From f40c7887d3cc9bb0b56576ed9edbe505ff8058c0 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Thu, 22 Sep 2022 12:10:41 +0200 Subject: scripts: Extract glibcpp.py from check-obsolete-constructs.py The C tokenizer is useful separately. Reviewed-by: Siddhesh Poyarekar --- scripts/glibcpp.py | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 scripts/glibcpp.py (limited to 'scripts/glibcpp.py') diff --git a/scripts/glibcpp.py b/scripts/glibcpp.py new file mode 100644 index 0000000000..b44c6a4392 --- /dev/null +++ b/scripts/glibcpp.py @@ -0,0 +1,212 @@ +#! /usr/bin/python3 +# Approximation to C preprocessing. +# Copyright (C) 2019-2022 Free Software Foundation, Inc. +# This file is part of the GNU C Library. +# +# The GNU C Library is free software; you can redistribute it and/or +# modify it under the terms of the GNU Lesser General Public +# License as published by the Free Software Foundation; either +# version 2.1 of the License, or (at your option) any later version. +# +# The GNU C Library is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public +# License along with the GNU C Library; if not, see +# . + +""" +Simplified lexical analyzer for C preprocessing tokens. + +Does not implement trigraphs. + +Does not implement backslash-newline in the middle of any lexical +item other than a string literal. + +Does not implement universal-character-names in identifiers. + +Treats prefixed strings (e.g. L"...") as two tokens (L and "..."). + +Accepts non-ASCII characters only within comments and strings. +""" + +import collections +import re + +# Caution: The order of the outermost alternation matters. +# STRING must be before BAD_STRING, CHARCONST before BAD_CHARCONST, +# BLOCK_COMMENT before BAD_BLOCK_COM before PUNCTUATOR, and OTHER must +# be last. +# Caution: There should be no capturing groups other than the named +# captures in the outermost alternation. + +# For reference, these are all of the C punctuators as of C11: +# [ ] ( ) { } , ; ? ~ +# ! != * *= / /= ^ ^= = == +# # ## +# % %= %> %: %:%: +# & &= && +# | |= || +# + += ++ +# - -= -- -> +# . ... +# : :> +# < <% <: << <<= <= +# > >= >> >>= + +# The BAD_* tokens are not part of the official definition of pp-tokens; +# they match unclosed strings, character constants, and block comments, +# so that the regex engine doesn't have to backtrack all the way to the +# beginning of a broken construct and then emit dozens of junk tokens. + +PP_TOKEN_RE_ = re.compile(r""" + (?P \"(?:[^\"\\\r\n]|\\(?:[\r\n -~]|\r\n))*\") + |(?P \"(?:[^\"\\\r\n]|\\[ -~])*) + |(?P \'(?:[^\'\\\r\n]|\\(?:[\r\n -~]|\r\n))*\') + |(?P \'(?:[^\'\\\r\n]|\\[ -~])*) + |(?P /\*(?:\*(?!/)|[^*])*\*/) + |(?P /\*(?:\*(?!/)|[^*])*\*?) + |(?P //[^\r\n]*) + |(?P [_a-zA-Z][_a-zA-Z0-9]*) + |(?P \.?[0-9](?:[0-9a-df-oq-zA-DF-OQ-Z_.]|[eEpP][+-]?)*) + |(?P + [,;?~(){}\[\]] + | [!*/^=]=? + | \#\#? + | %(?:[=>]|:(?:%:)?)? + | &[=&]? + |\|[=|]? + |\+[=+]? + | -[=->]? + |\.(?:\.\.)? + | :>? + | <(?:[%:]|<(?:=|<=?)?)? + | >(?:=|>=?)?) + |(?P \\(?:\r|\n|\r\n)) + |(?P [ \t\n\r\v\f]+) + |(?P .) +""", re.DOTALL | re.VERBOSE) + +HEADER_NAME_RE_ = re.compile(r""" + < [^>\r\n]+ > + | " [^"\r\n]+ " +""", re.DOTALL | re.VERBOSE) + +ENDLINE_RE_ = re.compile(r"""\r|\n|\r\n""") + +# based on the sample code in the Python re documentation +Token_ = collections.namedtuple("Token", ( + "kind", "text", "line", "column", "context")) +Token_.