v1.4.2

README.md

@@ -12,7 +12,7 @@ Add this line to your application's Gemfile:
 
 And then execute:
 
-    $ bundle
+    $ bundle install
 
 Or install it yourself as:
 
@@ -176,11 +176,14 @@ 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.
+* `: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
 
@@ -190,19 +193,96 @@ Rscons::Environment.new do |env|
 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
 
-### Default Builders
+### Builders
 
-Rscons ships with a number of default 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:
@@ -214,10 +294,17 @@ An Rscons::Environment consists of:
 * a collection of targets to build
 * a collection of build hooks
 
-When cloning an environment, the construction variables and builders are
-cloned, but the new environment does not inherit any of the targets, build
+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:
 
@@ -233,8 +320,7 @@ cloned_env["CPPPATH"] << "three"
 ### Construction Variable Naming
 
 * uppercase strings - the default construction variables that Rscons uses
-* lowercase symbols - Rscons options
-* lowercase strings - reserved as user-defined construction variables
+* symbols, lowercase strings - reserved as user-defined construction variables
 
 ### API documentation
 
@@ -243,7 +329,39 @@ http://rubydoc.info/github/holtrop/rscons/frames.
 
 ## Release Notes
 
+### v1.4.2
+
+- add Environment#expand_path
+- expand construction variable references in builder targets and sources before invoking builder
+
+### v1.4.1
+
+- fix invoking a builder with no sources while a build root defined
+
+### 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=
 

lib/rscons.rb

@@ -5,15 +5,21 @@ require_relative "rscons/varset"
 require_relative "rscons/version"
 
 # default builders
+require_relative "rscons/builders/cfile"
+require_relative "rscons/builders/disassemble"
 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 = [
+    :CFile,
+    :Disassemble,
     :Library,
     :Object,
+    :Preprocess,
     :Program,
   ]
 
@@ -21,7 +27,7 @@ module Rscons
 
   # 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)
@@ -33,7 +39,7 @@ 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

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

@@ -1,7 +1,7 @@
 module Rscons
   module Builders
     # A default Rscons builder that produces a static library archive.
-    class Rscons::Builders::Library < Rscons::Builder
+    class Library < Builder
       def default_variables(env)
         {
           'AR' => 'ar',

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

@@ -2,7 +2,7 @@ module Rscons
   module Builders
     # A default Rscons builder that knows how to link object files into an
     # executable program.
-    class Rscons::Builders::Program < Rscons::Builder
+    class Program < Builder
       def default_variables(env)
         {
           'LD' => nil,

lib/rscons/cache.rb

@@ -1,100 +1,100 @@
-require 'yaml'
-require 'fileutils'
-require 'digest/md5'
-require 'set'
-require 'rscons/version'
+require "digest/md5"
+require "fileutils"
+require "json"
+require "set"
+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',
-  #     targets: {
-  #       'program' => {
-  #         'checksum' => 'A1B2C3D4',
-  #         'command' => ['gcc', '-o', 'program', 'program.o'],
-  #         'deps' => [
+  #     "version" => "1.2.3",
+  #     "targets" => {
+  #       "program" => {
+  #         "checksum" => "A1B2C3D4",
+  #         "command" => "13543518FE",
+  #         "deps" => [
   #           {
-  #             'fname' => 'program.o',
-  #             'checksum' => '87654321',
+  #             "fname" => "program.o",
+  #             "checksum" => "87654321",
   #           },
   #         ],
-  #         'user_deps' => [
+  #         "user_deps" => [
   #           {
-  #             'fname' => 'lscript.ld',
-  #             'checksum' => '77551133',
+  #             "fname" => "lscript.ld",
+  #             "checksum" => "77551133",
   #           },
   #         ],
   #       },
-  #       'program.o' => {
-  #         'checksum' => '87654321',
-  #         'command' => ['gcc', '-c', '-o', 'program.o', 'program.c'],
-  #         'deps' => [
+  #       "program.o" => {
+  #         "checksum" => "87654321",
+  #         "command" => "98765ABCD",
+  #         "deps" => [
   #           {
-  #             'fname' => 'program.c',
-  #             'checksum' => '456789ABC',
+  #             "fname" => "program.c",
+  #             "checksum" => "456789ABC",
   #           },
   #           {
-  #             'fname' => 'program.h',
-  #             'checksum' => '7979764643',
+  #             "fname" => "program.h",
+  #             "checksum" => "7979764643",
   #           },
   #         ],
-  #         'user_deps' => [],
+  #         "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'
-
-    #### Class Methods
-
-    # Remove the cache file
-    def self.clear
-      FileUtils.rm_f(CACHE_FILE)
-    end
-
-    #### Instance Methods
+    CACHE_FILE = ".rsconscache"
 
