v1.9.0

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    rscons (1.7.0)
+    rscons (1.9.0)
       json (~> 1.0)
 
 GEM
@@ -12,6 +12,8 @@ GEM
     json (1.8.1)
     multi_json (1.10.1)
     rake (10.3.2)
+    rdoc (4.1.2)
+      json (~> 1.4)
     redcarpet (3.1.2)
     rspec (3.0.0)
       rspec-core (~> 3.0.0)
@@ -38,6 +40,7 @@ PLATFORMS
 
 DEPENDENCIES
   rake
+  rdoc
   redcarpet
   rscons!
   rspec

README.md

@@ -1,6 +1,7 @@
 # Rscons
 
-Software construction library inspired by SCons and implemented in Ruby
+Rscons is a software construction framework inspired by SCons and implemented
+in Ruby.
 
 [![Gem Version](https://badge.fury.io/rb/rscons.png)](http://badge.fury.io/rb/rscons)
 
@@ -20,9 +21,10 @@ Or install it yourself as:
 
 ## Usage
 
-Rscons is a Ruby library.
-It can be called from a standalone Ruby script or it can be used with rake and
-called from your Rakefile.
+Rscons is implemented as a Ruby library and distributed as a gem.
+It also provides a "rscons" executable which can evaluate a build script (by
+default named Rsconsfile or Rsconsfile.rb).
+It can also be used from rake or from a standalone Ruby script.
 
 ### Example: Building a C Program
 
@@ -154,6 +156,31 @@ Rscons::Environment.new do |env|
 end
 ```
 
+### Example: Custom Builder Using Environment#add_builder()
+
+The `add_builder` method of the `Rscons::Environment` class optionally allows
+you to define and register a builder by providing a name and action block. This
+can be useful if the builder you are trying to define is easily expressed as a
+short ruby procedure. When `add_builder` is called in this manner a new builder
+will be registered with the environment with the given name. When this builder
+is used it will call the provided block in order to build the target.
+
+```ruby
+Rscons::Environment.new do |env|
+  env.add_builder(:JsonToYaml) do |target, sources, cache, env, vars|
+    unless cache.up_to_date?(target, :JsonToYaml, sources, env)
+      cache.mkdir_p(File.dirname(target))
+      File.open(target, 'w') do |f|
+        f.write(YAML.dump(JSON.load(IO.read(sources.first))))
+      end
+      cache.register_build(target, :JsonToYaml, sources, env)
+    end
+    target
+  end
+  env.JsonToYaml('foo.yml','foo.json')
+end
+```
+
 ### Example: Using different compilation flags for some sources
 
 ```ruby
@@ -210,16 +237,32 @@ end
 
 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
+* Command, which executes a user-defined command to produce the target.
+* Copy, which is identical to Install.
+* 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.
+* Install, which installs files or directories to a specified destination.
+* 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.
 
+#### Command
+
+```ruby
+env.Command(target, sources, "CMD" => command)
+# Example
+env.Command("docs.html", "docs.md",
+    "CMD" => ["pandoc", "-fmarkdown", "-thtml", "-o${_TARGET}", "${_SOURCES}"],
+    "CMD_DESC" => "PANDOC")
+```
+
+The command builder executes a user-defined command in order to produce the
+desired target file based on the provided source files.
+
 #### CFile
 
 ```ruby
@@ -242,6 +285,15 @@ env.Disassemble("module.dis", "module.o")
 The Disassemble builder generates a disassembly listing using objdump from
 and object file.
 
+#### Install
+
+```ruby
+env.Install(destination, sources)
+# Example
+env.Install("dist/bin", "app.exe")
+env.Install("dist/share", "share")
+```
+
 #### Library
 
 ```ruby
@@ -333,6 +385,15 @@ Post-build hooks are only invoked if the build operation was a success.
 Post-build hooks can invoke commands using the newly-built files, or register
 new build targets.
 
+### Phony Targets
+
+A build target name given as a Symbol instead of a String is interpreted as a
+"phony" target.
+Phony targets operate similarly to normal build targets, except that a file is
+not expected to be produced by the builder.
+Phony targets will still be "rebuilt" if any source or the command is out of
+date.
+
 ### Construction Variable Naming
 
 * uppercase strings - the default construction variables that Rscons uses
@@ -345,6 +406,36 @@ http://rubydoc.info/github/holtrop/rscons/frames.
 
 ## Release Notes
 
+### v1.9.0
+
+#### New Features
+
+- #6 - add Install and Copy builders
+- #22 - allow overriding Command builder short description with CMD_DESC variable
+- #24 - add "rscons" executable
+- #25 - add support for phony targets given as Symbols instead of Strings
+- #26 - support registering multiple build targets with the same target name
+- #27 - add Directory builder
+
+#### Fixes
+
+- #20 - fix variable references that expand to arrays in build target sources
+- #21 - rework Preprocess builder to consider deep dependencies
+- fix Rscons.set_suffix to append the given suffix if the filename has none
+- remove ${CFLAGS} from default CPP_CMD
+
+### v1.8.1
+
+- fix Environment#dump when construction variables are symbols
+
+### v1.8.0
+
+- new Command builder to execute arbitrary user commands
+- new SimpleBuilder class
+  - create new builders quickly by passing a block to Environment#add_builder
+- improved YARD documentation
+- add Environment#dump to debug Environment construction variables
+
 ### v1.7.0
 
 - allow build hooks to register new build targets

Rakefile.rb

@@ -13,7 +13,11 @@ require "rake/clean"
 CLEAN.include %w[build_test_run .yardoc doc coverage]
 CLOBBER.include %w[pkg]
 
-RSpec::Core::RakeTask.new(:spec)
+RSpec::Core::RakeTask.new(:spec, :example_string) do |task, args|
+  if args.example_string
+    task.rspec_opts = %W[-e "#{args.example_string}" -f documentation]
+  end
+end
 
 YARD::Rake::YardocTask.new do |yard|
   yard.files = ['lib/**/*.rb']

bin/rscons

@@ -0,0 +1,3 @@
+require "rscons/cli"
+
+Rscons::Cli.run(ARGV)

build_tests/json_to_yaml/foo.json

@@ -0,0 +1 @@
+{ "key": "value" }

build_tests/preprocess/bar.h

@@ -0,0 +1 @@
+#define BAR xyz42abc

build_tests/preprocess/foo.h

@@ -0,0 +1,2 @@
+#include "bar.h"
+BAR

lib/rscons.rb

@@ -7,19 +7,28 @@ require_relative "rscons/version"
 
 # default builders
 require_relative "rscons/builders/cfile"
+require_relative "rscons/builders/command"
+require_relative "rscons/builders/directory"
 require_relative "rscons/builders/disassemble"
+require_relative "rscons/builders/install"
 require_relative "rscons/builders/library"
 require_relative "rscons/builders/object"
 require_relative "rscons/builders/preprocess"
 require_relative "rscons/builders/program"
+require_relative "rscons/builders/simple_builder"
 
