Add freeze_template_literals option to avoid String#freeze

`"foo".freeze` generates an `opt_str_freeze` instruction while `"foo"` when frozen string literals is enabled generated a `putobject` instruction. The performance difference between the two is not that big, but it's still less work as it doesn't have to check wether String#freeze was redefined. It also generate much less native code with YJIT.
jeremyevans · Jul 27, 2022 · a9a2d35 · a9a2d35
1 parent d8a3d0a
commit a9a2d35
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diff --git a/lib/erubi.rb b/lib/erubi.rb
@@ -12,7 +12,6 @@ module Erubi
     RANGE_LAST = -1..-1
   end
 
-  TEXT_END = RUBY_VERSION >= '2.1' ? "'.freeze" : "'"
   MATCH_METHOD = RUBY_VERSION >= '2.4' ? :match? : :match
   SKIP_DEFINED_FOR_INSTANCE_VARIABLE = RUBY_VERSION > '3'
   # :nocov:
@@ -69,6 +68,7 @@ class Engine
     # +:escape_html+ :: Same as +:escape+, with lower priority.
     # +:filename+ :: The filename for the template.
     # +:freeze+ :: Whether to enable frozen string literals in the resulting source code.
+    # +:freeze_template_literals+ :: Wether suffix all literal strings with <tt>.freeze</tt> (default: <tt>true</tt> on Ruby 2.1+, <tt>false</tt> on Ruby2.0 and older).
     # +:literal_prefix+ :: The prefix to output when using escaped tag delimiters (default <tt>'<%'</tt>).
     # +:literal_postfix+ :: The postfix to output when using escaped tag delimiters (default <tt>'%>'</tt>).
     # +:outvar+ :: Same as +:bufvar+, with lower priority.
@@ -89,6 +89,11 @@ def initialize(input, properties={})
       preamble   = properties[:preamble] || "#{bufvar} = #{bufval};"
       postamble  = properties[:postamble] || "#{bufvar}.to_s\n"
       @chain_appends = properties[:chain_appends]
+      @text_end = if properties.fetch(:freeze_template_literals, RUBY_VERSION >= '2.1')
+        "'.freeze"
+      else
+        "'"
+      end
 
       @buffer_on_stack = false
       @src = src = properties[:src] || String.new
@@ -200,7 +205,7 @@ def add_text(text)
         text.gsub!(/['\\]/, '\\\\\&')
       end
 
-      with_buffer{@src << " << '" << text << TEXT_END}
+      with_buffer{@src << " << '" << text << @text_end}
     end
 
     # Add ruby code to the template

diff --git a/test/test.rb b/test/test.rb
@@ -35,11 +35,11 @@
     @options = {}
   end
 
-  def check_output(input, src, result, &block)
+  def check_output(input, src, result, strip_freeze: RUBY_VERSION >= '2.1', &block)
     t = (@options[:engine] || Erubi::Engine).new(input, @options)
     tsrc = t.src
     eval(tsrc, block.binding).must_equal result
-    tsrc = tsrc.gsub(/\.freeze/, '') if RUBY_VERSION >= '2.1'
+    tsrc = tsrc.gsub(/\.freeze/, '') if strip_freeze
     tsrc.must_equal src
   end
 
@@ -336,6 +336,94 @@ def self.quux
 END3
   end
 
+  it "should handle :freeze_template_literals => true option" do
+    @options[:freeze_template_literals] = true
+    list = list = ['&\'<>"2']
+    check_output(<<END1, <<END2, <<END3, strip_freeze: false){}
+<table>
+ <tbody>
+  <% i = 0
+     list.each_with_index do |item, i| %>
+  <tr>
+   <td><%= i+1 %></td>
+   <td><%== item %></td>
+  </tr>
+ <% end %>
+ </tbody>
+</table>
+<%== i+1 %>
+END1
+_buf = ::String.new; _buf << '<table>
+ <tbody>
+'.freeze;   i = 0
+     list.each_with_index do |item, i| 
+ _buf << '  <tr>
+   <td>'.freeze; _buf << ( i+1 ).to_s; _buf << '</td>
+   <td>'.freeze; _buf << ::Erubi.h(( item )); _buf << '</td>
+  </tr>
+'.freeze;  end 
+ _buf << ' </tbody>
+</table>
+'.freeze; _buf << ::Erubi.h(( i+1 )); _buf << '
+'.freeze;
+_buf.to_s
+END2
+<table>
+ <tbody>
+  <tr>
+   <td>1</td>
+   <td>&amp;&#39;&lt;&gt;&quot;2</td>
+  </tr>
+ </tbody>
+</table>
+1
+END3
+  end
+
+  it "should handle :freeze_template_literals => false option" do
+    @options[:freeze_template_literals] = false
+    list = list = ['&\'<>"2']
+    check_output(<<END1, <<END2, <<END3, strip_freeze: false){}
+<table>
+ <tbody>
+  <% i = 0
+     list.each_with_index do |item, i| %>
+  <tr>
+   <td><%= i+1 %></td>
+   <td><%== item %></td>
+  </tr>
+ <% end %>
+ </tbody>
+</table>
+<%== i+1 %>
+END1
+_buf = ::String.new; _buf << '<table>
+ <tbody>
+';   i = 0
+     list.each_with_index do |item, i| 
+ _buf << '  <tr>
+   <td>'; _buf << ( i+1 ).to_s; _buf << '</td>
+   <td>'; _buf << ::Erubi.h(( item )); _buf << '</td>
+  </tr>
+';  end 
+ _buf << ' </tbody>
+</table>
+'; _buf << ::Erubi.h(( i+1 )); _buf << '
+';
+_buf.to_s
+END2
+<table>
+ <tbody>
+  <tr>
+   <td>1</td>
+   <td>&amp;&#39;&lt;&gt;&quot;2</td>
+  </tr>
+ </tbody>
+</table>
+1
+END3
+  end
+
   it "should handle ensure option with no bufvar" do
     list = list = ['&\'<>"2']
     @options[:ensure] = true