src/**/*.c'])
+    end
     `./build_dir`.should == "Hello from two()\n"
     File.exists?('build_one/one.o').should be_true
     File.exists?('build_two/two.o').should be_true
@@ -162,14 +244,78 @@ EOF
   end
 
   it 'allows Ruby classes as custom builders to be used to construct files' do
-    lines = test_dir('custom_builder')
+    test_dir('custom_builder')
+    class MySource < Rscons::Builder
+      def run(target, sources, cache, env, vars)
+        File.open(target, 'w') do |fh|
+          fh.puts <<EOF
+    #define THE_VALUE 5678
+EOF
+        end
+        target
+      end
+    end
+
+    Rscons::Environment.new do |env|
+      env.add_builder(MySource.new)
+      env.MySource('inc.h', [])
+      env.Program('program', Dir['*.c'])
+    end
+
     lines.should == ['CC program.o', 'LD program']
     File.exists?('inc.h').should be_true
     `./program`.should == "The value is 5678\n"
   end
 
+  it 'supports custom builders with multiple targets' do
+    test_dir('custom_builder')
+    class CHGen < Rscons::Builder
+      def run(target, sources, cache, env, vars)
+        c_fname = target
+        h_fname = target.sub(/\.c$/, ".h")
+        unless cache.up_to_date?([c_fname, h_fname], "", sources, env)
+          puts "CHGen #{c_fname}"
+          File.open(c_fname, "w") {|fh| fh.puts "int THE_VALUE = 42;"}
+          File.open(h_fname, "w") {|fh| fh.puts "extern int THE_VALUE;"}
+          cache.register_build([c_fname, h_fname], "", sources, env)
+        end
+        target
+      end
+    end
+
+    env = Rscons::Environment.new do |env|
+      env.add_builder(CHGen.new)
+      env.CHGen("inc.c", ["program.c"])
+      env.Program("program", Dir["*.c"] + ["inc.c"])
+    end
+
+    lines.should == ["CHGen inc.c", "CC program.o", "CC inc.o", "LD program"]
+    File.exists?("inc.c").should be_true
+    File.exists?("inc.h").should be_true
+    `./program`.should == "The value is 42\n"
+
+    File.open("inc.c", "w") {|fh| fh.puts "int THE_VALUE = 33;"}
+    env.process
+    lines.should == ["CHGen inc.c"]
+    `./program`.should == "The value is 42\n"
+  end
+
   it 'allows cloning Environment objects' do
-    lines = test_dir('clone_env')
+    test_dir('clone_env')
+
+    debug = Rscons::Environment.new(echo: :command) do |env|
+      env.build_dir('src', 'debug')
+      env['CFLAGS'] = '-O2'
+      env['CPPFLAGS'] = '-DSTRING="Debug Version"'
+      env.Program('program-debug', Dir['src/*.c'])
+    end
+
+    release = debug.clone do |env|
+      env["CPPFLAGS"] = '-DSTRING="Release Version"'
+      env.build_dir('src', 'release')
+      env.Program('program-release', Dir['src/*.c'])
+    end
+
     lines.should == [
       %q{gcc -c -o debug/program.o -MMD -MF debug/program.mf '-DSTRING="Debug Version"' -O2 src/program.c},
       %q{gcc -o program-debug debug/program.o},
@@ -178,14 +324,44 @@ EOF
     ]
   end
 
+  it 'allows cloning all attributes of an Environment object' do
+    test_dir('clone_env')
+
+    env1 = Rscons::Environment.new(echo: :command) do |env|
+      env.build_dir('src', 'build')
+      env['CFLAGS'] = '-O2'
+      env.add_build_hook do |build_op|
+        build_op[:vars]['CPPFLAGS'] = '-DSTRING="Hello"'
+      end
+      env.Program('program', Dir['src/*.c'])
+    end
+
+    env2 = env1.clone(clone: :all) do |env|
+      env.Program('program2', Dir['src/*.c'])
+    end
+
+    lines.should == [
+      %q{gcc -c -o build/program.o -MMD -MF build/program.mf -DSTRING="Hello" -O2 src/program.c},
+      %q{gcc -o program build/program.o},
+      %q{gcc -o program2 build/program.o},
+    ]
+  end
+
   it 'builds a C++ program with one source file' do
     test_dir('simple_cc')
+    Rscons::Environment.new do |env|
+      env.Program('simple', Dir['*.cc'])
+    end
     File.exists?('simple.o').should be_true
     `./simple`.should == "This is a simple C++ program\n"
   end
 
   it 'allows overriding construction variables for individual builder calls' do
-    lines = test_dir('two_sources')
+    test_dir('two_sources')
+    Rscons::Environment.new(echo: :command) do |env|
+      env.Object("one.o", "one.c", 'CPPFLAGS' => ['-DONE'])
+      env.Program('two_sources', ['one.o', 'two.c'])
+    end
     lines.should == [
       'gcc -c -o one.o -MMD -MF one.mf -DONE one.c',
       'gcc -c -o two.o -MMD -MF two.mf two.c',
@@ -196,7 +372,11 @@ EOF
   end
 
   it 'builds a static library archive' do
-    lines = test_dir('library')
+    test_dir('library')
+    Rscons::Environment.new(echo: :command) do |env|
+      env.Program('library', ['lib.a', 'three.c'])
+      env.Library("lib.a", ['one.c', 'two.c'], 'CPPFLAGS' => ['-Dmake_lib'])
+    end
     lines.should == [
       'gcc -c -o one.o -MMD -MF one.mf -Dmake_lib one.c',
       'gcc -c -o two.o -MMD -MF two.mf -Dmake_lib two.c',
@@ -208,13 +388,100 @@ EOF
     `ar t lib.a`.should == "one.o\ntwo.o\n"
   end
 
