Cache translateToString calls inside BufferLine

Fixes #5863
2026-05-01 14:06:39 -07:00
parent ad4a6e8cb9
commit 2a18600d18
2 changed files with 82 additions and 1 deletions
@@ -807,5 +807,62 @@ describe('BufferLine', function(): void {
      assert.equal(extendedAttributes(line, 3), extendedAttributes(initial, 3));
      assert.equal(extendedAttributes(line, 4), extendedAttributes(initial, 4));
    });
+
+    it('should cache canonical trimmed string translations', () => {
+      const line = new TestBufferLine(3);
+      line.setCell(0, createCellData(1, 'a', 1));
+      line.setCell(1, createCellData(1, 'b', 1));
+      line.setCell(2, createCellData(1, 'c', 1));
+
+      const originalGetTrimmedLength = line.getTrimmedLength.bind(line);
+      let trimmedLengthCalls = 0;
+      line.getTrimmedLength = (): number => {
+        trimmedLengthCalls++;
+        return originalGetTrimmedLength();
+      };
+
+      assert.equal(line.translateToString(true, undefined, undefined, undefined), 'abc');
+      assert.equal(line.translateToString(true, undefined, undefined, undefined), 'abc');
+      assert.equal(trimmedLengthCalls, 1);
+    });
+
+    it('should invalidate cached trimmed strings on line mutations', () => {
+      const assertCacheInvalidated = (mutate: (line: TestBufferLine) => void): void => {
+        const line = new TestBufferLine(5);
+        line.fill(createCellData(1, 'a', 1));
+        const originalGetTrimmedLength = line.getTrimmedLength.bind(line);
+        let trimmedLengthCalls = 0;
+        line.getTrimmedLength = (): number => {
+          trimmedLengthCalls++;
+          return originalGetTrimmedLength();
+        };
+        assert.equal(line.translateToString(true, undefined, undefined, undefined), 'aaaaa');
+        assert.equal(line.translateToString(true, undefined, undefined, undefined), 'aaaaa');
+        assert.equal(trimmedLengthCalls, 1);
+        mutate(line);
+        line.translateToString(true, undefined, undefined, undefined);
+        assert.equal(trimmedLengthCalls, 2);
+      };
+
+      assertCacheInvalidated(line => line.set(0, [0, 'b', 1, 'b'.charCodeAt(0)]));
+      assertCacheInvalidated(line => line.setCell(0, createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => line.setCellFromCodepoint(0, 'b'.charCodeAt(0), 1, createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => line.addCodepointToCell(0, 0x301, 0));
+      assertCacheInvalidated(line => line.insertCells(1, 1, createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => line.deleteCells(1, 1, createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => line.replaceCells(1, 3, createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => line.resize(6, createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => line.fill(createCellData(1, 'b', 1)));
+      assertCacheInvalidated(line => {
+        const src = new TestBufferLine(5);
+        src.fill(createCellData(1, 'x', 1));
+        line.copyFrom(src);
+      });
+      assertCacheInvalidated(line => {
+        const src = new TestBufferLine(5);
+        src.fill(createCellData(1, 'x', 1));
+        line.copyCellsFrom(src, 0, 0, 2, false);
+      });
+    });
  });
 });
@@ -63,6 +63,7 @@ export class BufferLine implements IBufferLine {
  protected _data: Uint32Array;
  protected _combined: {[index: number]: string} = {};
  protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} = {};
+  private _cachedTrimmedString: string | undefined;
  public length: number;

  constructor(cols: number, fillCellData?: ICellData, public isWrapped: boolean = false) {
@@ -98,6 +99,7 @@ export class BufferLine implements IBufferLine {
   * @deprecated
   */
  public set(index: number, value: CharData): void {
+    this._invalidateStringCache();
    this._data[index * CELL_SIZE + Cell.FG] = value[CHAR_DATA_ATTR_INDEX];
    if (value[CHAR_DATA_CHAR_INDEX].length > 1) {
      this._combined[index] = value[1];
@@ -197,6 +199,7 @@ export class BufferLine implements IBufferLine {
   * Set data at `index` to `cell`.
   */
  public setCell(index: number, cell: ICellData): void {
+    this._invalidateStringCache();
    if (cell.content & Content.IS_COMBINED_MASK) {
      this._combined[index] = cell.combinedData;
    }
@@ -214,6 +217,7 @@ export class BufferLine implements IBufferLine {
   * it gets an optimized access method.
   */
  public setCellFromCodepoint(index: number, codePoint: number, width: number, attrs: IAttributeData): void {
+    this._invalidateStringCache();
    if (attrs.bg & BgFlags.HAS_EXTENDED) {
      this._extendedAttrs[index] = attrs.extended;
    }
@@ -229,6 +233,7 @@ export class BufferLine implements IBufferLine {
   * by the previous `setDataFromCodePoint` call, we can omit it here.
   */
  public addCodepointToCell(index: number, codePoint: number, width: number): void {
+    this._invalidateStringCache();
    let content = this._data[index * CELL_SIZE + Cell.CONTENT];
    if (content & Content.IS_COMBINED_MASK) {
      // we already have a combined string, simply add
@@ -255,6 +260,7 @@ export class BufferLine implements IBufferLine {
  }

