Refactor messageformat-parser, moving from PEG.js to moo #288
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BREAKING CHANGE: The parser is completely rewritten in TypeScript. The
new implementation uses `moo` to create a lexer, rather than PEG.js.
During this change, the AST output changes slightly:
- Static strings are wrapped in a { type: 'content', value: string }
token, rather than plain strings.
- Each token includes a `ctx` object, with information about its source
context.
- For plural & selectordinal tokens, the offset is renamed as
`pluralOffset`.
- Some of the errors change; braces with contents that are not
MessageFormat are mostly parsed without error.
- The TypeScript types are slightly refactored, as they're no longer
manually maintained.
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As PEG.js is clearly not currently under active development (see pegjs/pegjs#639), this PR completely refactors the parser by reimplementing it in TypeScript and using moo to generate an efficient lexer.
The main benefit of the change is a significant improvement in error reporting, as the errors now include a pointer to the source of the error. Tokens now also include a
ctxobject, with information about tis source context. All of this is also partly groundwork for supporting any later spec changes that might arise from the MessageFormat Working GroupThis PR does introduce some breaking changes:
{ type: 'content', value: string }token, rather than plain strings.pluralOffset.{}with contents that are not MessageFormat are mostly parsed without error.