-  it 'supports tweakers to override construction variables' do
+  it 'supports build hooks to override construction variables' do
-    lines = test_dir("build_dir", "tweaker_build.rb")
+    test_dir("build_dir")
-    `./tweaker`.should == "Hello from two()\n"
+    Rscons::Environment.new(echo: :command) do |env|
+      env.append('CPPPATH' => Dir['src/**/*/'])
+      env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
+      env.add_build_hook do |build_op|
+        if build_op[:target] =~ %r{build_one/.*\.o}
+          build_op[:vars]["CFLAGS"] << "-O1"
+        elsif build_op[:target] =~ %r{build_two/.*\.o}
+          build_op[:vars]["CFLAGS"] << "-O2"
+        end
+      end
+      env.Program('build_hook', Dir['src/**/*.c'])
+    end
+    `./build_hook`.should == "Hello from two()\n"
     lines.should =~ [
       'gcc -c -o build_one/one.o -MMD -MF build_one/one.mf -Isrc/one/ -Isrc/two/ -O1 src/one/one.c',
       'gcc -c -o build_two/two.o -MMD -MF build_two/two.mf -Isrc/one/ -Isrc/two/ -O2 src/two/two.c',
-      'gcc -o tweaker build_one/one.o build_two/two.o',
+      'gcc -o build_hook build_one/one.o build_two/two.o',
     ]
   end
+
+  it 'rebuilds when user-specified dependencies change' do
+    test_dir('simple')
+    Rscons::Environment.new do |env|
+      env.Program('simple', Dir['*.c'])
+      File.open("file.ld", "w") do |fh|
+        fh.puts("foo")
+      end
+      env.depends('simple', 'file.ld')
+    end
+    lines.should == ["CC simple.o", "LD simple"]
+    File.exists?('simple.o').should be_true
+    `./simple`.should == "This is a simple C program\n"
+    Rscons::Environment.new do |env|
+      env.Program('simple', Dir['*.c'])
+      File.open("file.ld", "w") do |fh|
+        fh.puts("bar")
+      end
+      env.depends('simple', 'file.ld')
+    end
+    lines.should == ["LD simple"]
+    Rscons::Environment.new do |env|
+      env.Program('simple', Dir['*.c'])
+      File.unlink("file.ld")
+    end
+    lines.should == ["LD simple"]
+    Rscons::Environment.new do |env|
+      env.Program('simple', Dir['*.c'])
+    end
+    lines.should == []
+  end
+
+  unless ENV["omit_gdc_tests"]
+    it "supports building D sources" do
+      test_dir("d")
+      Rscons::Environment.new(echo: :command) do |env|
+        env.Program("hello-d", Dir["*.d"])
+      end
+      lines.should == [
+        "gdc -c -o main.o main.d",
+        "gdc -o hello-d main.o",
+      ]
+      `./hello-d`.rstrip.should == "Hello from D!"
+    end
+  end
+
+  it "supports disassembling object files" do
+    test_dir("simple")
+    Rscons::Environment.new do |env|
+      env.Object("simple.o", "simple.c")
+      env.Disassemble("simple.txt", "simple.o")
+    end
+    File.exists?("simple.txt").should be_true
+    File.read("simple.txt").should =~ /Disassembly of section .text:/
+  end
+
+  it "supports preprocessing C sources" do
+    test_dir("simple")
+    Rscons::Environment.new do |env|
+      env.Preprocess("simplepp.c", "simple.c")
+      env.Program("simple", "simplepp.c")
+    end
+    File.read("simplepp.c").should =~ /# \d+ "simple.c"/
+    `./simple`.should == "This is a simple C program\n"
+  end
+
+  it "supports preprocessing C++ sources" do
+    test_dir("simple_cc")
+    Rscons::Environment.new do |env|
+      env.Preprocess("simplepp.cc", "simple.cc")
+      env.Program("simple", "simplepp.cc")
+    end
+    File.read("simplepp.cc").should =~ /# \d+ "simple.cc"/
+    `./simple`.should == "This is a simple C++ program\n"
+  end
 end

spec/rscons/builders/cfile_spec.rb

@@ -0,0 +1,23 @@
+module Rscons
+  module Builders
+    describe CFile do
+      let(:env) {Environment.new}
+      subject {CFile.new}
+
+      it "invokes bison to create a .c file from a .y file" do
+        subject.should_receive(:standard_build).with("YACC parser.c", "parser.c", ["bison", "-d", "-o", "parser.c", "parser.y"], ["parser.y"], env, :cache)
+        subject.run("parser.c", ["parser.y"], :cache, env, {})
+      end
+
+      it "invokes a custom lexer to create a .cc file from a .ll file" do
+        env["LEX"] = "custom_lex"
+        subject.should_receive(:standard_build).with("LEX lexer.cc", "lexer.cc", ["custom_lex", "-o", "lexer.cc", "parser.ll"], ["parser.ll"], env, :cache)
+        subject.run("lexer.cc", ["parser.ll"], :cache, env, {})
+      end
+
+      it "raises an error when an unknown source file is specified" do
+        expect {subject.run("file.c", ["foo.bar"], :cache, env, {})}.to raise_error /Unknown source file .foo.bar. for CFile builder/
+      end
+    end
+  end
+end

