Reimplementation of Static Registers (Shopify#1157)

lib/liquid.rb

@@ -78,6 +78,7 @@ module Liquid
 require 'liquid/parse_context'
 require 'liquid/partial_cache'
 require 'liquid/usage'
+require 'liquid/static_registers'
 
 # Load all the tags of the standard library
 #

lib/liquid/context.rb

@@ -18,18 +18,17 @@ class Context
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
     # 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)
+    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {})
+      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments)
     end
 
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_registers = {}, static_environments = {})
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_environments = {})
       @environments = [environments]
       @environments.flatten!
 
       @static_environments = [static_environments].flat_map(&:freeze).freeze
       @scopes              = [(outer_scope || {})]
       @registers           = registers
-      @static_registers    = static_registers.freeze
       @errors              = []
       @partial             = false
       @strict_variables    = false
@@ -137,7 +136,7 @@ def new_isolated_subcontext
       Context.build(
         resource_limits: resource_limits,
         static_environments: static_environments,
-        static_registers: static_registers
+        registers: StaticRegisters.new(registers)
       ).tap do |subcontext|
         subcontext.base_scope_depth = base_scope_depth + 1
         subcontext.exception_renderer = exception_renderer

lib/liquid/static_registers.rb

@@ -0,0 +1,34 @@
+module Liquid
+  class StaticRegisters
+    attr_reader :static_registers, :registers
+
+    def initialize(registers = {})
+      @static_registers = registers.is_a?(StaticRegisters) ? registers.static_registers : registers.freeze
+      @registers = {}
+    end
+
+    def []=(key, value)
+      @registers[key] = value
+    end
+
+    def [](key)
+      if @registers.key?(key)
+        @registers[key]
+      else
+        @static_registers[key]
+      end
+    end
+
+    def delete(key)
+      @registers.delete(key)
+    end
+
+    def fetch(key, default = nil)
+      key?(key) ? self[key] : default
+    end
+
+    def key?(key)
+      @registers.key?(key) || @static_registers.key?(key)
+    end
+  end
+end

test/unit/context_unit_test.rb

@@ -518,15 +518,23 @@ def test_new_isolated_subcontext_does_not_inherit_non_static_registers
     registers = {
       my_register: :my_value,
     }
-    super_context = Context.new({}, {}, registers)
+    super_context = Context.new({}, {}, StaticRegisters.new(registers))
+    super_context.registers[:my_register] = :my_alt_value
     subcontext = super_context.new_isolated_subcontext
-    assert_nil subcontext.registers[:my_register]
+    assert_equal :my_value, subcontext.registers[:my_register]
   end
 
   def test_new_isolated_subcontext_inherits_static_registers
-    super_context = Context.build(static_registers: { my_register: :my_value })
+    super_context = Context.build(registers: { my_register: :my_value })
     subcontext = super_context.new_isolated_subcontext
-    assert_equal :my_value, subcontext.static_registers[:my_register]
+    assert_equal :my_value, subcontext.registers[:my_register]
+  end
+
+  def test_new_isolated_subcontext_registers_do_not_pollute_context
+    super_context = Context.build(registers: { my_register: :my_value })
+    subcontext = super_context.new_isolated_subcontext
+    subcontext.registers[:my_register] = :my_alt_value
+    assert_equal :my_value, super_context.registers[:my_register]
   end
 
