PEG.js Files

Major Changes

• Parsers can be generated in multiple module formats. The available formats are: CommonJS (the default), AMD, UMD, globals, and bare (not available from the command-line).

The format can be specified using the format option of the peg.generate function or the --format option on the command-line.

It is also possible to specify parser dependencies using the dependencies option of the peg.generate function or the --dependency/-d option on the command-line. This is mainly useful for the UMD format, where the dependencies are translated into both AMD dependencies and CommonJS require calls. - Browser version of PEG.js is now in the UMD format. This means it will try to detect AMD or Node.js/CommonJS module loader and define itself as a module. If no loader is found, it will export itself using a global variable. - API polishing. The peg.buildParser function was renamed to peg.generate. The global variable the browser version of PEG.js is available in when no loader is detected was renamed from PEG to peg. - CLI improvements. There is new --output/-o command-line option which allows to specify the output file. The old way of specifying the output file using a second argument was removed. To make room for the new -o option the old one (a shortcut for --optimize) was renamed to -O. All these changes make PEG.js conform to traditional compiler command-line interface.

It is now also possible to use - as a file name on the command-line (with the usual meaning of standard input/output). - Improved error messages. Both messages produced by PEG.js and generated parsers were improved. - Duplicate rule definitions are reported as errors. - Duplicate labels are reported as errors.

Minor Changes

• Exposed the AST node visitor builder as peg.compiler.visitor. This is useful mainly for plugins which manipulate the AST.
• Exposed the function which builds messages of exceptions produced by generated parsers as SyntaxError.buildMessage. This is useful mainly for customizing these error messages.
• The error and expected functions now accept an optional location parameter. This allows to customize the location in which the resulting syntax error is reported.
• Refactored expectations reported in the expected property of exceptions produced by generated parsers. They are no longer de-duplicated and sorted, their format changed to be more machine-readable, and they no longer contain human-readable descriptions.
• The found property of exceptions produced by the error function is now set to null.
• Removed access to the parser object in parser code via the parser variable.
• Made handling of optional parameters consistent with ES 2015. Specifically, passing undefined as a parameter value is now equivalent to not passing the parameter at all.
• Renamed several compiler passes.
• Generated parsers no longer consider \r, \u2028, and \u2029 as newlines (only \n and \r\n).
• Simplified the arithmetics example grammar.
• Switched from first/rest to head/tail in PEG.js grammar and example grammars.
• Started using ESLint instead of JSHint and fixed various problems it found.
• Added contribution guidelines.
• Removed support for io.js.

Bug Fixes

• Fixed bin/pegjs so that invoking it with one non-option argument which is an extension-less file doesn’t cause that file to be overwritten.
• Fixed label scoping so that labels in expressions like (a:"a") or (a:"a" b:"b" c:"c") aren’t visible from the outside.
• Fixed escaping of generated JavaScript strings & regexps to also escape DEL (U+007F).
• Fixed the JSON example grammar to correctly handle characters with code points above U+10FF in strings.
• Fixed multiple compatibility issues of tools/impact on OS X.
• Fixed slow deduplication of expectation descriptions.

Complete set of changes