spec/rscons/cache_spec.rb

@@ -0,0 +1,271 @@
+module Rscons
+  describe Cache do
+    before do
+      File.stub(:read) { nil }
+    end
+
+    def build_from(cache)
+      JSON.stub(:load) do
+        cache
+      end
+      Cache.instance.tap do |cache|
+        cache.send(:initialize!)
+      end
+    end
+
+    describe "#initialize" do
+      context "when corrupt" do
+        it "prints a warning and defaults to an empty hash" do
+          JSON.should_receive(:load).and_return("string")
+          $stderr.should_receive(:puts).with(/Warning:.*was.corrupt/)
+          c = Cache.instance
+          c.send(:initialize!)
+          c.instance_variable_get(:@cache).is_a?(Hash).should be_true
+        end
+      end
+    end
+
+    describe "#clear" do
+      it "removes the cache file" do
+        FileUtils.should_receive(:rm_f).with(Cache::CACHE_FILE)
+        JSON.stub(:load) {{}}
+        Cache.instance.clear
+      end
+    end
+
+    describe "#write" do
+      it "should fill in 'version' and write to file" do
+        cache = {}
+        fh = $stdout
+        fh.should_receive(:puts)
+        File.should_receive(:open).and_yield(fh)
+        build_from(cache).write
+        cache["version"].should == Rscons::VERSION
+      end
+    end
+
+    describe "#up_to_date?" do
+      empty_env = "env"
+      before do
+        empty_env.stub(:get_user_deps) { nil }
+      end
+
+      it "returns false when target file does not exist" do
+        File.should_receive(:exists?).with("target").and_return(false)
+        build_from({}).up_to_date?("target", "command", [], empty_env).should be_false
+      end
+
+      it "returns false when target is not registered in the cache" do
+        File.should_receive(:exists?).with("target").and_return(true)
+        build_from({}).up_to_date?("target", "command", [], empty_env).should be_false
+      end
+
+      it "returns false when the target's checksum does not match" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc"}}}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("def")
+        cache.up_to_date?("target", "command", [], empty_env).should be_false
+      end
+
+      it "returns false when the build command has changed" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc", "command" => Digest::MD5.hexdigest("old command".inspect)}}}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.up_to_date?("target", "command", [], empty_env).should be_false
+      end
+
+      it "returns false when there is a new dependency" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc",
+                                         "command" => Digest::MD5.hexdigest("command".inspect),
+                                         "deps" => [{"fname" => "dep.1"}]}}}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env).should be_false
+      end
+
+      it "returns false when a dependency's checksum has changed" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc",
+                                         "command" => Digest::MD5.hexdigest("command".inspect),
+                                         "deps" => [{"fname" => "dep.1",
+                                                 "checksum" => "dep.1.chk"},
+                                                {"fname" => "dep.2",
+                                                 "checksum" => "dep.2.chk"},
+                                                {"fname" => "extra.dep",
+                                                 "checksum" => "extra.dep.chk"}],
+                                         "user_deps" => []}}}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.should_receive(:calculate_checksum).with("dep.1").and_return("dep.1.chk")
+        cache.should_receive(:calculate_checksum).with("dep.2").and_return("dep.2.changed")
+        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env).should be_false
+      end
+
+      it "returns false with strict_deps=true when cache has an extra dependency" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc",
+                                         "command" => Digest::MD5.hexdigest("command".inspect),
+                                         "deps" => [{"fname" => "dep.1",
+                                                 "checksum" => "dep.1.chk"},
+                                                {"fname" => "dep.2",
+                                                 "checksum" => "dep.2.chk"},
+                                                {"fname" => "extra.dep",
+                                                 "checksum" => "extra.dep.chk"}],
+                                         "user_deps" => []}}}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env, strict_deps: true).should be_false
+      end
+
+      it "returns false when there is a new user dependency" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc",
+                                         "command" => Digest::MD5.hexdigest("command".inspect),
+                                         "deps" => [{"fname" => "dep.1"}],
+                                         "user_deps" => []}}}
+        cache = build_from(_cache)
+        env = "env"
+        env.should_receive(:get_user_deps).with("target").and_return(["file.ld"])
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.up_to_date?("target", "command", ["dep.1"], env).should be_false
+      end
+
+      it "returns false when a user dependency checksum has changed" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc",
+                                         "command" => Digest::MD5.hexdigest("command".inspect),
+                                         "deps" => [{"fname" => "dep.1",
+                                                 "checksum" => "dep.1.chk"},
+                                                {"fname" => "dep.2",
+                                                 "checksum" => "dep.2.chk"},
+                                                {"fname" => "extra.dep",
+                                                 "checksum" => "extra.dep.chk"}],
+                                         "user_deps" => [{"fname" => "user.dep",
+                                                      "checksum" => "user.dep.chk"}]}}}
+        cache = build_from(_cache)
+        env = "env"
+        env.should_receive(:get_user_deps).with("target").and_return(["user.dep"])
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.should_receive(:calculate_checksum).with("dep.1").and_return("dep.1.chk")
+        cache.should_receive(:calculate_checksum).with("dep.2").and_return("dep.2.chk")
+        cache.should_receive(:calculate_checksum).with("extra.dep").and_return("extra.dep.chk")
+        cache.should_receive(:calculate_checksum).with("user.dep").and_return("INCORRECT")
+        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], env).should be_false
+      end
+
+      it "returns true when no condition for false is met" do
+        _cache = {"targets" => {"target" => {"checksum" => "abc",
+                                         "command" => Digest::MD5.hexdigest("command".inspect),
+                                         "deps" => [{"fname" => "dep.1",
+                                                 "checksum" => "dep.1.chk"},
+                                                {"fname" => "dep.2",
+                                                 "checksum" => "dep.2.chk"},
+                                                {"fname" => "extra.dep",
+                                                 "checksum" => "extra.dep.chk"}],
+                                         "user_deps" => []}}}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("target").and_return(true)
+        cache.should_receive(:calculate_checksum).with("target").and_return("abc")
+        cache.should_receive(:calculate_checksum).with("dep.1").and_return("dep.1.chk")
+        cache.should_receive(:calculate_checksum).with("dep.2").and_return("dep.2.chk")
+        cache.should_receive(:calculate_checksum).with("extra.dep").and_return("extra.dep.chk")
+        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env).should be_true
+      end
+    end
+
+    describe "#register_build" do
+      it "stores the given information in the cache" do
+        _cache = {}
+        cache = build_from(_cache)
+        env = "env"
+        env.should_receive(:get_user_deps).with("the target").and_return(["user.dep"])
+        cache.should_receive(:calculate_checksum).with("the target").and_return("the checksum")
+        cache.should_receive(:calculate_checksum).with("dep 1").and_return("dep 1 checksum")
+        cache.should_receive(:calculate_checksum).with("dep 2").and_return("dep 2 checksum")
+        cache.should_receive(:calculate_checksum).with("user.dep").and_return("user.dep checksum")
+        cache.register_build("the target", "the command", ["dep 1", "dep 2"], env)
+        cached_target = cache.instance_variable_get(:@cache)["targets"]["the target"]
+        cached_target.should_not be_nil
+        cached_target["command"].should == Digest::MD5.hexdigest("the command".inspect)
+        cached_target["checksum"].should == "the checksum"
+        cached_target["deps"].should == [
+          {"fname" => "dep 1", "checksum" => "dep 1 checksum"},
+          {"fname" => "dep 2", "checksum" => "dep 2 checksum"},
+        ]
+        cached_target["user_deps"].should == [
+          {"fname" => "user.dep", "checksum" => "user.dep checksum"},
+        ]
+      end
+    end
+
+    describe "#targets" do
+      it "returns a list of targets that are cached" do
+        cache = {"targets" => {"t1" => {}, "t2" => {}, "t3" => {}}}
+        build_from(cache).targets.should == ["t1", "t2", "t3"]
+      end
+    end
+
+    describe "#mkdir_p" do
+      it "makes directories and records any created in the cache" do
+        _cache = {}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("one").and_return(true)
+        File.should_receive(:exists?).with("one/two").and_return(false)
+        FileUtils.should_receive(:mkdir).with("one/two")
+        File.should_receive(:exists?).with("one/two/three").and_return(false)
+        FileUtils.should_receive(:mkdir).with("one/two/three")
+        File.should_receive(:exists?).with("one").and_return(true)
+        File.should_receive(:exists?).with("one/two").and_return(true)
+        File.should_receive(:exists?).with("one/two/four").and_return(false)
+        FileUtils.should_receive(:mkdir).with("one/two/four")
+        cache.mkdir_p("one/two/three")
+        cache.mkdir_p("one\\two\\four")
+        cache.directories.should == ["one/two", "one/two/three", "one/two/four"]
+      end
+
+      it "handles absolute paths" do
+        _cache = {}
+        cache = build_from(_cache)
+        File.should_receive(:exists?).with("/one").and_return(true)
+        File.should_receive(:exists?).with("/one/two").and_return(false)
+        FileUtils.should_receive(:mkdir).with("/one/two")
+        cache.mkdir_p("/one/two")
+        cache.directories.should == ["/one/two"]
+      end
+    end
+
+    describe "#directories" do
+      it "returns a list of directories that are cached" do
+        _cache = {"directories" => {"dir1" => true, "dir2" => true}}
+        build_from(_cache).directories.should == ["dir1", "dir2"]
+      end
+    end
+
+    describe "#lookup_checksum" do
+      it "does not re-calculate the checksum when it is already cached" do
+        cache = build_from({})
+        cache.instance_variable_set(:@lookup_checksums, {"f1" => "f1.chk"})
+        cache.should_not_receive(:calculate_checksum)
+        cache.send(:lookup_checksum, "f1").should == "f1.chk"
+      end
+
+      it "calls calculate_checksum when the checksum is not cached" do
+        cache = build_from({})
+        cache.should_receive(:calculate_checksum).with("f1").and_return("ck")
+        cache.send(:lookup_checksum, "f1").should == "ck"
+      end
+    end
+
+    describe "#calculate_checksum" do
+      it "calculates the MD5 of the file contents" do
+        contents = "contents"
+        File.should_receive(:read).with("fname", mode: "rb").and_return(contents)
+        Digest::MD5.should_receive(:hexdigest).with(contents).and_return("the_checksum")
+        build_from({}).send(:calculate_checksum, "fname").should == "the_checksum"
+      end
+    end
+  end
+end

