fix: correct #line offset and unquoted filename detection in Show in Source

Author: theodevelop

client/src/lineDirectiveNavigation.ts

@@ -2,37 +2,11 @@ import * as fs from 'fs';
 import * as path from 'path';
 import { window, workspace, Uri, Position, Range, ViewColumn } from 'vscode';
 
-// ── Detection ─────────────────────────────────────────────────────────────────
-
-/** Returns true if the file header looks like a Bison or Flex generated C file. */
-export function isGeneratedFile(text: string): boolean {
-  const header = text.slice(0, 600);
-  return (
-    header.includes('/* A Bison parser, made by GNU Bison') ||
-    header.includes('/* Generated by GNU Bison') ||
-    header.includes('/* Generated by flex') ||
-    header.includes('/* A lexical scanner generated by flex')
-  );
-}
+export { isGeneratedFile } from './lineDirectiveUtils';
+import { isGeneratedFile, findNearestLineDirective } from './lineDirectiveUtils';
 
 // ── Direction 1: generated → source ──────────────────────────────────────────
 
-interface LineDirective {
-  sourceLine: number; // 1-based line number in the source file
-  sourceFile: string;
-}
-
-/** Scan backwards from cursorLine to find the nearest #line N "file" directive. */
-function findNearestLineDirective(lines: string[], cursorLine: number): LineDirective | null {
-  for (let i = cursorLine; i >= 0; i--) {
-    const m = lines[i].match(/^#line\s+(\d+)\s+"([^"]+)"/);
-    if (m) {
-      return { sourceLine: parseInt(m[1], 10), sourceFile: m[2] };
-    }
-  }
-  return null;
-}
-
 /** Navigate from the generated C file at cursorLine to the original grammar source. */
 export async function showInSource(): Promise<void> {
   const editor = window.activeTextEditor;
@@ -70,7 +44,8 @@ export async function showInSource(): Promise<void> {
     sourcePath = found;
   }
 
-  const targetLine = Math.max(0, directive.sourceLine - 1); // convert to 0-based
+  const offset = cursorLine - directive.directiveLine; // lines between directive and cursor
+  const targetLine = Math.max(0, directive.sourceLine - 1 + offset);
   const doc = await workspace.openTextDocument(Uri.file(sourcePath));
   const pos = new Position(targetLine, 0);
   await window.showTextDocument(doc, { selection: new Range(pos, pos), viewColumn: ViewColumn.Active });
@@ -197,6 +172,7 @@ function findLineInGenerated(generatedLines: string[], sourceFilePath: string, s
   let bestSrcLine = -1;
 
   for (let i = 0; i < generatedLines.length; i++) {
+    // NOTE: only handles quoted filenames; unquoted form not yet supported (see showInSource / lineDirectiveUtils.ts)
     const m = generatedLines[i].match(/^#line\s+(\d+)\s+"([^"]+)"/);
     if (!m) continue;
     const dirSrcLine = parseInt(m[1], 10);

client/src/lineDirectiveUtils.ts

@@ -0,0 +1,43 @@
+/**
+ * Pure helper functions for line directive navigation.
+ * No VS Code dependencies — designed for testability and reusability.
+ */
+
+// ── Detection ─────────────────────────────────────────────────────────────────
+
+/** Returns true if the file header looks like a Bison or Flex generated C file. */
+export function isGeneratedFile(text: string): boolean {
+  const header = text.slice(0, 600);
+  return (
+    header.includes('/* A Bison parser, made by GNU Bison') ||
+    header.includes('/* Generated by GNU Bison') ||
+    header.includes('/* Generated by flex') ||
+    header.includes('/* A lexical scanner generated by flex')
+  );
+}
+
+// ── Line directive helpers ────────────────────────────────────────────────────
+
+export interface LineDirective {
+  sourceLine: number;    // 1-based line number in the source file
+  sourceFile: string;
+  directiveLine: number; // 0-based line index in the generated file where directive was found
+}
+
+/**
+ * Scan backwards from cursorLine to find the nearest #line N "file" or #line N file directive.
+ * Returns the directive data including the line index where it was found.
+ */
+export function findNearestLineDirective(lines: string[], cursorLine: number): LineDirective | null {
+  for (let i = cursorLine; i >= 0; i--) {
+    const m = lines[i].match(/^#line\s+(\d+)\s+"?([^"\s]+)"?/);
+    if (m) {
+      return {
+        sourceLine: parseInt(m[1], 10),
+        sourceFile: m[2],
+        directiveLine: i,
+      };
+    }
+  }
+  return null;
+}