 # Namespace module for rscons classes
 module Rscons
+
   # Names of the default builders which will be added to all newly created
   # {Environment} objects.
   DEFAULT_BUILDERS = [
     :CFile,
+    :Command,
+    :Copy,
+    :Directory,
     :Disassemble,
+    :Install,
     :Library,
     :Object,
     :Preprocess,
@@ -29,8 +38,12 @@ module Rscons
   # Class to represent a fatal error while building a target.
   class BuildError < RuntimeError; end
 
+  class << self
+
     # Remove all generated files.
-  def self.clean
+    #
+    # @return [void]
+    def clean
       cache = Cache.instance
       # remove all built files
       cache.targets.each do |target|
@@ -51,25 +64,34 @@ module Rscons
     # @param path [String] the path to examine.
     #
     # @return [Boolean] Whether the given path is an absolute filesystem path.
-  def self.absolute_path?(path)
+    def absolute_path?(path)
       path =~ %r{^(/|\w:[\\/])}
     end
 
+    # Return whether the given target is a phony target.
+    #
+    # @param target [Symbol, String] Target name.
+    #
+    # @return [Boolean] Whether the given target is a phony target.
+    def phony_target?(target)
+      target.is_a?(Symbol)
+    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, e.g. ".exe".
     #
     # @return [String] New path.
-  def self.set_suffix(path, suffix)
-    path.sub(/\.[^.]*$/, suffix)
+    def set_suffix(path, suffix)
+      path.sub(/\.[^.]*$/, "") + suffix
     end
 
     # Return the system shell and arguments for executing a shell command.
     #
     # @return [Array<String>] The shell and flag.
-  def self.get_system_shell
-    @@shell ||=
+    def get_system_shell
+      @shell ||=
         begin
           test_shell = lambda do |*args|
             begin
@@ -101,8 +123,8 @@ module Rscons
     # that it is running in MSYS then ["env"] will be returned.
     #
     # @return [Array<String>] Command used to execute commands.
-  def self.command_executer
-    @@command_executer ||=
+    def command_executer
+      @command_executer ||=
         if Object.const_get("RUBY_PLATFORM") =~ /mingw/
           if ENV.keys.find {|key| key =~ /MSYS/}
             begin
@@ -118,8 +140,12 @@ module Rscons
     # Set the command executer array.
     #
     # @param val [Array<String>] Command used to execute commands.
-  def self.command_executer=(val)
-    @@command_executer = val
+    #
+    # @return [Array<String>] Command used to execute commands.
+    def command_executer=(val)
+      @command_executer = val
+    end
+
   end
 end
 

lib/rscons/builder.rb

@@ -9,6 +9,8 @@ module Rscons
     # Return the name of the builder.
     #
     # If not overridden this defaults to the last component of the class name.
+    #
+    # @return [String] The name of the builder.
     def name
       self.class.name.split(":").last
     end
@@ -44,7 +46,7 @@ module Rscons
     # file name from a given source file name.
     #
     # @param target [String] The target file name.
-    # @param source [String, Array] The source file name(s).
+    # @param source [String] The source file name.
     # @param env [Environment] The Environment.
     #
     # @return [Boolean]
@@ -54,6 +56,20 @@ module Rscons
       false
     end
 
+    # Run the builder to produce a build target.
+    #
+    # @param target [String] Target file name.
+    # @param sources [Array<String>] Source file name(s).
+    # @param cache [Cache] The Cache object.
+    # @param env [Environment] The Environment executing the builder.
+    # @param vars [Hash,VarSet] Extra construction variables.
+    #
+    # @return [String,false]
+    #   Name of the target file on success or false on failure.
+    def run(target, sources, cache, env, vars)
+      raise "This method must be overridden in a subclass"
+    end
+
     # Check if the cache is up to date for the target and if not execute the
     # build command.
     #
@@ -71,8 +87,10 @@ module Rscons
     #   The name of the target on success or false on failure.
     def standard_build(short_cmd_string, target, command, sources, env, cache)
       unless cache.up_to_date?(target, command, sources, env)
+        unless Rscons.phony_target?(target)
           cache.mkdir_p(File.dirname(target))
           FileUtils.rm_f(target)
+        end
         return false unless env.execute(short_cmd_string, command)
         cache.register_build(target, command, sources, env)
       end

lib/rscons/builders/command.rb

@@ -0,0 +1,33 @@
+module Rscons
+  module Builders
+    # Execute a command that will produce the given target based on the given
+    # sources.
+    #
+    # @since 1.8.0
+    #
+    # Example:
+    #   env.Command("docs.html", "docs.md",
+    #               CMD => %w[pandoc -fmarkdown -thtml -o${_TARGET} ${_SOURCES}])
+    class Command < Builder
+      # Run the builder to produce a build target.
+      #
+      # @param target [String] Target file name.
+      # @param sources [Array<String>] Source file name(s).
+      # @param cache [Cache] The Cache object.
+      # @param env [Environment] The Environment executing the builder.
+      # @param vars [Hash,VarSet] Extra construction variables.
+      #
+      # @return [String,false]
+      #   Name of the target file on success or false on failure.
+      def run(target, sources, cache, env, vars)
+        vars = vars.merge({
+          "_TARGET" => target,
+          "_SOURCES" => sources,
+        })
+        command = env.build_command("${CMD}", vars)
+        cmd_desc = vars["CMD_DESC"] || "Command"
+        standard_build("#{cmd_desc} #{target}", target, command, sources, env, cache)
+      end
+    end
+  end
+end

lib/rscons/builders/directory.rb

@@ -0,0 +1,31 @@
+module Rscons
+  module Builders
+    # The Directory builder creates a directory.
+    class Directory < Builder
+
+      # Run the builder to produce a build target.
+      #
+      # @param target [String] Target file name.
+      # @param sources [Array<String>] Source file name(s).
+      # @param cache [Cache] The Cache object.
+      # @param env [Environment] The Environment executing the builder.
+      # @param vars [Hash,VarSet] Extra construction variables.
+      #
+      # @return [String,false]
+      #   Name of the target file on success or false on failure.
+      def run(target, sources, cache, env, vars)
+        if File.directory?(target)
+          target
+        elsif File.exists?(target)
+          $stderr.puts "Error: `#{target}' already exists and is not a directory"
+          false
+        else
+          puts "Directory #{target}"
+          cache.mkdir_p(target)
+          target
+        end
+      end
+
+    end
+  end
+end

