Separate expression parsing and rendering from Context#resolve.

lib/liquid.rb

@@ -52,11 +52,14 @@ require 'liquid/extensions'
 require 'liquid/errors'
 require 'liquid/interrupts'
 require 'liquid/strainer'
+require 'liquid/expression'
 require 'liquid/context'
 require 'liquid/tag'
 require 'liquid/block'
 require 'liquid/document'
 require 'liquid/variable'
+require 'liquid/variable_lookup'
+require 'liquid/range_lookup'
 require 'liquid/file_system'
 require 'liquid/template'
 require 'liquid/standardfilters'

lib/liquid/context.rb

@@ -16,15 +16,13 @@ module Liquid
     attr_reader :scopes, :errors, :registers, :environments, :resource_limits
     attr_accessor :exception_handler
 
-    SQUARE_BRACKETED = /\A\[(.*)\]\z/m
-
     def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = {})
       @environments     = [environments].flatten
       @scopes           = [(outer_scope || {})]
       @registers        = registers
       @errors           = []
       @resource_limits  = (resource_limits || {}).merge!({ :render_score_current => 0, :assign_score_current => 0 })
-      @parsed_variables = Hash.new{ |cache, markup| cache[markup] = variable_parse(markup) } 
+      @parsed_expression = Hash.new{ |cache, markup| cache[markup] = Expression.parse(markup) }
       squash_instance_assigns_with_environments
 
       @this_stack_used = false
@@ -163,23 +161,6 @@ module Liquid
       @scopes[0][key] = value
     end
 
-    def [](key)
-      resolve(key)
-    end
-
-    def has_key?(key)
-      resolve(key) != nil
-    end
-
-    private
-      LITERALS = {
-        nil => nil, 'nil'.freeze => nil, 'null'.freeze => nil, ''.freeze => nil,
-        'true'.freeze  => true,
-        'false'.freeze => false,
-        'blank'.freeze => :blank?,
-        'empty'.freeze => :empty?
-      }
-
     # Look up variable, either resolve directly after considering the name. We can directly handle
     # Strings, digits, floats and booleans (true,false).
     # If no match is made we lookup the variable in the current scope and
@@ -188,25 +169,16 @@ module Liquid
     #
     # Example:
     #   products == empty #=> products.empty?
-      def resolve(key)
+    def [](expression)
-        if LITERALS.key?(key)
+      evaluate(@parsed_expression[expression])
-          LITERALS[key]
-        else
-          case key
-          when /\A'(.*)'\z/m # Single quoted strings
-            $1
-          when /\A"(.*)"\z/m # Double quoted strings
-            $1
-          when /\A(-?\d+)\z/ # Integer and floats
-            $1.to_i
-          when /\A\((\S+)\.\.(\S+)\)\z/ # Ranges
-            (resolve($1).to_i..resolve($2).to_i)
-          when /\A(-?\d[\d\.]+)\z/ # Floats
-            $1.to_f
-          else
-            variable(key)
     end
+
+    def has_key?(key)
+      self[key] != nil
     end
+
+    def evaluate(object)
+      object.respond_to?(:evaluate) ? object.evaluate(self) : object
     end
 
     # Fetches an object starting at the local scope and then moving up the hierachy
@@ -238,74 +210,15 @@ module Liquid
       return variable
     end
 
-      def variable_parse(markup)
-        parts = markup.scan(VariableParser)
-        needs_resolution = false
-        if parts.first =~ SQUARE_BRACKETED 
-          needs_resolution = true
-          parts[0] = $1
-        end
-        {:first => parts.shift, :needs_resolution => needs_resolution, :rest => parts} 
-      end
-
-      # Resolves namespaced queries gracefully.
-      #
-      # Example
-      #  @context['hash'] = {"name" => 'tobi'}
-      #  assert_equal 'tobi', @context['hash.name']
-      #  assert_equal 'tobi', @context['hash["name"]']
-      def variable(markup)
-        parts = @parsed_variables[markup]
-
-        first_part = parts[:first] 
-        if parts[:needs_resolution]
-          first_part = resolve(parts[:first])
-        end
-
-        if object = find_variable(first_part)
-
-          parts[:rest].each do |part|
-            part = resolve($1) if part_resolved = (part =~ SQUARE_BRACKETED)
-
-            # If object is a hash- or array-like object we look for the
-            # presence of the key and if its available we return it
-            if object.respond_to?(:[]) and
-              ((object.respond_to?(:has_key?) and object.has_key?(part)) or
-               (object.respond_to?(:fetch) and part.is_a?(Integer)))
-
-              # if its a proc we will replace the entry with the proc
-              res = lookup_and_evaluate(object, part)
-              object = res.to_liquid
-
-              # Some special cases. If the part wasn't in square brackets and
-              # no key with the same name was found we interpret following calls
-              # as commands and call them on the current object
-            elsif !part_resolved and object.respond_to?(part) and ['size'.freeze, 'first'.freeze, 'last'.freeze].include?(part)
-
-              object = object.send(part.intern).to_liquid
-
-              # No key was present with the desired value and it wasn't one of the directly supported
-              # keywords either. The only thing we got left is to return nil
-            else
-              return nil
-            end
-
-            # If we are dealing with a drop here we have to
-            object.context = self if object.respond_to?(:context=)
-          end
-        end
-
-        object
-      end # variable
-
     def lookup_and_evaluate(obj, key)
       if (value = obj[key]).is_a?(Proc) && obj.respond_to?(:[]=)
         obj[key] = (value.arity == 0) ? value.call : value.call(self)
       else
         value
       end
-      end # lookup_and_evaluate
+    end
 
