[jerf]

This could be a step in that process, but in the grand scheme of things required to compile one language to another, the mere front-end parser is not generally all that significant a portion of the effort. The vast majority of the effort would be the bug-for-bug compatible implementation of PHP semantics and base libraries and functionality.

("Bug-for-bug" here does not mean that PHP has a lot of bugs per se. What it is is the highest level of compatibility. An emulator of a game console strives to be "bug-for-bug" compatible, for instance. Programming and programming languages being what they are, anything less often turns out to be surprisingly non-linearly less useful, i.e., "80% compatible" isn't anywhere near "80% useful".)