   def test_new_isolated_subcontext_inherits_filters

test/unit/static_registers_unit_test.rb

@@ -0,0 +1,209 @@
+require 'test_helper'
+
+class StaticRegistersUnitTest < Minitest::Test
+  include Liquid
+
+  def set
+    static_register = StaticRegisters.new
+    static_register[nil] = true
+    static_register[1] = :one
+    static_register[:one] = "one"
+    static_register["two"] = "three"
+    static_register["two"] = 3
+    static_register[false] = nil
+
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.registers)
+
+    static_register
+  end
+
+  def test_get
+    static_register = set
+
+    assert_equal true, static_register[nil]
+    assert_equal :one, static_register[1]
+    assert_equal "one", static_register[:one]
+    assert_equal 3, static_register["two"]
+    assert_nil static_register[false]
+    assert_nil static_register["unknown"]
+  end
+
+  def test_delete
+    static_register = set
+
+    assert_equal true, static_register.delete(nil)
+    assert_equal :one, static_register.delete(1)
+    assert_equal "one", static_register.delete(:one)
+    assert_equal 3, static_register.delete("two")
+    assert_nil static_register.delete(false)
+    assert_nil static_register.delete("unknown")
+
+    assert_equal({}, static_register.registers)
+  end
+
+  def test_fetch
+    static_register = set
+
+    assert_equal true, static_register.fetch(nil)
+    assert_equal :one, static_register.fetch(1)
+    assert_equal "one", static_register.fetch(:one)
+    assert_equal 3, static_register.fetch("two")
+    assert_nil static_register.fetch(false)
+    assert_nil static_register.fetch("unknown")
+  end
+
+  def test_fetch_default
+    static_register = StaticRegisters.new
+
+    assert_equal true, static_register.fetch(nil, true)
+    assert_equal :one, static_register.fetch(1, :one)
+    assert_equal "one", static_register.fetch(:one, "one")
+    assert_equal 3, static_register.fetch("two", 3)
+    assert_nil static_register.fetch(false, nil)
+  end
+
+  def test_key
+    static_register = set
+
+    assert_equal true, static_register.key?(nil)
+    assert_equal true, static_register.key?(1)
+    assert_equal true, static_register.key?(:one)
+    assert_equal true, static_register.key?("two")
+    assert_equal true, static_register.key?(false)
+    assert_equal false, static_register.key?("unknown")
+    assert_equal false, static_register.key?(true)
+  end
+
+  def set_with_static
+    static_register = StaticRegisters.new(nil => true, 1 => :one, :one => "one", "two" => 3, false => nil)
+    static_register[nil] = false
+    static_register["two"] = 4
+    static_register[true] = "foo"
+
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+    assert_equal({ nil => false, "two" => 4, true => "foo" }, static_register.registers)
+
+    static_register
+  end
+
+  def test_get_with_static
+    static_register = set_with_static
+
+    assert_equal false, static_register[nil]
+    assert_equal :one, static_register[1]
+    assert_equal "one", static_register[:one]
+    assert_equal 4, static_register["two"]
+    assert_equal "foo", static_register[true]
+    assert_nil static_register[false]
+  end
+
+  def test_delete_with_static
+    static_register = set_with_static
+
+    assert_equal false, static_register.delete(nil)
+    assert_equal 4, static_register.delete("two")
+    assert_equal "foo", static_register.delete(true)
+    assert_nil static_register.delete("unknown")
+    assert_nil static_register.delete(:one)
+
+    assert_equal({}, static_register.registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+  end
+
+  def test_fetch_with_static
+    static_register = set_with_static
+
+    assert_equal false, static_register.fetch(nil)
+    assert_equal :one, static_register.fetch(1)
+    assert_equal "one", static_register.fetch(:one)
+    assert_equal 4, static_register.fetch("two")
+    assert_equal "foo", static_register.fetch(true)
+    assert_nil static_register.fetch(false)
+  end
+
+  def test_key_with_static
+    static_register = set_with_static
+
+    assert_equal true, static_register.key?(nil)
+    assert_equal true, static_register.key?(1)
+    assert_equal true, static_register.key?(:one)
+    assert_equal true, static_register.key?("two")
+    assert_equal true, static_register.key?(false)
+    assert_equal false, static_register.key?("unknown")
+    assert_equal true, static_register.key?(true)
+  end
+
+  def test_static_register_frozen
+    static_register = set_with_static
+
+    static = static_register.static_registers
+
+    assert_raises(RuntimeError) do
+      static["two"] = "foo"
+    end
+
+    assert_raises(RuntimeError) do
+      static["unknown"] = "foo"
+    end
+
+    assert_raises(RuntimeError) do
+      static.delete("two")
+    end
+  end
+
+  def test_new_static_retains_static
+    static_register = StaticRegisters.new(nil => true, 1 => :one, :one => "one", "two" => 3, false => nil)
+    static_register["one"] = 1
+    static_register["two"] = 2
+    static_register["three"] = 3
+
+    new_register = StaticRegisters.new(static_register)
+    assert_equal({}, new_register.registers)
+
+    new_register["one"] = 4
+    new_register["two"] = 5
+    new_register["three"] = 6
+
+    newest_register = StaticRegisters.new(new_register)
+    assert_equal({}, newest_register.registers)
+
+    newest_register["one"] = 7
+    newest_register["two"] = 8
+    newest_register["three"] = 9
+
+    assert_equal({ "one" => 1, "two" => 2, "three" => 3 }, static_register.registers)
+    assert_equal({ "one" => 4, "two" => 5, "three" => 6 }, new_register.registers)
+    assert_equal({ "one" => 7, "two" => 8, "three" => 9 }, newest_register.registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, new_register.static_registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, newest_register.static_registers)
+  end
+
+  def test_multiple_instances_are_unique
+    static_register = StaticRegisters.new(nil => true, 1 => :one, :one => "one", "two" => 3, false => nil)
+    static_register["one"] = 1
+    static_register["two"] = 2
+    static_register["three"] = 3
+
+    new_register = StaticRegisters.new(foo: :bar)
+    assert_equal({}, new_register.registers)
+
+    new_register["one"] = 4
+    new_register["two"] = 5
+    new_register["three"] = 6
+
+    newest_register = StaticRegisters.new(bar: :foo)
+    assert_equal({}, newest_register.registers)
+
+    newest_register["one"] = 7
+    newest_register["two"] = 8
+    newest_register["three"] = 9
+
+    assert_equal({ "one" => 1, "two" => 2, "three" => 3 }, static_register.registers)
+    assert_equal({ "one" => 4, "two" => 5, "three" => 6 }, new_register.registers)
+    assert_equal({ "one" => 7, "two" => 8, "three" => 9 }, newest_register.registers)
+    assert_equal({ nil => true, 1 => :one, :one => "one", "two" => 3, false => nil }, static_register.static_registers)
+    assert_equal({ foo: :bar }, new_register.static_registers)
+    assert_equal({ bar: :foo }, newest_register.static_registers)
+  end
+end