1 files changed, 155 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/utils/url_encoded_pair_parser.rb b/actionpack/lib/action_dispatch/utils/url_encoded_pair_parser.rb
new file mode 100644
index 0000000000..f2e832a977
--- /dev/null
+++ b/actionpack/lib/action_dispatch/utils/url_encoded_pair_parser.rb
@@ -0,0 +1,155 @@
+module ActionDispatch
+  class UrlEncodedPairParser < StringScanner #:nodoc:
+    class << self
+      def parse_query_parameters(query_string)
+        return {} if query_string.blank?
+
+        pairs = query_string.split('&').collect do |chunk|
+          next if chunk.empty?
+          key, value = chunk.split('=', 2)
+          next if key.empty?
+          value = value.nil? ? nil : CGI.unescape(value)
+          [ CGI.unescape(key), value ]
+        end.compact
+
+        new(pairs).result
+      end
+
+      def parse_hash_parameters(params)
+        parser = new
+
+        params = params.dup
+        until params.empty?
+          for key, value in params
+            if key.blank?
+              params.delete(key)
+            elsif value.is_a?(Array)
+              parser.parse(key, get_typed_value(value.shift))
+              params.delete(key) if value.empty?
+            else
+              parser.parse(key, get_typed_value(value))
+              params.delete(key)
+            end
+          end
+        end
+
+        parser.result
+      end
+
+      private
+        def get_typed_value(value)
+          case value
+          when String
+            value
+          when NilClass
+            ''
+          when Array
+            value.map { |v| get_typed_value(v) }
+          when Hash
+            if value.has_key?(:tempfile) && value[:filename].any?
+              upload = value[:tempfile]
+              upload.extend(UploadedFile)
+              upload.original_path = value[:filename]
+              upload.content_type = value[:type]
+              upload
+            else
+              nil
+            end
+          else
+            raise "Unknown form value: #{value.inspect}"
+          end
+        end
+    end
+
+    attr_reader :top, :parent, :result
+
+    def initialize(pairs = [])
+      super('')
+      @result = {}
+      pairs.each { |key, value| parse(key, value) }
+    end
+
+    KEY_REGEXP = %r{([^\[\]=&]+)}
+    BRACKETED_KEY_REGEXP = %r{\[([^\[\]=&]+)\]}
+
+    # Parse the query string
+    def parse(key, value)
+      self.string = key
+      @top, @parent = result, nil
+
+      # First scan the bare key
+      key = scan(KEY_REGEXP) or return
+      key = post_key_check(key)
+
+      # Then scan as many nestings as present
+      until eos?
+        r = scan(BRACKETED_KEY_REGEXP) or return
+        key = self[1]
+        key = post_key_check(key)
+      end
+
+      bind(key, value)
+    end
+
+    private
+      # After we see a key, we must look ahead to determine our next action. Cases:
+      #
+      #   [] follows the key. Then the value must be an array.
+      #   = follows the key. (A value comes next)
+      #   & or the end of string follows the key. Then the key is a flag.
+      #   otherwise, a hash follows the key.
+      def post_key_check(key)
+        if scan(/\[\]/) # a[b][] indicates that b is an array
+          container(key, Array)
+          nil
+        elsif check(/\[[^\]]/) # a[b] indicates that a is a hash
+          container(key, Hash)
+          nil
+        else # End of key? We do nothing.
+          key
+        end
+      end
+
+      # Add a container to the stack.
+      def container(key, klass)
+        type_conflict! klass, top[key] if top.is_a?(Hash) && top.key?(key) && ! top[key].is_a?(klass)
+        value = bind(key, klass.new)
+        type_conflict! klass, value unless value.is_a?(klass)
+        push(value)
+      end
+
+      # Push a value onto the 'stack', which is actually only the top 2 items.
+      def push(value)
+        @parent, @top = @top, value
+      end
+
+      # Bind a key (which may be nil for items in an array) to the provided value.
+      def bind(key, value)
+        if top.is_a? Array
+          if key
+            if top[-1].is_a?(Hash) && ! top[-1].key?(key)
+              top[-1][key] = value
+            else
+              top << {key => value}.with_indifferent_access
+            end
+            push top.last
+            return top[key]
+          else
+            top << value
+            return value
+          end
+        elsif top.is_a? Hash
+          key = CGI.unescape(key)
+          parent << (@top = {}) if top.key?(key) && parent.is_a?(Array)
+          top[key] ||= value
+          return top[key]
+        else
+          raise ArgumentError, "Don't know what to do: top is #{top.inspect}"
+        end
+      end
+
+      def type_conflict!(klass, value)
+        raise TypeError, "Conflicting types for parameter containers. Expected an instance of #{klass} but found an instance of #{value.class}. This can be caused by colliding Array and Hash parameters like qs[]=value&qs[key]=value. (The parameters received were #{value.inspect}.)"
+      end
+  end
+end