Marcos Paulo
72 lines
2.0 KiB
Rust
72 lines
2.0 KiB
Rust
//! Cursor position and document statistics — pure helpers over the text.
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/// (line, column) of `cursor` (byte offset), both 0-based; column counts
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/// characters of the line, not bytes.
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#[must_use]
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pub fn line_col(text: &str, cursor: usize) -> (usize, usize) {
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let floored = if text.is_char_boundary(cursor) {
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usize::min(cursor, text.len())
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} else {
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let mut p = cursor;
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while p > 0 && !text.is_char_boundary(p) {
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p -= 1;
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}
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p
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};
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let before = text.get(..floored).unwrap_or("");
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let line = before.matches('\n').count();
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let col = before.chars().rev().take_while(|c| *c != '\n').count();
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(line, col)
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}
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/// Words in the text: runs of characters that are alphanumeric or `_`.
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#[must_use]
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pub fn word_count(text: &str) -> usize {
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let mut count = 0usize;
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let mut in_word = false;
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for c in text.chars() {
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if c.is_alphanumeric() || c == '_' {
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if !in_word {
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count += 1;
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}
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in_word = true;
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} else {
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in_word = false;
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}
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}
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count
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn line_col_counts_chars() {
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let text = "ab é\nxyz";
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let byte_x = text.find('x').unwrap_or(0);
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assert_eq!(line_col(text, byte_x), (1, 0));
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assert_eq!(line_col(text, 0), (0, 0));
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let end = text.len();
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assert_eq!(line_col(text, end), (1, 3));
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}
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#[test]
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fn line_col_at_char_start() {
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let mut text = String::from("éx");
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let byte_after_e = text.find('x').unwrap_or(0);
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assert_eq!(line_col(&text, byte_after_e), (0, 1));
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text.push_str("\nq");
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let byte_q = text.find('q').unwrap_or(0);
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assert_eq!(line_col(&text, byte_q), (1, 0));
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}
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#[test]
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fn word_count_runs() {
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assert_eq!(word_count(""), 0);
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assert_eq!(word_count("hello world"), 2);
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assert_eq!(word_count("éx_ one-two #tag"), 4);
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assert_eq!(word_count("...,,, "), 0);
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}
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}
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