     # Create a Cache object and load in the previous contents from the cache
     # file.
     def initialize
-      @cache = YAML.load(File.read(CACHE_FILE)) rescue {}
-      unless @cache.is_a?(Hash)
-        $stderr.puts "Warning: #{CACHE_FILE} was corrupt. Contents:\n#{@cache.inspect}"
-        @cache = {}
+      initialize!
     end
-      @cache[:targets] ||= {}
-      @cache[:directories] ||= {}
+
+    # Remove the cache file.
+    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
-      @cache[:version] = VERSION
-      File.open(CACHE_FILE, 'w') do |fh|
-        fh.puts(YAML.dump(@cache))
+      if @dirty || (@cache["version"] != VERSION)
+        @cache["version"] = VERSION
+        File.open(CACHE_FILE, "w") do |fh|
+          fh.puts(JSON.dump(@cache))
         end
       end
+      @dirty = false
+    end
 
     # 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 env [Environment] The Rscons::Environment.
-    # @param options [Hash] Optional options. Can contain the following keys:
-    #   :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 if the targets are all 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
@@ -111,16 +111,16 @@ module Rscons
         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] || []
-        cached_deps_fnames = cached_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_fnames
@@ -131,13 +131,13 @@ 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_fnames = cached_user_deps.map { |dc| dc[:fname] }
+        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
         (cached_deps + cached_user_deps).each do |dep_cache|
-          return false unless dep_cache[:checksum] == lookup_checksum(dep_cache[:fname])
+          return false unless dep_cache["checksum"] == lookup_checksum(dep_cache["fname"])
         end
       end
 
@@ -148,54 +148,70 @@ module Rscons
     # @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.
+    # @param env [Environment] The {Rscons::Environment}.
     def register_build(targets, command, deps, env)
       Array(targets).each do |target|
-        @cache[:targets][target.encode(__ENCODING__)] = {
-          command: command,
-          checksum: calculate_checksum(target),
-          deps: deps.map do |dep|
+        @cache["targets"][target] = {
+          "command" => Digest::MD5.hexdigest(command.inspect),
+          "checksum" => calculate_checksum(target),
+          "deps" => deps.map do |dep|
             {
-              fname: dep.encode(__ENCODING__),
-              checksum: lookup_checksum(dep),
+              "fname" => dep,
+              "checksum" => lookup_checksum(dep),
             }
           end,
-          user_deps: (env.get_user_deps(target) || []).map do |dep|
+          "user_deps" => (env.get_user_deps(target) || []).map do |dep|
             {
-              fname: dep.encode(__ENCODING__),
-              checksum: lookup_checksum(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-1).each do |i|
-        subpath = File.join(*parts[0, i + 1]).encode(__ENCODING__)
+      parts.each_index do |i|
+        next if parts[i] == ""
+        subpath = File.join(*parts[0, i + 1])
         unless File.exists?(subpath)
           FileUtils.mkdir(subpath)
-          @cache[:directories][subpath] = true
+          @cache["directories"][subpath] = true
+          @dirty = true
         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.
@@ -206,7 +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

@@ -86,7 +86,7 @@ module Rscons
           env.add_builder(builder)
         end
       end
-      env.append(@varset.clone) if clone.include?(: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|
@@ -164,39 +164,45 @@ 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
 
