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- """
- This module provides functionality for caching and looking up fully qualified function
- and class names from Python source files by line number.
- It uses Python's tokenize module to parse source files and tracks function/class
- definitions along with their nesting to build fully qualified names (e.g. 'class.method'
- or 'module.function'). The results are cached in a two-level dictionary mapping:
- filename -> (line_number -> fully_qualified_name)
- Example usage:
- name = get_funcname("myfile.py", 42) # Returns name of function/class at line 42
- clearcache() # Clear the cache if file contents have changed
- The parsing is done lazily when a file is first accessed. Invalid Python files or
- IO errors are handled gracefully by returning empty cache entries.
- """
- import tokenize
- from typing import Optional
- cache: dict[str, dict[int, str]] = {}
- def clearcache() -> None:
- cache.clear()
- def _add_file(filename: str) -> None:
- try:
- with tokenize.open(filename) as f:
- tokens = list(tokenize.generate_tokens(f.readline))
- except (OSError, tokenize.TokenError):
- cache[filename] = {}
- return
- # NOTE: undefined behavior if file is not valid Python source,
- # since tokenize will have undefined behavior.
- result: dict[int, str] = {}
- # current full funcname, e.g. xxx.yyy.zzz
- cur_name = ""
- cur_indent = 0
- significant_indents: list[int] = []
- for i, token in enumerate(tokens):
- if token.type == tokenize.INDENT:
- cur_indent += 1
- elif token.type == tokenize.DEDENT:
- cur_indent -= 1
- # possible end of function or class
- if significant_indents and cur_indent == significant_indents[-1]:
- significant_indents.pop()
- # pop the last name
- cur_name = cur_name.rpartition(".")[0]
- elif (
- token.type == tokenize.NAME
- and i + 1 < len(tokens)
- and tokens[i + 1].type == tokenize.NAME
- and (token.string == "class" or token.string == "def")
- ):
- # name of class/function always follows class/def token
- significant_indents.append(cur_indent)
- if cur_name:
- cur_name += "."
- cur_name += tokens[i + 1].string
- result[token.start[0]] = cur_name
- cache[filename] = result
- def get_funcname(filename: str, lineno: int) -> Optional[str]:
- if filename not in cache:
- _add_file(filename)
- return cache[filename].get(lineno, None)
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