introduce to_liquid_value on variable look and conditional statements

.rubocop.yml

@@ -10,7 +10,7 @@ Performance:
   Enabled: true
 
 AllCops:
-  TargetRubyVersion: 2.4
+  TargetRubyVersion: 2.5
   NewCops: disable
   Exclude:
     - 'vendor/bundle/**/*'
@@ -18,3 +18,7 @@ AllCops:
 Naming/MethodName:
   Exclude:
     - 'example/server/liquid_servlet.rb'
+
+# Backport https://github.com/Shopify/ruby-style-guide/pull/258
+Layout/BeginEndAlignment:
+  Enabled: true

lib/liquid/standardfilters.rb

@@ -5,6 +5,7 @@ require 'bigdecimal'
 
 module Liquid
   module StandardFilters
+    MAX_INT = (1 << 31) - 1
     HTML_ESCAPE = {
       '&' => '&amp;',
       '>' => '&gt;',
@@ -93,7 +94,13 @@ module Liquid
       words = Utils.to_integer(words)
       words = 1 if words <= 0
 
-      wordlist = input.split(" ", words + 1)
+      wordlist = begin
+        input.split(" ", words + 1)
+      rescue RangeError
+        raise if words + 1 < MAX_INT
+        # e.g. integer #{words} too big to convert to `int'
+        raise Liquid::ArgumentError, "integer #{words} too big for truncatewords"
+      end
       return input if wordlist.length <= words
 
       wordlist.pop

lib/liquid/tags/case.rb

@@ -52,7 +52,14 @@ module Liquid
       @blocks.each do |block|
         if block.else?
           block.attachment.render_to_output_buffer(context, output) if execute_else_block
-        elsif block.evaluate(context)
+          next
+        end
+
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
           execute_else_block = false
           block.attachment.render_to_output_buffer(context, output)
         end

lib/liquid/tags/if.rb

@@ -50,7 +50,11 @@ module Liquid
 
     def render_to_output_buffer(context, output)
       @blocks.each do |block|
-        if block.evaluate(context)
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
           return block.attachment.render_to_output_buffer(context, output)
         end
       end

lib/liquid/tags/unless.rb

@@ -11,13 +11,20 @@ module Liquid
     def render_to_output_buffer(context, output)
       # First condition is interpreted backwards ( if not )
       first_block = @blocks.first
-      unless first_block.evaluate(context)
+      result = Liquid::Utils.to_liquid_value(
+        first_block.evaluate(context)
+      )
+
+      unless result
         return first_block.attachment.render_to_output_buffer(context, output)
       end
 
       # After the first condition unless works just like if
       @blocks[1..-1].each do |block|
-        if block.evaluate(context)
+        result = block.evaluate(context)
+        result = result.to_liquid_value if result.is_a?(Liquid::Drop)
+
+        if result
           return block.attachment.render_to_output_buffer(context, output)
         end
       end

lib/liquid/utils.rb

@@ -81,5 +81,13 @@ module Liquid
     rescue ::ArgumentError
       nil
     end
+
+    def self.to_liquid_value(obj)
+      # Enable "obj" to represent itself as a primitive value like integer, string, or boolean
+      return obj.to_liquid_value if obj.respond_to?(:to_liquid_value)
+
+      # Otherwise return the object itself
+      obj
+    end
   end
 end

lib/liquid/variable_lookup.rb

@@ -40,6 +40,9 @@ module Liquid
       @lookups.each_index do |i|
         key = context.evaluate(@lookups[i])
 
+        # Cast "key" to its liquid value to enable it to act as a primitive value
+        key = Liquid::Utils.to_liquid_value(key)
+
         # 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?(:[]) &&

test/integration/standard_filter_test.rb

@@ -178,6 +178,10 @@ class StandardFiltersTest < Minitest::Test
     assert_equal('one two three...', @filters.truncatewords("one  two\tthree\nfour", 3))
     assert_equal('one two...', @filters.truncatewords("one two three four", 2))
     assert_equal('one...', @filters.truncatewords("one two three four", 0))
+    exception = assert_raises(Liquid::ArgumentError) do
+      @filters.truncatewords("one two three four", 1 << 31)
+    end
+    assert_equal("Liquid error: integer #{1 << 31} too big for truncatewords", exception.message)
   end
 
   def test_strip_html

test/integration/variable_test.rb

@@ -15,6 +15,31 @@ class VariableTest < Minitest::Test
     assert_template_result('foobar', '{{ foo }}', 'foo' => ThingWithToLiquid.new)
   end
 
+  def test_variable_lookup_calls_to_liquid_value
+    assert_template_result('1', '{{ foo }}', 'foo' => IntegerDrop.new('1'))
+    assert_template_result('2', '{{ list[foo] }}', 'foo' => IntegerDrop.new('1'), 'list' => [1, 2, 3])
+    assert_template_result('one', '{{ list[foo] }}', 'foo' => IntegerDrop.new('1'), 'list' => { 1 => 'one' })
+    assert_template_result('Yay', '{{ foo }}', 'foo' => BooleanDrop.new(true))
+    assert_template_result('YAY', '{{ foo | upcase }}', 'foo' => BooleanDrop.new(true))
+  end
+
+  def test_if_tag_calls_to_liquid_value
+    assert_template_result('one', '{% if foo == 1 %}one{% endif %}', 'foo' => IntegerDrop.new('1'))
+    assert_template_result('true', '{% if foo == true %}true{% endif %}', 'foo' => BooleanDrop.new(true))
+    assert_template_result('true', '{% if foo %}true{% endif %}', 'foo' => BooleanDrop.new(true))
+
+    assert_template_result('', '{% if foo %}true{% endif %}', 'foo' => BooleanDrop.new(false))
+    assert_template_result('', '{% if foo == true %}True{% endif %}', 'foo' => BooleanDrop.new(false))
+  end
+
+  def test_unless_tag_calls_to_liquid_value
+    assert_template_result('', '{% unless foo %}true{% endunless %}', 'foo' => BooleanDrop.new(true))
+  end
+
+  def test_case_tag_calls_to_liquid_value
+    assert_template_result('One', '{% case foo %}{% when 1 %}One{% endcase %}', 'foo' => IntegerDrop.new('1'))
+  end
+
   def test_simple_with_whitespaces
     template = Template.parse(%(  {{ test }}  ))
     assert_equal('  worked  ', template.render!('test' => 'worked'))
@@ -104,4 +129,8 @@ class VariableTest < Minitest::Test
   def test_dynamic_find_var
     assert_template_result('bar', '{{ [key] }}', 'key' => 'foo', 'foo' => 'bar')
   end
+
+  def test_raw_value_variable
+    assert_template_result('bar', '{{ [key] }}', 'key' => 'foo', 'foo' => 'bar')
+  end
 end

test/test_helper.rb

@@ -119,6 +119,44 @@ class ThingWithToLiquid
   end
 end
 
+class IntegerDrop < Liquid::Drop
+  def initialize(value)
+    super()
+    @value = value.to_i
+  end
+
+  def ==(other)
+    @value == other
+  end
+
+  def to_s
+    @value.to_s
+  end
+
+  def to_liquid_value
+    @value
+  end
+end
+
+class BooleanDrop < Liquid::Drop
+  def initialize(value)
+    super()
+    @value = value
+  end
+
+  def ==(other)
+    @value == other
+  end
+
+  def to_liquid_value
+    @value
+  end
+
+  def to_s
+    @value ? "Yay" : "Nay"
+  end
+end
+
 class ErrorDrop < Liquid::Drop
   def standard_error
     raise Liquid::StandardError, 'standard error'