spec/rscons/environment_spec.rb

@@ -1,6 +1,30 @@
 module Rscons
   describe Environment do
-    describe '.clone' do
+    describe "#initialize" do
+      it "adds the default builders when they are not excluded" do
+        env = Environment.new
+        env.builders.size.should be > 0
+        env.builders.map {|name, builder| builder.is_a?(Builder)}.all?.should be_true
+        env.builders.find {|name, builder| name == "Object"}.should_not be_nil
+        env.builders.find {|name, builder| name == "Program"}.should_not be_nil
+        env.builders.find {|name, builder| name == "Library"}.should_not be_nil
+      end
+
+      it "excludes the default builders with exclude_builders: :all" do
+        env = Environment.new(exclude_builders: true)
+        env.builders.size.should == 0
+      end
+
+      context "when a block is given" do
+        it "yields self and invokes #process()" do
+          env = Environment.new do |env|
+            env.should_receive(:process)
+          end
+        end
+      end
+    end
+
+    describe "#clone" do
       it 'should create unique copies of each construction variable' do
         env = Environment.new
         env["CPPPATH"] << "path1"
@@ -9,15 +33,317 @@ module Rscons
         env["CPPPATH"].should == ["path1"]
         env2["CPPPATH"].should == ["path1", "path2"]
       end
+
+      context "when a block is given" do
+        it "yields self and invokes #process()" do
+          env = Environment.new
+          env.clone do |env2|
+            env2.should_receive(:process)
+          end
+        end
+      end
     end
 
