441 lines
17 KiB
JavaScript
441 lines
17 KiB
JavaScript
// Partial port of python's argparse module, version 3.9.0 (only wrap and fill functions):
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// https://github.com/python/cpython/blob/v3.9.0b4/Lib/textwrap.py
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'use strict'
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/*
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* Text wrapping and filling.
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*/
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// Copyright (C) 1999-2001 Gregory P. Ward.
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// Copyright (C) 2002, 2003 Python Software Foundation.
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// Copyright (C) 2020 argparse.js authors
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// Originally written by Greg Ward <gward@python.net>
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// Hardcode the recognized whitespace characters to the US-ASCII
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// whitespace characters. The main reason for doing this is that
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// some Unicode spaces (like \u00a0) are non-breaking whitespaces.
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//
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// This less funky little regex just split on recognized spaces. E.g.
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// "Hello there -- you goof-ball, use the -b option!"
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// splits into
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// Hello/ /there/ /--/ /you/ /goof-ball,/ /use/ /the/ /-b/ /option!/
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const wordsep_simple_re = /([\t\n\x0b\x0c\r ]+)/
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class TextWrapper {
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/*
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* Object for wrapping/filling text. The public interface consists of
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* the wrap() and fill() methods; the other methods are just there for
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* subclasses to override in order to tweak the default behaviour.
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* If you want to completely replace the main wrapping algorithm,
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* you'll probably have to override _wrap_chunks().
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*
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* Several instance attributes control various aspects of wrapping:
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* width (default: 70)
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* the maximum width of wrapped lines (unless break_long_words
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* is false)
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* initial_indent (default: "")
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* string that will be prepended to the first line of wrapped
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* output. Counts towards the line's width.
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* subsequent_indent (default: "")
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* string that will be prepended to all lines save the first
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* of wrapped output; also counts towards each line's width.
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* expand_tabs (default: true)
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* Expand tabs in input text to spaces before further processing.
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* Each tab will become 0 .. 'tabsize' spaces, depending on its position
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* in its line. If false, each tab is treated as a single character.
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* tabsize (default: 8)
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* Expand tabs in input text to 0 .. 'tabsize' spaces, unless
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* 'expand_tabs' is false.
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* replace_whitespace (default: true)
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* Replace all whitespace characters in the input text by spaces
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* after tab expansion. Note that if expand_tabs is false and
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* replace_whitespace is true, every tab will be converted to a
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* single space!
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* fix_sentence_endings (default: false)
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* Ensure that sentence-ending punctuation is always followed
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* by two spaces. Off by default because the algorithm is
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* (unavoidably) imperfect.
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* break_long_words (default: true)
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* Break words longer than 'width'. If false, those words will not
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* be broken, and some lines might be longer than 'width'.
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* break_on_hyphens (default: true)
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* Allow breaking hyphenated words. If true, wrapping will occur
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* preferably on whitespaces and right after hyphens part of
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* compound words.
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* drop_whitespace (default: true)
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* Drop leading and trailing whitespace from lines.
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* max_lines (default: None)
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* Truncate wrapped lines.
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* placeholder (default: ' [...]')
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* Append to the last line of truncated text.
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*/
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constructor(options = {}) {
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let {
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width = 70,
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initial_indent = '',
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subsequent_indent = '',
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expand_tabs = true,
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replace_whitespace = true,
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fix_sentence_endings = false,
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break_long_words = true,
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drop_whitespace = true,
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break_on_hyphens = true,
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tabsize = 8,
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max_lines = undefined,
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placeholder=' [...]'
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} = options
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this.width = width
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this.initial_indent = initial_indent
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this.subsequent_indent = subsequent_indent
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this.expand_tabs = expand_tabs
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this.replace_whitespace = replace_whitespace
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this.fix_sentence_endings = fix_sentence_endings
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this.break_long_words = break_long_words
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this.drop_whitespace = drop_whitespace
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this.break_on_hyphens = break_on_hyphens
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this.tabsize = tabsize
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this.max_lines = max_lines
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this.placeholder = placeholder
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}
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// -- Private methods -----------------------------------------------
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// (possibly useful for subclasses to override)
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_munge_whitespace(text) {
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/*
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* _munge_whitespace(text : string) -> string
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*
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* Munge whitespace in text: expand tabs and convert all other
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* whitespace characters to spaces. Eg. " foo\\tbar\\n\\nbaz"
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* becomes " foo bar baz".
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*/
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if (this.expand_tabs) {
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text = text.replace(/\t/g, ' '.repeat(this.tabsize)) // not strictly correct in js
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}
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if (this.replace_whitespace) {
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text = text.replace(/[\t\n\x0b\x0c\r]/g, ' ')
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}
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return text
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}
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_split(text) {
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/*
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* _split(text : string) -> [string]
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*
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* Split the text to wrap into indivisible chunks. Chunks are
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* not quite the same as words; see _wrap_chunks() for full
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* details. As an example, the text
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* Look, goof-ball -- use the -b option!
