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Lib/textwrap.py (part 2)

cpython 3.14 @ ab2d84fe1023/Lib/textwrap.py

This annotation covers dedent, shorten, and indent from Lib/textwrap.py. For the TextWrapper class, fill, and wrap see the lib_textwrap annotation.

Map​

LinesSymbolRole
1-80dedentStrip common leading whitespace
81-160indentAdd prefix to lines matching a predicate
161-260shortenWord-wrap then truncate with placeholder

Reading​

dedent​

dedent(text) removes the longest common leading whitespace prefix from all non-empty lines. It handles mixed tabs and spaces by treating tabs as 8-space tab stops for prefix comparison purposes.

# CPython: Lib/textwrap.py:408 dedent
def dedent(text):
    ...
    _whitespace_only_re = re.compile('^[ \t]+$', re.MULTILINE)
    _leading_whitespace_re = re.compile('(^[ \t]*)(?:[^ \t\n])', re.MULTILINE)
    text = _whitespace_only_re.sub('', text)
    indents = _leading_whitespace_re.findall(text)
    margin = None
    for indent in indents:
        if margin is None:
            margin = indent
        elif indent.startswith(margin):
            pass
        elif margin.startswith(indent):
            margin = indent
        else:
            margin = ''
            break
    ...
    return re.sub(r'(?m)^' + margin, '', text) if margin else text

indent​

indent(text, prefix, predicate=None) prepends prefix to each line for which predicate(line) is true. The default predicate is "non-empty after stripping whitespace", which skips blank lines.

shorten​

shorten(text, width, **kwargs) word-wraps text to width columns, then takes the first line and appends placeholder (default ' [...]') if the text was truncated. This is useful for generating one-line summaries.

gopy notes​

dedent is used by docstring processing tools and has no gopy analogue yet. It will be part of module/textwrap/. The regex-based common prefix algorithm is straightforward to port to Go's regexp package.