Optional line numbers for liquid errors

lib/liquid.rb

@@ -66,11 +66,11 @@ require 'liquid/standardfilters'
 require 'liquid/condition'
 require 'liquid/module_ex'
 require 'liquid/utils'
+require 'liquid/token'
 
 # Load all the tags of the standard library
 #
 Dir[File.dirname(__FILE__) + '/liquid/tags/*.rb'].each { |f| require f }
 
 require 'liquid/profiler'
-require 'liquid/profiler/token'
 require 'liquid/profiler/hooks'

lib/liquid/block.rb

@@ -144,7 +144,7 @@ module Liquid
         rescue MemoryError => e
           raise e
         rescue ::StandardError => e
-          output << (context.handle_error(e))
+          output << (context.handle_error(e, token))
         end
       end
 

lib/liquid/context.rb

@@ -91,17 +91,12 @@ module Liquid
       @interrupts.pop
     end
 
-    def handle_error(e)
+
+    def handle_error(e, token)
+      e = Liquid::Error.error_with_line_number(e, token)
       errors.push(e)
-
       raise if exception_handler && exception_handler.call(e)
-
-      case e
-      when SyntaxError
-        "Liquid syntax error: #{e.message}"
-      else
-        "Liquid error: #{e.message}"
-      end
+      Liquid::Error.render(e)
     end
 
     def invoke(method, *args)

lib/liquid/errors.rb

@@ -1,5 +1,35 @@
 module Liquid
-  class Error < ::StandardError; end
+  class Error < ::StandardError
+    attr_accessor :line_number
+
+    def self.render(e)
+      msg = if e.is_a?(Liquid::Error) && e.line_number
+        "#{e.line_number}: #{e.message}"
+      else
+        e.message
+      end
+
+      case e
+      when SyntaxError
+        "Liquid syntax error: #{msg}"
+      else
+        "Liquid error: #{msg}"
+      end
+    end
+
+    def self.error_with_line_number(e, token)
+      if e.is_a?(Liquid::Error)
+        e.set_line_number_from_token(token)
+      end
+
+      e
+    end
+
+    def set_line_number_from_token(token)
+      return unless token.respond_to?(:line_number)
+      self.line_number = token.line_number
+    end
+  end
 
   class ArgumentError < Error; end
   class ContextError < Error; end

lib/liquid/template.rb

@@ -104,6 +104,7 @@ module Liquid
     # Returns self for easy chaining
     def parse(source, options = {})
       @profiling = options.delete(:profile)
+      @line_numbers = options.delete(:line_numbers) || @profiling
       @root = Document.parse(tokenize(source), DEFAULT_OPTIONS.merge(options))
       @warnings = nil
       self
@@ -196,7 +197,7 @@ module Liquid
         end
         result.respond_to?(:join) ? result.join : result
       rescue Liquid::MemoryError => e
-        context.handle_error(e)
+        context.handle_error(e, nil)
       ensure
         @errors = context.errors
       end
@@ -223,7 +224,7 @@ module Liquid
     end
 
     def calculate_line_numbers(raw_tokens)
-      return raw_tokens unless @profiling
+      return raw_tokens unless @line_numbers
 
       current_line = 1
       raw_tokens.map do |token|
@@ -247,6 +248,5 @@ module Liquid
         yield
       end
     end
-
   end
 end

lib/liquid/token.rb

@@ -1,6 +1,5 @@
 module Liquid
   class Token < String
-
     attr_reader :line_number
 
     def initialize(content, line_number)
@@ -11,6 +10,5 @@ module Liquid
     def raw
       "<raw>"
     end
-
   end
 end

test/integration/error_handling_test.rb

@@ -22,6 +22,39 @@ end
 class ErrorHandlingTest < Minitest::Test
   include Liquid
 
+  def test_templates_parsed_with_line_numbers_renders_them_in_errors
+    template = <<-LIQUID
+      Hello,
+
+      {{ errors.standard_error }} will raise a standard error.
+
+      Bla bla test.
+
+      {{ errors.syntax_error }} will raise a syntax error.
+
+      This is an argument error: {{ errors.argument_error }}
+
+      Bla.
+    LIQUID
+
+    expected = <<-TEXT
+      Hello,
+
+      Liquid error: 3: standard error will raise a standard error.
+
+      Bla bla test.
+
+      Liquid syntax error: 7: syntax error will raise a syntax error.
+
+      This is an argument error: Liquid error: 9: argument error
+
+      Bla.
+    TEXT
+
+    output = Liquid::Template.parse(template, line_numbers: true).render('errors' => ErrorDrop.new)
+    assert_equal expected, output
+  end
+
   def test_standard_error
     template = Liquid::Template.parse( ' {{ errors.standard_error }} '  )
     assert_equal ' Liquid error: standard error ', template.render('errors' => ErrorDrop.new)
@@ -59,7 +92,7 @@ class ErrorHandlingTest < Minitest::Test
       end
     end
   end
-  
+
   def test_lax_unrecognized_operator
     template = Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', :error_mode => :lax)
     assert_equal ' Liquid error: Unknown operator =! ', template.render
@@ -91,8 +124,8 @@ class ErrorHandlingTest < Minitest::Test
   # Liquid should not catch Exceptions that are not subclasses of StandardError, like Interrupt and NoMemoryError
   def test_exceptions_propagate
     assert_raises Exception do
-      template = Liquid::Template.parse( ' {{ errors.exception }} '  )
+      template = Liquid::Template.parse('{{ errors.exception }}')
       template.render('errors' => ErrorDrop.new)
     end
   end
-end # ErrorHandlingTest
+end