feat: adaptive LL(*) lookahead - Githubissues

Chevrotain / chevrotain

Parser Building Toolkit for JavaScript

https://chevrotain.io

Apache License 2.0

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feat: adaptive LL(*) lookahead #1793

Closed msujew closed 1 year ago

msujew commented 2 years ago

Final version (hopefully) of the adaptive lookahead feature. Contains changes to:

General lookahead changes to accommodate the ATNSimulator parser trait
Deprecation of the maxLookahead property
Updates to error message generation for noViableAlt errors
Lots of test cases for the new lookahead behavior
Updated documentation

Based on the ALL(*) method employed by ANTLR4 (2011 and 2014 papers).

Performance benchmark after all the lookahead changes (parser only):

Library	Ops/sec	Relative Speed
JSON	9184.94 ± 0,76%	99.06%
CSS	3092.55 ± 0,68%	98.20%
ECMA5	470.71 ± 0,37%	94.82%