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text_util: extract generic truncation helpers to support &[u8]

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This commit is contained in:
Yuya Nishihara 2024-10-16 18:26:18 +09:00
parent 6a1db0dc21
commit 8a1cdd9215
1 changed files with 50 additions and 12 deletions
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62
cli/src/text_util.rs
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@ -96,12 +96,23 @@ pub fn elide_end<'a>(text: &'a str, ellipsis: &'a str, max_width: usize) -> (Cow
///
/// The truncated string may have 0-width decomposed characters at start.
fn truncate_start_pos(text: &str, max_width: usize) -> (usize, usize) {
truncate_start_pos_with_indices(
text.char_indices()
.rev()
.map(|(start, c)| (start + c.len_utf8(), c)),
max_width,
)
}
fn truncate_start_pos_with_indices(
char_indices_rev: impl Iterator<Item = (usize, char)>,
max_width: usize,
) -> (usize, usize) {
let mut acc_width = 0;
for (i, c) in text.char_indices().rev() {
for (end, c) in char_indices_rev {
let new_width = acc_width + c.width().unwrap_or(0);
if new_width > max_width {
let prev_index = i + c.len_utf8();
return (prev_index, acc_width);
return (end, acc_width);
}
acc_width = new_width;
}
@ -111,15 +122,23 @@ fn truncate_start_pos(text: &str, max_width: usize) -> (usize, usize) {
/// Shortens `text` to `max_width` by removing trailing characters, returning
/// `(end_index, width)`.
fn truncate_end_pos(text: &str, max_width: usize) -> (usize, usize) {
truncate_end_pos_with_indices(text.char_indices(), text.len(), max_width)
}
fn truncate_end_pos_with_indices(
char_indices_fwd: impl Iterator<Item = (usize, char)>,
text_len: usize,
max_width: usize,
) -> (usize, usize) {
let mut acc_width = 0;
for (i, c) in text.char_indices() {
for (start, c) in char_indices_fwd {
let new_width = acc_width + c.width().unwrap_or(0);
if new_width > max_width {
return (i, acc_width);
return (start, acc_width);
}
acc_width = new_width;
}
(text.len(), acc_width)
(text_len, acc_width)
}
/// Skips `width` leading characters, returning `(start_index, skipped_width)`.
@ -129,14 +148,22 @@ fn truncate_end_pos(text: &str, max_width: usize) -> (usize, usize) {
///
/// The truncated string may have 0-width decomposed characters at start.
fn skip_start_pos(text: &str, width: usize) -> (usize, usize) {
skip_start_pos_with_indices(text.char_indices(), text.len(), width)
}
fn skip_start_pos_with_indices(
char_indices_fwd: impl Iterator<Item = (usize, char)>,
text_len: usize,
width: usize,
) -> (usize, usize) {
let mut acc_width = 0;
for (i, c) in text.char_indices() {
for (start, c) in char_indices_fwd {
if acc_width >= width {
return (i, acc_width);
return (start, acc_width);
}
acc_width += c.width().unwrap_or(0);
}
(text.len(), acc_width)
(text_len, acc_width)
}
/// Skips `width` trailing characters, returning `(end_index, skipped_width)`.
@ -144,11 +171,22 @@ fn skip_start_pos(text: &str, width: usize) -> (usize, usize) {
/// The `skipped_width` may exceed the given `width` if `width` is not at
/// character boundary.
fn skip_end_pos(text: &str, width: usize) -> (usize, usize) {
skip_end_pos_with_indices(
text.char_indices()
.rev()
.map(|(start, c)| (start + c.len_utf8(), c)),
width,
)
}
fn skip_end_pos_with_indices(
char_indices_rev: impl Iterator<Item = (usize, char)>,
width: usize,
) -> (usize, usize) {
let mut acc_width = 0;
for (i, c) in text.char_indices().rev() {
for (end, c) in char_indices_rev {
if acc_width >= width {
let prev_index = i + c.len_utf8();
return (prev_index, acc_width);
return (end, acc_width);
}
acc_width += c.width().unwrap_or(0);
}