Rick Hightower
This supports handlebar templates, freemarker-like jstl and JSTL-like templates.
{{#if foo}}
{{foo}} //Escaped
{{{foo}}} //Unescaped
{{/if foo}}
{{#with foo}}
{{foo}} //Escaped
{{{foo}}} /Unescaped
{{/with}}
{{#each fruits}}
{{this}}
{{/each}}
see http://www.tutorialspoint.com/jsp/jsp_standard_tag_library.htm
see http://www.tutorialspoint.com/jsp/jstl_core_foreach_tag.htm
see http://docs.oracle.com/javaee/5/jstl/1.1/docs/tlddocs/c/forEach.html
${fn:escapeXml(foo)} //Escaped
${foo} //Unescaped
${fn:escapeXml(foo)} //Escaped
${foo} //Unescaped
${item}
Freemarker like
<#if foo>
${fn:escapeXml(foo)} //Escaped
${foo} //Unescaped
<#with foo>
${fn:escapeXml(foo)} //Escaped
${foo} //Unescaped
<#list fruits as fruit>
${fruit}
<#list fruits>
${item}
Freemarker has an expression language for if and such.
There are no plans to add a full expression langauge to this jstl.
The same goes for JSTL-like. Simple boolean expressions and calls to functions but no logic.
Velocity-like
#foreach( $product in $allProducts )
- $product
#end
#if( $foo )
Velocity!
#end
Velocity and Freemarker have if and else, else if.
Handlebars has if / else. Handlebars also has unless.
JSTL just has if.
Velocity, JSTL and Freemarker have full expression languages.
Handlebars does not.
The plan (currently) is for this templating to have no expressions.
You have property paths that are either true or false only, and you can call functions
that return true or false. Or rather true-y or falsey (null = false, empty list = false, etc.).
Python style true or false which is more ore less what handlebars/mustache do.
So this will be a stupid jstl, i.e., no logic other than true/false.
Start of block characters
Freemarker-like
<#if = '<#'
Velocity-like
#if = '#'
JSTL-like
END of start block character
Freemarker-like
<#if blah> = '>'
^
|
Velocity-like
#if = ' '
^
|
JSTL-like
= '>'
^
|
Mustache
{{#if } = '>'
^
|
This parser merely delivers up the stuff between start and stop.
Then there are handlers to further divide up the strings as the syntax varies a lot of how
expression of {{if}}, {{each}}, and {{with}} are handled.
Start of expression characters
Freemarker-like
${
Velocity-like
$
JSTL-like
${
Mustache/Handlebar
{{
Mustache/Handlebar
{{{
End of expression characters
Freemarker-like
}
Velocity-like
JSTL-like
}
Mustache/Handlebar
}}
Mustache/Handlebar (NOT HANDLED BY PARSER, HANDLED BY LOOKUP)
}}}
Rather than treat mustache as having two expressions (tried that), I will treat it as one.
Then the lookupWithDefault mechanism will handle the other case.
Velocity allows $vice and ${vice}maniac forms. Rather than handling two forms.
All parsers treat $vice as an expression. So that $foo is always an expression.
This would mean for mustache you would have $vice or {{vice}}maniac.
The caveat being that $expression handlng is a flag so you can turn it off for handlebars by default.
One of the goals is to have the ability to write scripts 100% compatible with Handlebars.
There is not a similar goal with Velocity, JSTL, and Freemarker.
You can only ever write scripts that are similar to JSTL not true JSTL scripts.
You can only ever write scripts that are similar to Velocity not true Velocity scripts.
You can only ever write scripts that are similar to Freemarker not true Freemarker scripts.
The goal is the ability to write scripts that are 100% Handlebar compatible and can be rendered by browser or Java.
The goal is for BoonTemplate is to be a superset of Handlebars and always only a subset of JSTL,
Velocity and Freemarker.
Order of importance:
- ,
- JSTL style support
,
- Freemarker style support
- and then Velocity style support
Handlebars has the advantage of the expression, and commands start with the same character, which
will help with parsing.
if (sameStart) {
look for start char of command and expression
} else {
look for start char of expression or command #NOTE this takes longer
}
Velocity like multiline
##.
.##
Freemarker like
<#--
-->
Handlebar like
{{!
}}
JSTL like (I made this one up JSTL does not have comments JSP does. :)
Input:
char[]
Output array of tokens in IndexOverlay style
Array item: TemplateToken (Block or Text or Expression or Comment, startIndex, stopIndex)
There is no logic in this parser. Just an array of token positions.
It is up to BoonTemplate on how to interpret those tokens.