tests/test-line-directive.ts

@@ -0,0 +1,133 @@
+/**
+ * Tests for lineDirectiveUtils pure helpers.
+ * Run: TS_NODE_PROJECT=tsconfig.base.json npx ts-node tests/test-line-directive.ts
+ */
+import { isGeneratedFile, findNearestLineDirective } from '../client/src/lineDirectiveUtils';
+
+let passed = 0, failed = 0;
+function assert(cond: boolean, msg: string, extra?: unknown) {
+  if (cond) { console.log(`  [PASS] ${msg}`); passed++; }
+  else { console.error(`  [FAIL] ${msg}${extra !== undefined ? `  →  ${JSON.stringify(extra)}` : ''}`); failed++; }
+}
+
+// ── isGeneratedFile ────────────────────────────────────────────────────────────
+console.log('\nisGeneratedFile');
+
+assert(
+  isGeneratedFile('/* A Bison parser, made by GNU Bison 3.8.2.  */\n...rest...'),
+  'detects Bison generated file (made by)'
+);
+assert(
+  isGeneratedFile('/* Generated by GNU Bison 3.8 */\n...rest...'),
+  'detects Bison generated file (generated by)'
+);
+assert(
+  isGeneratedFile('/* Generated by flex 2.6.4 */\n...rest...'),
+  'detects Flex generated file (generated by flex)'
+);
+assert(
+  isGeneratedFile('/* A lexical scanner generated by flex */\n'),
+  'detects Flex generated file (lexical scanner)'
+);
+assert(
+  !isGeneratedFile('// My hand-written parser\n'),
+  'rejects non-generated file'
+);
+assert(
+  !isGeneratedFile(''),
+  'rejects empty file'
+);
+
+// ── findNearestLineDirective ───────────────────────────────────────────────────
+console.log('\nfindNearestLineDirective — quoted filenames');
+
+{
+  // Cursor ON the directive line → offset = 0
+  const lines = ['#line 28 "parser.y"', 'some_func();'];
+  const d = findNearestLineDirective(lines, 0);
+  assert(d !== null, 'quoted: finds directive on cursor line');
+  if (d) {
+    assert(d.sourceLine === 28, 'quoted: sourceLine = 28', d.sourceLine);
+    assert(d.sourceFile === 'parser.y', 'quoted: sourceFile = parser.y', d.sourceFile);
+    assert(d.directiveLine === 0, 'quoted: directiveLine = 0', d.directiveLine);
+  }
+}
+
+{
+  // Cursor 4 lines below the directive → offset = 4
+  // The caller should compute: targetLine = sourceLine - 1 + (cursorLine - directiveLine) = 27 + 4 = 31
+  const lines = [
+    '#line 28 "parser.y"',
+    '#include "config.h"',
+    '#include <stdlib.h>',
+    '#include <string.h>',
+    'void some_func(int mode) {',
+  ];
+  const d = findNearestLineDirective(lines, 4);
+  assert(d !== null, 'quoted: finds directive 4 lines above cursor');
+  if (d) {
+    assert(d.sourceLine === 28, 'quoted: sourceLine = 28', d.sourceLine);
+    assert(d.sourceFile === 'parser.y', 'quoted: sourceFile (cursor 4 lines below)', d.sourceFile);
+    assert(d.directiveLine === 0, 'quoted: directiveLine = 0', d.directiveLine);
+  }
+}
+
+console.log('\nfindNearestLineDirective — unquoted filenames');
+
+{
+  // GitMensch case: no quotes
+  const lines = ['#line 28 parser.y', 'some_func();'];
+  const d = findNearestLineDirective(lines, 1);
+  assert(d !== null, 'unquoted: finds directive');
+  if (d) {
+    assert(d.sourceLine === 28, 'unquoted: sourceLine = 28', d.sourceLine);
+    assert(d.sourceFile === 'parser.y', 'unquoted: sourceFile = parser.y', d.sourceFile);
+    assert(d.directiveLine === 0, 'unquoted: directiveLine = 0', d.directiveLine);
+  }
+}
+
+{
+  // Unquoted relative path
+  const lines = ['#line 5 src/parser.y', 'x = 1;'];
+  const d = findNearestLineDirective(lines, 1);
+  assert(d !== null, 'unquoted path: finds directive');
+  if (d) {
+    assert(d.sourceFile === 'src/parser.y', 'unquoted path: sourceFile', d.sourceFile);
+  }
+}
+
+console.log('\nfindNearestLineDirective — edge cases');
+
+{
+  // No directive anywhere → null
+  const lines = ['int x = 0;', 'return x;'];
+  const d = findNearestLineDirective(lines, 1);
+  assert(d === null, 'returns null when no directive exists');
+}
+
+{
+  // Multiple directives — picks the nearest one above cursor
+  const lines = [
+    '#line 10 "a.y"',
+    'foo();',
+    '#line 20 "b.y"',
+    'bar();',
+  ];
+  const d = findNearestLineDirective(lines, 3);
+  assert(d !== null, 'picks nearest directive above cursor');
+  if (d) {
+    assert(d.sourceLine === 20, 'picks nearest directive above cursor (line)', d.sourceLine);
+    assert(d.sourceFile === 'b.y', 'picks nearest directive above cursor (file)', d.sourceFile);
+    assert(d.directiveLine === 2, 'directiveLine of nearest directive', d.directiveLine);
+  }
+}
+
+{
+  // Cursor on line 0 with no directive → null
+  const lines = ['int x = 0;'];
+  const d = findNearestLineDirective(lines, 0);
+  assert(d === null, 'no directive on line 0 → null');
+}
+
+console.log(`\nResults: ${passed} passed, ${failed} failed`);
+if (failed > 0) process.exit(1);