Change Log ========== This file documents all notable changes to PEG.js. The releases follow [semantic versioning](http://semver.org/). 0.9.0 ----- Released: August 30, 2015 ### Major Changes * **Tracing support.** Parsers can be compiled with support for tracing their progress, which can help debugging complex grammars. This feature is experimental and is expected to evolve over time as experience is gained. [More details](https://github.com/pegjs/pegjs/commit/da57118a43a904f753d44d407994cf0b36358adc) * **Infinite loop detection.** Grammar constructs that could cause infinite loops in generated parsers are detected during compilation and cause errors. * **Improved location information API.** The `line`, `column`, and `offset` functions available in parser code were replaced by a single `location` function which returns an object describing the current location. Similarly, the `line`, `column`, and `offset` properties of exceptions were replaced by a single `location` property. The location is no longer a single point but a character range, which is meaningful mainly in actions where the range covers action’s expression. [More details](https://github.com/pegjs/pegjs/compare/e75f21dc8f0e66b3d87c4c19b3fcb8f89d9c3acd...eaca5f0acf97b66ef141fed84aa95d4e72e33757) * **Improved error reporting.** All exceptions thrown when generating a parser have associated location information. And all exceptions thrown by generated parser and PEG.js itself have a stack trace (the `stack` property) in environments that support `Error.captureStackTrace`. * **Strict mode code**. All PEG.js and generated parser code is written using [JavaScript strict mode](https://developer.mozilla.org/cs/docs/Web/JavaScript/Reference/Strict_mode). ### Minor Changes * Labels behave like block-scoped variables. This means parser code can see labels defined outside expressions containing code. * Empty sequences are no longer allowed. * Label names can’t be JavaScript reserved words. * Rule and label names can contain Unicode characters like in JavaScript. * Rules have to be separated either by `;` or a newline (until now, any whitespace was enough). * The PEG.js grammar and all the example grammars were completely rewritten. This rewrite included a number of cleanups, formatting changes, naming changes, and bug fixes. * The parser object can now be accessed as `parser` in parser code. * Location information computation is faster. * Added support for Node.js >= 0.10.x, io.js, and Edge. Removed support for Node.js < 0.10.x. ### Bug Fixes * Fixed left recursion detector which missed many cases. * Fixed escaping of U+0100—U+107F and U+1000—U+107F in generated code and error messages. * Renamed `parse` and `SyntaxError` to `peg$parse` and `peg$SyntaxError` to mark them as internal identifiers. [Complete set of changes](https://github.com/pegjs/pegjs/compare/v0.8.0...v0.9.0) 0.8.0 ----- Released: December 24, 2013 ### Big Changes * Completely rewrote the code generator. Among other things, it allows optimizing generated parsers for parsing speed or code size using the `optimize` option of the `PEG.buildParser` method or the `--optimize`/`-o` option on the command-line. All internal identifiers in generated code now also have a `peg$` prefix to discourage their use and avoid conflicts. [[#35](https://github.com/dmajda/pegjs/issues/35), [#92](https://github.com/dmajda/pegjs/issues/92)] * Completely redesigned error handling. Instead of returning `null` inside actions to indicate match failure, new `expected` and `error` functions can be called to trigger an error. Also, expectation inside the `SyntaxError` exceptions are now structured to allow easier machine processing. [[#198](https://github.com/dmajda/pegjs/issues/198)] * Implemented a plugin API. The list of plugins to use can be specified using the `plugins` option of the `PEG.buildParser` method or the `--plugin` option on the command-line. Also implemented the `--extra-options` and `--extra-options-file` command-line options, which are mainly useful to pass additional options to plugins. [[#106](https://github.com/dmajda/pegjs/issues/106)] * Made `offset`, `line` and `column` functions, not variables. They are now available in all parsers and return lazily-computed position data. Removed now useless `trackLineAndColumn` option of the `PEG.buildParser` method and the `--track-line-and-column` option on the command-line. * Added a new `text` function. When called inside an action, it returns the text matched by action's expression. [[#131](https://github.com/dmajda/pegjs/issues/131)] * Added a new `$` operator. It extracts matched strings from expressions. * The `?