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lib.rs
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lib.rs
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// Copyright 2016 Indoc Developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! ## Unindent
//!
//! This crate provides [`indoc`]'s indentation logic for use with strings that
//! are not statically known at compile time. For unindenting string literals,
//! use `indoc` instead.
//!
//! [`indoc`]: https://github.com/dtolnay/indoc
//!
//! This crate exposes two functions:
//!
//! - `unindent(&str) -> String`
//! - `unindent_bytes(&[u8]) -> Vec<u8>`
//!
//! ```rust
//! extern crate unindent;
//! use unindent::unindent;
//!
//! fn main() {
//! let indented = "
//! line one
//! line two";
//! assert_eq!("line one\nline two", unindent(indented));
//! }
//! ```
#![doc(html_root_url = "https://docs.rs/unindent/0.1.2")]
#![cfg_attr(feature = "cargo-clippy", allow(type_complexity))]
use std::iter::Peekable;
use std::slice::Split;
pub fn unindent(s: &str) -> String {
let bytes = s.as_bytes();
let unindented = unindent_bytes(bytes);
String::from_utf8(unindented).unwrap()
}
// Compute the maximal number of spaces that can be removed from every line, and
// remove them.
pub fn unindent_bytes(s: &[u8]) -> Vec<u8> {
// Document may start either on the same line as opening quote or
// on the next line
let ignore_first_line = s.starts_with(b"\n") ||
s.starts_with(b"\r\n");
// Largest number of spaces that can be removed from every
// non-whitespace-only line after the first
let spaces = s.lines()
.skip(1)
.filter_map(count_spaces)
.min()
.unwrap_or(0);
let mut result = Vec::with_capacity(s.len());
for (i, line) in s.lines().enumerate() {
if i > 1 || (i == 1 && !ignore_first_line) {
result.push(b'\n');
}
if i == 0 {
// Do not un-indent anything on same line as opening quote
result.extend_from_slice(line);
} else if line.len() > spaces {
// Whitespace-only lines may have fewer than the number of spaces
// being removed
result.extend_from_slice(&line[spaces..]);
}
}
result
}
// Number of leading spaces in the line, or None if the line is entirely spaces.
fn count_spaces(line: &[u8]) -> Option<usize> {
for (i, ch) in line.iter().enumerate() {
if *ch != b' ' {
return Some(i);
}
}
None
}
// Based on core::str::StrExt.
trait BytesExt {
fn lines(&self) -> Lines;
}
impl BytesExt for [u8] {
fn lines(&self) -> Lines {
fn is_newline(b: &u8) -> bool {
*b == b'\n'
}
Lines {
split: self.split(is_newline as fn(&u8) -> bool).peekable(),
}
}
}
struct Lines<'a> {
split: Peekable<Split<'a, u8, fn(&u8) -> bool>>,
}
impl<'a> Iterator for Lines<'a> {
type Item = &'a [u8];
fn next(&mut self) -> Option<Self::Item> {
match self.split.next() {
None => None,
Some(fragment) => {
if fragment.is_empty() && self.split.peek().is_none() {
None
} else {
Some(fragment)
}
}
}
}
}