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// The following code has been copied from rust-analyzer.
//! `LineIndex` maps flat `TextSize` offsets into `(Line, Column)`
//! representation.
use std::iter;
use cstree::{TextRange, TextSize};
use rustc_hash::FxHashMap;
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct LineIndex {
/// Offset the the beginning of each line, zero-based
pub(crate) newlines: Vec<TextSize>,
/// List of non-ASCII characters on each line
pub(crate) utf16_lines: FxHashMap<u32, Vec<Utf16Char>>,
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct LineColUtf16 {
/// Zero-based
pub line: u32,
/// Zero-based
pub col: u32,
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct LineCol {
/// Zero-based
pub line: u32,
/// Zero-based utf8 offset
pub col: u32,
}
#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub(crate) struct Utf16Char {
/// Start offset of a character inside a line, zero-based
pub(crate) start: TextSize,
/// End offset of a character inside a line, zero-based
pub(crate) end: TextSize,
}
impl Utf16Char {
/// Returns the length in 8-bit UTF-8 code units.
fn len(&self) -> TextSize {
self.end - self.start
}
/// Returns the length in 16-bit UTF-16 code units.
fn len_utf16(&self) -> usize {
if self.len() == TextSize::from(4) {
2
} else {
1
}
}
}
impl LineIndex {
pub fn new(text: &str) -> LineIndex {
let mut utf16_lines = FxHashMap::default();
let mut utf16_chars = Vec::new();
let mut newlines = vec![0.into()];
let mut curr_row = 0.into();
let mut curr_col = 0.into();
let mut line = 0;
for c in text.chars() {
let c_len = TextSize::of(c);
curr_row += c_len;
if c == '\n' {
newlines.push(curr_row);
// Save any utf-16 characters seen in the previous line
if !utf16_chars.is_empty() {
utf16_lines.insert(line, utf16_chars);
utf16_chars = Vec::new();
}
// Prepare for processing the next line
curr_col = 0.into();
line += 1;
continue;
}
if !c.is_ascii() {
utf16_chars.push(Utf16Char {
start: curr_col,
end: curr_col + c_len,
});
}
curr_col += c_len;
}
// Save any utf-16 characters seen in the last line
if !utf16_chars.is_empty() {
utf16_lines.insert(line, utf16_chars);
}
LineIndex {
newlines,
utf16_lines,
}
}
pub fn line_col(&self, offset: TextSize) -> LineCol {
let line = partition_point(&self.newlines, |&it| it <= offset) - 1;
let line_start_offset = self.newlines[line];
let col = offset - line_start_offset;
LineCol {
line: line as u32,
col: col.into(),
}
}
pub fn offset(&self, line_col: LineCol) -> TextSize {
self.newlines[line_col.line as usize] + TextSize::from(line_col.col)
}
pub fn to_utf16(&self, line_col: LineCol) -> LineColUtf16 {
let col = self.utf8_to_utf16_col(line_col.line, line_col.col.into());
LineColUtf16 {
line: line_col.line,
col: col as u32,
}
}
pub fn to_utf8(&self, line_col: LineColUtf16) -> LineCol {
let col = self.utf16_to_utf8_col(line_col.line, line_col.col);
LineCol {
line: line_col.line,
col: col.into(),
}
}
pub fn lines(&self, range: TextRange) -> impl Iterator<Item = TextRange> + '_ {
let lo = partition_point(&self.newlines, |&it| it < range.start());
let hi = partition_point(&self.newlines, |&it| it <= range.end());
let all = iter::once(range.start())
.chain(self.newlines[lo..hi].iter().copied())
.chain(iter::once(range.end()));
all.clone()
.zip(all.skip(1))
.map(|(lo, hi)| TextRange::new(lo, hi))
.filter(|it| !it.is_empty())
}
fn utf8_to_utf16_col(&self, line: u32, col: TextSize) -> usize {
let mut res: usize = col.into();
if let Some(utf16_chars) = self.utf16_lines.get(&line) {
for c in utf16_chars {
if c.end <= col {
res -= usize::from(c.len()) - c.len_utf16();
} else {
// From here on, all utf16 characters come *after* the character we are mapping,
// so we don't need to take them into account
break;
}
}
}
res
}
fn utf16_to_utf8_col(&self, line: u32, mut col: u32) -> TextSize {
if let Some(utf16_chars) = self.utf16_lines.get(&line) {
for c in utf16_chars {
if col > u32::from(c.start) {
col += u32::from(c.len()) - c.len_utf16() as u32;
} else {
// From here on, all utf16 characters come *after* the character we are mapping,
// so we don't need to take them into account
break;
}
}
}
col.into()
}
}
/// Returns `idx` such that:
///
/// ```text
/// ∀ x in slice[..idx]: pred(x)
/// && ∀ x in slice[idx..]: !pred(x)
/// ```
///
/// https://github.com/rust-lang/rust/issues/73831
fn partition_point<T, P>(slice: &[T], mut pred: P) -> usize
where
P: FnMut(&T) -> bool,
{
let mut left = 0;
let mut right = slice.len();
while left != right {
let mid = left + (right - left) / 2;
// SAFETY:
// When left < right, left <= mid < right.
// Therefore left always increases and right always decreases,
// and either of them is selected.
// In both cases left <= right is satisfied.
// Therefore if left < right in a step,
// left <= right is satisfied in the next step.
// Therefore as long as left != right, 0 <= left < right <= len is satisfied
// and if this case 0 <= mid < len is satisfied too.
let value = unsafe { slice.get_unchecked(mid) };
if pred(value) {
left = mid + 1;
} else {
right = mid;
}
}
left
}
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