[GROOVY-1205] GStringTemplateEngine does not always parse single line comments '//' within <% and %> sections correctly

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0-JSR-3
• Component/s: Groovlet / GSP
• Assignee: John Wilson
• Reporter: Andy DePue
• Created: 11/Jan/06 15:26
• Updated: 30/Nov/07 06:23
• Resolved: 12/Jan/06 03:57

Description

This bug affects groovy.text.GStringTemplateEngine. SimpleTemplateEngine seems to be immune.
If you put a single line comment (using double forward slashes '//') within a scriptlet section (enclosed in <% and %>), it will cause a parse error if there is no new line between the end of the comment and the closing '%>' sequence. This is often done to place comments into a template that the developer does not want showing up in the output. For example:

<tag1 attr="someValue">
<% // Some comment that I don't want showing up in the output %>
<tag2/>
</tag1>

The above will cause a parse error. However, this will not:

<tag1 attr="someValue">
<% // Some comment that I don't want showing up in the output
%>
<tag2/>
</tag1>

Further debugging indicates that this is because GStringTemplateEngine does not place a newline in the resulting Groovy script code after outputting code enclosed in a <% %> section. (It currently places the characters "; " after the scriptlet code). For example, the following template:

<% // This is a comment that will be filtered from output %>
Hello World!

Produces this Groovy script:

package groovy.tmp.templates
def getTemplate() { return

{ out -> delegate = new Binding(delegate); out << """"""; // This is a comment that will be filtered from output ; out << """ Hello World!"""}

.asWritable()}

Notice that GStringTemplateEngine appended "; " to the end of the comment '//', but since it did not append a newline after the "; ", the following "out << ..." code is considered part of the comment and so completely borks the parsing.

I've attached a very simple TestCase that contains a failing unit test to reproduce the problem.