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* breaks into the following chunks:
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* 'Look,', ' ', 'goof-', 'ball', ' ', '--', ' ',
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* 'use', ' ', 'the', ' ', '-b', ' ', 'option!'
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* if break_on_hyphens is True, or in:
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* 'Look,', ' ', 'goof-ball', ' ', '--', ' ',
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* 'use', ' ', 'the', ' ', '-b', ' ', option!'
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* otherwise.
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*/
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let chunks = text.split(wordsep_simple_re)
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chunks = chunks.filter(Boolean)
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return chunks
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}
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_handle_long_word(reversed_chunks, cur_line, cur_len, width) {
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/*
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* _handle_long_word(chunks : [string],
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* cur_line : [string],
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* cur_len : int, width : int)
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*
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* Handle a chunk of text (most likely a word, not whitespace) that
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* is too long to fit in any line.
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*/
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// Figure out when indent is larger than the specified width, and make
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// sure at least one character is stripped off on every pass
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let space_left
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if (width < 1) {
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space_left = 1
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} else {
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space_left = width - cur_len
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}
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// If we're allowed to break long words, then do so: put as much
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// of the next chunk onto the current line as will fit.
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if (this.break_long_words) {
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cur_line.push(reversed_chunks[reversed_chunks.length - 1].slice(0, space_left))
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reversed_chunks[reversed_chunks.length - 1] = reversed_chunks[reversed_chunks.length - 1].slice(space_left)
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// Otherwise, we have to preserve the long word intact. Only add
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// it to the current line if there's nothing already there --
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// that minimizes how much we violate the width constraint.
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} else if (!cur_line) {
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cur_line.push(...reversed_chunks.pop())
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}
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// If we're not allowed to break long words, and there's already
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// text on the current line, do nothing. Next time through the
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// main loop of _wrap_chunks(), we'll wind up here again, but
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// cur_len will be zero, so the next line will be entirely
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// devoted to the long word that we can't handle right now.
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}
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_wrap_chunks(chunks) {
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/*
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* _wrap_chunks(chunks : [string]) -> [string]
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*
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* Wrap a sequence of text chunks and return a list of lines of
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* length 'self.width' or less. (If 'break_long_words' is false,
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* some lines may be longer than this.) Chunks correspond roughly
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* to words and the whitespace between them: each chunk is
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* indivisible (modulo 'break_long_words'), but a line break can
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* come between any two chunks. Chunks should not have internal
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* whitespace; ie. a chunk is either all whitespace or a "word".
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* Whitespace chunks will be removed from the beginning and end of
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* lines, but apart from that whitespace is preserved.
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*/
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let lines = []
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let indent
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if (this.width <= 0) {
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throw Error(`invalid width ${this.width} (must be > 0)`)
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}
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if (this.max_lines !== undefined) {
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if (this.max_lines > 1) {
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indent = this.subsequent_indent
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} else {
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indent = this.initial_indent
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}
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if (indent.length + this.placeholder.trimStart().length > this.width) {
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throw Error('placeholder too large for max width')
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}
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}
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// Arrange in reverse order so items can be efficiently popped
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// from a stack of chucks.
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chunks = chunks.reverse()
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while (chunks.length > 0) {
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// Start the list of chunks that will make up the current line.
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// cur_len is just the length of all the chunks in cur_line.
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let cur_line = []
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let cur_len = 0
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// Figure out which static string will prefix this line.
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let indent
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if (lines) {
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indent = this.subsequent_indent
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} else {
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indent = this.initial_indent
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}
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// Maximum width for this line.
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let width = this.width - indent.length
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// First chunk on line is whitespace -- drop it, unless this
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// is the very beginning of the text (ie. no lines started yet).
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if (this.drop_whitespace && chunks[chunks.length - 1].trim() === '' && lines.length > 0) {
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chunks.pop()
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}
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while (chunks.length > 0) {
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let l = chunks[chunks.length - 1].length
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// Can at least squeeze this chunk onto the current line.
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if (cur_len + l <= width) {
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cur_line.push(chunks.pop())
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cur_len += l
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// Nope, this line is full.
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} else {
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break
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}
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}
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// The current line is full, and the next chunk is too big to
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// fit on *any* line (not just this one).
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if (chunks.length && chunks[chunks.length - 1].length > width) {
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this._handle_long_word(chunks, cur_line, cur_len, width)
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cur_len = cur_line.map(l => l.length).reduce((a, b) => a + b, 0)
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}
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// If the last chunk on this line is all whitespace, drop it.
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if (this.drop_whitespace && cur_line.length > 0 && cur_line[cur_line.length - 1].trim() === '') {
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cur_len -= cur_line[cur_line.length - 1].length
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cur_line.pop()
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}
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if (cur_line) {
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if (this.max_lines === undefined ||
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lines.length + 1 < this.max_lines ||
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(chunks.length === 0 ||
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this.drop_whitespace &&
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chunks.length === 1 &&
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!chunks[0].trim()) && cur_len <= width) {
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// Convert current line back to a string and store it in
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// list of all lines (return value).