  public insertCells(pos: number, n: number, fillCellData: ICellData): void {
+    this._invalidateStringCache();
    pos %= this.length;

    // handle fullwidth at pos: reset cell one to the left if pos is second cell of a wide char
@@ -282,6 +288,7 @@ export class BufferLine implements IBufferLine {
  }

  public deleteCells(pos: number, n: number, fillCellData: ICellData): void {
+    this._invalidateStringCache();
    pos %= this.length;
    if (n < this.length - pos) {
      for (let i = 0; i < this.length - pos - n; ++i) {
@@ -308,6 +315,7 @@ export class BufferLine implements IBufferLine {
  }

  public replaceCells(start: number, end: number, fillCellData: ICellData, respectProtect: boolean = false): void {
+    this._invalidateStringCache();
    // full branching on respectProtect==true, hopefully getting fast JIT for standard case
    if (respectProtect) {
      if (start && this.getWidth(start - 1) === 2 && !this.isProtected(start - 1)) {
@@ -347,6 +355,7 @@ export class BufferLine implements IBufferLine {
   * excess memory (true after shrinking > CLEANUP_THRESHOLD).
   */
  public resize(cols: number, fillCellData: ICellData): boolean {
+    this._invalidateStringCache();
    if (cols === this.length) {
      return this._data.length * 4 * CLEANUP_THRESHOLD < this._data.buffer.byteLength;
    }
@@ -406,6 +415,7 @@ export class BufferLine implements IBufferLine {

  /** fill a line with fillCharData */
  public fill(fillCellData: ICellData, respectProtect: boolean = false): void {
+    this._invalidateStringCache();
    // full branching on respectProtect==true, hopefully getting fast JIT for standard case
    if (respectProtect) {
      for (let i = 0; i < this.length; ++i) {
@@ -424,6 +434,7 @@ export class BufferLine implements IBufferLine {

  /** alter to a full copy of line  */
  public copyFrom(line: BufferLine): void {
+    this._invalidateStringCache();
    if (this.length !== line.length) {
      this._data = new Uint32Array(line._data);
    } else {
@@ -476,6 +487,7 @@ export class BufferLine implements IBufferLine {
  }

  public copyCellsFrom(src: BufferLine, srcCol: number, destCol: number, length: number, applyInReverse: boolean): void {
+    this._invalidateStringCache();
    const srcData = src._data;
    if (applyInReverse) {
      for (let cell = length - 1; cell >= 0; cell--) {
@@ -508,7 +520,8 @@ export class BufferLine implements IBufferLine {
  }

  /**
-   * Translates the buffer line to a string.
+   * Translates the buffer line to a string. Using any of the optional arguments will disable the
+   * cache.
   *
   * @param trimRight Whether to trim any empty cells on the right.
   * @param startCol The column to start the string (0-based inclusive).
@@ -521,6 +534,10 @@ export class BufferLine implements IBufferLine {
   * returned string, the corresponding entries in `outColumns` will have the same column number.
   */
  public translateToString(trimRight?: boolean, startCol?: number, endCol?: number, outColumns?: number[]): string {
+    const isCanonicalTrimmedRequest = !trimRight && !startCol && endCol === undefined && outColumns === undefined;
+    if (isCanonicalTrimmedRequest && this._cachedTrimmedString !== undefined) {
+      return this._cachedTrimmedString;
+    }
    startCol = startCol ?? 0;
    endCol = endCol ?? this.length;
    if (trimRight) {
@@ -545,6 +562,13 @@ export class BufferLine implements IBufferLine {
    if (outColumns) {
      outColumns.push(startCol);
    }
+    if (isCanonicalTrimmedRequest) {
+      this._cachedTrimmedString = result;
+    }
    return result;
  }
+
+  private _invalidateStringCache(): void {
+    this._cachedTrimmedString = undefined;
+  }
 }