[PERF] Don't split and join lines when using TextFile

libs/execution/src/lib/debugging/debug-log-visitor.ts

@@ -6,6 +6,7 @@ import {
   type WrapperFactoryProvider,
   internalValueToString,
 } from '@jvalue/jayvee-language-server';
+import { either } from 'fp-ts';
 
 import { type Logger } from '../logging/logger';
 import { type Workbook } from '../types';
@@ -15,6 +16,7 @@ import { type TextFile } from '../types/io-types/filesystem-node-file-text';
 import { type IoTypeVisitor } from '../types/io-types/io-type-implementation';
 import { type Sheet } from '../types/io-types/sheet';
 import { type Table } from '../types/io-types/table';
+import { findLineBounds } from '../util/string-util';
 
 import { type DebugGranularity } from './debug-configuration';
 
@@ -115,18 +117,31 @@ export class DebugLogVisitor implements IoTypeVisitor<void> {
     this.logPeekComment();
   }
 
-  visitTextFile(binaryFile: TextFile): void {
-    if (this.debugGranularity === 'minimal') {
-      return;
-    }
-
-    for (let i = 0; i < binaryFile.content.length; ++i) {
-      if (i > this.PEEK_NUMBER_OF_LINES) {
-        break;
+  visitTextFile(textFile: TextFile): void {
+    switch (this.debugGranularity) {
+      case 'minimal':
+        return;
+
+      case 'exhaustive':
+        this.log(textFile.content);
+        return;
+
+      case 'peek': {
+        // BUG: /\r?\n/ might not be the correct line break
+        const result = findLineBounds(
+          [this.PEEK_NUMBER_OF_LINES - 1],
+          /\r?\n/,
+          textFile.content,
+        );
+        const { start: firsNonIncludedLineStart } = (either.isRight(result)
+          ? result.right[0]
+          : undefined) ?? {
+          start: textFile.content.length,
+        };
+        this.log(textFile.content.slice(0, firsNonIncludedLineStart));
+        this.logPeekComment();
       }
-      this.log(`[Line ${i}] ${binaryFile.content[i] ?? '<undefined>'}`);
     }
-    this.logPeekComment();
   }
 
   private logPeekComment(): void {

libs/execution/src/lib/util/index.ts

@@ -4,3 +4,4 @@
 
 export * from './implements-static-decorator';
 export * from './file-util';
+export * from './string-util';

libs/execution/src/lib/util/string-util.spec.ts

@@ -0,0 +1,90 @@
+// SPDX-FileCopyrightText: 2025 Friedrich-Alexander-Universitat Erlangen-Nurnberg
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+// eslint-disable-next-line unicorn/prefer-node-protocol
+import { AssertionError } from 'assert';
+
+import { either } from 'fp-ts';
+
+import { ensureGlobal, findLineBounds } from './string-util';
+
+describe('Validation of string-util', () => {
+  describe('Function ensureGlobal', () => {
+    it('should make a non global RegExp global', () => {
+      const result = ensureGlobal(/someregex/);
+
+      expect(result.global).toBe(true);
+      expect(result.source).toBe('someregex');
+    });
+    it('should keep a global RegExp global', () => {
+      const result = ensureGlobal(/someregex/g);
+
+      expect(result.global).toBe(true);
+      expect(result.source).toBe('someregex');
+    });
+  });
+  describe('Function findLineBounds', () => {
+    it('should return empty array for empty array', () => {
+      const result = findLineBounds([], /\r?\n/, 'some text');
+
+      expect(either.isRight(result)).toBe(true);
+      assert(either.isRight(result));
+      expect(result.right).toStrictEqual([]);
+    });
+    it('should return first non existent lineIdx', () => {
+      const result = findLineBounds(
+        [0, 30, 300],
+        /\r?\n/,
+        `some text
+
+`,
+      );
+
+      expect(either.isLeft(result)).toBe(true);
+      assert(either.isLeft(result));
+      expect(result.left.firstNonExistentLineIdx).toBe(30);
+      expect(result.left.existingBounds).toStrictEqual([
+        { start: 0, length: 10 },
+      ]);
+    });
+    it('should return the entire string if there is no newline', () => {
+      const result = findLineBounds(
+        [0, 1],
+        /\r?\n/,
+        'some text without a newline',
+      );
+
+      expect(either.isLeft(result)).toBe(true);
+      assert(either.isLeft(result));
+      expect(result.left.firstNonExistentLineIdx).toBe(1);
+      expect(result.left.existingBounds).toStrictEqual([
+        { start: 0, length: 27 },
+      ]);
+    });
+    it('should correctly map multiple indices', () => {
+      const result = findLineBounds(
+        [0, 1, 2, 3],
+        /\r?\n/,
+        `some
+text  with
+newlines
+`,
+      );
+
+      expect(either.isLeft(result)).toBe(true);
+      assert(either.isLeft(result));
+      expect(result.left.firstNonExistentLineIdx).toBe(3);
+      expect(result.left.existingBounds).toStrictEqual([
+        { start: 0, length: 5 },
+        { start: 5, length: 11 },
+        { start: 16, length: 9 },
+      ]);
+    });
+    it('should throw an error on out of order indices', () => {
+      expect(() => findLineBounds([1, 0], /\r?\n/, '')).toThrowError(
+        AssertionError,
+      );
+    });
+  });
+});