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lines.push(indent + cur_line.join(''))
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} else {
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let had_break = false
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while (cur_line) {
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if (cur_line[cur_line.length - 1].trim() &&
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cur_len + this.placeholder.length <= width) {
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cur_line.push(this.placeholder)
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lines.push(indent + cur_line.join(''))
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had_break = true
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break
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}
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cur_len -= cur_line[-1].length
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cur_line.pop()
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}
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if (!had_break) {
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if (lines) {
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let prev_line = lines[lines.length - 1].trimEnd()
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if (prev_line.length + this.placeholder.length <=
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this.width) {
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lines[lines.length - 1] = prev_line + this.placeholder
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break
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}
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}
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lines.push(indent + this.placeholder.lstrip())
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}
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break
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}
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}
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}
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return lines
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}
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_split_chunks(text) {
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text = this._munge_whitespace(text)
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return this._split(text)
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}
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// -- Public interface ----------------------------------------------
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wrap(text) {
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/*
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* wrap(text : string) -> [string]
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*
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* Reformat the single paragraph in 'text' so it fits in lines of
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* no more than 'self.width' columns, and return a list of wrapped
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* lines. Tabs in 'text' are expanded with string.expandtabs(),
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* and all other whitespace characters (including newline) are
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* converted to space.
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*/
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let chunks = this._split_chunks(text)
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// not implemented in js
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//if (this.fix_sentence_endings) {
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// this._fix_sentence_endings(chunks)
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//}
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return this._wrap_chunks(chunks)
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}
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fill(text) {
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/*
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* fill(text : string) -> string
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*
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* Reformat the single paragraph in 'text' to fit in lines of no
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* more than 'self.width' columns, and return a new string
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* containing the entire wrapped paragraph.
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*/
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return this.wrap(text).join('\n')
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}
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}
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// -- Convenience interface ---------------------------------------------
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function wrap(text, options = {}) {
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/*
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* Wrap a single paragraph of text, returning a list of wrapped lines.
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*
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* Reformat the single paragraph in 'text' so it fits in lines of no
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* more than 'width' columns, and return a list of wrapped lines. By
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* default, tabs in 'text' are expanded with string.expandtabs(), and
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* all other whitespace characters (including newline) are converted to
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* space. See TextWrapper class for available keyword args to customize
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* wrapping behaviour.
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*/
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let { width = 70, ...kwargs } = options
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let w = new TextWrapper(Object.assign({ width }, kwargs))
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return w.wrap(text)
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}
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function fill(text, options = {}) {
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/*
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* Fill a single paragraph of text, returning a new string.
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*
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* Reformat the single paragraph in 'text' to fit in lines of no more
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* than 'width' columns, and return a new string containing the entire
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* wrapped paragraph. As with wrap(), tabs are expanded and other
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* whitespace characters converted to space. See TextWrapper class for
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* available keyword args to customize wrapping behaviour.
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*/
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let { width = 70, ...kwargs } = options
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let w = new TextWrapper(Object.assign({ width }, kwargs))
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return w.fill(text)
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}
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// -- Loosely related functionality -------------------------------------
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let _whitespace_only_re = /^[ \t]+$/mg
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let _leading_whitespace_re = /(^[ \t]*)(?:[^ \t\n])/mg
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function dedent(text) {
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/*
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* Remove any common leading whitespace from every line in `text`.
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*
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* This can be used to make triple-quoted strings line up with the left
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* edge of the display, while still presenting them in the source code
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* in indented form.
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*
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* Note that tabs and spaces are both treated as whitespace, but they
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* are not equal: the lines " hello" and "\\thello" are
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* considered to have no common leading whitespace.
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*
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* Entirely blank lines are normalized to a newline character.
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*/
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// Look for the longest leading string of spaces and tabs common to
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// all lines.
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let margin = undefined
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text = text.replace(_whitespace_only_re, '')
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let indents = text.match(_leading_whitespace_re) || []
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for (let indent of indents) {
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indent = indent.slice(0, -1)
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if (margin === undefined) {
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margin = indent
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// Current line more deeply indented than previous winner:
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// no change (previous winner is still on top).
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} else if (indent.startsWith(margin)) {
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// pass
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// Current line consistent with and no deeper than previous winner:
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// it's the new winner.
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} else if (margin.startsWith(indent)) {
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margin = indent
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// Find the largest common whitespace between current line and previous
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// winner.
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} else {
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for (let i = 0; i < margin.length && i < indent.length; i++) {
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if (margin[i] !== indent[i]) {
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margin = margin.slice(0, i)
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break
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}
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}
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}
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}
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if (margin) {
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text = text.replace(new RegExp('^' + margin, 'mg'), '')
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}
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return text
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}
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module.exports = { wrap, fill, dedent }
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