https://github.com/python/cpython/commit/72cabb2aa636272e608285f5a6ba83b62be... commit: 72cabb2aa636272e608285f5a6ba83b62be9be4e branch: master author: Pablo Galindo <Pablogsal@gmail.com> committer: GitHub <noreply@github.com> date: 2020-07-27T11:20:36-07:00 summary: bpo-40939: Use the new grammar for the grammar specification documentation (GH-19969) (We censor the heck out of actions and some other stuff using a custom "highlighter".) Co-authored-by: Guido van Rossum <guido@python.org> files: A Doc/tools/extensions/peg_highlight.py D Grammar/Grammar M Doc/conf.py M Doc/reference/grammar.rst diff --git a/Doc/conf.py b/Doc/conf.py index 12d74ea24ce4a..bfb2a98fc63a2 100644 --- a/Doc/conf.py +++ b/Doc/conf.py @@ -15,7 +15,7 @@ extensions = ['sphinx.ext.coverage', 'sphinx.ext.doctest', 'pyspecific', 'c_annotations', 'escape4chm', - 'asdl_highlight'] + 'asdl_highlight', 'peg_highlight'] doctest_global_setup = ''' diff --git a/Doc/reference/grammar.rst b/Doc/reference/grammar.rst index 83d0f8532c636..acf83765b5796 100644 --- a/Doc/reference/grammar.rst +++ b/Doc/reference/grammar.rst @@ -1,7 +1,19 @@ Full Grammar specification ========================== -This is the full Python grammar, as it is read by the parser generator and used -to parse Python source files: +This is the full Python grammar, derived directly from the grammar +used to generate the CPython parser (see :source:`Grammar/python.gram`). +The version here omits details related to code generation and +error recovery. -.. literalinclude:: ../../Grammar/Grammar +The notation is a mixture of `EBNF +<https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form>`_ +and `PEG <https://en.wikipedia.org/wiki/Parsing_expression_grammar>`_. +In particular, ``&`` followed by a symbol, token or parenthesized +group indicates a positive lookahead (i.e., is required to match but +not consumed), while ``!`` indicates a negative lookahead (i.e., is +required _not_ to match). We use the ``|`` separator to mean PEG's +"ordered choice" (written as ``/`` in traditional PEG grammars). + +.. literalinclude:: ../../Grammar/python.gram + :language: peg diff --git a/Doc/tools/extensions/peg_highlight.py b/Doc/tools/extensions/peg_highlight.py new file mode 100644 index 0000000000000..f02515d3919cf --- /dev/null +++ b/Doc/tools/extensions/peg_highlight.py @@ -0,0 +1,75 @@ +from pygments.lexer import RegexLexer, bygroups, include +from pygments.token import Comment, Generic, Keyword, Name, Operator, Punctuation, Text + +from sphinx.highlighting import lexers + + +class PEGLexer(RegexLexer): + """Pygments Lexer for PEG grammar (.gram) files + + This lexer strips the following elements from the grammar: + + - Meta-tags + - Variable assignments + - Actions + - Lookaheads + - Rule types + - Rule options + - Rules named `invalid_*` or `incorrect_*` + """ + + name = "PEG" + aliases = ["peg"] + filenames = ["*.gram"] + _name = r"([^\W\d]\w*)" + _text_ws = r"(\s*)" + + tokens = { + "ws": [(r"\n", Text), (r"\s+", Text), (r"#.*$", Comment.Singleline),], + "lookaheads": [ + (r"(?<=\|\s)(&\w+\s?)", bygroups(None)), + (r"(?<=\|\s)(&'.+'\s?)", bygroups(None)), + (r'(?<=\|\s)(&".+"\s?)', bygroups(None)), + (r"(?<=\|\s)(&\(.+\)\s?)", bygroups(None)), + ], + "metas": [ + (r"(@\w+ '''(.|\n)+?''')", bygroups(None)), + (r"^(@.*)$", bygroups(None)), + ], + "actions": [(r"{(.|\n)+?}", bygroups(None)),], + "strings": [ + (r"'\w+?'", Keyword), + (r'"\w+?"', Keyword), + (r"'\W+?'", Text), + (r'"\W+?"', Text), + ], + "variables": [(_name + _text_ws + "(=)", bygroups(None, None, None),),], + "invalids": [ + (r"^(\s+\|\s+invalid_\w+\s*\n)", bygroups(None)), + (r"^(\s+\|\s+incorrect_\w+\s*\n)", bygroups(None)), + (r"^(#.*invalid syntax.*(?:.|\n)*)", bygroups(None),), + ], + "root": [ + include("invalids"), + include("ws"), + include("lookaheads"), + include("metas"), + include("actions"), + include("strings"), + include("variables"), + (r"\b(?!(NULL|EXTRA))([A-Z_]+)\b\s*(?!\()", Text,), + ( + r"^\s*" + _name + "\s*" + "(\[.*\])?" + "\s*" + "(\(.+\))?" + "\s*(:)", + bygroups(Name.Function, None, None, Punctuation), + ), + (_name, Name.Function), + (r"[\||\.