76 lines
2.6 KiB
Rust
76 lines
2.6 KiB
Rust
// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use core::{
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fmt::{self, Write},
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iter::FusedIterator,
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};
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use tinyvec::ArrayVec;
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/// External iterator for replacements for a string's characters.
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#[derive(Clone)]
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pub struct Replacements<I> {
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iter: I,
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// At this time, the longest replacement sequence has length 2, so we just
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// need buffer space for 1 codepoint.
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buffer: Option<char>,
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}
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impl<I: Iterator<Item = char>> Replacements<I> {
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/// Create a new iterator that replaces [CJK Compatibility Ideograph] codepoints with normal forms using [Standardized Variation Sequences].
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///
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/// Note that this iterator can also be obtained by directly calling [`.cjk_compat_variants()`] on the iterator.
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///
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/// [CJK Compatibility Ideograph]: https://www.unicode.org/glossary/#compatibility_ideograph
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/// [Standardized Variation Sequences]: https://www.unicode.org/glossary/#standardized_variation_sequence
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/// [`.cjk_compat_variants()`]: crate::UnicodeNormalization::cjk_compat_variants
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#[inline]
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pub fn new_cjk_compat_variants(iter: I) -> Replacements<I> {
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Replacements { iter, buffer: None }
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}
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}
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impl<I: Iterator<Item = char>> Iterator for Replacements<I> {
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type Item = char;
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#[inline]
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fn next(&mut self) -> Option<char> {
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if let Some(c) = self.buffer.take() {
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return Some(c);
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}
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match self.iter.next() {
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Some(ch) => {
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// At this time, the longest replacement sequence has length 2.
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let mut buffer = ArrayVec::<[char; 2]>::new();
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super::char::decompose_cjk_compat_variants(ch, |d| buffer.push(d));
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self.buffer = buffer.get(1).copied();
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Some(buffer[0])
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}
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None => None,
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}
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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let (lower, _) = self.iter.size_hint();
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(lower, None)
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}
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}
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impl<I: Iterator<Item = char> + FusedIterator> FusedIterator for Replacements<I> {}
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impl<I: Iterator<Item = char> + Clone> fmt::Display for Replacements<I> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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for c in self.clone() {
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f.write_char(c)?;
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}
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Ok(())
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}
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}
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