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Suggestion: collapse unchanged regions in diff

Fresh3 days ago
Mar 14, 20260 views
Confidence Score95%
95%

Problem

When viewing a diff (2 pane or inline) it would be useful to collapse the unchanged lines. This helps focus in on just the changes, especially when the changes are few an spread out.

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1 Fix

Canonical Fix
Unverified Fix
New Fix – Awaiting Verification

Implement Collapsible Unchanged Regions in Diff View

Medium Risk

The current diff viewer does not provide a mechanism to collapse unchanged lines, which leads to a cluttered interface when changes are minimal or dispersed. This is due to the lack of a user interface feature that recognizes and groups unchanged lines, making it difficult for users to focus on significant modifications.

Awaiting Verification

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  1. 1

    Identify Unchanged Lines

    Modify the diff parsing algorithm to identify unchanged lines between the two versions of the file. This will involve comparing each line and marking those that are identical.

    javascript
    const unchangedLines = []; 
    for (let i = 0; i < oldLines.length; i++) { 
      if (oldLines[i] === newLines[i]) { 
        unchangedLines.push(i); 
      } 
    }
  2. 2

    Group Unchanged Lines

    Create a data structure to group the unchanged lines together. This will help in rendering them as collapsible sections in the UI.

    javascript
    const groupedLines = []; 
    let currentGroup = []; 
    unchangedLines.forEach((line, index) => { 
      if (currentGroup.length === 0 || line === currentGroup[currentGroup.length - 1] + 1) { 
        currentGroup.push(line); 
      } else { 
        groupedLines.push(currentGroup); 
        currentGroup = [line]; 
      } 
    }); 
    if (currentGroup.length > 0) groupedLines.push(currentGroup);
  3. 3

    Update UI to Render Collapsible Sections

    Modify the diff viewer's rendering logic to include collapsible sections for the grouped unchanged lines. This will involve adding event listeners for toggling the visibility of these sections.

    javascript
    function renderDiff(diff) { 
      diff.forEach(section => { 
        if (section.isUnchanged) { 
          createCollapsibleSection(section); 
        } else { 
          renderLine(section); 
        } 
      }); 
    }
  4. 4

    Test Collapsible Functionality

    Conduct thorough testing of the new collapsible functionality to ensure that it works correctly across various scenarios, including files with no changes, many changes, and mixed changes.

    javascript
    describe('Collapsible Unchanged Regions', () => { 
      it('should collapse unchanged lines correctly', () => { 
        // Test implementation here 
      }); 
    });

Validation

To confirm the fix worked, open the diff viewer and check if unchanged lines are grouped and can be collapsed. Test with multiple files to ensure consistent behavior and that the collapsible feature does not interfere with the display of changed lines.

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Environment

Submitted by

AC

Alex Chen

2450 rep

Tags

vscodeideeditorfeature-requestdiff-editoron-testplan