|\+|\*|\?]", Operator), + (r"{|}|\(|\)|\[|\]", Punctuation), + (r".", Text), + ], + } + + +def setup(app): + lexers["peg"] = PEGLexer() + return {"version": "1.0", "parallel_read_safe": True} diff --git a/Grammar/Grammar b/Grammar/Grammar deleted file mode 100644 index 61a26243f886b..0000000000000 --- a/Grammar/Grammar +++ /dev/null @@ -1,206 +0,0 @@ -# Grammar for Python - -# NOTE: Editing this file has no effect except on the docs. - -# Start symbols for the grammar: -# single_input is a single interactive statement; -# file_input is a module or sequence of commands read from an input file; -# eval_input is the input for the eval() functions. -# func_type_input is a PEP 484 Python 2 function type comment -# NB: compound_stmt in single_input is followed by extra NEWLINE! -# NB: due to the way TYPE_COMMENT is tokenized it will always be followed by a NEWLINE -single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE -file_input: (NEWLINE | stmt)* ENDMARKER -eval_input: testlist NEWLINE* ENDMARKER - -decorator: '@' namedexpr_test NEWLINE -decorators: decorator+ -decorated: decorators (classdef | funcdef | async_funcdef) - -async_funcdef: ASYNC funcdef -funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMENT] func_body_suite - -parameters: '(' [typedargslist] ')' - -# The following definition for typedarglist is equivalent to this set of rules: -# -# arguments = argument (',' [TYPE_COMMENT] argument)* -# argument = tfpdef ['=' test] -# kwargs = '**' tfpdef [','] [TYPE_COMMENT] -# args = '*' [tfpdef] -# kwonly_kwargs = (',' [TYPE_COMMENT] argument)* (TYPE_COMMENT | [',' [TYPE_COMMENT] [kwargs]]) -# args_kwonly_kwargs = args kwonly_kwargs | kwargs -# poskeyword_args_kwonly_kwargs = arguments ( TYPE_COMMENT | [',' [TYPE_COMMENT] [args_kwonly_kwargs]]) -# typedargslist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs -# typedarglist = (arguments ',' [TYPE_COMMENT] '/' [',' [[TYPE_COMMENT] typedargslist_no_posonly]])|(typedargslist_no_posonly)" -# -# It needs to be fully expanded to allow our LL(1) parser to work on it. - -typedargslist: ( - (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* ',' [TYPE_COMMENT] '/' [',' [ [TYPE_COMMENT] tfpdef ['=' test] ( - ',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [ - '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) - | '**' tfpdef [','] [TYPE_COMMENT]]]) - | '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) - | '**' tfpdef [','] [TYPE_COMMENT]]] ) -| (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [ - '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) - | '**' tfpdef [','] [TYPE_COMMENT]]]) - | '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) - | '**' tfpdef [','] [TYPE_COMMENT]) -) -tfpdef: NAME [':' test] - -# The following definition for varargslist is equivalent to this set of rules: -# -# arguments = argument (',' argument )* -# argument = vfpdef ['=' test] -# kwargs = '**' vfpdef [','] -# args = '*' [vfpdef] -# kwonly_kwargs = (',' argument )* [',' [kwargs]] -# args_kwonly_kwargs = args kwonly_kwargs | kwargs -# poskeyword_args_kwonly_kwargs = arguments [',' [args_kwonly_kwargs]] -# vararglist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs -# varargslist = arguments ',' '/' [','[(vararglist_no_posonly)]] | (vararglist_no_posonly) -# -# It needs to be fully expanded to allow our LL(1) parser to work on it. - -varargslist: vfpdef ['=' test ](',' vfpdef ['=' test])* ',' '/' [',' [ (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [ - '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]] - | '**' vfpdef [',']]] - | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]] - | '**' vfpdef [',']) ]] | (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [ - '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]] - | '**' vfpdef [',']]] - | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]] - | '**' vfpdef [','] -) -vfpdef: NAME - -stmt: simple_stmt | compound_stmt -simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE -small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt | - import_stmt | global_stmt | nonlocal_stmt | assert_stmt) -expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) | - [('=' (yield_expr|testlist_star_expr))+ [TYPE_COMMENT]] ) -annassign: ':' test ['=' (yield_expr|testlist_star_expr)] -testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [','] -augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' | - '<<=' | '>>=' | '**=' | '//=') -# For normal and annotated assignments, additional restrictions enforced by the interpreter -del_stmt: 'del' exprlist -pass_stmt: 'pass' -flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt -break_stmt: 'break' -continue_stmt: 'continue' -return_stmt: 'return' [testlist_star_expr] -yield_stmt: yield_expr -raise_stmt: 'raise' [test ['from' test]] -import_stmt: import_name | import_from -import_name: 'import' dotted_as_names -# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS -import_from: ('from' (('.' | '...')