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102 lines
3.5 KiB
102 lines
3.5 KiB
2 years ago
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"""Best-effort parser for requirements.txt files"""
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import urllib.parse
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from pathlib import Path
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import sys
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import os
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import re
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# `#` starts a comment only at end of line and after whitespace
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COMMENT_RE = re.compile(r'(^|\s+)#.*$')
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# Assume URLs start with a scheme; don't look for "egg=" URLs otherwise
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URL_START_RE = re.compile(r'^[-_+a-zA-Z0-9]+://')
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ENV_VAR_RE = re.compile(r'(?P<var>\$\{(?P<name>[A-Z0-9_]+)\})')
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PKGNAME_RE = re.compile(r'^[-_a-zA-Z0-9]+')
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# The requirements.txt format evolved rather organically; expect weirdness.
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def convert_requirements_txt(lines, path:Path = None):
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"""Convert lines of a requirements file to PEP 440-style requirement strs
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This does NOT handle all of requirements.txt features (only pip can do
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that), but tries its best.
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The resulting requirements might not actually be valid (either because
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they're wrong in the file, or because we missed a special case).
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path is the path to the requirements.txt file, used for options like `-r`.
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"""
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requirements = []
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lines = combine_logical_lines(lines)
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lines = strip_comments(lines)
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lines = expand_env_vars(lines)
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if path:
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filename = path.name
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else:
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filename = '<requirements file>'
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for line in lines:
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if URL_START_RE.match(line):
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# Handle URLs with "egg=..." fragments
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# see https://pip.pypa.io/en/stable/cli/pip_install/#vcs-support
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parsed_url = urllib.parse.urlparse(line)
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parsed_fragment = urllib.parse.parse_qs(parsed_url.fragment)
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if 'egg' in parsed_fragment:
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# Prepend the package name to the URL.
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match = PKGNAME_RE.match(parsed_fragment['egg'][0])
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if match:
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pkg_name = match[0]
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requirements.append(f'{pkg_name}@{line}')
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continue
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# If that didn't work, pass the line on;
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# the caller will deal with invalid requirements
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requirements.append(line)
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elif line.startswith('-r'):
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recursed_path = line[2:].strip()
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if path:
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recursed_path = path.parent / recursed_path
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recursed_path = Path(recursed_path)
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with recursed_path.open() as f:
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requirements.extend(convert_requirements_txt(f, recursed_path))
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elif line.startswith('-'):
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raise ValueError(f'{filename}: unsupported requirements file option: {line}')
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else:
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requirements.append(line)
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return requirements
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def combine_logical_lines(lines):
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"""Combine logical lines together (backslash line-continuation)"""
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pieces = []
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for line in lines:
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line = line.rstrip('\n')
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# Whole-line comments *only* are removed before line-contionuation
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if COMMENT_RE.match(line):
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continue
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if line.endswith('\\'):
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pieces.append(line[:-1])
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else:
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# trailing whitespace is only removed from full logical lines
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pieces.append(line.rstrip())
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yield ''.join(pieces)
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pieces = []
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yield ''.join(pieces)
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def strip_comments(lines):
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for line in lines:
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line, *rest = COMMENT_RE.split(line, maxsplit=1)
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line = line.strip()
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if line:
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yield line
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def expand_env_vars(lines):
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def repl(match):
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value = os.getenv(match['name'])
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if value is None:
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return match['var']
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return value
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for line in lines:
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yield ENV_VAR_RE.sub(repl, line)
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