lib/rscons/builders/install.rb

@@ -0,0 +1,64 @@
+require "pathname"
+
+module Rscons
+  module Builders
+    # The Install builder copies files/directories to new locations.
+    class Install < Builder
+
+      # Run the builder to produce a build target.
+      #
+      # @param target [String] Target file name.
+      # @param sources [Array<String>] Source file name(s).
+      # @param cache [Cache] The Cache object.
+      # @param env [Environment] The Environment executing the builder.
+      # @param vars [Hash,VarSet] Extra construction variables.
+      #
+      # @return [String,false]
+      #   Name of the target file on success or false on failure.
+      def run(target, sources, cache, env, vars)
+        target_is_dir = (sources.length > 1) ||
+                        Dir.exists?(sources.first) ||
+                        Dir.exists?(target)
+        outdir = target_is_dir ? target : File.dirname(target)
+        # Collect the list of files to copy over.
+        file_map = {}
+        if target_is_dir
+          sources.each do |src|
+            if Dir.exists? src
+              Dir.glob("#{src}/**/*", File::FNM_DOTMATCH).select do |f|
+                File.file?(f)
+              end.each do |subfile|
+                subpath = Pathname.new(subfile).relative_path_from(Pathname.new(src)).to_s
+                file_map[subfile] = "#{outdir}/#{subpath}"
+              end
+            else
+              file_map[src] = "#{outdir}/#{File.basename(src)}"
+            end
+          end
+        else
+          file_map[sources.first] = target
+        end
+        printed_message = false
+        file_map.each do |src, dest|
+          # Check the cache and copy if necessary
+          unless cache.up_to_date?(dest, :Copy, [src], env)
+            unless printed_message
+              puts "#{name} #{target}"
+              printed_message = true
+            end
+            cache.mkdir_p(File.dirname(dest))
+            FileUtils.cp(src, dest, :preserve => true)
+          end
+          cache.register_build(dest, :Copy, [src], env)
+        end
+        target if (target_is_dir ? Dir.exists?(target) : File.exists?(target))
+      end
+
+
+    end
+
+    # The Copy builder is identical to the Install builder.
+    class Copy < Install; end
+
+  end
+end

lib/rscons/builders/object.rb

@@ -62,7 +62,7 @@ module Rscons
       # file name from a given source file name.
       #
       # @param target [String] The target file name.
-      # @param source [String, Array] The source file name(s).
+      # @param source [String] The source file name.
       # @param env [Environment] The Environment.
       #
       # @return [Boolean]

lib/rscons/builders/preprocess.rb

@@ -1,7 +1,10 @@
+require "fileutils"
+
 module Rscons
   module Builders
     # The Preprocess builder invokes the C preprocessor
     class Preprocess < Builder
+
       # Return default construction variables for the builder.
       #
       # @param env [Environment] The Environment using the builder.
@@ -9,7 +12,9 @@ module Rscons
       # @return [Hash] Default construction variables for the builder.
       def default_variables(env)
         {
-          "CPP_CMD" => ["${_PREPROCESS_CC}", "-E", "-o", "${_TARGET}", "-I${CPPPATH}", "${CPPFLAGS}", "${CFLAGS}", "${_SOURCES}"],
+          "CPP_CMD" => %w[
+            ${_PREPROCESS_CC} -E ${_PREPROCESS_DEPGEN}
+            -o ${_TARGET} -I${CPPPATH} ${CPPFLAGS} ${_SOURCES}],
         }
       end
 
@@ -24,17 +29,32 @@ module Rscons
       # @return [String,false]
       #   Name of the target file on success or false on failure.
       def run(target, sources, cache, env, vars)
-        pp_cc = if sources.find {|s| s.end_with?(*env.expand_varref("${CXXSUFFIX}", vars))}
-                  "${CXX}"
+        if sources.find {|s| s.end_with?(*env.expand_varref("${CXXSUFFIX}", vars))}
+          pp_cc = "${CXX}"
+          depgen = "${CXXDEPGEN}"
         else
-                  "${CC}"
+          pp_cc = "${CC}"
+          depgen = "${CCDEPGEN}"
         end
         vars = vars.merge("_PREPROCESS_CC" => pp_cc,
+                          "_PREPROCESS_DEPGEN" => depgen,
                           "_TARGET" => target,
-                          "_SOURCES" => sources)
+                          "_SOURCES" => sources,
+                          "_DEPFILE" => Rscons.set_suffix(target, env.expand_varref("${DEPFILESUFFIX}", vars)))
         command = env.build_command("${CPP_CMD}", vars)
-        standard_build("Preprocess #{target}", target, command, sources, env, cache)
+        unless cache.up_to_date?(target, command, sources, env)
+          cache.mkdir_p(File.dirname(target))
+          return false unless env.execute("Preprocess #{target}", command)
+          deps = sources
+          if File.exists?(vars["_DEPFILE"])
+            deps += Environment.parse_makefile_deps(vars["_DEPFILE"], nil)
+            FileUtils.rm_f(vars["_DEPFILE"])
           end
+          cache.register_build(target, command, deps.uniq, env)
+        end
+        target
+      end
+
     end
   end
 end

lib/rscons/builders/simple_builder.rb

@@ -0,0 +1,39 @@
+module Rscons
+  module Builders
+    # A Generic builder class whose name and operation is defined at
+    # instantiation.
+    #
+    # @since 1.8.0
+    class SimpleBuilder < Builder
+      # @return [String] The name of this builder.
+      attr_reader :name
+
+      # Create a new builder with the given name and action.
+      #
+      # @param name  [String,Symbol] The name of the builder when registered.
+      # @param block [Block]
+      #   The action to perform when the builder is processed. The provided
+      #   block must return the target file on success or false on failure.
+      #   The provided block should have the same signature as {Builder#run}.
+      def initialize(name, &block)
+        @name  = name.to_s
+        @block = block
+      end
+
+      # Run the builder to produce a build target.
+      #
+      # @param target [String] Target file name.
+      # @param sources [Array<String>] Source file name(s).
+      # @param cache [Cache] The Cache object.
+      # @param env [Environment] The Environment executing the builder.
+      # @param vars [Hash,VarSet] Extra construction variables.
+      #
+      # @return [String,false]
+      #   Name of the target file on success or false on failure.
+      def run(target, sources, cache, env, vars)
+        @block.call(target, sources, cache, env, vars)
+      end
+    end
+  end
+end
+

lib/rscons/cache.rb

@@ -56,6 +56,9 @@ module Rscons
     # Name of the file to store cache information in
     CACHE_FILE = ".rsconscache"
 
+    # Prefix for phony cache entries.
+    PHONY_PREFIX = ":PHONY:"
+
     # Create a Cache object and load in the previous contents from the cache
     # file.
     def initialize
@@ -63,17 +66,23 @@ module Rscons
     end
 
     # Remove the cache file.
+    #
+    # @return [void]
     def clear
       FileUtils.rm_f(CACHE_FILE)
       initialize!
     end
 
     # Clear the cached file checksums.
+    #
+    # @return [void]
     def clear_checksum_cache!
       @lookup_checksums = {}
     end
 
     # Write the cache to disk to be loaded next time.
+    #
+    # @return [void]
     def write
       if @dirty || (@cache["version"] != VERSION)
         @cache["version"] = VERSION
@@ -86,9 +95,15 @@ module Rscons
 