* dotted_name | ('.' | '...')+) - 'import' ('*' | '(' import_as_names ')' | import_as_names)) -import_as_name: NAME ['as' NAME] -dotted_as_name: dotted_name ['as' NAME] -import_as_names: import_as_name (',' import_as_name)* [','] -dotted_as_names: dotted_as_name (',' dotted_as_name)* -dotted_name: NAME ('.' NAME)* -global_stmt: 'global' NAME (',' NAME)* -nonlocal_stmt: 'nonlocal' NAME (',' NAME)* -assert_stmt: 'assert' test [',' test] - -compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt -async_stmt: ASYNC (funcdef | with_stmt | for_stmt) -if_stmt: 'if' namedexpr_test ':' suite ('elif' namedexpr_test ':' suite)* ['else' ':' suite] -while_stmt: 'while' namedexpr_test ':' suite ['else' ':' suite] -for_stmt: 'for' exprlist 'in' testlist ':' [TYPE_COMMENT] suite ['else' ':' suite] -try_stmt: ('try' ':' suite - ((except_clause ':' suite)+ - ['else' ':' suite] - ['finally' ':' suite] | - 'finally' ':' suite)) -with_stmt: 'with' with_item (',' with_item)* ':' [TYPE_COMMENT] suite -with_item: test ['as' expr] -# NB compile.c makes sure that the default except clause is last -except_clause: 'except' [test ['as' NAME]] -suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT - -namedexpr_test: test [':=' test] -test: or_test ['if' or_test 'else' test] | lambdef -test_nocond: or_test | lambdef_nocond -lambdef: 'lambda' [varargslist] ':' test -lambdef_nocond: 'lambda' [varargslist] ':' test_nocond -or_test: and_test ('or' and_test)* -and_test: not_test ('and' not_test)* -not_test: 'not' not_test | comparison -comparison: expr (comp_op expr)* -# <> isn't actually a valid comparison operator in Python. It's here for the -# sake of a __future__ import described in PEP 401 (which really works :-) -comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not' -star_expr: '*' expr -expr: xor_expr ('|' xor_expr)* -xor_expr: and_expr ('^' and_expr)* -and_expr: shift_expr ('&' shift_expr)* -shift_expr: arith_expr (('<<'|'>>') arith_expr)* -arith_expr: term (('+'|'-') term)* -term: factor (('*'|'@'|'/'|'%'|'//') factor)* -factor: ('+'|'-'|'~') factor | power -power: atom_expr ['**' factor] -atom_expr: [AWAIT] atom trailer* -atom: ('(' [yield_expr|testlist_comp] ')' | - '[' [testlist_comp] ']' | - '{' [dictorsetmaker] '}' | - NAME | NUMBER | STRING+ | '...' | 'None' | 'True' | 'False') -testlist_comp: (namedexpr_test|star_expr) ( comp_for | (',' (namedexpr_test|star_expr))* [','] ) -trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME -subscriptlist: subscript (',' subscript)* [','] -subscript: test | [test] ':' [test] [sliceop] -sliceop: ':' [test] -exprlist: (expr|star_expr) (',' (expr|star_expr))* [','] -testlist: test (',' test)* [','] -dictorsetmaker: ( ((test ':' test | '**' expr) - (comp_for | (',' (test ':' test | '**' expr))* [','])) | - ((test | star_expr) - (comp_for | (',' (test | star_expr))* [','])) ) - -classdef: 'class' NAME ['(' [arglist] ')'] ':' suite - -arglist: argument (',' argument)* [','] - -# The reason that keywords are test nodes instead of NAME is that using NAME -# results in an ambiguity. ast.c makes sure it's a NAME. -# "test '=' test" is really "keyword '=' test", but we have no such token. -# These need to be in a single rule to avoid grammar that is ambiguous -# to our LL(1) parser. Even though 'test' includes '*expr' in star_expr, -# we explicitly match '*' here, too, to give it proper precedence. -# Illegal combinations and orderings are blocked in ast.c: -# multiple (test comp_for) arguments are blocked; keyword unpackings -# that precede iterable unpackings are blocked; etc. -argument: ( test [comp_for] | - test ':=' test | - test '=' test | - '**' test | - '*' test ) - -comp_iter: comp_for | comp_if -sync_comp_for: 'for' exprlist 'in' or_test [comp_iter] -comp_for: [ASYNC] sync_comp_for -comp_if: 'if' test_nocond [comp_iter] - -# not used in grammar, but may appear in "node" passed from Parser to Compiler -encoding_decl: NAME - -yield_expr: 'yield' [yield_arg] -yield_arg: 'from' test | testlist_star_expr - -# the TYPE_COMMENT in suites is only parsed for funcdefs, -# but can't go elsewhere due to ambiguity -func_body_suite: simple_stmt | NEWLINE [TYPE_COMMENT NEWLINE] INDENT stmt+ DEDENT - -func_type_input: func_type NEWLINE* ENDMARKER -func_type: '(' [typelist] ')' '->' test -# typelist is a modified typedargslist (see above) -typelist: (test (',' test)* [',' - ['*' [test] (',' test)* [',' '**' test] | '**' test]] - | '*' [test] (',' test)* [',' '**' test] | '**' test)