` operator now returns `null` on unsuccessful match. * Predicates now always return `undefined`. * Replaced the `startRule` parameter of the `parse` method in generated parsers with more generic `options` parameter. The start rule can now be specified as the `startRule` option. The `options` parameter can be also used to pass custom options to the parser because it is visible as the `options` variable inside parser code. [[#37](https://github.com/dmajda/pegjs/issues/37)] * The list of allowed start rules of a generated parser now has to be specified explicitly using the `allowedStartRules` option of the `PEG.buildParser` method or the `--allowed-start-rule` option on the command-line. This will make certain optimizations like rule inlining easier in the future. * Removed the `toSource` method of generated parsers and introduced a new `output` option of the `PEG.buildParser` method. It allows callers to specify whether they want to get back the parser object or its source code. * The source code is now a valid npm package. This makes using development versions easier. [[#32](https://github.com/dmajda/pegjs/issues/32)] * Generated parsers are now ~25% faster and ~62%/~3% smaller (when optimized for size/speed) than those generated by 0.7.0. * Requires Node.js 0.8.0+. ### Small Changes * `bin/pegjs` now outputs just the parser source if the value of the `--export-var` option is empty. This makes embedding generated parsers into other files easier. [[#143](https://github.com/dmajda/pegjs/issues/143)] * Changed the value of the `name` property of `PEG.GrammarError` instances from “PEG.GrammarError” to just “GrammarError”. This better reflects the fact that PEG.js can get required with different variable name than `PEG`. * Setup prototype chain for `PEG.GrammarError` correctly. * Setup prototype chain for `SyntaxError` in generated parsers correctly. * Fixed error messages in certain cases with trailing input [[#119](https://github.com/dmajda/pegjs/issues/119)] * Fixed code generated for classes starting with `\^`. [[#125](https://github.com/dmajda/pegjs/issues/125)] * Fixed too eager proxy rules removal. [[#137](https://github.com/dmajda/pegjs/issues/137)] * Added a license to all vendored libraries. [[#207](https://github.com/dmajda/pegjs/issues/207)] * Converted the test suite from QUnit to Jasmine, cleaning it up on the way. * Travis CI integration. * Various internal code improvements and fixes. * Various generated code improvements and fixes. * Various example grammar improvements and fixes. * Improved `README.md`. * Converted `CHANGELOG` to Markdown. 0.7.0 ----- Released: April 18, 2012 ### Big Changes * Added ability to pass options to `PEG.buildParser`. * Implemented the `trackLineAndColumn` option for `PEG.buildParser` (together with the `--track-line-and-column` command-line option). It makes the generated parser track line and column during parsing. These are made available inside actions and predicates as `line` and `column` variables. * Implemented the `cache` option for `PEG.buildParser` (together with the `--cache` command-line option). This option enables/disables the results cache in generated parsers, resulting in dramatic speedup when the cache is disabled (the default now). The cost is breaking the linear parsing time guarantee. * The current parse position is visible inside actions and predicates as the `offset` variable. * Exceptions thrown by the parser have `offset`, `expected` and `found` properties containing machine-readable information about the parse failure (based on a patch by Marcin Stefaniuk). * Semantic predicates have access to preceding labels. [[GH-69](https://github.com/dmajda/pegjs/issues/69)] * Implemented case-insensitive literal and class matching. [[GH-34](https://github.com/dmajda/pegjs/issues/34)] * Rewrote the code generator — split some computations into separate passes and based it on a proper templating system (Codie). * Rewrote variable handling in generated parsers in a stack-like fashion, simplifying the code and making the parsers smaller and faster. * Adapted to Node.js 0.6.6+ (no longer supported in older versions). * Dropped support for IE < 8. * As a result of several optimizations, parsers generated by 0.7.0 are ~6.4 times faster and ~19% smaller than those generated by 0.6.2 (as reported by `/tools/impact`). ### Small Changes * Fixed reported error position when part of the input is not consumed. [[GH-48](https://github.com/dmajda/pegjs/issues/48)] * Fixed incorrect disjunction operator in `computeErrorPosition` (original patch by Wolfgang Kluge). * Fixed regexp for detecting command-line options in `/bin/pegjs`. [[GH-51](https://github.com/dmajda/pegjs/issues/51)] * Generate more efficient code for empty literals (original patch by Wolfgang Kluge). * Fixed comment typos (patches by Wolfgang Kluge and Jason Davies). [[GH-59](https://github.com/dmajda/pegjs/issues/59)] * Fixed a typo in JavaScript example grammar. [[GH-62](https://github.com/dmajda/pegjs/issues/62)] * Made copy & paste inclusion of the PEG.js library into another code easier by changing how the library is exported. * Improved the copyright comment and the “Generated by...” header. * Replaced `Jakefile` with `Makefile`. * Added `make hint` task that checks all JavaScript files using JSHint and resolved all issues it reported. All JavaScript files and also generated parsers are JSHint-clean now. * Fixed output printed during test failures (expected value was being printed instead of the actual one). Original patch by Wolfgang Kluge. * Added a `/tools/impact` script to measure speed and size impact of commits. * Various generated code improvements and fixes. * Various internal code improvements and fixes. * Improved `README.md`. 