     # Check if target(s) are up to date.
     #
-    # @param targets [String, Array] The name(s) of the target file(s).
-    # @param command [String, Array] The command used to build the target.
-    # @param deps [Array] List of the target's dependency files.
+    # @param targets [Symbol, String, Array<String>]
+    #   The name(s) of the target file(s).
+    # @param command [String, Array, Hash]
+    #   The command used to build the target. The command parameter can
+    #   actually be a String, Array, or Hash and could contain information
+    #   other than just the actual command used to build the target. For the
+    #   purposes of the Cache, any difference in the command argument will
+    #   trigger a rebuild.
+    # @param deps [Array<String>] List of the target's dependency files.
     # @param env [Environment] The Rscons::Environment.
     # @param options [Hash] Optional options.
     # @option options [Boolean] :strict_deps
@@ -109,19 +124,25 @@ module Rscons
     #     stored in the cache file
     def up_to_date?(targets, command, deps, env, options = {})
       Array(targets).each do |target|
+        cache_key = get_cache_key(target)
+
+        unless Rscons.phony_target?(target)
           # target file must exist on disk
           return false unless File.exists?(target)
+        end
 
         # target must be registered in the cache
-        return false unless @cache["targets"].has_key?(target)
+        return false unless @cache["targets"].has_key?(cache_key)
 
+        unless Rscons.phony_target?(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"][cache_key]["checksum"] == lookup_checksum(target)
+        end
 
         # command used to build target must be identical
-        return false unless @cache["targets"][target]["command"] == Digest::MD5.hexdigest(command.inspect)
+        return false unless @cache["targets"][cache_key]["command"] == Digest::MD5.hexdigest(command.inspect)
 
-        cached_deps = @cache["targets"][target]["deps"] || []
+        cached_deps = @cache["targets"][cache_key]["deps"] || []
         cached_deps_fnames = cached_deps.map { |dc| dc["fname"] }
         if options[:strict_deps]
           # depedencies passed in must exactly equal those in the cache
@@ -133,7 +154,7 @@ module Rscons
 
         # set of user dependencies must match
         user_deps = env.get_user_deps(target) || []
-        cached_user_deps = @cache["targets"][target]["user_deps"] || []
+        cached_user_deps = @cache["targets"][cache_key]["user_deps"] || []
         cached_user_deps_fnames = cached_user_deps.map { |dc| dc["fname"] }
         return false unless user_deps == cached_user_deps_fnames
 
@@ -148,17 +169,24 @@ module Rscons
 
     # 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 targets [Symbol, String, Array<String>]
+    #   The name of the target(s) built.
+    # @param command [String, Array, Hash]
+    #   The command used to build the target. The command parameter can
+    #   actually be a String, Array, or Hash and could contain information
+    #   other than just the actual command used to build the target. For the
+    #   purposes of the Cache, any difference in the command argument will
+    #   trigger a rebuild.
+    # @param deps [Array<String>] List of dependencies for the target.
     # @param env [Environment] The {Rscons::Environment}.
     #
     # @return [void]
     def register_build(targets, command, deps, env)
       Array(targets).each do |target|
-        @cache["targets"][target] = {
+        target_checksum = Rscons.phony_target?(target) ? "" : calculate_checksum(target)
+        @cache["targets"][get_cache_key(target)] = {
           "command" => Digest::MD5.hexdigest(command.inspect),
-          "checksum" => calculate_checksum(target),
+          "checksum" => target_checksum,
           "deps" => deps.map do |dep|
             {
               "fname" => dep,
@@ -212,6 +240,21 @@ module Rscons
 
     private
 
+    # Return a String key based on the target name to use in the on-disk cache.
+    #
+    # @param target_name [Symbol, String]
+    #   Target name.
+    #
+    # @return [String]
+    #   Key name.
+    def get_cache_key(target_name)
+      if Rscons.phony_target?(target_name)
+        PHONY_PREFIX + target_name.to_s
+      else
+        target_name
+      end
+    end
+
     # Create a Cache object and load in the previous contents from the cache
     # file.
     def initialize!

lib/rscons/cli.rb

@@ -0,0 +1,78 @@
+require "rscons"
+require "optparse"
+
+module Rscons
+  # Command-Line Interface functionality.
+  module Cli
+
+    # Default files to look for to execute if none specified.
+    DEFAULT_RSCONSFILES = %w[Rsconsfile Rsconsfile.rb]
+
+    class << self
+
+      # Run the Rscons CLI.
+      #
+      # @param argv [Array]
+      #   Command-line parameters.
+      #
+      # @return [void]
+      def run(argv)
+        argv = argv.dup
+        rsconsfile = nil
+
+        OptionParser.new do |opts|
+          opts.banner = "Usage: #{$0} [options]"
+
+          opts.separator ""
+          opts.separator "Options:"
+
+          opts.on("-c", "--clean", "Perform clean operation") do
+            Rscons.clean
+            exit 0
+          end
+
+          opts.on("-f FILE", "Execute FILE (default Rsconsfile)") do |f|
+            rsconsfile = f
+          end
+
+          opts.on_tail("--version", "Show version") do
+            puts "Rscons version #{Rscons::VERSION}"
+            exit 0
+          end
+
+          opts.on_tail("-h", "--help", "Show this help.") do
+            puts opts
+            exit 0
+          end
+
+        end.parse!(argv)
+
+        if rsconsfile
+          unless File.exists?(rsconsfile)
+            $stderr.puts "Cannot read #{rsconsfile}"
+            exit 1
+          end
+        else
+          rsconsfile = DEFAULT_RSCONSFILES.find do |f|
+            File.exists?(f)
+          end
+          unless rsconsfile
+            $stderr.puts "Could not find the Rsconsfile to execute."
+            $stderr.puts "Looked in: [#{DEFAULT_RSCONSFILES.join(", ")}]"
+            exit 1
+          end
+        end
+
+        begin
+          load rsconsfile
+        rescue Rscons::BuildError => e
+          $stderr.puts e.message
+          exit 1
+        end
+
+        exit 0
+      end
+
+    end
+  end
+end

lib/rscons/environment.rb

@@ -10,7 +10,7 @@ module Rscons
     # @return [Hash] Set of !{"builder_name" => builder_object} pairs.
     attr_reader :builders
 
-    # :command, :short, or :off
+    # @return [Symbol] :command, :short, or :off
     attr_accessor :echo
 
     # @return [String, nil] The build root.
@@ -79,7 +79,7 @@ module Rscons
     #
     # Any options that #initialize receives can also be specified here.
     #
-    # @return a new {Environment} object.
+    # @return [Environment] The newly created {Environment} object.
     def clone(options = {})
       clone = options[:clone] || Set[:variables, :builders]
       clone = Set[:variables, :builders, :build_root, :build_dirs, :build_hooks] if clone == :all
@@ -120,10 +120,32 @@ module Rscons
 
