Add ActiveSupport::JSON and Object#to_json for converting Ruby objects to JSON strings

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3356 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

6 files changed, 144 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/core_ext/object_and_class.rb b/activesupport/lib/active_support/core_ext/object_and_class.rb
index aef1f22c6f..4856a9f5d5 100644
--- a/activesupport/lib/active_support/core_ext/object_and_class.rb
+++ b/activesupport/lib/active_support/core_ext/object_and_class.rb
@@ -54,6 +54,17 @@ class Object #:nodoc:
   def with_options(options)
     yield ActiveSupport::OptionMerger.new(self, options)
   end
+  
+  def instance_values
+    instance_variables.inject({}) do |values, name|
+      values[name[1..-1]] = instance_variable_get(name)
+      values
+    end
+  end
+  
+  def to_json
+    ActiveSupport::JSON.encode(self)
+  end
 end
 
 class Class #:nodoc:
diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index 979f8a0515..240e1ff1da 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -2,10 +2,12 @@ require File.dirname(__FILE__) + '/string/inflections'
 require File.dirname(__FILE__) + '/string/conversions'
 require File.dirname(__FILE__) + '/string/access'
 require File.dirname(__FILE__) + '/string/starts_ends_with'
+require File.dirname(__FILE__) + '/string/iterators'
 
 class String #:nodoc:
   include ActiveSupport::CoreExtensions::String::Access
   include ActiveSupport::CoreExtensions::String::Conversions
   include ActiveSupport::CoreExtensions::String::Inflections
   include ActiveSupport::CoreExtensions::String::StartsEndsWith
+  include ActiveSupport::CoreExtensions::String::Iterators
 end
diff --git a/activesupport/lib/active_support/core_ext/string/iterators.rb b/activesupport/lib/active_support/core_ext/string/iterators.rb
new file mode 100644
index 0000000000..73114d9d5f
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/string/iterators.rb
@@ -0,0 +1,17 @@
+require 'strscan'
+
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module String #:nodoc:
+      # Custom string iterators
+      module Iterators
+        # Yields a single-character string for each character in the string.
+        # When $KCODE = 'UTF8', multi-byte characters are yielded appropriately.
+        def each_char
+          scanner, char = StringScanner.new(self), /./mu
+          loop { yield(scanner.scan(char) || break) }
+        end
+      end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/json.rb b/activesupport/lib/active_support/json.rb
new file mode 100644
index 0000000000..77c7225c66
--- /dev/null
+++ b/activesupport/lib/active_support/json.rb
@@ -0,0 +1,28 @@
+require 'active_support/json/encoders'
+
+module ActiveSupport
+  module JSON #:nodoc:
+    class CircularReferenceError < StandardError; end
+      
+    class << self
+      REFERENCE_STACK_VARIABLE = :json_reference_stack
+      
+      def encode(value)
+        raise_on_circular_reference(value) do
+          Encoders[value.class].call(value)
+        end
+      end
+      
+      protected
+        def raise_on_circular_reference(value)
+          stack = Thread.current[REFERENCE_STACK_VARIABLE] ||= []
+          raise CircularReferenceError, 'object references itself' if
+            stack.include? value
+          stack << value
+          yield
+        ensure
+          stack.pop
+        end
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/json/encoders.rb b/activesupport/lib/active_support/json/encoders.rb
new file mode 100644
index 0000000000..c3e3619f59
--- /dev/null
+++ b/activesupport/lib/active_support/json/encoders.rb
@@ -0,0 +1,25 @@
+module ActiveSupport
+  module JSON #:nodoc:
+    module Encoders
+      mattr_accessor :encoders
+      @@encoders = {}
+
+      class << self        
+        def define_encoder(klass, &block)
+          encoders[klass] = block
+        end
+        
+        def [](klass)
+          klass.ancestors.each do |k|
+            encoder = encoders[k]
+            return encoder if encoder
+          end
+        end
+      end
+    end
+  end
+end
+
+Dir[File.dirname(__FILE__) + '/encoders/*.rb'].each do |file|
+  require file[0..-4]
+end
diff --git a/activesupport/lib/active_support/json/encoders/core.rb b/activesupport/lib/active_support/json/encoders/core.rb
new file mode 100644
index 0000000000..003c938be4
--- /dev/null
+++ b/activesupport/lib/active_support/json/encoders/core.rb
@@ -0,0 +1,61 @@
+module ActiveSupport
+  module JSON #:nodoc:
+    module Encoders
+      define_encoder Object do |object|
+        object.instance_values.to_json
+      end
+      
+      define_encoder TrueClass do
+        'true'
+      end
+      
+      define_encoder FalseClass do
+        'false'
+      end
+      
+      define_encoder NilClass do
+        'null'
+      end
+      
+      define_encoder String do |string|
+        returning value = '"' do
+          string.each_char do |char|
+            value << case
+            when char == "\010":  '\b'
+            when char == "\f":    '\f'
+            when char == "\n":    '\n'
+            when char == "\r":    '\r'
+            when char == "\t":    '\t'
+            when char == '"':     '\"'
+            when char == '\\':    '\\\\'  
+            when char.length > 1: "\\u#{'%04x' % char.unpack('U').first}"
+            else;                 char
+            end
+          end
+          value << '"'
+        end
+      end
+      
+      define_encoder Numeric do |numeric|
+        numeric.to_s
+      end
+      
+      define_encoder Symbol do |symbol|
+        symbol.to_s.to_json
+      end
+
+      define_encoder Enumerable do |enumerable|
+        "[#{enumerable.map { |value| value.to_json } * ', '}]"
+      end
+      
+      define_encoder Hash do |hash|
+        returning result = '{' do
+          result << hash.map do |pair|
+            pair.map { |value| value.to_json } * ': '
+          end * ', '
+          result << '}'
+        end
+      end
+    end
+  end
+end