mirror of https://github.com/python/cpython
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>
This commit is contained in:
Pablo Galindo
GitHub
parent
67987acd5d
commit
72cabb2aa6
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@ -15,7 +15,7 @@ sys.path.append(os.path.abspath('includes'))
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extensions = ['sphinx.ext.coverage', 'sphinx.ext.doctest',
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'pyspecific', 'c_annotations', 'escape4chm',
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'asdl_highlight']
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'asdl_highlight', 'peg_highlight']
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doctest_global_setup = '''
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@ -1,7 +1,19 @@
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Full Grammar specification
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==========================
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This is the full Python grammar, as it is read by the parser generator and used
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to parse Python source files:
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This is the full Python grammar, derived directly from the grammar
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used to generate the CPython parser (see :source:`Grammar/python.gram`).
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The version here omits details related to code generation and
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error recovery.
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.. literalinclude:: ../../Grammar/Grammar
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The notation is a mixture of `EBNF
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<https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form>`_
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and `PEG <https://en.wikipedia.org/wiki/Parsing_expression_grammar>`_.
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In particular, ``&`` followed by a symbol, token or parenthesized
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group indicates a positive lookahead (i.e., is required to match but
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not consumed), while ``!`` indicates a negative lookahead (i.e., is
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required _not_ to match). We use the ``|`` separator to mean PEG's
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"ordered choice" (written as ``/`` in traditional PEG grammars).
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.. literalinclude:: ../../Grammar/python.gram
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:language: peg
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@ -0,0 +1,75 @@
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from pygments.lexer import RegexLexer, bygroups, include
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from pygments.token import Comment, Generic, Keyword, Name, Operator, Punctuation, Text
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from sphinx.highlighting import lexers
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class PEGLexer(RegexLexer):
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"""Pygments Lexer for PEG grammar (.gram) files
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This lexer strips the following elements from the grammar:
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- Meta-tags
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- Variable assignments
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- Actions
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- Lookaheads
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- Rule types
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- Rule options
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- Rules named `invalid_*` or `incorrect_*`
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"""
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name = "PEG"
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aliases = ["peg"]
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filenames = ["*.gram"]
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_name = r"([^\W\d]\w*)"
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_text_ws = r"(\s*)"
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tokens = {
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"ws": [(r"\n", Text), (r"\s+", Text), (r"#.*$", Comment.Singleline),],
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"lookaheads": [
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(r"(?<=\|\s)(&\w+\s?)", bygroups(None)),
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(r"(?<=\|\s)(&'.+'\s?)", bygroups(None)),
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(r'(?<=\|\s)(&".+"\s?)', bygroups(None)),
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(r"(?<=\|\s)(&\(.+\)\s?)", bygroups(None)),
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],
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"metas": [
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(r"(@\w+ '''(.|\n)+?''')", bygroups(None)),
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(r"^(@.*)$", bygroups(None)),
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],
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"actions": [(r"{(.|\n)+?}", bygroups(None)),],
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"strings": [
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(r"'\w+?'", Keyword),
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(r'"\w+?"', Keyword),
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(r"'\W+?'", Text),
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(r'"\W+?"', Text),
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],
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"variables": [(_name + _text_ws + "(=)", bygroups(None, None, None),),],
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"invalids": [
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(r"^(\s+\|\s+invalid_\w+\s*\n)", bygroups(None)),
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(r"^(\s+\|\s+incorrect_\w+\s*\n)", bygroups(None)),
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(r"^(#.*invalid syntax.*(?:.|\n)*)", bygroups(None),),
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],
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"root": [
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include("invalids"),
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include("ws"),
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include("lookaheads"),
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include("metas"),
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include("actions"),
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include("strings"),
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include("variables"),
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(r"\b(?!(NULL|EXTRA))([A-Z_]+)\b\s*(?!\()", Text,),
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(
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r"^\s*" + _name + "\s*" + "(\[.*\])?" + "\s*" + "(\(.+\))?" + "\s*(:)",
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bygroups(Name.Function, None, None, Punctuation),
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),
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(_name, Name.Function),
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(r"[\||\.|\+|\*|\?]", Operator),
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(r"{|}|\(|\)|\[|\]", Punctuation),
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(r".", Text),
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],
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}
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def setup(app):
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lexers["peg"] = PEGLexer()
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return {"version": "1.0", "parallel_read_safe": True}
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206
Grammar/Grammar
206
Grammar/Grammar
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@ -1,206 +0,0 @@
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# Grammar for Python
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# NOTE: Editing this file has no effect except on the docs.
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# Start symbols for the grammar:
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# single_input is a single interactive statement;
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# file_input is a module or sequence of commands read from an input file;
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# eval_input is the input for the eval() functions.