libs/execution/src/lib/util/string-util.ts

@@ -0,0 +1,125 @@
+// SPDX-FileCopyrightText: 2025 Friedrich-Alexander-Universitat Erlangen-Nurnberg
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+// eslint-disable-next-line unicorn/prefer-node-protocol
+import assert from 'assert';
+
+import { either } from 'fp-ts';
+
+export function ensureGlobal(regex: RegExp): RegExp {
+  if (regex.global) {
+    return regex;
+  }
+
+  return RegExp(regex.source, regex.flags + 'g');
+}
+
+function isSortedAscending(numbers: number[]): boolean {
+  return numbers.every((lineIdx, i, arr) => {
+    if (i === 0) {
+      return true;
+    }
+    const prev = arr[i - 1];
+    assert(prev !== undefined);
+    return prev <= lineIdx;
+  });
+}
+
+function findSingleLineBounds(
+  searchIdx: number,
+  lineBreakPattern: RegExp,
+  text: string,
+): { start: number; length: number } | undefined {
+  let currentLineIdx = 0;
+  let currentLineStart = 0;
+
+  for (const lineBreak of text.matchAll(ensureGlobal(lineBreakPattern))) {
+    assert(currentLineIdx <= searchIdx);
+    if (currentLineIdx < searchIdx) {
+      currentLineIdx += 1;
+      currentLineStart += lineBreak.index + 1;
+      continue;
+    }
+
+    const lineLengthWithoutNewline = lineBreak.index - currentLineStart;
+    return {
+      start: currentLineStart,
+      length: lineLengthWithoutNewline + 1,
+    };
+  }
+
+  // HINT: Line with idx `lineIdx` not found.
+  if (currentLineIdx !== searchIdx) {
+    return undefined;
+  }
+  return {
+    start: currentLineStart,
+    length: text.length - currentLineStart,
+  };
+}
+
+type Bounds = { start: number; length: number }[];
+
+/**
+ * Map line idxs to line bounds.
+ *
+ * @param lineIdxs the indices of the lines to find bounds for. MUST be sorted in ASCENDING order.
+ * @param lineBreakPattern the pattern that marks a new line.
+ * @param text the text containing newlines.
+ * @returns a new array which contains either the bounds for the requested line or undefined
+ *
+ * @example
+ * let [{start, length}, outOfBounds ] = findLineBounds("some\ntext\n", /\r?\n/, [0, 300]);
+ * assert(inclusiveStart === 0);
+ * assert(length === 5);
+ * assert(outOfBounds === undefined);
+ */
+export function findLineBounds(
+  lineIdxs: number[],
+  lineBreakPattern: RegExp,
+  text: string,
+): either.Either<
+  { existingBounds: Bounds; firstNonExistentLineIdx: number },
+  Bounds
+> {
+  assert(isSortedAscending(lineIdxs));
+  let lineIdxOffset = 0;
+  let charIdxOffset = 0;
+
+  const bounds: { start: number; length: number }[] = [];
+
+  for (const searchIdx of lineIdxs) {
+    if (searchIdx > 0 && text.length === 0) {
+      return either.left({
+        existingBounds: bounds,
+        firstNonExistentLineIdx: searchIdx,
+      });
+    }
+    assert(searchIdx >= lineIdxOffset);
+    const tmp = findSingleLineBounds(
+      searchIdx - lineIdxOffset,
+      lineBreakPattern,
+      text,
+    );
+    if (tmp === undefined) {
+      return either.left({
+        existingBounds: bounds,
+        firstNonExistentLineIdx: searchIdx,
+      });
+    }
+
+    const { start, length } = tmp;
+
+    bounds.push({
+      start: charIdxOffset + start,
+      length,
+    });
+
+    charIdxOffset += start + length;
+    lineIdxOffset = searchIdx + 1;
+    text = text.slice(length);
+  }
+
+  return either.right(bounds);
+}

libs/extensions/std/exec/src/text-line-deleter-executor.spec.ts

@@ -125,7 +125,7 @@ Test  File
     expect(R.isOk(result)).toEqual(false);
     if (R.isErr(result)) {
       expect(result.left.message).toEqual(
-        'Line 1 does not exist in the text file, only 0 line(s) are present',
+        'Line 1 does not exist in the text file.',
       );
     }
   });