Make error locations available for non-Liquid::Error exceptions.

Although the author of the liquid template wants to see these errors, they
probably don't want the visitor to see the liquid errors.  Probably the
best fallback when rendering the page for visitors is to render the empty
string for tags with errors.

lib/liquid.rb

@@ -50,6 +50,7 @@ require 'liquid/i18n'
 require 'liquid/drop'
 require 'liquid/extensions'
 require 'liquid/errors'
+require 'liquid/error_location'
 require 'liquid/interrupts'
 require 'liquid/strainer'
 require 'liquid/expression'

lib/liquid/context.rb

@@ -12,16 +12,18 @@ module Liquid
   #
   #   context['bob']  #=> nil  class Context
   class Context
-    attr_reader :scopes, :errors, :registers, :environments, :resource_limits
-    attr_accessor :exception_handler
+    attr_reader :scopes, :errors, :error_locations, :registers, :environments, :resource_limits
+    attr_accessor :exception_handler, :render_errors, :template_name
 
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil)
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, render_errors = true)
       @environments     = [environments].flatten
       @scopes           = [(outer_scope || {})]
       @registers        = registers
       @errors           = []
+      @error_locations  = []
       @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
       squash_instance_assigns_with_environments
+      @render_errors    = render_errors
 
       @this_stack_used = false
 
@@ -64,12 +66,14 @@ module Liquid
 
     def handle_error(e, token = nil)
       if e.is_a?(Liquid::Error)
+        e.template_name = template_name
         e.set_line_number_from_token(token)
       end
 
       errors.push(e)
+      error_locations.push(ErrorLocation.from_token(template_name, token))
       raise if exception_handler && exception_handler.call(e)
-      Liquid::Error.render(e)
+      render_errors ? Liquid::Error.render(e) : ''
     end
 
     def invoke(method, *args)

lib/liquid/error_location.rb

@@ -0,0 +1,11 @@
+module Liquid
+  ErrorLocation = Struct.new(:template_name, :line_number) do
+    def self.line_number_from_token(token)
+      token.respond_to?(:line_number) ? token.line_number : nil
+    end
+
+    def self.from_token(template_name, token)
+      new(template_name, line_number_from_token(token))
+    end
+  end
+end

lib/liquid/errors.rb

@@ -1,6 +1,7 @@
 module Liquid
   class Error < ::StandardError
     attr_accessor :line_number
+    attr_accessor :template_name
     attr_accessor :markup_context
 
     def to_s(with_prefix = true)
@@ -17,9 +18,8 @@ module Liquid
     end
 
     def set_line_number_from_token(token)
-      return unless token.respond_to?(:line_number)
       return if line_number
-      self.line_number = token.line_number
+      self.line_number = ErrorLocation.line_number_from_token(token)
     end
 
     def self.render(e)
@@ -41,7 +41,9 @@ module Liquid
       end
 
       if line_number
-        str << " (line #{line_number})"
+        str << " ("
+        str << template_name << " " if template_name
+        str << "line " << line_number.to_s << ")"
       end
 
       str << ": "

lib/liquid/tags/include.rb

@@ -41,9 +41,9 @@ module Liquid
     end
 
     def render(context)
-      partial = load_cached_partial(context)
-
       template_name = context.evaluate(@template_name_expr)
+      partial = load_cached_partial(template_name, context)
+
       context_variable_name = template_name.split('/'.freeze).last
 
       variable = if @variable_name_expr
@@ -52,28 +52,33 @@ module Liquid
         context.find_variable(template_name)
       end
 
-      context.stack do
-        @attributes.each do |key, value|
-          context[key] = context.evaluate(value)
-        end
+      old_template_name = context.template_name
+      begin
+        context.template_name = template_name
+        context.stack do
+          @attributes.each do |key, value|
+            context[key] = context.evaluate(value)
+          end
 
-        if variable.is_a?(Array)
-          variable.collect do |var|
-            context[context_variable_name] = var
+          if variable.is_a?(Array)
+            variable.collect do |var|
+              context[context_variable_name] = var
+              partial.render(context)
+            end
+          else
+            context[context_variable_name] = variable
             partial.render(context)
           end
-        else
-          context[context_variable_name] = variable
-          partial.render(context)
         end
+      ensure
+        context.template_name = old_template_name
       end
     end
 
     private
 
-    def load_cached_partial(context)
+    def load_cached_partial(template_name, context)
       cached_partials = context.registers[:cached_partials] || {}
-      template_name = context.evaluate(@template_name_expr)
 
       if cached = cached_partials[template_name]
         return cached

lib/liquid/template.rb

@@ -17,7 +17,7 @@ module Liquid
       locale: I18n.new
     }
 
-    attr_accessor :root
+    attr_accessor :root, :render_errors
     attr_reader :resource_limits
 
     @@file_system = BlankFileSystem.new
@@ -112,6 +112,7 @@ module Liquid
 
     def initialize
       @resource_limits = ResourceLimits.new(self.class.default_resource_limits)
+      @render_errors = true
     end
 
     # Parse source code.
@@ -163,6 +164,8 @@ module Liquid
     def render(*args)
       return ''.freeze if @root.nil?
 
+      render_errors = self.render_errors
+
       context = case args.first
       when Liquid::Context
         c = args.shift
@@ -174,11 +177,11 @@ module Liquid
         c
       when Liquid::Drop
         drop = args.shift
-        drop.context = Context.new([drop, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits)
+        drop.context = Context.new([drop, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits, render_errors)
       when Hash
-        Context.new([args.shift, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits)
+        Context.new([args.shift, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits, render_errors)
       when nil
-        Context.new(assigns, instance_assigns, registers, @rethrow_errors, @resource_limits)
+        Context.new(assigns, instance_assigns, registers, @rethrow_errors, @resource_limits, render_errors)
       else
         raise ArgumentError, "Expected Hash or Liquid::Context as parameter"
       end