Improve boolean conversions. (Closes #29)

Prior to this commit, code like

    %param{ :value => 'false' }
    %param{ :value => 'true' }

 would be treated like boolean values, but they should be
 passed unmodified. This behaviour was changed in the
 HAML compiler, but leads to a further change:

 The boolean logic conversion at runtime, wasn't able to
 distinguish between real booleans and boolean like text
 attributes. The workaround to this is to let the clean function
 (`$c`) mark real boolean values with a hidden unicode marker
 character.

README.md

@@ -493,7 +493,10 @@ since there is no Haml markup for this to instruct the compiler to change the es
 * Default: `true`
 
 Every output that is generated from evaluating CoffeeScript code is cleaned before inserting into the document. The
-default implementation converts `null` or `undefined` values into an empty string.
+default implementation converts `null` or `undefined` values into an empty string and marks real boolean values with a
+hidden marker character. The hidden marker character is necessary to distinguish between String values like `'true'`,
+`'false'` and real boolean values `true`, `false` in the markup, so that a boolean attribute conversion can quickly
+convert these values to the correct HTML5/XHTML/HTML4 representation.
 
 #### Preserve whitespace tags
 

spec/suites/templates/text/boolean_attributes_html5.html

@@ -1,11 +1,11 @@
 <input checked>
-<input checked>
-<input>
+<input checked='true'>
 <input>
+<input checked='false'>
 <input checked>
-<input checked>
-<input>
+<input checked='true'>
 <input>
+<input checked='false'>
 <tag name='value' name2 tag='100'></tag>
 <tag name='value' name2>
 <tag name='value' name2 ns:tag='100'></tag>

spec/suites/templates/text/boolean_attributes_xhtml.html

@@ -1,11 +1,11 @@
 <input checked='checked' />
-<input checked='checked' />
-<input />
+<input checked='true' />
 <input />
+<input checked='false' />
 <input checked='checked' />
-<input checked='checked' />
-<input />
+<input checked='true' />
 <input />
+<input checked='false' />
 <tag name='value' name2='name2' tag='100'></tag>
 <tag name='value' name2='name2' />
 <tag name='value' name2='name2' ns:tag='100'></tag>

src/haml-coffee.coffee

@@ -343,7 +343,11 @@ module.exports = class HamlCoffee
       if @options.customCleanValue
         fn += "$c = #{ @options.customCleanValue }\n"
       else
-        fn += "$c = (text) -> if text is null or text is undefined then '' else text\n"
+        fn += "$c = (text) ->\n"
+        fn += "   switch text\n"
+        fn += "     when null, undefined then ''\n"
+        fn += "     when true, false then '\u0093' + text"
+        fn += "     else text\n"
 
     # Preserve whitespace
     if code.indexOf('$p') isnt -1 || code.indexOf('$fp') isnt -1
@@ -466,7 +470,11 @@ module.exports = class HamlCoffee
     combined
 
   # Adds a boolean convert logic that changes boolean attribute
-  # values depending on the output format.
+  # values depending on the output format. This works only when
+  # the clean value function add a hint marker (\u0093) to each
+  # boolean value, so that the conversion logic can disinguish
+  # between dynamic, real boolean values and string values like
+  # 'false' and 'true' or  compile time attributes.
   #
   # With the XHTML format, an attribute `checked='true'` will be
   # converted to `checked='checked'` and `checked='false'` will
@@ -480,9 +488,9 @@ module.exports = class HamlCoffee
   #
   convertBooleans: (code) ->
     if @options.format is 'xhtml'
-      '.replace(/\\s(\\w+)=\'true\'/mg, " $1=\'$1\'").replace(/\\s(\\w+)=\'false\'/mg, \'\')'
+      '.replace(/\\s(\\w+)=\'\u0093true\'/mg, " $1=\'$1\'").replace(/\\s(\\w+)=\'\u0093false\'/mg, \'\')'
     else
-      '.replace(/\\s(\\w+)=\'true\'/mg, \' $1\').replace(/\\s(\\w+)=\'false\'/mg, \'\')'
+      '.replace(/\\s(\\w+)=\'\u0093true\'/mg, \' $1\').replace(/\\s(\\w+)=\'\u0093false\'/mg, \'\')'
 
