cpython/Tools/peg_generator/scripts/show_parse.py
Lysandros Nikolaou 9645930b5b
bpo-40688: Use the correct parser in the peg_generator scripts (GH-20235)
The scripts in `Tools/peg_generator/scripts` mostly assume that
`ast.parse` and `compile` use the old parser, since this was the
state of things, while we were developing them. They need to be
updated to always use the correct parser. `_peg_parser` is being
extended to support both parsing and compiling with both parsers.
2020-05-25 20:51:58 +01:00

116 lines
3.1 KiB
Python
Executable file

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