__doc__ = """ + One C preprocessing token, comment, or chunk of whitespace. + 'kind' identifies the token type, which will be one of: + STRING, CHARCONST, BLOCK_COMMENT, LINE_COMMENT, IDENT, + PP_NUMBER, PUNCTUATOR, ESCNL, WHITESPACE, HEADER_NAME, + or OTHER. The BAD_* alternatives in PP_TOKEN_RE_ are + handled within tokenize_c, below. + + 'text' is the sequence of source characters making up the token; + no decoding whatsoever is performed. + + 'line' and 'column' give the position of the first character of the + token within the source file. They are both 1-based. + + 'context' indicates whether or not this token occurred within a + preprocessing directive; it will be None for running text, + '' for the leading '#' of a directive line (because '#' + all by itself on a line is a "null directive"), or the name of + the directive for tokens within a directive line, starting with + the IDENT for the name itself. +""" + +def tokenize_c(file_contents, reporter): + """Yield a series of Token objects, one for each preprocessing + token, comment, or chunk of whitespace within FILE_CONTENTS. + The REPORTER object is expected to have one method, + reporter.error(token, message), which will be called to + indicate a lexical error at the position of TOKEN. + If MESSAGE contains the four-character sequence '{!r}', that + is expected to be replaced by repr(token.text). + """ + + Token = Token_ + PP_TOKEN_RE = PP_TOKEN_RE_ + ENDLINE_RE = ENDLINE_RE_ + HEADER_NAME_RE = HEADER_NAME_RE_ + + line_num = 1 + line_start = 0 + pos = 0 + limit = len(file_contents) + directive = None + at_bol = True + while pos < limit: + if directive == "include": + mo = HEADER_NAME_RE.match(file_contents, pos) + if mo: + kind = "HEADER_NAME" + directive = "after_include" + else: + mo = PP_TOKEN_RE.match(file_contents, pos) + kind = mo.lastgroup + if kind != "WHITESPACE": + directive = "after_include" + else: + mo = PP_TOKEN_RE.match(file_contents, pos) + kind = mo.lastgroup + + text = mo.group() + line = line_num + column = mo.start() - line_start + adj_line_start = 0 + # only these kinds can contain a newline + if kind in ("WHITESPACE", "BLOCK_COMMENT", "LINE_COMMENT", + "STRING", "CHARCONST", "BAD_BLOCK_COM", "ESCNL"): + for tmo in ENDLINE_RE.finditer(text): + line_num += 1 + adj_line_start = tmo.end() + if adj_line_start: + line_start = mo.start() + adj_line_start + + # Track whether or not we are scanning a preprocessing directive. + if kind == "LINE_COMMENT" or (kind == "WHITESPACE" and adj_line_start): + at_bol = True + directive = None + else: + if kind == "PUNCTUATOR" and text == "#" and at_bol: + directive = "" + elif kind == "IDENT" and directive == "": + directive = text + at_bol = False + + # Report ill-formed tokens and rewrite them as their well-formed + # equivalents, so downstream processing doesn't have to know about them. + # (Rewriting instead of discarding provides better error recovery.) + if kind == "BAD_BLOCK_COM": + reporter.error(Token("BAD_BLOCK_COM", "", line, column+1, ""), + "unclosed block comment") + text += "*/" + kind = "BLOCK_COMMENT" + elif kind == "BAD_STRING": + reporter.error(Token("BAD_STRING", "", line, column+1, ""), + "unclosed string") + text += "\"" + kind = "STRING" + elif kind == "BAD_CHARCONST": + reporter.error(Token("BAD_CHARCONST", "", line, column+1, ""), + "unclosed char constant") + text += "'" + kind = "CHARCONST" + + tok = Token(kind, text, line, column+1, + "include" if directive == "after_include" else directive) + # Do not complain about OTHER tokens inside macro definitions. + # $ and @ appear in macros defined by headers intended to be + # included from assembly language, e.g. sysdeps/mips/sys/asm.h. + if kind == "OTHER" and directive != "define": + self.error(tok, "stray {!r} in program") + + yield tok + pos = mo.end() -- cgit 1.4.1