   # Adds whitespace cleanup function when needed by the
   # template. The cleanup must be done AFTER the template

src/nodes/haml.coffee

@@ -264,41 +264,37 @@ module.exports = class Haml extends Node
 
     # Prepare all attributes
     for key, value of @extractAttributes(exp)
-      bool  = false
-
-      # Ignore attributes some attribute values
-      if ['false', ''].indexOf(value) is -1
-
-        # Set key to value if the value is boolean true
-        if ['true'].indexOf(value) isnt -1
-          value = "'#{ key }'"
-          bool  = true
-
-        # Wrap plain attributes into an interpolation, expect boolean values
-        else if not value.match /^("|').*\1$/
-          if @escapeAttributes
-            if @cleanValue
-              value = '\'#{ $e($c(' + value + ')) }\''
-            else
-              value = '\'#{ $e(' + value + ') }\''
+      bool = false
+
+      # Handle boolean values
+      if value is 'true' or value is 'false'
+        bool = true
+
+      # Wrap plain attributes into an interpolation, expect boolean values
+      else if not value.match /^("|').*\1$/
+        if @escapeAttributes
+          if @cleanValue
+            value = '\'#{ $e($c(' + value + ')) }\''
           else
-            if @cleanValue
-              value = '\'#{ $c(' + value + ') }\''
-            else
-              value = '\'#{ (' + value + ') }\''
-
-        # Unwrap value from quotes
-        value = quoted[2] if quoted = value.match /^("|')(.*)\1$/
+            value = '\'#{ $e(' + value + ') }\''
+        else
+          if @cleanValue
+            value = '\'#{ $c(' + value + ') }\''
+          else
+            value = '\'#{ (' + value + ') }\''
 
-        # Unwrap key from quotes
-        key = quoted[2] if quoted = key.match /^("|')(.*)\1$/
+      # Unwrap value from quotes
+      value = quoted[2] if quoted = value.match /^("|')(.*)\1$/
 
-        attributes.push {
-          key   : key
-          value : value
-          bool  : bool
-        }
+      # Unwrap key from quotes
+      key = quoted[2] if quoted = key.match /^("|')(.*)\1$/
 
+      attributes.push {
+        key   : key
+        value : value
+        bool  : bool
+      }
+
     attributes
 
   # Extracts the attributes from the expression.
@@ -351,7 +347,8 @@ module.exports = class Haml extends Node
     # Split into key value pairs
     pairs = exp.split(keys).filter(Boolean)
 
-    dataAttribute = false
+    inDataAttribute = false
+    hasDataAttribute = false
 
     # Process the pairs in a group of two
     while pairs.length
@@ -365,19 +362,22 @@ module.exports = class Haml extends Node
       value = keyValue[1]?.replace(/^\s+|[\s,]+$/g, '').replace(/\u0090/, '')
 
       if key is 'data'
-        dataAttribute = true
+        inDataAttribute = true
+        hasDataAttribute = true
 
       else if key and value
-        if dataAttribute
+        if inDataAttribute
           key = "data-#{ key }"
-          dataAttribute = false if /}\s*$/.test value
+          inDataAttribute = false if /}\s*$/.test value
 
       switch type
         when '('
           attributes[key] = value.replace(/^\s+|[\s)]+$/g, '')
         when '{'
           attributes[key] = value.replace(/^\s+|[\s}]+$/g, '')
 
+    delete attributes['data'] if hasDataAttribute
+
     attributes
 
   # Build the HTML tag prefix by concatenating all the
@@ -424,8 +424,18 @@ module.exports = class Haml extends Node
     # Construct tag attributes
     if tokens.attributes
       for attribute in tokens.attributes
-        if attribute.bool and @format is 'html5'
-          tagParts.push "#{ attribute.key }"
+
+        # Boolean attribute logic
+        if attribute.bool
+
+          # Only show true values
+          if attribute.value is 'true'
+            if @format is 'html5'
+              tagParts.push "#{ attribute.key }" 
+            else
+              tagParts.push "#{ attribute.key }=#{ @quoteAttributeValue(attribute.key) }"
+
+        # Anything but booleans
         else
           tagParts.push "#{ attribute.key }=#{ @quoteAttributeValue(attribute.value) }"