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# func_type_input is a PEP 484 Python 2 function type comment
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# NB: compound_stmt in single_input is followed by extra NEWLINE!
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# NB: due to the way TYPE_COMMENT is tokenized it will always be followed by a NEWLINE
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single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
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file_input: (NEWLINE | stmt)* ENDMARKER
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eval_input: testlist NEWLINE* ENDMARKER
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decorator: '@' namedexpr_test NEWLINE
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decorators: decorator+
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decorated: decorators (classdef | funcdef | async_funcdef)
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async_funcdef: ASYNC funcdef
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funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMENT] func_body_suite
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parameters: '(' [typedargslist] ')'
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# The following definition for typedarglist is equivalent to this set of rules:
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#
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# arguments = argument (',' [TYPE_COMMENT] argument)*
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# argument = tfpdef ['=' test]
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# kwargs = '**' tfpdef [','] [TYPE_COMMENT]
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# args = '*' [tfpdef]
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# kwonly_kwargs = (',' [TYPE_COMMENT] argument)* (TYPE_COMMENT | [',' [TYPE_COMMENT] [kwargs]])
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# args_kwonly_kwargs = args kwonly_kwargs | kwargs
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# poskeyword_args_kwonly_kwargs = arguments ( TYPE_COMMENT | [',' [TYPE_COMMENT] [args_kwonly_kwargs]])
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# typedargslist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs
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# typedarglist = (arguments ',' [TYPE_COMMENT] '/' [',' [[TYPE_COMMENT] typedargslist_no_posonly]])|(typedargslist_no_posonly)"
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#
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# It needs to be fully expanded to allow our LL(1) parser to work on it.
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typedargslist: (
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(tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* ',' [TYPE_COMMENT] '/' [',' [ [TYPE_COMMENT] tfpdef ['=' test] (
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',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [
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'*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
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| '**' tfpdef [','] [TYPE_COMMENT]]])
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| '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
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| '**' tfpdef [','] [TYPE_COMMENT]]] )
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| (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [
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'*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
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| '**' tfpdef [','] [TYPE_COMMENT]]])
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| '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
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| '**' tfpdef [','] [TYPE_COMMENT])
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)
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tfpdef: NAME [':' test]
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# The following definition for varargslist is equivalent to this set of rules:
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#
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# arguments = argument (',' argument )*
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# argument = vfpdef ['=' test]
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# kwargs = '**' vfpdef [',']
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# args = '*' [vfpdef]
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# kwonly_kwargs = (',' argument )* [',' [kwargs]]
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# args_kwonly_kwargs = args kwonly_kwargs | kwargs
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# poskeyword_args_kwonly_kwargs = arguments [',' [args_kwonly_kwargs]]
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# vararglist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs
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# varargslist = arguments ',' '/' [','[(vararglist_no_posonly)]] | (vararglist_no_posonly)
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#
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# It needs to be fully expanded to allow our LL(1) parser to work on it.
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varargslist: vfpdef ['=' test ](',' vfpdef ['=' test])* ',' '/' [',' [ (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
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'*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
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| '**' vfpdef [',']]]
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| '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
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| '**' vfpdef [',']) ]] | (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
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'*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
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| '**' vfpdef [',']]]
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| '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
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| '**' vfpdef [',']
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)
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vfpdef: NAME
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stmt: simple_stmt | compound_stmt
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simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
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small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
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import_stmt | global_stmt | nonlocal_stmt | assert_stmt)
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expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
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[('=' (yield_expr|testlist_star_expr))+ [TYPE_COMMENT]] )
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annassign: ':' test ['=' (yield_expr|testlist_star_expr)]
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testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
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augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' |
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'<<=' | '>>=' | '**=' | '//=')
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# For normal and annotated assignments, additional restrictions enforced by the interpreter
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del_stmt: 'del' exprlist
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pass_stmt: 'pass'
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flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt
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break_stmt: 'break'
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continue_stmt: 'continue'
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return_stmt: 'return' [testlist_star_expr]
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yield_stmt: yield_expr
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raise_stmt: 'raise' [test ['from' test]]
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import_stmt: import_name | import_from
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import_name: 'import' dotted_as_names
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# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS
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import_from: ('from' (('.' | '...')* dotted_name | ('.' | '...')+)
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'import' ('*' | '(' import_as_names ')' | import_as_names))
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import_as_name: NAME ['as' NAME]
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dotted_as_name: dotted_name ['as' NAME]