     # 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?
+        expand_paths!
+        cache = Cache.instance
+        cache.clear_checksum_cache!
         targets_processed = {}
         process_target = proc do |target|
           targets_processed[target] ||= begin
-          @targets[target][:source].each do |src|
+            @targets[target][: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],
                                  target,
-                               @targets[target][:source],
+                                 @targets[target][:sources],
                                  cache,
                                  @targets[target][:vars] || {})
             unless result
-            cache.write
               raise BuildError.new("Failed to build #{target}")
             end
             result
           end
         end
-      @targets.each do |target, info|
+        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
@@ -224,7 +230,9 @@ module Rscons
     # @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(' ')
@@ -234,7 +242,9 @@ module Rscons
       elsif @echo == :short
         puts short_desc
       end
-      system(*command, options).tap do |result|
+      env_args = options[:env] ? [options[:env]] : []
+      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
@@ -242,25 +252,28 @@ module Rscons
       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)
-        @targets[target] = {
-          builder: @builders[method.to_s],
-          source: source,
-          vars: vars,
-          args: rest,
-        }
+        sources = Array(sources)
+        add_target(target, @builders[method.to_s], sources, vars, rest)
       else
-        orig_method_missing(method, *args)
+        super
       end
     end
 
+    def add_target(target, builder, sources, vars, args)
+      @targets[target] = {
+        builder: builder,
+        sources: sources,
+        vars: vars,
+        args: args,
+      }
+    end
+
     # Manually record a given target as depending on the specified
     # dependency files.
     def depends(target, *user_deps)
@@ -317,12 +330,45 @@ module Rscons
           target: target,
           sources: sources,
           vars: vars,
+          env: self,
         }
         build_hook_block.call(build_operation)
       end
       builder.run(target, sources, cache, self, vars)
     end
 
+    # Expand a path to be relative to the Environment's build root.
+    #
+    # Paths beginning with "^/" are expanded by replacing "^" with the
+    # Environment's build root.
+    #
+    # @param path [String] The path to expand.
+    #
+    # @return [String] The expanded path.
+    def expand_path(path)
+      path.sub(%r{^\^(?=[\\/])}, @build_root)
+    end
+
+    private
+
+    # Expand target and source paths before invoking builders.
+    #
+    # This method expand construction variable references in the target and
+    # source file names before passing them to the builder. It also expands
+    # "^/" prefixes to the Environment's build root if a build root is defined.
+    def expand_paths!
+      @targets = @targets.reduce({}) do |result, (target, target_params)|
+        sources = target_params[:sources].map do |source|
+          source = expand_path(source) if @build_root
+          expand_varref(source)
+        end
+        target = expand_path(target) if @build_root
+        target = expand_varref(target)
+        result[target] = target_params.merge(sources: sources)
+        result
+      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.

lib/rscons/varset.rb

@@ -1,45 +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
-    attr_reader :vars
-
-    # Create a VarSet
+    # Create a VarSet.
     # @param vars [Hash] Optional initial variables.
     def initialize(vars = {})
-      if vars.is_a?(VarSet)
-        @vars = vars.clone.vars
-      else
-        @vars = vars
-      end
+      @my_vars = {}
+      @coa_vars = []
+      append(vars)
     end
 
     # Access the value of variable as a particular type
     # @param key [String, Symbol] The variable name.
+    # @return [Object] The variable's value.
     def [](key)
-      @vars[key]
+      if @my_vars.include?(key)
+        @my_vars[key]
+      else
+        @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)
-      @vars.merge!(Marshal.load(Marshal.dump(values)))
+      coa!
+      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
 
@@ -54,18 +82,47 @@ module Rscons
       else
         if varref =~ /^(.*)\$\{([^}]+)\}(.*)$/
           prefix, varname, suffix = $1, $2, $3
-          varval = expand_varref(@vars[varname])
+          varval = expand_varref(self[varname])
           if varval.is_a?(String)
             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} => #{@vars[varname].inspect})"
+            raise "I do not know how to expand a variable reference to a #{varval.class.name} (from #{varname.inspect} => #{self[varname].inspect})"
           end
         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 = "1.2.0"
+  VERSION = "1.4.2"
 end

spec/build_tests_spec.rb

@@ -1,5 +1,14 @@
 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"
 