-    describe '.parse_makefile_deps' do
+    describe "#add_builder" do
+      it "adds the builder to the list of builders" do
+        env = Environment.new(exclude_builders: true)
+        env.builders.keys.should == []
+        env.add_builder(Rscons::Builders::Object.new)
+        env.builders.keys.should == ["Object"]
+      end
+    end
+
+    describe "#get_build_fname" do
+      context "with no build directories" do
+        it "returns the name of the source file with suffix changed" do
+          env = Environment.new
+          env.get_build_fname("src/dir/file.c", ".o").should == "src/dir/file.o"
+          env.get_build_fname("src\\dir\\other.d", ".a").should == "src/dir/other.a"
+          env.get_build_fname("source.cc", ".o").should == "source.o"
+        end
+
+        context "with a build_root" do
+          it "uses the build_root unless the path is absolute" do
+            env = Environment.new
+            env.build_root = "build/proj"
+            env.get_build_fname("src/dir/file.c", ".o").should == "build/proj/src/dir/file.o"
+            env.get_build_fname("/some/lib.c", ".a").should == "/some/lib.a"
+            env.get_build_fname("C:\\abspath\\mod.cc", ".o").should == "C:/abspath/mod.o"
+            env.get_build_fname("build\\proj\\generated.c", ".o").should == "build/proj/generated.o"
+            env.get_build_fname("build/proj.XX", ".yy").should == "build/proj/build/proj.yy"
+          end
+        end
+      end
+
+      context "with build directories" do
+        it "uses the build directories to create the output file name" do
+          env = Environment.new
+          env.build_dir("src", "bld")
+          env.build_dir(%r{^libs/([^/]+)}, 'build/libs/\1')
+          env.get_build_fname("src/input.cc", ".o").should == "bld/input.o"
+          env.get_build_fname("libs/lib1/some/file.c", ".o").should == "build/libs/lib1/some/file.o"
+          env.get_build_fname("libs/otherlib/otherlib.cc", ".o").should == "build/libs/otherlib/otherlib.o"
+          env.get_build_fname("other_directory/o.d", ".a").should == "other_directory/o.a"
+        end
+
+        context "with a build_root" do
+          it "uses the build_root unless a build directory matches or the path is absolute" do
+            env = Environment.new
+            env.build_dir("src", "bld")
+            env.build_dir(%r{^libs/([^/]+)}, 'build/libs/\1')
+            env.build_root = "bldit"
+
+            env.get_build_fname("src/input.cc", ".o").should == "bld/input.o"
+            env.get_build_fname("libs/lib1/some/file.c", ".o").should == "build/libs/lib1/some/file.o"
+            env.get_build_fname("libs/otherlib/otherlib.cc", ".o").should == "build/libs/otherlib/otherlib.o"
+            env.get_build_fname("other_directory/o.d", ".a").should == "bldit/other_directory/o.a"
+            env.get_build_fname("bldit/some/mod.d", ".a").should == "bldit/some/mod.a"
+          end
+        end
+      end
+    end
+
+    describe "#[]" do
+      it "allows reading construction variables" do
+        env = Environment.new
+        env["CFLAGS"] = ["-g", "-Wall"]
+        env["CFLAGS"].should == ["-g", "-Wall"]
+      end
+    end
+
+    describe "#[]=" do
+      it "allows writing construction variables" do
+        env = Environment.new
+        env["CFLAGS"] = ["-g", "-Wall"]
+        env["CFLAGS"] -= ["-g"]
+        env["CFLAGS"] += ["-O3"]
+        env["CFLAGS"].should == ["-Wall", "-O3"]
+        env["other_var"] = "val33"
+        env["other_var"].should == "val33"
+      end
+    end
+
+    describe "#append" do
+      it "allows adding many construction variables at once" do
+        env = Environment.new
+        env["CFLAGS"] = ["-g"]
+        env["CPPPATH"] = ["inc"]
+        env.append("CFLAGS" => ["-Wall"], "CPPPATH" => ["include"])
+        env["CFLAGS"].should == ["-Wall"]
+        env["CPPPATH"].should == ["include"]
+      end
+    end
+
+    describe "#process" do
+      it "runs builders for all of the targets specified" do
+        env = Environment.new
+        env.Program("a.out", "main.c")
+
+        cache = "cache"
+        Cache.should_receive(:instance).and_return(cache)
+        cache.should_receive(:clear_checksum_cache!)
+        env.should_receive(:run_builder).with(anything, "a.out", ["main.c"], cache, {}).and_return(true)
+        cache.should_receive(:write)
+
+        env.process
+      end
+
+      it "builds dependent targets first" do
+        env = Environment.new
+        env.Program("a.out", "main.o")
+        env.Object("main.o", "other.cc")
+
+        cache = "cache"
+        Cache.should_receive(:instance).and_return(cache)
+        cache.should_receive(:clear_checksum_cache!)
+        env.should_receive(:run_builder).with(anything, "main.o", ["other.cc"], cache, {}).and_return("main.o")
+        env.should_receive(:run_builder).with(anything, "a.out", ["main.o"], cache, {}).and_return("a.out")
+        cache.should_receive(:write)
+
+        env.process
+      end
+
+      it "raises a BuildError when building fails" do
+        env = Environment.new
+        env.Program("a.out", "main.o")
+        env.Object("main.o", "other.cc")
+
+        cache = "cache"
+        Cache.should_receive(:instance).and_return(cache)
+        cache.should_receive(:clear_checksum_cache!)
+        env.should_receive(:run_builder).with(anything, "main.o", ["other.cc"], cache, {}).and_return(false)
+        cache.should_receive(:write)
+
+        expect { env.process }.to raise_error BuildError, /Failed.to.build.main.o/
+      end
+
+      it "writes the cache when the Builder raises an exception" do
+        env = Environment.new
+        env.Object("module.o", "module.c")
+
+        cache = "cache"
+        Cache.should_receive(:instance).and_return(cache)
+        cache.should_receive(:clear_checksum_cache!)
+        env.stub(:run_builder) do |builder, target, sources, cache, vars|
+          raise "Ruby exception thrown by builder"
+        end
+        cache.should_receive(:write)
+
+        expect { env.process }.to raise_error RuntimeError, /Ruby exception thrown by builder/
+      end
+    end
+
+    describe "#clear_targets" do
+      it "resets @targets to an empty hash" do
+        env = Environment.new
+        env.Program("a.out", "main.o")
+        expect(env.instance_variable_get(:@targets).keys).to eq(["a.out"])
+
+        env.clear_targets
+
+        expect(env.instance_variable_get(:@targets).keys).to eq([])
