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Refactor trimLineEndPreserveAnsi to simpler regex approach

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This commit is contained in:
Jared Miller 2026-01-28 14:26:22 -05:00
parent a90da23cbc
commit 0489864652
Signed by: shmup
GPG key ID: 22B5C6D66A38B06C
1 changed files with 6 additions and 29 deletions
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35
src/ansi.ts
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@ -55,40 +55,17 @@ interface ExtendedColorResult {
// Trim trailing whitespace from each line to prevent background color bleeding. // Trim trailing whitespace from each line to prevent background color bleeding.
// Terminal buffers often pad lines with spaces. Preserve trailing ANSI resets. // Terminal buffers often pad lines with spaces. Preserve trailing ANSI resets.
// ESC character code
const ESC = "\x1b";
export function trimLineEndPreserveAnsi(line: string): string { export function trimLineEndPreserveAnsi(line: string): string {
// Peel off any ANSI sequences at the end of the line
let end = line.length; let end = line.length;
let ansiSuffix = ""; let ansiSuffix = "";
while (end > 0) { while (end > 0) {
// Check for ANSI escape sequence at end: ESC [ params letter // biome-ignore lint/suspicious/noControlCharactersInRegex: ESC character is intentional for ANSI sequences
const suffix = line.slice(0, end); const match = line.slice(0, end).match(/\u001b\[[0-9;?]*[A-Za-z]$/);
if (!suffix.endsWith("]")) { if (!match) break;
// Look for the closing letter (A-Z, a-z) ansiSuffix = match[0] + ansiSuffix;
const lastChar = suffix[suffix.length - 1]; end -= match[0].length;
if (!lastChar || !/[A-Za-z]/.test(lastChar)) break;
// Walk back to find ESC [
let seqStart = suffix.length - 2;
while (seqStart >= 0 && /[0-9;?]/.test(suffix[seqStart] || "")) {
seqStart--;
}
if (seqStart < 0 || suffix[seqStart] !== "[") break;
seqStart--;
if (seqStart < 0 || suffix[seqStart] !== ESC) break;
// Found a valid ANSI sequence
const seq = suffix.slice(seqStart);
ansiSuffix = seq + ansiSuffix;
end = seqStart;
} else {
break;
}
} }
const trimmed = line.slice(0, end).trimEnd(); return line.slice(0, end).trimEnd() + ansiSuffix;
return trimmed + ansiSuffix;
} }
// Parse extended color: 38;2;R;G;B (24-bit) or 38;5;N (256-color) // Parse extended color: 38;2;R;G;B (24-bit) or 38;5;N (256-color)