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gh-113299: Move cpp.py into libclinic (#113526)
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Erlend E. Aasland
GitHub
parent
87295b4068
commit
7ab9efdd6a
3 changed files with 7 additions and 4 deletions
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@ -1,191 +0,0 @@
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import dataclasses as dc
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import re
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import sys
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from typing import NoReturn
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from libclinic.errors import ParseError
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TokenAndCondition = tuple[str, str]
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TokenStack = list[TokenAndCondition]
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def negate(condition: str) -> str:
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"""
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Returns a CPP conditional that is the opposite of the conditional passed in.
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"""
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if condition.startswith('!'):
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return condition[1:]
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return "!" + condition
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is_a_simple_defined = re.compile(r'^defined\s*\(\s*[A-Za-z0-9_]+\s*\)$').match
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@dc.dataclass(repr=False)
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class Monitor:
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"""
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A simple C preprocessor that scans C source and computes, line by line,
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what the current C preprocessor #if state is.
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Doesn't handle everything--for example, if you have /* inside a C string,
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without a matching */ (also inside a C string), or with a */ inside a C
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string but on another line and with preprocessor macros in between...
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the parser will get lost.
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Anyway this implementation seems to work well enough for the CPython sources.
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"""
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filename: str
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_: dc.KW_ONLY
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verbose: bool = False
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def __post_init__(self) -> None:
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self.stack: TokenStack = []
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self.in_comment = False
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self.continuation: str | None = None
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self.line_number = 0
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def __repr__(self) -> str:
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parts = (
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str(id(self)),
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f"line={self.line_number}",
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f"condition={self.condition()!r}"
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)
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return f"<clinic.Monitor {' '.join(parts)}>"
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def status(self) -> str:
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return str(self.line_number).rjust(4) + ": " + self.condition()
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def condition(self) -> str:
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"""
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Returns the current preprocessor state, as a single #if condition.
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"""
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return " && ".join(condition for token, condition in self.stack)
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def fail(self, msg: str) -> NoReturn:
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raise ParseError(msg, filename=self.filename, lineno=self.line_number)
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def writeline(self, line: str) -> None:
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self.line_number += 1
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line = line.strip()
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def pop_stack() -> TokenAndCondition:
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if not self.stack:
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self.fail(f"#{token} without matching #if / #ifdef / #ifndef!")
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return self.stack.pop()
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if self.continuation:
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line = self.continuation + line
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self.continuation = None
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if not line:
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return
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if line.endswith('\\'):
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self.continuation = line[:-1].rstrip() + " "
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return
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# we have to ignore preprocessor commands inside comments
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#
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# we also have to handle this:
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# /* start
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# ...
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# */ /* <-- tricky!
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# ...
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# */
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# and this:
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# /* start
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# ...
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# */ /* also tricky! */
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if self.in_comment:
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if '*/' in line:
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# snip out the comment and continue
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#
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# GCC allows
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# /* comment
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# */ #include <stdio.h>
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# maybe other compilers too?
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_, _, line = line.partition('*/')
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self.in_comment = False
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while True:
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if '/*' in line:
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if self.in_comment:
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self.fail("Nested block comment!")
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before, _, remainder = line.partition('/*')
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comment, comment_ends, after = remainder.partition('*/')
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if comment_ends:
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# snip out the comment
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line = before.rstrip() + ' ' + after.lstrip()
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continue
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# comment continues to eol
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self.in_comment = True
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line = before.rstrip()
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break
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# we actually have some // comments
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# (but block comments take precedence)
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before, line_comment, comment = line.partition('//')
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if line_comment:
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line = before.rstrip()
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if not line.startswith('#'):
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return
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line = line[1:].lstrip()
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assert line
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fields = line.split()
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token = fields[0].lower()
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condition = ' '.join(fields[1:]).strip()
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if token in {'if', 'ifdef', 'ifndef', 'elif'}:
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if not condition:
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self.fail(f"Invalid format for #{token} line: no argument!")
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if token in {'if', 'elif'}:
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if not is_a_simple_defined(condition):
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condition = "(" + condition + ")"
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if token == 'elif':
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previous_token, previous_condition = pop_stack()
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self.stack.append((previous_token, negate(previous_condition)))
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else:
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fields = condition.split()
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if len(fields) != 1:
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self.fail(f"Invalid format for #{token} line: "
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"should be exactly one argument!")
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symbol = fields[0]
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condition = 'defined(' + symbol + ')'
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if token == 'ifndef':
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condition = '!' + condition
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token = 'if'
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self.stack.append((token, condition))
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elif token == 'else':
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previous_token, previous_condition = pop_stack()
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self.stack.append((previous_token, negate(previous_condition)))
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elif token == 'endif':
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while pop_stack()[0] != 'if':
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pass
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else:
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return
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if self.verbose:
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print(self.status())
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def _main(filenames: list[str] | None = None) -> None:
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filenames = filenames or sys.argv[1:]
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for filename in filenames:
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with open(filename) as f:
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cpp = Monitor(filename, verbose=True)
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print()
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print(filename)
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for line in f:
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cpp.writeline(line)
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if __name__ == '__main__':
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_main()
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