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import_as_names: import_as_name (',' import_as_name)* [',']
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dotted_as_names: dotted_as_name (',' dotted_as_name)*
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dotted_name: NAME ('.' NAME)*
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global_stmt: 'global' NAME (',' NAME)*
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nonlocal_stmt: 'nonlocal' NAME (',' NAME)*
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assert_stmt: 'assert' test [',' test]
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compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt
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async_stmt: ASYNC (funcdef | with_stmt | for_stmt)
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if_stmt: 'if' namedexpr_test ':' suite ('elif' namedexpr_test ':' suite)* ['else' ':' suite]
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while_stmt: 'while' namedexpr_test ':' suite ['else' ':' suite]
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for_stmt: 'for' exprlist 'in' testlist ':' [TYPE_COMMENT] suite ['else' ':' suite]
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try_stmt: ('try' ':' suite
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((except_clause ':' suite)+
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['else' ':' suite]
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['finally' ':' suite] |
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'finally' ':' suite))
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with_stmt: 'with' with_item (',' with_item)* ':' [TYPE_COMMENT] suite
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with_item: test ['as' expr]
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# NB compile.c makes sure that the default except clause is last
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except_clause: 'except' [test ['as' NAME]]
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suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT
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namedexpr_test: test [':=' test]
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test: or_test ['if' or_test 'else' test] | lambdef
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test_nocond: or_test | lambdef_nocond
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lambdef: 'lambda' [varargslist] ':' test
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lambdef_nocond: 'lambda' [varargslist] ':' test_nocond
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or_test: and_test ('or' and_test)*
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and_test: not_test ('and' not_test)*
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not_test: 'not' not_test | comparison
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comparison: expr (comp_op expr)*
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# <> isn't actually a valid comparison operator in Python. It's here for the
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# sake of a __future__ import described in PEP 401 (which really works :-)
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comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
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star_expr: '*' expr
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expr: xor_expr ('|' xor_expr)*
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xor_expr: and_expr ('^' and_expr)*
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and_expr: shift_expr ('&' shift_expr)*
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shift_expr: arith_expr (('<<'|'>>') arith_expr)*
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arith_expr: term (('+'|'-') term)*
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term: factor (('*'|'@'|'/'|'%'|'//') factor)*
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factor: ('+'|'-'|'~') factor | power
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power: atom_expr ['**' factor]
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atom_expr: [AWAIT] atom trailer*
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atom: ('(' [yield_expr|testlist_comp] ')' |
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'[' [testlist_comp] ']' |
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'{' [dictorsetmaker] '}' |
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NAME | NUMBER | STRING+ | '...' | 'None' | 'True' | 'False')
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testlist_comp: (namedexpr_test|star_expr) ( comp_for | (',' (namedexpr_test|star_expr))* [','] )
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trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
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subscriptlist: subscript (',' subscript)* [',']
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subscript: test | [test] ':' [test] [sliceop]
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sliceop: ':' [test]
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exprlist: (expr|star_expr) (',' (expr|star_expr))* [',']
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testlist: test (',' test)* [',']
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dictorsetmaker: ( ((test ':' test | '**' expr)
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(comp_for | (',' (test ':' test | '**' expr))* [','])) |
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((test | star_expr)
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(comp_for | (',' (test | star_expr))* [','])) )
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classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
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arglist: argument (',' argument)* [',']
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# The reason that keywords are test nodes instead of NAME is that using NAME
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# results in an ambiguity. ast.c makes sure it's a NAME.
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# "test '=' test" is really "keyword '=' test", but we have no such token.
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# These need to be in a single rule to avoid grammar that is ambiguous
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# to our LL(1) parser. Even though 'test' includes '*expr' in star_expr,
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# we explicitly match '*' here, too, to give it proper precedence.
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# Illegal combinations and orderings are blocked in ast.c:
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# multiple (test comp_for) arguments are blocked; keyword unpackings
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# that precede iterable unpackings are blocked; etc.
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argument: ( test [comp_for] |
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test ':=' test |
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test '=' test |
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'**' test |
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'*' test )
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comp_iter: comp_for | comp_if
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sync_comp_for: 'for' exprlist 'in' or_test [comp_iter]
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comp_for: [ASYNC] sync_comp_for
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comp_if: 'if' test_nocond [comp_iter]
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# not used in grammar, but may appear in "node" passed from Parser to Compiler
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encoding_decl: NAME
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yield_expr: 'yield' [yield_arg]
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yield_arg: 'from' test | testlist_star_expr
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# the TYPE_COMMENT in suites is only parsed for funcdefs,
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# but can't go elsewhere due to ambiguity
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func_body_suite: simple_stmt | NEWLINE [TYPE_COMMENT NEWLINE] INDENT stmt+ DEDENT
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func_type_input: func_type NEWLINE* ENDMARKER
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func_type: '(' [typelist] ')' '->' test
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# typelist is a modified typedargslist (see above)
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typelist: (test (',' test)* [','
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['*' [test] (',' test)* [',' '**' test] | '**' test]]
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| '*' [test] (',' test)* [',' '**' test] | '**' test)
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