@@ -180,6 +189,23 @@ describe Rscons do
     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
     test_dir('build_dir')
     Rscons::Environment.new do |env|
@@ -428,4 +454,74 @@ EOF
       `./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
+
+  it "supports invoking builders with no sources and a build_root defined" do
+    class TestBuilder < Rscons::Builder
+      def run(target, sources, cache, env, vars)
+        target
+      end
+    end
+    test_dir("simple")
+    Rscons::Environment.new do |env|
+      env.build_root = "build"
+      env.add_builder(TestBuilder.new)
+      env.TestBuilder("file")
+    end
+  end
+
+  it "expands construction variables in builder target and sources before invoking the builder" do
+    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 678
+EOF
+        end
+        target
+      end
+    end
+
+    Rscons::Environment.new do |env|
+      env["hdr"] = "inc.h"
+      env["src"] = "program.c"
+      env.add_builder(MySource.new)
+      env.MySource('${hdr}')
+      env.Program('program', "${src}")
+    end
+
+    lines.should == ['CC program.o', 'LD program']
+    File.exists?('inc.h').should be_true
+    `./program`.should == "The value is 678\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

@@ -5,35 +5,42 @@ module Rscons
     end
 
     def build_from(cache)
-      YAML.should_receive(:load).and_return(cache)
-      Cache.new
+      JSON.stub(:load) do
+        cache
       end
-
-    describe ".clear" do
-      it "removes the cache file" do
-        FileUtils.should_receive(:rm_f).with(Cache::CACHE_FILE)
-        Cache.clear
+      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
-          YAML.should_receive(:load).and_return("string")
+          JSON.should_receive(:load).and_return("string")
           $stderr.should_receive(:puts).with(/Warning:.*was.corrupt/)
-          Cache.new.instance_variable_get(:@cache).is_a?(Hash).should be_true
+          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
+      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
+        cache["version"].should == Rscons::VERSION
       end
     end
 
@@ -54,7 +61,7 @@ module Rscons
       end
 
       it "returns false when the target's checksum does not match" do
-        _cache = {targets: {"target" => {checksum: "abc"}}}
+        _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")
@@ -62,7 +69,7 @@ module Rscons
       end
 
       it "returns false when the build command has changed" do
-        _cache = {targets: {"target" => {checksum: "abc", command: "old command"}}}
+        _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")
@@ -70,9 +77,9 @@ module Rscons
       end
 
       it "returns false when there is a new dependency" do
-        _cache = {targets: {"target" => {checksum: "abc",
-                                         command: "command",
-                                         deps: [{fname: "dep.1"}]}}}
+        _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")
@@ -80,15 +87,15 @@ module Rscons
       end
 
       it "returns false when a dependency's checksum has changed" do
-        _cache = {targets: {"target" => {checksum: "abc",
-                                         command: "command",
-                                         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 = {"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")
@@ -98,15 +105,15 @@ module Rscons
       end
 
       it "returns false with strict_deps=true when cache has an extra dependency" do
-        _cache = {targets: {"target" => {checksum: "abc",
-                                         command: "command",
-                                         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 = {"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")
@@ -114,10 +121,10 @@ module Rscons
       end
 
       it "returns false when there is a new user dependency" do
-        _cache = {targets: {"target" => {checksum: "abc",
-                                         command: "command",
-                                         deps: [{fname: "dep.1"}],
-                                         user_deps: []}}}
+        _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"])
@@ -127,16 +134,16 @@ module Rscons
       end
 
       it "returns false when a user dependency checksum has changed" do
-        _cache = {targets: {"target" => {checksum: "abc",
-                                         command: "command",
-                                         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 = {"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"])
@@ -150,15 +157,15 @@ module Rscons
       end
 
