Maintenance + Python 3.8

• 竜 TatSu is now only tested against Python 3.8. Earlier versions of Python are now deprecated, and Python 2.X versions are no longer supported (@apalala).
• Apply nameguard only if token[0].isalpha(). This solves a regression afecting previous TatSu and Grako grammars (@apalala).
• Remove pygraphviz from develoment requirements, as it doesn't build under Py38 (@apalala)
• #56 Include missing tatsu/g2e/antlr.ebnf in distribution (@apalala)
• #138 Reimplement the calculation of FIRST, FOLLOW, and LOOKAHEAD sets using latest theories. For now, this should improve parser error reporting, but should eventually enable the simplification of parsing of leftrec grammars (@apalala).
• #153 Import ABCs from collections.abc (@tirkarthi)
• Remove support for Cythonand pypy3 (@apalala).

Implementation of left recursion complete

• The default regexp for whitespace was changed to `(?s)s+
• Allow empty patterns (//) like Python does
• #65 Allow initial, consecutive, and trailing @namechars
• #73 Allow @@whitespace :: None and @@whitespace :: False
• #75 Complete implemenation of left recursion(@Victorious3)
• #77 Allow @keyword throughout the grammar
• #89 Make all attributes defined in the rule present in the resulting AST or Node even if the associated expression was not parsed
• #93 Fix trace colorization on Windows
• #96 Documented each @@directive
• Switched the documentation to the "Alabaster" theme
• Various code and documentation fixes (@davesque, @nicholasbishop, @rayjolt)

ModelBuilder upgrade

• #66 Fix multiline ( (?x) ) patterns not properly supported in grammar (@pdw-mb)
• #70 Important upgrade to ModelBuilder and grammar specification of classes for generated nodes. See pull request #78 for details (@Victorious3)

Bug fix release

• #56 Add missing tatsu/g2e/antlr.ebnf to distribution (@Ruth-Polymnia)
• #62 Fix TatSu ignoring start rule provided in command line (@r-chaves)
• Fix typos in documentation (@mjdominus

Bug fix release

• #42 Rename vim files from grako.vim to tatsu.vim (@fcoelho)
• #51 Fix inconsistent code generation for whitespace (@fpom)
• #54 Only care about case of first letter of rule name for determining advance over whitespace (@acw1251)

Bug fix release

• #40 Make the start rule default to the first rule defined in the grammar (@hariedo)
• #43 Import re from tatsu.util to support optional regex-only features (@azazel75)
• #47 Fix incorrect sample code in documentation

Bug-fix release (includes not working)

• #37 Regression: The #include pragma works by using the EBNFBuffer from grammars.py. Somehow the default EBNFBootstrapBuffer from bootstrap.py has been used instead (@gegenschall).

• #38 Documentation: Use of json.dumps() requires ast.asjson() (@davidchen).

Revert incorrect changes to left recursion

• #27 Undo the fixes to dropped input on left recursion because they broke previously expected behavior.

• #33 Fixes to the calc example and mini tutorial (@heronils)

• #34 More left-recursion test cases (@manueljacob).

Left recursion bug fix

Fixed

• #27 Left-recursive parsers would drop or skip input on many combinations of grammars and correct/incorrect inputs(@manueljacob)

• Documentation fixes (@manueljacob, @paulhoule)

provisions for recovery, optimizations, cleanup

Added

• Parse speeds on large files reduced by 5-20% by optimizing parse contexts and closures, and unifying the AST_ and CST_ stacks.

• Added the "skip to" expression ( ->), useful for writing recovery rules. The parser will advance over input, one character at time, until the expression matches. Whitespace and comments will be skipped at each step.

• Added the any expression ( /./) for matching the next character in the input.

• The ANTLR_ grammar for Python3_ to the g2e example, and udate g2e to handle more ANTLR_ syntax.

• Check typing with Mypy_.

Changed

• Removed the very old regex example.

• Make parse traces more compact. Add a sample to the docs.

• Explain Grako_ compatibility in docs.