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207//! Suffix styling.
//!
//! GNU ls supports styling regular files based on a suffix (typically a file extension).
//! For example,
//!
//! ```text
//! export LS_COLORS="*.gz=01;31:*.mp3=00;36:"
//! ```
//!
//! will color `archive.tar.gz` bold red, and `music.mp3` cyan.
//!
//! Later suffixes override earlier ones, so
//!
//! ```text
//! export LS_COLORS="*.gz=01;31:*.tar.gz=01;33:"
//! ```
//!
//! will color `foo.gz` and `bar.tar.gz` differently, while
//!
//! ```text
//! export LS_COLORS="*.tar.gz=01;33:*.gz=01;31:"
//! ```
//!
//! will color them both the same.
//!
//! Matching is ASCII case insensitive, unless two different capitalizations with different styles
//! are given for the same suffix:
//!
//! ```text
//! export LS_COLORS="*README=01:*readme=00:"
//! ```
use aho_corasick::{AhoCorasick, Anchored, Input, MatchKind, StartKind};
use std::collections::{HashMap, HashSet};
use crate::style::Style;
/// A key in the suffix map.
#[derive(Debug, Clone, Eq, Hash, PartialEq)]
struct SuffixKey {
/// The suffix, reversed so we can use leftmost-first matching.
rev_bytes: Box<[u8]>,
}
impl SuffixKey {
fn new(suffix: &[u8]) -> Self {
let mut suffix: Box<[u8]> = Box::from(suffix);
suffix.reverse();
Self { rev_bytes: suffix }
}
}
impl AsRef<[u8]> for SuffixKey {
fn as_ref(&self) -> &[u8] {
&self.rev_bytes
}
}
/// A [SuffixMap] builder.
#[derive(Debug, Default)]
pub struct SuffixMapBuilder {
/// The list of keys, in order.
keys: Vec<SuffixKey>,
/// The list of styles, in order.
styles: Vec<Option<Style>>,
/// The length of the longest suffix, in bytes.
max_len: usize,
}
impl SuffixMapBuilder {
/// Add a new suffix to the map.
pub fn push(&mut self, suffix: impl AsRef<[u8]>, style: Option<Style>) {
let suffix = suffix.as_ref();
self.keys.push(SuffixKey::new(suffix));
self.styles.push(style);
self.max_len = self.max_len.max(suffix.len());
}
/// Build the suffix map.
pub fn build(mut self) -> SuffixMap {
// Reverse the lists, so that leftmost-*first* returns the *last* match instead
self.keys.reverse();
self.styles.reverse();
// Build the case-sensitive matcher
let cs_matcher = AhoCorasick::builder()
.match_kind(MatchKind::LeftmostFirst)
.start_kind(StartKind::Anchored)
.build(&self.keys)
.unwrap();
// Turn all the keys lowercase
let mut lower_keys = self.keys.clone();
for key in lower_keys.iter_mut() {
key.rev_bytes.make_ascii_lowercase();
}
// Map keys to their first case-(in)sensitive occurrence
let mut cs_map: HashMap<&SuffixKey, usize> = HashMap::new();
let mut ci_map: HashMap<&SuffixKey, usize> = HashMap::new();
self.keys
.iter()
.zip(lower_keys.iter())
.enumerate()
.for_each(|(i, (cs_key, ci_key))| {
cs_map.entry(cs_key).or_insert(i);
ci_map.entry(ci_key).or_insert(i);
});
// Find keys that should be case-sensitive
let mut cs_set: HashSet<&SuffixKey> = HashSet::new();
for i in cs_map.values().copied() {
let ci_key = &lower_keys[i];
let j = *ci_map.get(ci_key).unwrap();
if self.styles[i] != self.styles[j] {
cs_set.insert(ci_key);
}
}
// Keep only the case-insensitive keys
let (ci_ids, ci_keys): (Vec<_>, Vec<_>) = lower_keys
.iter()
.enumerate()
.filter(|(_i, k)| !cs_set.contains(k))
.unzip();
// Build the case-insensitive matcher
let ci_matcher = AhoCorasick::builder()
.ascii_case_insensitive(true)
.match_kind(MatchKind::LeftmostFirst)
.start_kind(StartKind::Anchored)
.build(ci_keys)
.unwrap();
SuffixMap {
cs_matcher,
ci_matcher,
styles: self.styles,
ci_ids,
max_len: self.max_len,
}
}
}
/// Maps filename suffixes to styles.
#[derive(Clone, Debug)]
pub struct SuffixMap {
/// Case-sensitive matcher.
cs_matcher: AhoCorasick,
/// Case-insensitive suffixes.
ci_matcher: AhoCorasick,
/// List of styles (indexed by cs_matcher IDs)
styles: Vec<Option<Style>>,
/// Map from ci_matcher to cs_matcher IDs.
ci_ids: Vec<usize>,
/// The length of the longest suffix, in bytes.
max_len: usize,
}
impl SuffixMap {
/// Get the style for a matching suffix, if one exists.
pub fn get(&self, name: impl AsRef<[u8]>) -> Option<&Style> {
let name = name.as_ref();
// Split off only the longest suffix necessary
let len = self.max_len.min(name.len());
let i = name.len() - len;
// Copy the suffix to the stack if small, otherwise the heap
let mut name_stack = [0; 32];
let mut name_heap: Box<[u8]>;
let name = if len <= name_stack.len() {
name_stack[..len].copy_from_slice(&name[i..]);
&mut name_stack[..len]
} else {
name_heap = name[i..].into();
&mut name_heap
};
// Reverse the suffix for matching
name.reverse();
// Find a case-sensitive match
let cs_index = Self::find(&self.cs_matcher, name);
// Find a case-insensitive match
let ci_index = Self::find(&self.ci_matcher, name).map(|i| self.ci_ids[i]);
// Return the later match (earlier index)
let i = match (cs_index, ci_index) {
(Some(cs), Some(ci)) => cs.min(ci),
(Some(cs), _) => cs,
(_, Some(ci)) => ci,
(_, _) => return None,
};
self.styles[i].as_ref()
}
/// Get the index of a match in a single matcher.
fn find(matcher: &AhoCorasick, name: &[u8]) -> Option<usize> {
let input = Input::new(name).anchored(Anchored::Yes);
matcher.find(input).map(|m| m.pattern().as_usize())
}
}