Split dependency classes into separate files

1 files changed, 109 insertions, 0 deletions

diff --git a/Library/Homebrew/requirement.rb b/Library/Homebrew/requirement.rb
new file mode 100644
index 000000000..074d6ce07
--- /dev/null
+++ b/Library/Homebrew/requirement.rb
@@ -0,0 +1,109 @@
+require 'dependable'
+require 'build_environment'
+
+# A base class for non-formula requirements needed by formulae.
+# A "fatal" requirement is one that will fail the build if it is not present.
+# By default, Requirements are non-fatal.
+class Requirement
+  include Dependable
+  extend BuildEnvironmentDSL
+
+  attr_reader :tags
+
+  def initialize(*tags)
+    @tags = tags.flatten.compact
+    @tags << :build if self.class.build
+  end
+
+  # The message to show when the requirement is not met.
+  def message; "" end
+
+  # Overriding #satisfied? is deprepcated.
+  # Pass a block or boolean to the satisfied DSL method instead.
+  def satisfied?
+    result = self.class.satisfy.yielder do |proc|
+      instance_eval(&proc)
+    end
+
+    infer_env_modification(result)
+    !!result
+  end
+
+  # Overriding #fatal? is deprecated.
+  # Pass a boolean to the fatal DSL method instead.
+  def fatal?
+    self.class.fatal || false
+  end
+
+  # Overriding #modify_build_environment is deprecated.
+  # Pass a block to the the env DSL method instead.
+  def modify_build_environment
+    satisfied? and env.modify_build_environment(self)
+  end
+
+  def env
+    @env ||= self.class.env
+  end
+
+  def eql?(other)
+    other.is_a?(self.class) && hash == other.hash
+  end
+
+  def hash
+    message.hash
+  end
+
+  private
+
+  def infer_env_modification(o)
+    case o
+    when Pathname
+      self.class.env do
+        unless ENV["PATH"].split(":").include?(o.parent.to_s)
+          append("PATH", o.parent, ":")
+        end
+      end
+    end
+  end
+
+  class << self
+    def fatal(val=nil)
+      val.nil? ? @fatal : @fatal = val
+    end
+
+    def build(val=nil)
+      val.nil? ? @build : @build = val
+    end
+
+    def satisfy(options={}, &block)
+      @satisfied ||= Requirement::Satisfier.new(options, &block)
+    end
+  end
+
+  class Satisfier
+    def initialize(options={}, &block)
+      case options
+      when Hash
+        @options = { :build_env => true }
+        @options.merge!(options)
+      else
+        @satisfied = options
+      end
+      @proc = block
+    end
+
+    def yielder
+      if instance_variable_defined?(:@satisfied)
+        @satisfied
+      elsif @options[:build_env]
+        require 'superenv'
+        ENV.with_build_environment do
+          ENV.userpaths!
+          yield @proc
+        end
+      else
+        yield @proc
+      end
+    end
+  end
+end