       it "returns true when no condition for false is met" do
-        _cache = {targets: {"target" => {checksum: "abc",
-                                         command: "command",
-                                         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 = {"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")
@@ -180,23 +187,23 @@ module Rscons
         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 = cache.instance_variable_get(:@cache)["targets"]["the target"]
         cached_target.should_not be_nil
-        cached_target[:command].should == "the command"
-        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["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"},
+        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" => {}}}
+        cache = {"targets" => {"t1" => {}, "t2" => {}, "t3" => {}}}
         build_from(cache).targets.should == ["t1", "t2", "t3"]
       end
     end
@@ -218,11 +225,21 @@ module Rscons
         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}}
+        _cache = {"directories" => {"dir1" => true, "dir2" => true}}
         build_from(_cache).directories.should == ["dir1", "dir2"]
       end
     end

spec/rscons/environment_spec.rb

@@ -140,7 +140,8 @@ module Rscons
         env.Program("a.out", "main.c")
 
         cache = "cache"
-        Cache.should_receive(:new).and_return(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)
 
@@ -153,7 +154,8 @@ module Rscons
         env.Object("main.o", "other.cc")
 
         cache = "cache"
-        Cache.should_receive(:new).and_return(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)
@@ -167,12 +169,28 @@ module Rscons
         env.Object("main.o", "other.cc")
 
         cache = "cache"
-        Cache.should_receive(:new).and_return(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
@@ -219,7 +237,7 @@ module Rscons
           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.should_receive(:system).with("a", "command").and_return(true)
             env.execute("short desc", ["a", "command"])
           end
         end
@@ -228,7 +246,7 @@ module Rscons
           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)
+            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"])
@@ -240,8 +258,8 @@ module Rscons
         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("a", "command", "--arg=val with spaces", opt: :val).and_return(false)
-          env.execute("short desc", ["a", "command", "--arg=val with spaces"], opt: :val)
+          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
@@ -249,8 +267,7 @@ module Rscons
     describe "#method_missing" do
       it "calls the original method missing when the target method is not a known builder" do
         env = Environment.new
-        env.should_receive(:orig_method_missing).with(:foobar)
-        env.foobar
+        expect {env.foobar}.to raise_error /undefined method .foobar./
       end
 
       it "records the target when the target method is a known builder" do
@@ -260,7 +277,7 @@ module Rscons
         target = env.instance_variable_get(:@targets)["target"]
         target.should_not be_nil
         target[:builder].is_a?(Builder).should be_true
-        target[:source].should == ["src1", "src2"]
+        target[:sources].should == ["src1", "src2"]
         target[:vars].should == {var: "val"}
         target[:args].should == []
       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
@@ -20,10 +20,10 @@ 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
@@ -32,7 +32,7 @@ module Rscons
       end
     end
 
-    describe :[]= do
+    describe "#[]=" do
       it "allows assigning to variables" do
         v = VarSet.new("CFLAGS" => ["-Wall", "-O3"])
         v["CPPPATH"] = ["one", "two"]
@@ -41,40 +41,86 @@ 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"]
-        v["CPPPATH"].should == ["different_dir"]
+        expect(v["CFLAGS"]).to eq(["-O0"])
+        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"]
-        v2.vars.keys.should =~ ["foo", "baz"]
+        expect(v["foo"]).to eq("yoda")
+        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"]
-        v["bar"].should == 42
-        v2["foo"].should == ["a", "b", "c"]
-        v2["bar"].should == 33
+        expect(v["foo"]).to eq ["a", "b"]
+        expect(v["bar"]).to eq 42
+        expect(v2["foo"]).to eq ["a", "b", "c"]
+        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"],

spec/rscons_spec.rb

@@ -2,7 +2,7 @@ describe Rscons do
   describe ".clean" do
     it "removes all build targets and created directories" do
       cache = "cache"
-      Rscons::Cache.should_receive(:new).and_return(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")
@@ -18,7 +18,7 @@ describe Rscons do
       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"])
-      Rscons::Cache.should_receive(:clear)
+      cache.should_receive(:clear)
 
       Rscons.clean
     end