+      end
+    end
+
+    describe "#build_command" do
+      it "returns a command based on the variables in the Environment" do
+        env = Environment.new
+        env["path"] = ["dir1", "dir2"]
+        env["flags"] = ["-x", "-y", "${specialflag}"]
+        env["specialflag"] = "-z"
+        template = ["cmd", "-I${path}", "${flags}", "${_source}", "${_dest}"]
+        cmd = env.build_command(template, "_source" => "infile", "_dest" => "outfile")
+        cmd.should == ["cmd", "-Idir1", "-Idir2", "-x", "-y", "-z", "infile", "outfile"]
+      end
+    end
+
+    describe "#expand_varref" do
+      it "returns the fully expanded variable reference" do
+        env = Environment.new
+        env["path"] = ["dir1", "dir2"]
+        env["flags"] = ["-x", "-y", "${specialflag}"]
+        env["specialflag"] = "-z"
+        env.expand_varref(["-p${path}", "${flags}"]).should == ["-pdir1", "-pdir2", "-x", "-y", "-z"]
+        env.expand_varref("foo").should == "foo"
+        expect {env.expand_varref("${foo}")}.to raise_error /expand.a.variable.reference/
+        env.expand_varref("${specialflag}").should == "-z"
+        env.expand_varref("${path}").should == ["dir1", "dir2"]
+      end
+    end
+
+    describe "#execute" do
+      context "with echo: :short" do
+        context "with no errors" do
+          it "prints the short description and executes the command" do
+            env = Environment.new(echo: :short)
+            env.should_receive(:puts).with("short desc")
+            env.should_receive(:system).with("a", "command").and_return(true)
+            env.execute("short desc", ["a", "command"])
+          end
+        end
+
+        context "with errors" do
+          it "prints the short description, executes the command, and prints the failed command line" do
+            env = Environment.new(echo: :short)
+            env.should_receive(:puts).with("short desc")
+            env.should_receive(:system).with("a", "command").and_return(false)
+            $stdout.should_receive(:write).with("Failed command was: ")
+            env.should_receive(:puts).with("a command")
+            env.execute("short desc", ["a", "command"])
+          end
+        end
+      end
+
+      context "with echo: :command" do
+        it "prints the command executed and executes the command" do
+          env = Environment.new(echo: :command)
+          env.should_receive(:puts).with("a command '--arg=val with spaces'")
+          env.should_receive(:system).with({modified: :environment}, "a", "command", "--arg=val with spaces", {opt: :val}).and_return(false)
+          env.execute("short desc", ["a", "command", "--arg=val with spaces"], env: {modified: :environment}, options: {opt: :val})
+        end
+      end
+    end
+
+    describe "#method_missing" do
+      it "calls the original method missing when the target method is not a known builder" do
+        env = Environment.new
+        expect {env.foobar}.to raise_error /undefined method .foobar./
+      end
+
+      it "records the target when the target method is a known builder" do
+        env = Environment.new
+        env.instance_variable_get(:@targets).should == {}
+        env.Program("target", ["src1", "src2"], var: "val")
+        target = env.instance_variable_get(:@targets)["target"]
+        target.should_not be_nil
+        target[:builder].is_a?(Builder).should be_true
+        target[:sources].should == ["src1", "src2"]
+        target[:vars].should == {var: "val"}
+        target[:args].should == []
+      end
+
+      it "raises an error when vars is not a Hash" do
+        env = Environment.new
+        expect { env.Program("a.out", "main.c", "other") }.to raise_error /Unexpected construction variable set/
+      end
+    end
+
+    describe "#depends" do
+      it "records the given dependencies in @user_deps" do
+        env = Environment.new
+        env.depends("foo", "bar", "baz")
+        env.instance_variable_get(:@user_deps).should == {"foo" => ["bar", "baz"]}
+      end
+      it "records user dependencies only once" do
+        env = Environment.new
+        env.instance_variable_set(:@user_deps, {"foo" => ["bar"]})
+        env.depends("foo", "bar", "baz")
+        env.instance_variable_get(:@user_deps).should == {"foo" => ["bar", "baz"]}
+      end
+    end
+
+    describe "#build_sources" do
+      class ABuilder < Builder
+        def produces?(target, source, env)
+          target =~ /\.ab_out$/ and source =~ /\.ab_in$/
+        end
+      end
+
+      it "finds and invokes a builder to produce output files with the requested suffixes" do
+        cache = "cache"
+        env = Environment.new
+        env.add_builder(ABuilder.new)
+        env.builders["Object"].should_receive(:run).with("mod.o", ["mod.c"], cache, env, anything).and_return("mod.o")
+        env.builders["ABuilder"].should_receive(:run).with("mod2.ab_out", ["mod2.ab_in"], cache, env, anything).and_return("mod2.ab_out")
+        env.build_sources(["precompiled.o", "mod.c", "mod2.ab_in"], [".o", ".ab_out"], cache, {}).should == ["precompiled.o", "mod.o", "mod2.ab_out"]
+      end
+    end
+
+    describe "#run_builder" do
+      it "modifies the construction variables using given build hooks and invokes the builder" do
+        env = Environment.new
+        env.add_build_hook do |build_op|
+          if build_op[:sources].first =~ %r{src/special}
+            build_op[:vars]["CFLAGS"] += ["-O3", "-DSPECIAL"]
+          end
+        end
+        env.builders["Object"].stub(:run) do |target, sources, cache, env, vars|
+          vars["CFLAGS"].should == []
+        end
+        env.run_builder(env.builders["Object"], "build/normal/module.o", ["src/normal/module.c"], "cache", {})
+        env.builders["Object"].stub(:run) do |target, sources, cache, env, vars|
+          vars["CFLAGS"].should == ["-O3", "-DSPECIAL"]
+        end
+        env.run_builder(env.builders["Object"], "build/special/module.o", ["src/special/module.c"], "cache", {})
+      end
+    end
+
+    describe ".parse_makefile_deps" do
       it 'handles dependencies on one line' do
         File.should_receive(:read).with('makefile').and_return(<<EOS)
 module.o: source.cc
 EOS
-        env = Environment.new
+        Environment.parse_makefile_deps('makefile', 'module.o').should == ['source.cc']
-        env.parse_makefile_deps('makefile', 'module.o').should == ['source.cc']
       end
 