     # Add a {Builder} object to the Environment.
     #
-    # @param builder [Builder] The {Builder} object to add.
+    # @overload add_builder(builder)
+    #
+    #   Add the given builder to the Environment.
+    #
+    #   @param builder [Builder] An instance of the builder to register.
+    #
+    # @overload add_builder(builder,&action)
+    #
+    #   Create a new {Builders::SimpleBuilder} instance and add it to the
+    #   environment.
+    #
+    #   @since 1.8.0
+    #
+    #   @param builder [String,Symbol]
+    #     The name of the builder to add.
+    #
+    #   @param action [Block]
+    #     A block that will be called when the builder is executed to generate
+    #     a target file. The provided block should have the same prototype as
+    #     {Rscons::Builder#run}.
     #
     # @return [void]
-    def add_builder(builder)
+    def add_builder(builder, &action)
+      if not builder.is_a? Rscons::Builder
+        builder = Rscons::Builders::SimpleBuilder.new(builder, &action)
+      end
       @builders[builder.name] = builder
       var_defs = builder.default_variables(self)
       if var_defs
@@ -184,8 +206,13 @@ module Rscons
     #
     # Source files from src_dir will produce object files under obj_dir.
     #
-    # @param src_dir [String, Regexp] Path to the source directory.
-    # @param obj_dir [String] Path to the object directory.
+    # @param src_dir [String, Regexp]
+    #   Path to the source directory. If a Regexp is given, it will be matched
+    #   to source file names.
+    # @param obj_dir [String]
+    #   Path to the object directory. If a Regexp is given as src_dir, then
+    #   obj_dir can contain backreferences to groups matched from the source
+    #   file name.
     #
     # @return [void]
     def build_dir(src_dir, obj_dir)
@@ -223,25 +250,27 @@ module Rscons
       build_fname
     end
 
-    # Access a construction variable or environment option.
+    # Get a construction variable's value.
     #
     # @see VarSet#[]
     def [](*args)
       @varset.send(:[], *args)
     end
 
-    # Set a construction variable or environment option.
+    # Set a construction variable's value.
     #
     # @see VarSet#[]=
     def []=(*args)
       @varset.send(:[]=, *args)
     end
 
-    # Add a set of construction variables or environment options.
+    # Add a set of construction variables to the Environment.
     #
-    # @see VarSet#append
-    def append(*args)
-      @varset.append(*args)
+    # @param values [VarSet, Hash] New set of variables.
+    #
+    # @return [void]
+    def append(values)
+      @varset.append(values)
     end
 
     # Build all build targets specified in the Environment.
@@ -251,33 +280,35 @@ module Rscons
     #
     # @return [void]
     def process
-      expand_paths!
       while @targets.size > 0
+        expand_paths!
         targets = @targets
         @targets = {}
         cache = Cache.instance
         cache.clear_checksum_cache!
-        targets_processed = {}
+        targets_processed = Set.new
         process_target = proc do |target|
-          targets_processed[target] ||= begin
-            targets[target][:sources].each do |src|
+          unless targets_processed.include?(target)
+            targets_processed << target
+            targets[target].each do |target_params|
+              target_params[:sources].each do |src|
                 if targets.include?(src) and not targets_processed.include?(src)
                   process_target.call(src)
                 end
               end
-            result = run_builder(targets[target][:builder],
+              result = run_builder(target_params[:builder],
                                    target,
-                                 targets[target][:sources],
+                                   target_params[:sources],
                                    cache,
-                                 targets[target][:vars] || {})
+                                   target_params[:vars] || {})
               unless result
                 raise BuildError.new("Failed to build #{target}")
               end
-            result
+            end
           end
         end
         begin
-          targets.each do |target, target_params|
+          targets.each_key do |target|
             process_target.call(target)
           end
         ensure
@@ -287,6 +318,8 @@ module Rscons
     end
 
     # Clear all targets registered for the Environment.
+    #
+    # @return [void]
     def clear_targets
       @targets = {}
     end
@@ -373,7 +406,8 @@ module Rscons
     #
     # @return [void]
     def add_target(target, builder, sources, vars, args)
-      @targets[target] = {
+      @targets[target] ||= []
+      @targets[target] << {
         builder: builder,
         sources: sources,
         vars: vars,
@@ -410,8 +444,9 @@ module Rscons
     #
     # 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 sources [Array<String>] List of source files to build.
+    # @param suffixes [Array<String>]
+    #   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.
     #
@@ -440,7 +475,7 @@ module Rscons
     #
     # @param builder [Builder] The Builder to use.
     # @param target [String] The target output file.
-    # @param sources [Array] List of source files.
+    # @param sources [Array<String>] List of source files.
     # @param cache [Cache] The Cache.
     # @param vars [Hash] Extra variables to pass to the builder.
     #
@@ -506,10 +541,10 @@ module Rscons
     # Parse command-line flags for compilation/linking options into separate
     # construction variables.
     #
-    # The parsed construction variables are returned in a Hash instead of
-    # merging them directly to the Environment. They can be merged with
-    # {#merge_flags}. The {#parse_flags!} version immediately merges the parsed
-    # flags as well.
+    # For {#parse_flags}, the parsed construction variables are returned in a
+    # Hash instead of merging them directly to the Environment. They can be
+    # merged with {#merge_flags}. The {#parse_flags!} version immediately
+    # merges the parsed flags as well.
     #
     # Example:
     #   # Import FreeType build options
@@ -628,6 +663,15 @@ module Rscons
       end
     end
 
+    # Print the Environment's construction variables for debugging.
+    def dump
+      varset_hash = @varset.to_h
+      varset_hash.keys.sort_by(&:to_s).each do |var|
+        var_str = var.is_a?(Symbol) ? var.inspect : var
+        puts "#{var_str} => #{varset_hash[var].inspect}"
+      end
+    end
+
     private
 
     # Expand target and source paths before invoking builders.
@@ -638,14 +682,16 @@ module Rscons
     #
     # @return [void]
     def expand_paths!
-      @targets = @targets.reduce({}) do |result, (target, target_params)|
+      @targets = @targets.reduce({}) do |result, (target, target_params_list)|
+        target = expand_path(target) if @build_root
+        target = expand_varref(target)
+        result[target] = target_params_list.map do |target_params|
           sources = target_params[:sources].map do |source|
             source = expand_path(source) if @build_root
             expand_varref(source)
+          end.flatten
+          target_params.merge(sources: sources)
         end
-        target = expand_path(target) if @build_root
-        target = expand_varref(target)
-        result[target] = target_params.merge(sources: sources)
         result
       end
     end
@@ -655,7 +701,8 @@ module Rscons
     # 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.
+    # @param target [String, nil]
+    #   Name of the target to gather dependencies for, nil for any/all.
     #
     # @return [Array<String>] Paths of dependency files.
     def self.parse_makefile_deps(mf_fname, target)
@@ -668,7 +715,7 @@ module Rscons
           buildup += ' ' + line
           if buildup =~ /^(.*): (.*)$/
             mf_target, mf_deps = $1.strip, $2
-            if mf_target == target
+            if target.nil? or mf_target == target
               deps += mf_deps.split(' ').map(&:strip)
             end
           end

lib/rscons/varset.rb

@@ -58,7 +58,7 @@ module Rscons
     #
     # @param values [VarSet, Hash] New set of variables.
     #
-    # @return [self]
+    # @return [VarSet] Returns self.
     def append(values)
       coa!
       if values.is_a?(VarSet)
@@ -116,11 +116,33 @@ module Rscons
         expand_varref(varref[*lambda_args], lambda_args)
       elsif varref.nil?
         nil
+      elsif varref.is_a?(Symbol)
+        varref
       else
         raise "Unknown varref type: #{varref.class} (#{varref.inspect})"
       end
     end
 
