Handlebars: explore template compilation

[alandefreitas]

Templates are interpreted on every render. We miss opportunities to preprocess whitespace, comments, and block boundaries, which makes debugging harder.

Proposed solution

• Add a compilation pass that generates an intermediate representation.
• Pre-trim whitespace, strip comments, and resolve block boundaries up front.
• Update the renderer to iterate over compiled tags (adapt OutputRef if needed).
• Measure performance vs. the interpreted approach.

Requirements

• Compiled templates produce identical output.
• Performance measurements document the gains.
• Debugging workflows improve (parsing/rendering separated).
• Documentation explains how to compile templates.

Note
Plan to migrate this issue to the standalone Handlebars repository once it is ready.

[alandefreitas]

More details about this issue:

• The parser for handlebars.js is now available at: https://github.com/handlebars-lang/handlebars-parser/tree/master/src

Jison (with jison-lex) is the toolchain that accepts input like that.

• handlebars.yy → a Bison-style grammar for Jison, with JS actions and %ebnf.
• handlebars.l → a jison-lex (Lex-like) lexer with start conditions; actions are JS. This is not valid for Bison/Flex (they expect C/C++ actions) as-is.

So since our goal is C/C++ output instead of JS, we’d need to port the actions and token plumbing to Bison/Flex (same grammar style, but actions in C/C++).