       it 'handles dependencies split across many lines' do
@@ -26,8 +352,7 @@ module.o: module.c \\
   module.h \\
   other.h
 EOS
-        env = Environment.new
+        Environment.parse_makefile_deps('makefile', 'module.o').should == [
-        env.parse_makefile_deps('makefile', 'module.o').should == [
           'module.c', 'module.h', 'other.h']
       end
     end

spec/rscons/monkey/module_spec.rb

@@ -1,6 +0,0 @@
-describe "Module#short_name" do
-  it "returns the inner name of the module" do
-    Rscons::Environment.short_name.should == "Environment"
-    Rscons::Object.short_name.should == "Object"
-  end
-end

spec/rscons/varset_spec.rb

@@ -1,6 +1,6 @@
 module Rscons
   describe VarSet do
-    describe '.initialize' do
+    describe '#initialize' do
       it "initializes variables from a Hash" do
         v = VarSet.new({"one" => 1, "two" => :two})
         v["one"].should == 1
@@ -20,25 +20,19 @@ module Rscons
       end
     end
 
-    describe :[] do
+    describe "#[]" do
+      it "allows accessing a variable with its verbatim value if type is not specified" do
         v = VarSet.new({"fuz" => "a string", "foo" => 42, "bar" => :baz,
                         "qax" => [3, 6], "qux" => {a: :b}})
-      it "allows accessing a variable with its verbatim value if type is not specified" do
         v["fuz"].should == "a string"
         v["foo"].should == 42
         v["bar"].should == :baz
         v["qax"].should == [3, 6]
         v["qux"].should == {a: :b}
       end
-      it "allows accessing a non-array converted to an array" do
-        v["fuz", :array].should == ["a string"]
-      end
-      it "allows accessing an array as a single value" do
-        v["qax", :scalar].should == 3
-      end
     end
 
-    describe :[]= do
+    describe "#[]=" do
       it "allows assigning to variables" do
         v = VarSet.new("CFLAGS" => ["-Wall", "-O3"])
         v["CPPPATH"] = ["one", "two"]
@@ -47,67 +41,118 @@ module Rscons
       end
     end
 
-    describe '.append' do
+    describe "#include?" do
+      it "returns whether the variable is in the VarSet" do
+        v = VarSet.new("CFLAGS" => [], :foo => :bar)
+
+        expect(v.include?("CFLAGS")).to be_true
+        expect(v.include?(:CFLAGS)).to be_false
+        expect(v.include?(:foo)).to be_true
+        expect(v.include?("foo")).to be_false
+        expect(v.include?("bar")).to be_false
+
+        v2 = v.clone
+        v2.append("bar" => [])
+
+        expect(v2.include?("CFLAGS")).to be_true
+        expect(v2.include?(:CFLAGS)).to be_false
+        expect(v2.include?(:foo)).to be_true
+        expect(v2.include?("foo")).to be_false
+        expect(v2.include?("bar")).to be_true
+      end
+    end
+
+    describe '#append' do
       it "adds values from a Hash to the VarSet" do
         v = VarSet.new("LDFLAGS" => "-lgcc")
         v.append("LIBS" => "gcc", "LIBPATH" => ["mylibs"])
-        v.vars.keys.should =~ ["LDFLAGS", "LIBS", "LIBPATH"]
+        expect(v["LDFLAGS"]).to eq("-lgcc")
+        expect(v["LIBS"]).to eq("gcc")
+        expect(v["LIBPATH"]).to eq(["mylibs"])
       end
+
       it "adds values from another VarSet to the VarSet" do
         v = VarSet.new("CPPPATH" => ["mydir"])
         v2 = VarSet.new("CFLAGS" => ["-O0"], "CPPPATH" => ["different_dir"])
         v.append(v2)
-        v.vars.keys.should =~ ["CPPPATH", "CFLAGS"]
+        expect(v["CFLAGS"]).to eq(["-O0"])
-        v["CPPPATH"].should == ["different_dir"]
+        expect(v["CPPPATH"]).to eq(["different_dir"])
+      end
+
+      it "does not pick up subsequent variable changes from a given VarSet" do
+        v = VarSet.new("dirs" => ["a"])
+        v2 = VarSet.new
+        v2.append(v)
+        v["dirs"] << "b"
+        expect(v["dirs"]).to eq(["a", "b"])
+        expect(v2["dirs"]).to eq(["a"])
       end
     end
 