+    # Return a Hash containing all variables in the VarSet.
+    #
+    # @since 1.8.0
+    #
+    # This method is not terribly efficient. It is intended to be used only by
+    # debugging code to dump out a VarSet's variables.
+    #
+    # @return [Hash] All variables in the VarSet.
+    def to_h
+      result = deep_dup(@my_vars)
+      @coa_vars.reduce(result) do |result, coa_vars|
+        coa_vars.each_pair do |key, value|
+          unless result.include?(key)
+            result[key] = deep_dup(value)
+          end
+        end
+        result
+      end
+    end
+
     private
 
     # Move all VarSet variables into the copy-on-access list.

lib/rscons/version.rb

@@ -1,4 +1,4 @@
 module Rscons
   # gem version
-  VERSION = "1.7.0"
+  VERSION = "1.9.0"
 end

rscons.gemspec

@@ -24,5 +24,6 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "rake"
   gem.add_development_dependency "simplecov"
   gem.add_development_dependency "yard"
+  gem.add_development_dependency "rdoc"
   gem.add_development_dependency "redcarpet"
 end

spec/build_tests_spec.rb

@@ -249,6 +249,27 @@ describe Rscons do
     ]
   end
 
+  it 'supports simple builders' do
+    test_dir('json_to_yaml')
+    Rscons::Environment.new do |env|
+      require 'json'
+      require 'yaml'
+      env.add_builder(:JsonToYaml) do |target, sources, cache, env, vars|
+        unless cache.up_to_date?(target, :JsonToYaml, sources, env)
+          cache.mkdir_p(File.dirname(target))
+          File.open(target, 'w') do |f|
+            f.write(YAML.dump(JSON.load(IO.read(sources.first))))
+          end
+          cache.register_build(target, :JsonToYaml, sources, env)
+        end
+        target
+      end
+      env.JsonToYaml('foo.yml','foo.json')
+    end
+    expect(File.exists?('foo.yml')).to be_truthy
+    expect(IO.read('foo.yml')).to eq("---\nkey: value\n")
+  end
+
   it 'cleans built files' do
     test_dir('build_dir')
     Rscons::Environment.new do |env|
@@ -700,4 +721,246 @@ EOF
     expect(`./two_sources`).to eq "This is a C program with two sources.\n"
   end
 
+  it "supports dumping an Environment's construction variables" do
+    test_dir("simple")
+    env = Rscons::Environment.new do |env|
+      env["CFLAGS"] += %w[-O2 -fomit-frame-pointer]
+      env[:foo] = :bar
+    end
+    env.dump
+    result = lines
+    expect(result.include?(%{:foo => :bar})).to be_truthy
+    expect(result.include?(%{CFLAGS => ["-O2", "-fomit-frame-pointer"]})).to be_truthy
+    expect(result.include?(%{CPPPATH => []})).to be_truthy
+  end
+
+  it "considers deep dependencies when deciding whether to rerun Preprocess builder" do
+    test_dir("preprocess")
+    env = Rscons::Environment.new do |env|
+      env.Preprocess("pp", "foo.h")
+    end
+    expect(File.read("pp")).to match(%r{xyz42abc}m)
+    expect(lines).to eq(["Preprocess pp"])
+    env.Preprocess("pp", "foo.h")
+    env.process
+    expect(lines).to eq([])
+    File.open("bar.h", "w") do |fh|
+      fh.puts "#define BAR abc88xyz"
+    end
+    $ttt = true
+    env.Preprocess("pp", "foo.h")
+    env.process
+    expect(lines).to eq(["Preprocess pp"])
+    expect(File.read("pp")).to match(%r{abc88xyz}m)
+  end
+
+  it "allows construction variable references which expand to arrays in sources of a build target" do
+    test_dir("simple")
+    Rscons::Environment.new do |env|
+      env["sources"] = Dir["*.c"]
+      env.Program("simple", "${sources}")
+    end
+    expect(File.exists?("simple.o")).to be_truthy
+    expect(`./simple`).to eq "This is a simple C program\n"
+  end
+
+  it "supports registering multiple build targets with the same target path" do
+    test_dir("build_dir")
+    Rscons::Environment.new do |env|
+      env["CPPPATH"] << "src/two"
+      env.Object("one.o", "src/one/one.c")
+      env.Object("one.o", "src/two/two.c")
+    end
+    expect(File.exists?("one.o")).to be_truthy
+    expect(lines).to eq([
+      "CC one.o",
+      "CC one.o",
+    ])
+  end
+
+  it "expands target and source paths when builders are registered in build hooks" do
+    test_dir("build_dir")
+    Rscons::Environment.new do |env|
+      env["CPPPATH"] << "src/two"
+      env.Object("one.o", "src/one/one.c")
+      env.add_post_build_hook do |build_op|
+        if build_op[:target] == "one.o"
+          env["MODULE"] = "two"
+          env.Object("${MODULE}.o", "src/${MODULE}/${MODULE}.c")
+        end
+      end
+    end
+    expect(File.exists?("one.o")).to be_truthy
+    expect(File.exists?("two.o")).to be_truthy
+    expect(lines).to eq([
+      "CC one.o",
+      "CC two.o",
+    ])
+  end
+
+  context "Directory builder" do
+    it "creates the requested directory" do
+      test_dir("simple")
+      Rscons::Environment.new do |env|
+        env.Directory("teh_dir")
+      end
+      expect(File.directory?("teh_dir")).to be_truthy
+      expect(lines).to eq(["Directory teh_dir"])
+    end
+
+    it "succeeds when the requested directory already exists" do
+      test_dir("simple")
+      FileUtils.mkdir("teh_dir")
+      Rscons::Environment.new do |env|
+        env.Directory("teh_dir")
+      end
+      expect(File.directory?("teh_dir")).to be_truthy
+      expect(lines).to eq([])
+    end
+
+    it "fails when the target path is a file" do
+      test_dir("simple")
+      FileUtils.touch("teh_dir")
+      expect do
+        Rscons::Environment.new do |env|
+          env.Directory("teh_dir")
+        end
+      end.to raise_error /Failed to build teh_dir/
+      expect(lines).to eq([
+        "Error: `teh_dir' already exists and is not a directory",
+      ])
+    end
+  end
+
+  context "Install buildler" do
+    let(:base_env) do
+      test_dir("build_dir")
+      Rscons::Environment.new do |env|
+        env["CPPPATH"] = Dir["src/**/"]
+        env["sources"] = Dir["src/**/*.c"]
+        env.Program("simple.exe", "${sources}")
+      end
+    end
+
+    it "copies a file to the target file name" do
+      env = base_env.clone do |env|
+        lines
+        env.Install("inst.exe", "simple.exe")
+      end
+      expect(lines).to eq(["Install inst.exe"])
+      env.Install("inst.exe", "simple.exe")
+      env.process
+      expect(lines).to eq([])
+      expect(File.exists?("inst.exe")).to be_truthy
+      expect(File.read("inst.exe", mode: "rb")).to eq(File.read("simple.exe", mode: "rb"))
+      FileUtils.rm("inst.exe")
+      env.Install("inst.exe", "simple.exe")
+      env.process
+      expect(lines).to eq(["Install inst.exe"])
+    end
+
+    it "operates the same as a Copy builder" do
+      env = base_env.clone do |env|
+        lines
+        env.Copy("inst.exe", "simple.exe")
+      end
+      expect(lines).to eq(["Copy inst.exe"])
+      env.Copy("inst.exe", "simple.exe")
+      env.process
+      expect(lines).to eq([])
+      expect(File.exists?("inst.exe")).to be_truthy
+      expect(File.read("inst.exe", mode: "rb")).to eq(File.read("simple.exe", mode: "rb"))
+      FileUtils.rm("inst.exe")
+      env.Copy("inst.exe", "simple.exe")
+      env.process
+      expect(lines).to eq(["Copy inst.exe"])
+    end
+
+    it "copies a file to the target directory name" do
+      env = base_env.clone do |env|
+        lines
+        env.Directory("inst")
+        env.Install("inst", "simple.exe")
+      end
+      expect(lines).to eq([
+        "Directory inst",
+        "Install inst",
+      ])
+      env.Install("inst", "simple.exe")
+      env.process
+      expect(lines).to eq([])
+      expect(File.exists?("inst/simple.exe")).to be_truthy
+      expect(File.read("inst/simple.exe", mode: "rb")).to eq(File.read("simple.exe", mode: "rb"))
+    end
+
+    it "copies a directory to the non-existent target directory name" do
+      env = base_env.clone do |env|
+        lines
+        env.Install("dist/src", "src")
+      end
+      expect(lines).to eq(["Install dist/src"])
+      env.Install("dist/src", "src")
+      env.process
+      expect(lines).to eq([])
+      %w[src/one/one.c src/two/two.c src/two/two.h].each do |f|
+        expect(File.exists?("dist/#{f}")).to be_truthy
+        expect(File.read("dist/#{f}", mode: "rb")).to eq(File.read(f, mode: "rb"))
+      end
+    end
+
+    it "copies a directory to the existent target directory name" do
+      env = base_env.clone do |env|
+        lines
+        env.Directory("dist/src")
+        env.Install("dist/src", "src")
+      end
+      expect(lines).to eq([
+        "Directory dist/src",
+        "Install dist/src",
+      ])
+      env.Install("dist/src", "src")
+      env.process
+      expect(lines).to eq([])
+      %w[src/one/one.c src/two/two.c src/two/two.h].each do |f|
+        expect(File.exists?("dist/#{f}")).to be_truthy
+        expect(File.read("dist/#{f}", mode: "rb")).to eq(File.read(f, mode: "rb"))
+      end
+      FileUtils.rm("dist/src/two/two.c")
+      env.Install("dist/src", "src")
+      env.process
+      expect(lines).to eq(["Install dist/src"])
+    end
+  end
+
+  context "phony targets" do
+    it "allows specifying a Symbol as a target name and reruns the builder if the sources or command have changed" do
+      test_dir("simple")
+      env = Rscons::Environment.new do |env|
+        env.add_builder(:Checker) do |target, sources, cache, env, vars|
+          unless cache.up_to_date?(target, :Checker, sources, env)
+            puts "Checker #{sources.first}" if env.echo != :off
+            cache.register_build(target, :Checker, sources, env)
+          end
+          target
+        end
+        env.Program("simple.exe", "simple.c")
+        env.Checker(:checker, "simple.exe")
+      end
+      expect(lines).to eq(["CC simple.o", "LD simple.exe", "Checker simple.exe"])
+
+      env.clone do |env|
+        env.Checker(:checker, "simple.exe")
+      end
+      expect(lines).to eq([])
+
+      File.open("simple.exe", "w") do |fh|
+        fh.puts "Changed simple.exe"
+      end
+      env.clone do |env|
+        env.Checker(:checker, "simple.exe")
+      end
+      expect(lines).to eq(["Checker simple.exe"])
+    end
+  end
+
 end

