Move allocation outside of wrap application

Cargo.toml

@@ -18,6 +18,7 @@ lazy_static = "1.5.0"
 log = "0.4.22"
 regex = "1.11.0"
 similar = "2.6.0"
+unicode-width = "0.2.0"
 
 [profile.release]
 codegen-units = 1

src/format.rs

@@ -77,9 +77,14 @@ pub fn format_file(
                 if needs_wrap(&line, &temp_state, args) {
                     let wrapped_lines =
                         apply_wrap(&line, &temp_state, file, args, logs);
-                    if let Some((this_line, next_line)) = wrapped_lines {
-                        queue.push((linum_old, next_line));
-                        queue.push((linum_old, this_line));
+                    if let Some([this_line, next_line_start, next_line]) =
+                        wrapped_lines
+                    {
+                        queue.push((
+                            linum_old,
+                            [next_line_start, next_line].concat(),
+                        ));
+                        queue.push((linum_old, this_line.to_string()));
                         continue;
                     }
                 }

src/tests.rs

@@ -51,16 +51,14 @@ fn read_files_from_dir(dir: &str) -> Vec<String> {
 #[test]
 fn test_source() {
     let source_files = read_files_from_dir("./tests/source/");
-    let mut fail = false;
     for file in source_files {
         if !test_file(
             &format!("tests/source/{file}"),
             &format!("tests/target/{file}"),
         ) {
-            fail = true;
+            panic!("Failed in {file}");
         }
     }
-    assert!(!fail, "Some tests failed");
 }
 
 #[test]

src/wrap.rs

@@ -5,6 +5,12 @@ use crate::format::*;
 use crate::logging::*;
 use crate::parse::*;
 use log::Level::{Trace, Warn};
+use unicode_width::UnicodeWidthChar;
+
+// String slice to start wrapped text lines
+pub const TEXT_LINE_START: &str = "";
+// String slice to start wrapped comment lines
+pub const COMMENT_LINE_START: &str = "% ";
 
 /// Check if a line needs wrapping
 pub fn needs_wrap(line: &str, state: &State, args: &Cli) -> bool {
@@ -19,8 +25,13 @@ fn find_wrap_point(line: &str, args: &Cli) -> Option<usize> {
     let mut wrap_point: Option<usize> = None;
     let mut after_char = false;
     let mut prev_char: Option<char> = None;
-    for (i, c) in line.chars().enumerate() {
-        if i >= args.wrap_min.into() && wrap_point.is_some() {
+
+    let mut line_width = 0;
+
+    // Return *byte* index rather than *char* index.
+    for (i, c) in line.char_indices() {
+        line_width += c.width().expect("No control characters in text.");
+        if line_width > args.wrap_min.into() && wrap_point.is_some() {
             break;
         }
         if c == ' ' && prev_char != Some('\\') {
@@ -36,13 +47,13 @@ fn find_wrap_point(line: &str, args: &Cli) -> Option<usize> {
 }
 
 /// Wrap a long line into a short prefix and a suffix
-pub fn apply_wrap(
-    line: &str,
+pub fn apply_wrap<'a>(
+    line: &'a str,
     state: &State,
     file: &str,
     args: &Cli,
     logs: &mut Vec<Log>,
-) -> Option<(String, String)> {
+) -> Option<[&'a str; 3]> {
     if args.trace {
         record_line_log(
             logs,
@@ -73,11 +84,15 @@ pub fn apply_wrap(
     };
 
     wrap_point.map(|p| {
-        let line_start =
-            comment_index.map_or("", |c| if p > c { "%" } else { "" });
-        let line_1: String = line.chars().take(p).collect();
-        let mut line_2: String = line.chars().skip(p).collect();
-        line_2.insert_str(0, line_start);
-        (line_1, line_2)
+        let this_line = &line[0..p];
+        let next_line_start = comment_index.map_or("", |c| {
+            if p > c {
+                COMMENT_LINE_START
+            } else {
+                TEXT_LINE_START
+            }
+        });
+        let next_line = &line[p + 1..];
+        [this_line, next_line_start, next_line]
     })
 }