Allow flexible indentation for Sass docs.

lib/sass/engine.rb

@@ -6,6 +6,7 @@ require 'sass/tree/attr_node'
 require 'sass/tree/directive_node'
 require 'sass/constant'
 require 'sass/error'
+require 'haml/shared'
 
 module Sass
   # This is the class where all the parsing and processing of the Sass
@@ -146,7 +147,7 @@ module Sass
 
         if tabs # if line isn't blank
           if tabs - old_tabs > 1
-            raise SyntaxError.new("#{tabs * 2} spaces were used for indentation. Sass must be indented using two spaces.", @line)
+            raise SyntaxError.new("The line was indented #{tabs - old_tabs} levels deeper than the previous line.", @line)
           end
           @lines << [line.strip, tabs]
 
@@ -162,19 +163,20 @@ module Sass
     # Counts the tabulation of a line.
     def count_tabs(line)
       return nil if line.strip.empty?
-      return nil unless spaces = line.index(/[^ ]/)
+      return 0 unless whitespace = line[/^\s+/]
 
-      if spaces % 2 == 1
-          raise SyntaxError.new(<<END.strip, @line)
-#{spaces} space#{spaces == 1 ? ' was' : 's were'} used for indentation. Sass must be indented using two spaces.
-END
-      elsif line[spaces] == ?\t
-        raise SyntaxError.new(<<END.strip, @line)
-A tab character was used for indentation. Sass must be indented using two spaces.
-Are you sure you have soft tabs enabled in your editor?
-END
+      if @indentation.nil?
+        @indentation = whitespace
+        return 1
       end
-      spaces / 2
+
+      tabs = whitespace.length / @indentation.length
+      return tabs if whitespace == @indentation * tabs
+
+      raise SyntaxError.new(<<END.strip.gsub("\n", ' '), @line)
+Inconsistent indentation: #{Haml::Shared.human_indentation whitespace, true} used for indentation,
+but the rest of the document was indented using #{Haml::Shared.human_indentation @indentation}.
+END
     end
 
     def build_tree(index)

test/sass/engine_test.rb

@@ -36,12 +36,6 @@ class SassEngineTest < Test::Unit::TestCase
     "!a" => 'Invalid constant: "!a".',
     "! a" => 'Invalid constant: "! a".',
     "!a b" => 'Invalid constant: "!a b".',
-    "a\n\t:b c" => <<END.strip,
-A tab character was used for indentation. Sass must be indented using two spaces.
-Are you sure you have soft tabs enabled in your editor?
-END
-    "a\n :b c" => "1 space was used for indentation. Sass must be indented using two spaces.",
-    "a\n    :b c" => "4 spaces were used for indentation. Sass must be indented using two spaces.",
     "a\n  :b c\n  !d = 3" => "Constants may only be declared at the root of a document.",
     "!a = 1b + 2c" => "Incompatible units: b and c.",
     "& a\n  :b c" => "Base-level rules cannot contain the parent-selector-referencing character '&'.",
@@ -58,6 +52,14 @@ END
     "=foo\n  :color red\n.bar\n  +bang" => "Undefined mixin 'bang'.",
     ".bar\n  =foo\n    :color red\n" => "Mixins may only be defined at the root of a document.",
     "=foo\n  :color red\n.bar\n  +foo\n    :color red" => "Illegal nesting: Nothing may be nested beneath mixin directives.",
+    "a\n  b: c\n b: c" => ["Inconsistent indentation: 1 space was used for indentation, but the rest of the document was indented using 2 spaces.", 3],
+    "a\n  b: c\na\n b: c" => ["Inconsistent indentation: 1 space was used for indentation, but the rest of the document was indented using 2 spaces.", 4],
+    "a\n\t\tb: c\n\tb: c" => ["Inconsistent indentation: 1 tab was used for indentation, but the rest of the document was indented using 2 tabs.", 3],
+    "a\n  b: c\n   b: c" => ["Inconsistent indentation: 3 spaces were used for indentation, but the rest of the document was indented using 2 spaces.", 3],
+    "a\n \t b: c\n  \tb: c" => ['Inconsistent indentation: "  \t" was used for indentation, but the rest of the document was indented using " \t ".', 3],
+    "a\n  b: c\n  a\n   d: e" => ["Inconsistent indentation: 3 spaces were used for indentation, but the rest of the document was indented using 2 spaces.", 4],
+    "a\n  b: c\na\n    d: e" => ["The line was indented 2 levels deeper than the previous line.", 4],
+    "a\n  b: c\n  a\n        d: e" => ["The line was indented 3 levels deeper than the previous line.", 4],
 
     # Regression tests
     "a\n  b:\n    c\n    d" => ["Illegal nesting: Only attributes may be nested beneath attributes.", 3]
@@ -79,6 +81,15 @@ END
     renders_correctly "compressed", { :style => :compressed }
   end
   
+  def test_flexible_tabulation
+    assert_equal("p {\n  a: b; }\n  p q {\n    c: d; }\n",
+                 render("p\n a: b\n q\n  c: d\n"))
+    assert_equal("p {\n  a: b; }\n  p q {\n    c: d; }\n",
+                 render("p\n\ta: b\n\tq\n\t\tc: d\n"))
+    assert_equal("p {\n  a: b; }\n  p q {\n    c: d; }\n",
+                 render("p\n  \t \t a: b\n  \t \t q\n  \t \t   \t \t c: d\n"))
+  end
+  
   def test_exceptions
     EXCEPTION_MAP.each do |key, value|
       begin