spec/rscons/builder_spec.rb

@@ -0,0 +1,9 @@
+module Rscons
+  describe Builder do
+    describe "#run" do
+      it "raises an error if called directly and not through a subclass" do
+        expect{subject.run(:target, :sources, :cache, :env, :vars)}.to raise_error /This method must be overridden in a subclass/
+      end
+    end
+  end
+end

spec/rscons/builders/command_spec.rb

@@ -0,0 +1,18 @@
+module Rscons
+  module Builders
+    describe Command do
+
+      let(:command) { ['pandoc', '-fmarkdown', '-thtml', '-o${_TARGET}', '${_SOURCES}'] }
+      let(:env) {Environment.new}
+      subject {Command.new}
+
+      it "invokes the command to build the target" do
+        expected_cmd = ['pandoc', '-fmarkdown', '-thtml', '-ofoo.html', 'foo.md']
+        expect(subject).to receive(:standard_build).with("PANDOC foo.html", "foo.html", expected_cmd, ["foo.md"], env, :cache)
+        subject.run("foo.html", ["foo.md"], :cache, env,
+                    "CMD" => command, "CMD_DESC" => "PANDOC")
+      end
+
+    end
+  end
+end

spec/rscons/builders/preprocess_spec.rb

@@ -1,18 +1,48 @@
 module Rscons
   module Builders
     describe Preprocess do
+
       let(:env) {Environment.new}
       subject {Preprocess.new}
 
       it "supports overriding CC construction variable" do
-        expect(subject).to receive(:standard_build).with("Preprocess module.pp", "module.pp", ["my_cpp", "-E", "-o", "module.pp", "module.c"], ["module.c"], env, :cache)
-        subject.run("module.pp", ["module.c"], :cache, env, "CC" => "my_cpp")
+        cache = double(Cache)
+        command = %w[my_cpp -E -MMD -MF module.mf -o module.pp module.c]
+        expect(cache).to receive(:up_to_date?).with("module.pp", command, %w[module.c], env).and_return(false)
+        expect(cache).to receive(:mkdir_p).with(".")
+        expect(env).to receive(:execute).with("Preprocess module.pp", command).and_return(true)
+        expect(File).to receive(:exists?).with("module.mf").and_return(true)
+        expect(Environment).to receive(:parse_makefile_deps).with("module.mf", nil).and_return(%w[module.c one.h two.h])
+        expect(FileUtils).to receive(:rm_f).with("module.mf")
+        expect(cache).to receive(:register_build).with("module.pp", command, %w[module.c one.h two.h], env)
+
+        expect(subject.run("module.pp", ["module.c"], cache, env, "CC" => "my_cpp")).to eq("module.pp")
       end
 
