From 6e347d5cca282de32c639a5fe650804fedfe27fa Mon Sep 17 00:00:00 2001
From: Nathan Weizenbaum <nex342@gmail.com>
Date: Sun, 12 Oct 2008 20:26:56 -0700
Subject: [PATCH] Delay SassScript variable resolution until #perform.

---
 lib/sass/script.rb                 |  3 ++-
 lib/sass/script/funcall.rb         | 10 +++-------
 lib/sass/script/literal.rb         |  2 +-
 lib/sass/script/operation.rb       | 10 +++-------
 lib/sass/script/parser.rb          |  9 +++------
 lib/sass/script/unary_operation.rb |  8 ++------
 lib/sass/script/variable.rb        | 20 ++++++++++++++++++++
 7 files changed, 34 insertions(+), 28 deletions(-)
 create mode 100644 lib/sass/script/variable.rb

diff --git a/lib/sass/script.rb b/lib/sass/script.rb
index 3afbb30b..d625811f 100644
--- a/lib/sass/script.rb
+++ b/lib/sass/script.rb
@@ -1,4 +1,5 @@
 require 'strscan'
+require 'sass/script/variable'
 require 'sass/script/funcall'
 require 'sass/script/operation'
 require 'sass/script/literal'
@@ -22,7 +23,7 @@ module Sass
     end
 
     def self.parse(value, environment, line)
-      Parser.parse(value, environment).perform
+      Parser.parse(value).perform(environment)
     rescue Sass::SyntaxError => e
       if e.message == "SassScript error"
         e.instance_eval do
diff --git a/lib/sass/script/funcall.rb b/lib/sass/script/funcall.rb
index 519bbc97..e67a9278 100644
--- a/lib/sass/script/funcall.rb
+++ b/lib/sass/script/funcall.rb
@@ -8,18 +8,14 @@ module Sass
         @args = args
       end
 
-      def to_s
-        perform.to_s
-      end
-
       def inspect
         "#{name}(#{args.map {|a| a.inspect}.join(', ')})"
       end
 
-      def perform
-        args = self.args.map {|a| a.perform}
+      def perform(environment)
+        args = self.args.map {|a| a.perform(environment)}
         unless Functions.public_instance_methods.include?(name) && name !~ /^__/
-          return Script::String.new("#{name}(#{args.join(', ')})")
+          return Script::String.new("#{name}(#{args.map {|a| a.perform(environment)}.join(', ')})")
         end
 
         return Functions.send(name, *args)
diff --git a/lib/sass/script/literal.rb b/lib/sass/script/literal.rb
index fbe935a4..cfb97ef8 100644
--- a/lib/sass/script/literal.rb
+++ b/lib/sass/script/literal.rb
@@ -10,7 +10,7 @@ class Sass::Script::Literal # :nodoc:
     @value = value
   end
 
-  def perform
+  def perform(environment)
     self
   end
 
diff --git a/lib/sass/script/operation.rb b/lib/sass/script/operation.rb
index 75cbe820..4781a6b0 100644
--- a/lib/sass/script/operation.rb
+++ b/lib/sass/script/operation.rb
@@ -12,17 +12,13 @@ module Sass::Script
       @operator = operator
     end
 
-    def to_s
-      self.perform.to_s
-    end
-
     def inspect
       "(#{@operator.inspect} #{@operand1.inspect} #{@operand2.inspect})"
     end
 
-    def perform
-      literal1 = @operand1.perform
-      literal2 = @operand2.perform
+    def perform(environment)
+      literal1 = @operand1.perform(environment)
+      literal2 = @operand2.perform(environment)
       begin
         literal1.send(@operator, literal2)
       rescue NoMethodError => e
diff --git a/lib/sass/script/parser.rb b/lib/sass/script/parser.rb
index 96bd4138..7474cab2 100644
--- a/lib/sass/script/parser.rb
+++ b/lib/sass/script/parser.rb
@@ -2,10 +2,9 @@ require 'sass/script/lexer'
 
 module Sass
   module Script
-    class Parser # :nodoc:
-      def initialize(str, environment = {})
+    class Parser
+      def initialize(str)
         @lexer = Lexer.new(str)
-        @environment = environment
       end
 
       def parse
@@ -88,9 +87,7 @@ RUBY
 
       def variable
         return literal unless c = try_tok(:const)
-        (val = @environment[c.last]) && (return val)
-
-        raise SyntaxError.new("Undefined variable: \"!#{c.last}\".")
+        Variable.new(c.last)
       end
 
       def literal
diff --git a/lib/sass/script/unary_operation.rb b/lib/sass/script/unary_operation.rb
index 7209515e..9f82502d 100644
--- a/lib/sass/script/unary_operation.rb
+++ b/lib/sass/script/unary_operation.rb
@@ -5,17 +5,13 @@ module Sass::Script
       @operator = operator
     end
 
-    def to_s
-      self.perform.to_s
-    end
-
     def inspect
       "(#{@operator.inspect} #{@operand.inspect})"
     end
 
-    def perform
+    def perform(environment)
       operator = "unary_#{@operator}"
-      literal = @operand.perform
+      literal = @operand.perform(environment)
       literal.send(operator)
     rescue NoMethodError => e
       raise e unless e.name.to_s == operator.to_s
diff --git a/lib/sass/script/variable.rb b/lib/sass/script/variable.rb
new file mode 100644
index 00000000..33e157c0
--- /dev/null
+++ b/lib/sass/script/variable.rb
@@ -0,0 +1,20 @@
+module Sass
+  module Script
+    class Variable # :nodoc:
+      attr_reader :name
+
+      def initialize(name)
+        @name = name
+      end
+
+      def inspect
+        "!#{name}"
+      end
+
+      def perform(environment)
+        (val = environment[name]) && (return val)
+        raise SyntaxError.new("Undefined variable: \"!#{name}\".")
+      end
+    end
+  end
+end