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use std::fmt::{self, Write};
fn canonical_sort(comb: &mut [(char, u8)]) {
let len = comb.len();
for i in 0..len {
let mut swapped = false;
for j in 1..len-i {
let class_a = comb[j-1].1;
let class_b = comb[j].1;
if class_a != 0 && class_b != 0 && class_a > class_b {
comb.swap(j-1, j);
swapped = true;
}
}
if !swapped { break; }
}
}
#[derive(Clone)]
enum DecompositionType {
Canonical,
Compatible
}
#[derive(Clone)]
pub struct Decompositions<I> {
kind: DecompositionType,
iter: I,
buffer: Vec<(char, u8)>,
sorted: bool
}
#[inline]
pub fn new_canonical<I: Iterator<Item=char>>(iter: I) -> Decompositions<I> {
Decompositions {
iter: iter,
buffer: Vec::new(),
sorted: false,
kind: self::DecompositionType::Canonical,
}
}
#[inline]
pub fn new_compatible<I: Iterator<Item=char>>(iter: I) -> Decompositions<I> {
Decompositions {
iter: iter,
buffer: Vec::new(),
sorted: false,
kind: self::DecompositionType::Compatible,
}
}
impl<I: Iterator<Item=char>> Iterator for Decompositions<I> {
type Item = char;
#[inline]
fn next(&mut self) -> Option<char> {
use self::DecompositionType::*;
match self.buffer.first() {
Some(&(c, 0)) => {
self.sorted = false;
self.buffer.remove(0);
return Some(c);
}
Some(&(c, _)) if self.sorted => {
self.buffer.remove(0);
return Some(c);
}
_ => self.sorted = false
}
if !self.sorted {
for ch in self.iter.by_ref() {
let buffer = &mut self.buffer;
let sorted = &mut self.sorted;
{
let callback = |d| {
let class =
super::char::canonical_combining_class(d);
if class == 0 && !*sorted {
canonical_sort(buffer);
*sorted = true;
}
buffer.push((d, class));
};
match self.kind {
Canonical => {
super::char::decompose_canonical(ch, callback)
}
Compatible => {
super::char::decompose_compatible(ch, callback)
}
}
}
if *sorted {
break
}
}
}
if !self.sorted {
canonical_sort(&mut self.buffer);
self.sorted = true;
}
if self.buffer.is_empty() {
None
} else {
match self.buffer.remove(0) {
(c, 0) => {
self.sorted = false;
Some(c)
}
(c, _) => Some(c),
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (lower, _) = self.iter.size_hint();
(lower, None)
}
}
impl<I: Iterator<Item=char> + Clone> fmt::Display for Decompositions<I> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for c in self.clone() {
f.write_char(c)?;
}
Ok(())
}
}