       it "supports overriding CPP_CMD construction variable" do
-        expect(subject).to receive(:standard_build).with("Preprocess module.pp", "module.pp", ["my_cpp", "module.c"], ["module.c"], env, :cache)
-        subject.run("module.pp", ["module.c"], :cache, env, "CPP_CMD" => ["my_cpp", "${_SOURCES}"])
+        cache = double(Cache)
+        command = %w[my_cpp module.c]
+        expect(cache).to receive(:up_to_date?).with("module.pp", command, %w[module.c], env).and_return(false)
+        expect(cache).to receive(:mkdir_p).with(".")
+        expect(env).to receive(:execute).with("Preprocess module.pp", command).and_return(true)
+        expect(File).to receive(:exists?).with("module.mf").and_return(true)
+        expect(Environment).to receive(:parse_makefile_deps).with("module.mf", nil).and_return(%w[module.c one.h two.h])
+        expect(FileUtils).to receive(:rm_f).with("module.mf")
+        expect(cache).to receive(:register_build).with("module.pp", command, %w[module.c one.h two.h], env)
+
+        expect(subject.run("module.pp", ["module.c"], cache, env, "CPP_CMD" => ["my_cpp", "${_SOURCES}"])).to eq("module.pp")
       end
+
+      it "returns false if executing the preprocessor fails" do
+        cache = double(Cache)
+        command = %w[gcc -E -MMD -MF module.mf -o module.pp module.c]
+        expect(cache).to receive(:up_to_date?).with("module.pp", command, %w[module.c], env).and_return(false)
+        expect(cache).to receive(:mkdir_p).with(".")
+        expect(env).to receive(:execute).with("Preprocess module.pp", command).and_return(false)
+
+        expect(subject.run("module.pp", ["module.c"], cache, env, {})).to eq(false)
+      end
+
     end
   end
 end

spec/rscons/builders/simple_builder_spec.rb

@@ -0,0 +1,19 @@
+module Rscons
+  module Builders
+    describe SimpleBuilder do
+      let(:env) {Environment.new}
+
+      it "should create a new builder with the given name (as a symbol) and action" do
+        builder = Rscons::Builders::SimpleBuilder.new(:Foo) { 0x1234 }
+        expect(builder.name).to eq("Foo")
+        expect(builder.run(1,2,3,4,5)).to eq(0x1234)
+      end
+
+      it "should create a new builder with the given name (as a string) and action" do
+        builder = Rscons::Builders::SimpleBuilder.new("Foo") { 0x1234 }
+        expect(builder.name).to eq("Foo")
+        expect(builder.run(1,2,3,4,5)).to eq(0x1234)
+      end
+    end
+  end
+end

spec/rscons/environment_spec.rb

@@ -72,6 +72,13 @@ module Rscons
         env.add_builder(Rscons::Builders::Object.new)
         expect(env.builders.keys).to eq ["Object"]
       end
+
+      it "adds a new simple builder to the list of builders" do
+        env = Environment.new(exclude_builders: true)
+        expect(env.builders.keys).to eq []
+        env.add_builder(:Foo) {}
+        expect(env.builders.keys).to eq ["Foo"]
+      end
     end
 
     describe "#get_build_fname" do
@@ -298,10 +305,10 @@ module Rscons
         env.Object("target.o", ["src1.c", "src2.c"], var: "val")
         target = env.instance_variable_get(:@targets)["target.o"]
         expect(target).to_not be_nil
-        expect(target[:builder].is_a?(Builder)).to be_truthy
-        expect(target[:sources]).to eq ["src1.c", "src2.c"]
-        expect(target[:vars]).to eq({var: "val"})
-        expect(target[:args]).to eq []
+        expect(target[0][:builder].is_a?(Builder)).to be_truthy
+        expect(target[0][:sources]).to eq ["src1.c", "src2.c"]
+        expect(target[0][:vars]).to eq({var: "val"})
+        expect(target[0][:args]).to eq []
       end
 
       it "raises an error when vars is not a Hash" do

spec/rscons/varset_spec.rb

@@ -1,5 +1,6 @@
 module Rscons
   describe VarSet do
+
     describe '#initialize' do
       it "initializes variables from a Hash" do
         v = VarSet.new({"one" => 1, "two" => :two})
@@ -168,5 +169,35 @@ module Rscons
         expect { v.expand_varref("${bad}", :lambda_args) }.to raise_error /I do not know how to expand a variable reference to a Hash/
       end
     end
+
+    describe "#to_h" do
+      it "returns a Hash of all variables in the VarSet" do
+        v = VarSet.new({"fuz" => "a string", "foo" => 42, "bar" => :baz,
+                        "qax" => [3, 6], "qux" => {a: :b}})
+        v2 = v.merge("baz" => "qux", "qax" => [4, 7])
+        v3 = v2.merge("fuz" => nil)
+        v4 = v3.clone
+        v4["fuz"] = :fuzzy
+        v4["foo"] = 43
+        expect(v.to_h).to eq({
+          "fuz" => "a string", "foo" => 42, "bar" => :baz,
+          "qax" => [3, 6], "qux" => {a: :b},
+        })
+        expect(v2.to_h).to eq({
+          "fuz" => "a string", "foo" => 42, "bar" => :baz,
+          "qax" => [4, 7], "qux" => {a: :b}, "baz" => "qux",
+        })
+        expect(v3.to_h).to eq({
+          "fuz" => nil, "foo" => 42, "bar" => :baz,
+          "qax" => [4, 7], "qux" => {a: :b}, "baz" => "qux",
+        })
+        expect(v4.to_h).to eq({
+          "fuz" => :fuzzy, "foo" => 43, "bar" => :baz,
+          "qax" => [4, 7], "qux" => {a: :b}, "baz" => "qux",
+        })
+        expect(VarSet.new.to_h).to eq({})
+      end
+    end
+
   end
 end

spec/rscons_spec.rb

@@ -24,13 +24,23 @@ describe Rscons do
     end
   end
 
+  describe ".set_suffix" do
+    it "changes the suffix to the new one" do
+      expect(Rscons.set_suffix("foo.c", ".h")).to eq("foo.h")
+    end
+
+    it "appends a suffix if the given file name does not have one" do
+      expect(Rscons.set_suffix("bazz", ".d")).to eq("bazz.d")
+    end
+  end
+
   describe ".get_system_shell" do
     before(:each) do
-      Rscons.class_variable_set(:@@shell, nil)
+      Rscons.instance_variable_set(:@shell, nil)
     end
 
     after(:each) do
-      Rscons.class_variable_set(:@@shell, nil)
+      Rscons.instance_variable_set(:@shell, nil)
     end
 
     it "uses the SHELL environment variable if it tests successfully" do
@@ -70,11 +80,11 @@ describe Rscons do
   context "command executer" do
     describe ".command_executer" do
       before(:each) do
-        Rscons.class_variable_set(:@@command_executer, nil)
+        Rscons.instance_variable_set(:@command_executer, nil)
       end
 
       after(:each) do
-        Rscons.class_variable_set(:@@command_executer, nil)
+        Rscons.instance_variable_set(:@command_executer, nil)
       end
 
       it "returns ['env'] if mingw platform in MSYS and 'env' works" do
@@ -105,10 +115,10 @@ describe Rscons do
     end
 
     describe ".command_executer=" do
-      it "overrides the value of @@command_executer" do
-        Rscons.class_variable_set(:@@command_executer, ["env"])
+      it "overrides the value of @command_executer" do
+        Rscons.instance_variable_set(:@command_executer, ["env"])
         Rscons.command_executer = []
-        expect(Rscons.class_variable_get(:@@command_executer)).to eq([])
+        expect(Rscons.instance_variable_get(:@command_executer)).to eq([])
       end
     end
   end