0.6.2 ----- Released: August 20, 2011 ### Small Changes * Reset parser position when action returns `null`. * Fixed typo in JavaScript example grammar. 0.6.1 ----- Released: April 14, 2011 ### Small Changes * Use `--ascii` option when generating a minified version. 0.6.0 ----- Released: April 14, 2011 ### Big Changes * Rewrote the command-line mode to be based on Node.js instead of Rhino — no more Java dependency. This also means that PEG.js is available as a Node.js package and can be required as a module. * Version for the browser is built separately from the command-line one in two flavors (normal and minified). * Parser variable name is no longer required argument of `bin/pegjs` — it is `module.exports` by default and can be set using the `-e`/`--export-var` option. This makes parsers generated by `/bin/pegjs` Node.js modules by default. * Added ability to start parsing from any grammar rule. * Added several compiler optimizations — 0.6 is ~12% faster than 0.5.1 in the benchmark on V8. ### Small Changes * Split the source code into multiple files combined together using a build system. * Jake is now used instead of Rake for build scripts — no more Ruby dependency. * Test suite can be run from the command-line. * Benchmark suite can be run from the command-line. * Benchmark browser runner improvements (users can specify number of runs, benchmarks are run using `setTimeout`, table is centered and fixed-width). * Added PEG.js version to “Generated by...” line in generated parsers. * Added PEG.js version information and homepage header to `peg.js`. * Generated code improvements and fixes. * Internal code improvements and fixes. * Rewrote `README.md`. 0.5.1 ----- Released: November 28, 2010 ### Small Changes * Fixed a problem where “SyntaxError: Invalid range in character class.” error appeared when using command-line version on Widnows ([GH-13](https://github.com/dmajda/pegjs/issues/13)). * Fixed wrong version reported by `bin/pegjs --version`. * Removed two unused variables in the code. * Fixed incorrect variable name on two places. 0.5 --- Released: June 10, 2010 ### Big Changes * Syntax change: Use labeled expressions and variables instead of `$1`, `$2`, etc. * Syntax change: Replaced `:` after a rule name with `=`. * Syntax change: Allow trailing semicolon (`;`) for rules * Semantic change: Start rule of the grammar is now implicitly its first rule. * Implemented semantic predicates. * Implemented initializers. * Removed ability to change the start rule when generating the parser. * Added several compiler optimizations — 0.5 is ~11% faster than 0.4 in the benchmark on V8. ### Small Changes * `PEG.buildParser` now accepts grammars only in string format. * Added “Generated by ...” message to the generated parsers. * Formatted all grammars more consistently and transparently. * Added notes about ECMA-262, 5th ed. compatibility to the JSON example grammar. * Guarded against redefinition of `undefined`. * Made `bin/pegjs` work when called via a symlink ([issue #1](https://github.com/dmajda/pegjs/issues/1)). * Fixed bug causing incorrect error messages ([issue #2](https://github.com/dmajda/pegjs/issues/2)). * Fixed error message for invalid character range. * Fixed string literal parsing in the JavaScript grammar. * Generated code improvements and fixes. * Internal code improvements and fixes. * Improved `README.md`. 0.4 --- Released: April 17, 2010 ### Big Changes * Improved IE compatibility — IE6+ is now fully supported. * Generated parsers are now standalone (no runtime is required). * Added example grammars for JavaScript, CSS and JSON. * Added a benchmark suite. * Implemented negative character classes (e.g. `[^a-z]`). * Project moved from BitBucket to GitHub. ### Small Changes * Code generated for the character classes is now regexp-based (= simpler and more scalable). * Added `\uFEFF` (BOM) to the definition of whitespace in the metagrammar. * When building a parser, left-recursive rules (both direct and indirect) are reported as errors. * When building a parser, missing rules are reported as errors. * Expected items in the error messages do not contain duplicates and they are sorted. * Fixed several bugs in the example arithmetics grammar. * Converted `README` to GitHub Flavored Markdown and improved it. * Added `CHANGELOG`. * Internal code improvements. 0.3 --- Released: March 14, 2010 * Wrote `README`. * Bootstrapped the grammar parser. * Metagrammar recognizes JavaScript-like comments. * Changed standard grammar extension from `.peg` to `.pegjs` (it is more specific). * Simplified the example arithmetics grammar + added comment. * Fixed a bug with reporting of invalid ranges such as `[b-a]` in the metagrammar. * Fixed `--start` vs. `--start-rule` inconsistency between help and actual option processing code. * Avoided ugliness in QUnit output. * Fixed typo in help: `parserVar` → `parser_var`. * Internal code improvements. 0.2.1 ----- Released: March 8, 2010 * Added `pegjs-` prefix to the name of the minified runtime file. 0.2 --- Released: March 8, 2010 * Added `Rakefile` that builds minified runtime using Google Closure Compiler API. * Removed trailing commas in object initializers (Google Closure does not like them). 0.1 --- Released: March 8, 2010 * Initial release.