mirror of https://github.com/python/cpython
147 lines
4.3 KiB
Python
147 lines
4.3 KiB
Python
import contextlib
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from lexer import Token
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from typing import TextIO, Iterator
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class CWriter:
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"A writer that understands tokens and how to format C code"
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last_token: Token | None
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def __init__(self, out: TextIO, indent: int, line_directives: bool):
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self.out = out
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self.base_column = indent * 4
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self.indents = [i * 4 for i in range(indent + 1)]
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self.line_directives = line_directives
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self.last_token = None
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self.newline = True
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def set_position(self, tkn: Token) -> None:
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if self.last_token is not None:
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if self.last_token.line < tkn.line:
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self.out.write("\n")
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if self.line_directives:
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self.out.write(f'#line {tkn.line} "{tkn.filename}"\n')
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self.out.write(" " * self.indents[-1])
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else:
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gap = tkn.column - self.last_token.end_column
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self.out.write(" " * gap)
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elif self.newline:
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self.out.write(" " * self.indents[-1])
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self.last_token = tkn
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self.newline = False
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def emit_at(self, txt: str, where: Token) -> None:
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self.set_position(where)
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self.out.write(txt)
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def maybe_dedent(self, txt: str) -> None:
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parens = txt.count("(") - txt.count(")")
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if parens < 0:
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self.indents.pop()
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braces = txt.count("{") - txt.count("}")
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if braces < 0 or is_label(txt):
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self.indents.pop()
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def maybe_indent(self, txt: str) -> None:
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parens = txt.count("(") - txt.count(")")
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if parens > 0:
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if self.last_token:
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offset = self.last_token.end_column - 1
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if offset <= self.indents[-1] or offset > 40:
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offset = self.indents[-1] + 4
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else:
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offset = self.indents[-1] + 4
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self.indents.append(offset)
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if is_label(txt):
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self.indents.append(self.indents[-1] + 4)
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else:
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braces = txt.count("{") - txt.count("}")
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if braces > 0:
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assert braces == 1
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if 'extern "C"' in txt:
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self.indents.append(self.indents[-1])
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else:
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self.indents.append(self.indents[-1] + 4)
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def emit_text(self, txt: str) -> None:
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self.out.write(txt)
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def emit_multiline_comment(self, tkn: Token) -> None:
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self.set_position(tkn)
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lines = tkn.text.splitlines(True)
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first = True
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for line in lines:
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text = line.lstrip()
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if first:
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spaces = 0
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else:
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spaces = self.indents[-1]
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if text.startswith("*"):
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spaces += 1
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else:
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spaces += 3
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first = False
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self.out.write(" " * spaces)
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self.out.write(text)
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def emit_token(self, tkn: Token) -> None:
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if tkn.kind == "COMMENT" and "\n" in tkn.text:
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return self.emit_multiline_comment(tkn)
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self.maybe_dedent(tkn.text)
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self.set_position(tkn)
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self.emit_text(tkn.text)
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self.maybe_indent(tkn.text)
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def emit_str(self, txt: str) -> None:
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self.maybe_dedent(txt)
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if self.newline and txt:
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if txt[0] != "\n":
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self.out.write(" " * self.indents[-1])
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self.newline = False
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self.emit_text(txt)
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if txt.endswith("\n"):
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self.newline = True
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self.maybe_indent(txt)
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self.last_token = None
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def emit(self, txt: str | Token) -> None:
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if isinstance(txt, Token):
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self.emit_token(txt)
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elif isinstance(txt, str):
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self.emit_str(txt)
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else:
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assert False
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def start_line(self) -> None:
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if not self.newline:
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self.out.write("\n")
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self.newline = True
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self.last_token = None
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@contextlib.contextmanager
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def header_guard(self, name: str) -> Iterator[None]:
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self.out.write(
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f"""
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#ifndef {name}
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#define {name}
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#ifdef __cplusplus
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extern "C" {{
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#endif
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"""
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)
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yield
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self.out.write(
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f"""
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#ifdef __cplusplus
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}}
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#endif
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#endif /* !{name} */
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"""
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)
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def is_label(txt: str) -> bool:
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return not txt.startswith("//") and txt.endswith(":")
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