-    describe '.merge' do
+    describe '#merge' do
       it "returns a new VarSet merged with the given Hash" do
         v = VarSet.new("foo" => "yoda")
         v2 = v.merge("baz" => "qux")
-        v.vars.keys.should == ["foo"]
+        expect(v["foo"]).to eq("yoda")
-        v2.vars.keys.should =~ ["foo", "baz"]
+        expect(v2["foo"]).to eq("yoda")
+        expect(v2["baz"]).to eq("qux")
       end
+
       it "returns a new VarSet merged with the given VarSet" do
         v = VarSet.new("foo" => ["a", "b"], "bar" => 42)
         v2 = v.merge(VarSet.new("bar" => 33, "baz" => :baz))
         v2["foo"] << "c"
-        v["foo"].should == ["a", "b"]
+        expect(v["foo"]).to eq ["a", "b"]
-        v["bar"].should == 42
+        expect(v["bar"]).to eq 42
-        v2["foo"].should == ["a", "b", "c"]
+        expect(v2["foo"]).to eq ["a", "b", "c"]
-        v2["bar"].should == 33
+        expect(v2["bar"]).to eq 33
+      end
+
+      it "does not pick up subsequent variable changes from a given VarSet" do
+        v = VarSet.new("var" => ["a", "b"], "var2" => ["1", "2"])
+        v["var2"] << "3"
+        v2 = v.clone
+        v["var"] << "c"
+        expect(v["var"]).to eq(["a", "b", "c"])
+        expect(v["var2"]).to eq(["1", "2", "3"])
+        expect(v2["var"]).to eq(["a", "b"])
+        expect(v2["var2"]).to eq(["1", "2", "3"])
       end
     end
 
-    describe '.expand_varref' do
+    describe '#expand_varref' do
       v = VarSet.new("CFLAGS" => ["-Wall", "-O2"],
                      "CC" => "gcc",
                      "CPPPATH" => ["dir1", "dir2"],
-                     "compiler" => "$CC",
+                     "compiler" => "${CC}",
-                     "cmd" => ["$CC", "-c", "$CFLAGS", "-I$[CPPPATH]"])
+                     "cmd" => ["${CC}", "-c", "${CFLAGS}", "-I${CPPPATH}"])
       it "expands to the string itself if the string is not a variable reference" do
         v.expand_varref("CC").should == "CC"
         v.expand_varref("CPPPATH").should == "CPPPATH"
         v.expand_varref("str").should == "str"
       end
       it "expands a single variable reference beginning with a '$'" do
-        v.expand_varref("$CC").should == "gcc"
+        v.expand_varref("${CC}").should == "gcc"
-        v.expand_varref("$CPPPATH").should == ["dir1", "dir2"]
+        v.expand_varref("${CPPPATH}").should == ["dir1", "dir2"]
       end
-      it "expands a single variable reference in $[arr] notation" do
+      it "expands a single variable reference in ${arr} notation" do
-        v.expand_varref("prefix$[CFLAGS]suffix").should == ["prefix-Wallsuffix", "prefix-O2suffix"]
+        v.expand_varref("prefix${CFLAGS}suffix").should == ["prefix-Wallsuffix", "prefix-O2suffix"]
         v.expand_varref(v["cmd"]).should == ["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"]
       end
       it "expands a variable reference recursively" do
-        v.expand_varref("$compiler").should == "gcc"
+        v.expand_varref("${compiler}").should == "gcc"
-        v.expand_varref("$cmd").should == ["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"]
+        v.expand_varref("${cmd}").should == ["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"]
       end
-      it "raises an error when array notation is applied to a non-array variable" do
+      it "resolves multiple variable references in one element by enumerating all combinations" do
-        expect { v.expand_varref("$[CC]") }.to raise_error /Array.expected/
+        v.expand_varref("cflag: ${CFLAGS}, cpppath: ${CPPPATH}, compiler: ${compiler}").should == [
+          "cflag: -Wall, cpppath: dir1, compiler: gcc",
+          "cflag: -O2, cpppath: dir1, compiler: gcc",
+          "cflag: -Wall, cpppath: dir2, compiler: gcc",
+          "cflag: -O2, cpppath: dir2, compiler: gcc",
+        ]
       end
       it "raises an error when a variable reference refers to a non-existent variable" do
-        expect { v.expand_varref("$not_here") }.to raise_error /Could.not.find.variable..not_here/
+        expect { v.expand_varref("${not_here}") }.to raise_error /I do not know how to expand a variable reference to a NilClass/
       end
     end
   end

spec/rscons_spec.rb

@@ -0,0 +1,26 @@
+describe Rscons do
+  describe ".clean" do
+    it "removes all build targets and created directories" do
+      cache = "cache"
+      Rscons::Cache.should_receive(:instance).and_return(cache)
+      cache.should_receive(:targets).and_return(["build/a.out", "build/main.o"])
+      FileUtils.should_receive(:rm_f).with("build/a.out")
+      FileUtils.should_receive(:rm_f).with("build/main.o")
+      cache.should_receive(:directories).and_return(["build/one", "build/one/two", "build", "other"])
+      File.should_receive(:directory?).with("build/one/two").and_return(true)
+      Dir.should_receive(:entries).with("build/one/two").and_return([".", ".."])
+      Dir.should_receive(:rmdir).with("build/one/two")
+      File.should_receive(:directory?).with("build/one").and_return(true)
+      Dir.should_receive(:entries).with("build/one").and_return([".", ".."])
+      Dir.should_receive(:rmdir).with("build/one")
+      File.should_receive(:directory?).with("build").and_return(true)
+      Dir.should_receive(:entries).with("build").and_return([".", ".."])
+      Dir.should_receive(:rmdir).with("build")
+      File.should_receive(:directory?).with("other").and_return(true)
+      Dir.should_receive(:entries).with("other").and_return([".", "..", "other.file"])
+      cache.should_receive(:clear)
+
+      Rscons.clean
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,5 +1,7 @@
 require "simplecov"
 
-SimpleCov.start
+SimpleCov.start do
+  add_filter "/spec/"
+end
 
 require "rscons"