Function delete_visual_range

src/text_input.rs:2093–2154

Delete visible characters in the visual range `[visual_start, visual_end)`. Preserves all style tag structure (`{name|`, `}`) and only removes the content characters that fall within the visual range.

(raw: &str, visual_start: usize, visual_end: usize)

    /// Preserves all style tag structure (`{name|`, `}`) and only removes the content
    /// characters that fall within the visual range.
    pub fn delete_visual_range(raw: &str, visual_start: usize, visual_end: usize) -> String {
        if visual_start >= visual_end {
            return raw.to_string();
        }

        let chars: Vec<char> = raw.chars().collect();
        let len = chars.len();
        let mut result = String::with_capacity(raw.len());
        let mut visual = 0usize;
        let mut i = 0;
        let mut in_style_def = false;

        while i < len {
            let c = chars[i];

            match c {
                '\\' if !in_style_def && i + 1 < len => {
                    // Escaped pair `\X` counts as one visible char
                    let in_range = visual >= visual_start && visual < visual_end;
                    if !in_range {
                        result.push(c);
                        result.push(chars[i + 1]);
                    }
                    visual += 1;
                    i += 2;
                }
                '{' if !in_style_def => {
                    in_style_def = true;
                    result.push(c); // Always keep tag structure
                    i += 1;
                }
                '|' if in_style_def => {
                    in_style_def = false;
                    result.push(c);
                    // Check for empty content
                    if i + 1 < len && chars[i + 1] == '}' {
                        visual += 1; // Empty content has a visual position but is structural
                    }
                    i += 1;
                }
                '}' if !in_style_def => {
                    result.push(c); // Always keep `}`
                    visual += 1; // `}` has a visual position but is structural
                    i += 1;
                }
                _ if in_style_def => {
                    result.push(c); // Tag name chars — always keep
                    i += 1;
                }
                _ => {
                    let in_range = visual >= visual_start && visual < visual_end;
                    if !in_range {
                        result.push(c);
                    }
                    visual += 1;
                    i += 1;
                }
            }