+    private
       def squash_instance_assigns_with_environments
         @scopes.last.each_key do |k|
           @environments.each do |env|

lib/liquid/expression.rb

@@ -0,0 +1,33 @@
+module Liquid
+  class Expression
+    LITERALS = {
+      nil => nil, 'nil'.freeze => nil, 'null'.freeze => nil, ''.freeze => nil,
+      'true'.freeze  => true,
+      'false'.freeze => false,
+      'blank'.freeze => :blank?,
+      'empty'.freeze => :empty?
+    }
+
+    def self.parse(markup)
+      if LITERALS.key?(markup)
+        LITERALS[markup]
+      else
+        case markup
+        when /\A'(.*)'\z/m # Single quoted strings
+          $1
+        when /\A"(.*)"\z/m # Double quoted strings
+          $1
+        when /\A(-?\d+)\z/ # Integer and floats
+          $1.to_i
+        when /\A\((\S+)\.\.(\S+)\)\z/ # Ranges
+          RangeLookup.parse($1, $2)
+        when /\A(-?\d[\d\.]+)\z/ # Floats
+          $1.to_f
+        else
+          VariableLookup.parse(markup)
+        end
+      end
+    end
+
+  end
+end

lib/liquid/range_lookup.rb

@@ -0,0 +1,22 @@
+module Liquid
+  class RangeLookup
+    def self.parse(start_markup, end_markup)
+      start_obj = Expression.parse(start_markup)
+      end_obj = Expression.parse(end_markup)
+      if start_obj.respond_to?(:evaluate) || end_obj.respond_to?(:evaluate)
+        new(start_obj, end_obj)
+      else
+        start_obj.to_i..end_obj.to_i
+      end
+    end
+
+    def initialize(start_obj, end_obj)
+      @start_obj = start_obj
+      @end_obj = end_obj
+    end
+
+    def evaluate(context)
+      context.evaluate(@start_obj).to_i..context.evaluate(@end_obj).to_i
+    end
+  end
+end

lib/liquid/variable_lookup.rb

@@ -0,0 +1,68 @@
+module Liquid
+  class VariableLookup
+    SQUARE_BRACKETED = /\A\[(.*)\]\z/m
+    COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze]
+
+    def self.parse(markup)
+      new(markup)
+    end
+
+    def initialize(markup)
+      lookups = markup.scan(VariableParser)
+
+      name = lookups.shift
+      if name =~ SQUARE_BRACKETED
+        name = Expression.parse($1)
+      end
+      @name = name
+
+      @lookups = lookups
+      @command_flags = 0
+
+      @lookups.each_index do |i|
+        lookup = lookups[i]
+        if lookup =~ SQUARE_BRACKETED
+          lookups[i] = Expression.parse($1)
+        elsif COMMAND_METHODS.include?(lookup)
+          @command_flags |= 1 << i
+        end
+      end
+    end
+
+    def evaluate(context)
+      name = context.evaluate(@name)
+      object = context.find_variable(name)
+
+      @lookups.each_index do |i|
+        key = context.evaluate(@lookups[i])
+
+        # If object is a hash- or array-like object we look for the
+        # presence of the key and if its available we return it
+        if object.respond_to?(:[]) &&
+          ((object.respond_to?(:has_key?) && object.has_key?(key)) ||
+           (object.respond_to?(:fetch) && key.is_a?(Integer)))
+
+          # if its a proc we will replace the entry with the proc
+          res = context.lookup_and_evaluate(object, key)
+          object = res.to_liquid
+
+          # Some special cases. If the part wasn't in square brackets and
+          # no key with the same name was found we interpret following calls
+          # as commands and call them on the current object
+        elsif @command_flags & (1 << i) != 0 && object.respond_to?(key)
+          object = object.send(key).to_liquid
+
+          # No key was present with the desired value and it wasn't one of the directly supported
+          # keywords either. The only thing we got left is to return nil
+        else
+          return nil
+        end
+
+        # If we are dealing with a drop here we have to
+        object.context = context if object.respond_to?(:context=)
+      end
+
+      object
+    end
+  end
+end