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118 lines
3.2 KiB
Python
118 lines
3.2 KiB
Python
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#!/usr/bin/env python3.8
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"""Show the parse tree for a given program, nicely formatted.
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Example:
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$ scripts/show_parse.py a+b
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Module(
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body=[
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Expr(
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value=BinOp(
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left=Name(id="a", ctx=Load()), op=Add(), right=Name(id="b", ctx=Load())
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)
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)
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],
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type_ignores=[],
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)
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$
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Use -v to show line numbers and column offsets.
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The formatting is done using black. You can also import this module
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and call one of its functions.
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"""
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import argparse
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import ast
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import difflib
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import os
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import sys
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import tempfile
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from typing import List
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parser = argparse.ArgumentParser()
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parser.add_argument(
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"-d", "--diff", action="store_true", help="show diff between grammar and ast (requires -g)"
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)
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parser.add_argument("-g", "--grammar-file", help="grammar to use (default: use the ast module)")
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parser.add_argument(
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"-m",
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"--multiline",
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action="store_true",
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help="concatenate program arguments using newline instead of space",
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)
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parser.add_argument("-v", "--verbose", action="store_true", help="show line/column numbers")
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parser.add_argument("program", nargs="+", help="program to parse (will be concatenated)")
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def format_tree(tree: ast.AST, verbose: bool = False) -> str:
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with tempfile.NamedTemporaryFile("w+") as tf:
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tf.write(ast.dump(tree, include_attributes=verbose))
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tf.write("\n")
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tf.flush()
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cmd = f"black -q {tf.name}"
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sts = os.system(cmd)
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if sts:
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raise RuntimeError(f"Command {cmd!r} failed with status 0x{sts:x}")
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tf.seek(0)
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return tf.read()
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def diff_trees(a: ast.AST, b: ast.AST, verbose: bool = False) -> List[str]:
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sa = format_tree(a, verbose)
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sb = format_tree(b, verbose)
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la = sa.splitlines()
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lb = sb.splitlines()
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return list(difflib.unified_diff(la, lb, "a", "b", lineterm=""))
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def show_parse(source: str, verbose: bool = False) -> str:
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tree = ast.parse(source)
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return format_tree(tree, verbose).rstrip("\n")
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def print_parse(source: str, verbose: bool = False) -> None:
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print(show_parse(source, verbose))
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def main() -> None:
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args = parser.parse_args()
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if args.diff and not args.grammar_file:
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parser.error("-d/--diff requires -g/--grammar-file")
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if args.multiline:
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sep = "\n"
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else:
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sep = " "
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program = sep.join(args.program)
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if args.grammar_file:
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sys.path.insert(0, os.curdir)
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from pegen.build import build_parser_and_generator
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build_parser_and_generator(args.grammar_file, "peg_parser/parse.c", compile_extension=True)
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from pegen.parse import parse_string # type: ignore[import]
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tree = parse_string(program, mode=1)
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if args.diff:
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a = tree
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b = ast.parse(program)
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diff = diff_trees(a, b, args.verbose)
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if diff:
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for line in diff:
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print(line)
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else:
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print("# Trees are the same")
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else:
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print(f"# Parsed using {args.grammar_file}")
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print(format_tree(tree, args.verbose))
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else:
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tree = ast.parse(program)
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print("# Parse using ast.parse()")
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print(format_tree(tree, args.verbose))
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if __name__ == "__main__":
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main()
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