cpython/Tools/peg_generator/scripts/joinstats.py

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#!/usr/bin/env python3.8
"""Produce a report about the most-memoable types.
Reads a list of statistics from stdin. Each line must be two numbers,
being a type and a count. We then read some other files and produce a
list sorted by most frequent type.
There should also be something to recognize left-recursive rules.
"""
import os
import re
import sys
from typing import Dict
reporoot = os.path.dirname(os.path.dirname(__file__))
parse_c = os.path.join(reporoot, "peg_extension", "parse.c")
class TypeMapper:
"""State used to map types to names."""
def __init__(self, filename: str) -> None:
self.table: Dict[int, str] = {}
with open(filename) as f:
for line in f:
match = re.match(r"#define (\w+)_type (\d+)", line)
if match:
name, type = match.groups()
if "left" in line.lower():
name += " // Left-recursive"
self.table[int(type)] = name
def lookup(self, type: int) -> str:
return self.table.get(type, str(type))
def main() -> None:
mapper = TypeMapper(parse_c)
table = []
filename = sys.argv[1]
with open(filename) as f:
for lineno, line in enumerate(f, 1):
line = line.strip()
if not line or line.startswith("#"):
continue
parts = line.split()
# Extra fields ignored
if len(parts) < 2:
print(f"{lineno}: bad input ({line!r})")
continue
try:
type, count = map(int, parts[:2])
except ValueError as err:
print(f"{lineno}: non-integer input ({line!r})")
continue
table.append((type, count))
table.sort(key=lambda values: -values[1])
for type, count in table:
print(f"{type:4d} {count:9d} {mapper.lookup(type)}")
if __name__ == "__main__":
main()