Switch to aliasing methods

lib/liquid.rb

@@ -75,7 +75,12 @@ require 'liquid/utils'
 require 'liquid/tokenizer'
 require 'liquid/parse_context'
 require 'liquid/partial_cache'
+require 'liquid/usage'
 
 # Load all the tags of the standard library
 #
 Dir["#{__dir__}/liquid/tags/*.rb"].each { |f| require f }
+
+# Load all usage tracking
+#
+Dir["#{__dir__}/liquid/usages/*.rb"].each { |f| require f }

lib/liquid/context.rb

@@ -15,8 +15,6 @@ module Liquid
     attr_reader :scopes, :errors, :registers, :environments, :resource_limits, :static_registers, :static_environments
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
-    BLANK_SCOPE = {}
-
     # rubocop:disable Metrics/ParameterLists
     def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_registers: {}, static_environments: {})
       new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_registers, static_environments)
@@ -193,12 +191,15 @@ module Liquid
     def find_variable(key, raise_on_not_found: true)
       # This was changed from find() to find_index() because this is a very hot
       # path and find_index() is optimized in MRI to reduce object allocation
-      scope = (index = @scopes.find_index { |s| s.key?(key) }) && @scopes[index]
-      scope ||= (index = @environments.find_index { |s| s.key?(key) || s.default_proc }) && @environments[index]
-      scope ||= (index = @static_environments.find_index { |s| s.key?(key) }) && @static_environments[index]
-      scope ||= BLANK_SCOPE
+      index = @scopes.find_index { |s| s.key?(key) }
 
-      variable = lookup_and_evaluate(scope, key, raise_on_not_found: raise_on_not_found).to_liquid
+      variable = if index
+        lookup_and_evaluate(@scopes[index], key, raise_on_not_found: raise_on_not_found)
+      else
+        try_variable_find_in_environments(key, raise_on_not_found: raise_on_not_found)
+      end
+
+      variable = variable.to_liquid
       variable.context = self if variable.respond_to?(:context=)
 
       variable
@@ -226,6 +227,22 @@ module Liquid
 
     attr_reader :base_scope_depth
 
+    def try_variable_find_in_environments(key, raise_on_not_found:)
+      @environments.each do |environment|
+        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
+        if !found_variable.nil? || @strict_variables && raise_on_not_found
+          return found_variable
+        end
+      end
+      @static_environments.each do |environment|
+        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
+        if !found_variable.nil? || @strict_variables && raise_on_not_found
+          return found_variable
+        end
+      end
+      nil
+    end
+
     def check_overflow
       raise StackLevelError, "Nesting too deep".freeze if overflow?
     end

lib/liquid/usage.rb

@@ -0,0 +1,23 @@
+module Liquid
+  # Usage is used to store
+  class Usage
+    @messages = {}
+    class << self
+      def enable
+        Liquid::Context.send(:alias_method, :try_variable_find_in_environments, :try_variable_find_in_environments_usage)
+      end
+
+      def disable
+        Liquid::Context.send(:alias_method, :try_variable_find_in_environments, :try_variable_find_in_environments_original)
+      end
+
+      def track(message)
+        @messages[message] = true
+      end
+
+      def results
+        @messages
+      end
+    end
+  end
+end

lib/liquid/usages/try_variables.rb

@@ -0,0 +1,26 @@
+module Liquid
+  class Context
+    alias try_variable_find_in_environments_original try_variable_find_in_environments
+
+    def try_variable_find_in_environments_usage(key, raise_on_not_found:)
+      Usage.track("Using try_variable_find_in_environment")
+      @environments.each do |environment|
+        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
+        if !found_variable.nil? || @strict_variables && raise_on_not_found
+          return found_variable
+        end
+
+        Usage.track("try_variable_find_in_environment reports Nil but responds to key") if environment.key?(key)
+      end
+      @static_environments.each do |environment|
+        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
+        if !found_variable.nil? || @strict_variables && raise_on_not_found
+          return found_variable
+        end
+
+        Usage.track("try_variable_find_in_environment reports Nil but responds to key") if environment.key?(key)
+      end
+      nil
+    end
+  end
+end

lib/liquid/usages/usage_enabled.rb

@@ -0,0 +1 @@
+Liquid::Usage.track("Usage is enabled")

test/integration/usages/try_variables_test.rb

@@ -0,0 +1,14 @@
+require 'test_helper'
+
+class TryVariablesUsageTest < Minitest::Test
+  include Liquid
+
+  def test_test_usages
+    Usage.enable
+    template = Template.parse(%({{test}}))
+    assert_equal 'worked', template.render!('test' => 'worked')
+    assert_equal 'worked wonderfully', template.render!('test' => 'worked wonderfully')
+    assert_equal true, Usage.results["Using try_variable_find_in_environment"]
+    Usage.disable
+  end
+end

test/integration/usages/usage_enabled_test.rb

@@ -0,0 +1,9 @@
+require 'test_helper'
+
+class UsageEnabledUsageTest < Minitest::Test
+  include Liquid
+
+  def test_live_usages
+    assert_equal true, Usage.results["Usage is enabled"]
+  end
+end

test/integration/variable_test.rb

@@ -86,14 +86,6 @@ class VariableTest < Minitest::Test
     assert_equal "Unknown variable 'test'", e.message
   end
 
-  def test_environment_falsy
-    template = Template.parse(%({{ test }}{% assign test = 'bar' %}{{ test }}))
-    template.assigns['test'] = 'foo'
-    assert_equal 'foobar', template.render!
-    assert_equal 'bar', template.render!('test' => nil)
-    assert_equal 'falsebar', template.render!('test' => false)
-  end
-
   def test_multiline_variable
     assert_equal 'worked', Template.parse("{{\ntest\n}}").render!('test' => 'worked')
   end