Refactor/activity abc parser

[vanshika2720]

refactor: extract ABC parser into js/activity/abc-parser.js

Description

This PR extracts all ABC-notation parsing logic from the monolithic:

js/activity.js

into a new dedicated module:

js/activity/abc-parser.js

This is a pure refactor and introduces:

• No behavioral changes
• No UX changes
• No public API changes

The goal is to improve maintainability by separating a self-contained subsystem from the large Activity implementation.

---

Motivation

The current:

activity.js

file is approximately:

~8800 lines

long.

The ABC parser subsystem consists of:

• parseABC
• Four private helper functions

and spans roughly:

~580 lines

of code.

Because the parser is a self-contained feature with well-defined responsibilities, it does not need to live inline inside the Activity constructor.

This refactor follows the same modularization pattern already used for:

js/activity/recorder.js

and helps reduce the size and complexity of the core Activity implementation.

---

Changes

File	What changed
js/activity/abc-parser.js	New module containing _adjustPitch, _abcToStandardValue, _createPitchBlocks, _searchIndexForMusicBlock, and setupActivityAbcParser()
js/activity.js	Replaced ~580-line inline ABC parser implementation with a single setupActivityAbcParser(this); call. Added setupActivityAbcParser to the /* global */ declaration block
js/loader.js	Added RequireJS path alias for activity/abc-parser and registered it as a dependency of the activity/activity shim
js/__tests__/activity_startup_recovery.test.js	Added setupActivityAbcParser: () => {} no-op implementation for the VM sandbox used by startup recovery tests

---

New Module Structure

Created:

js/activity/abc-parser.js

The module now owns:

_adjustPitch()
_abcToStandardValue()
_createPitchBlocks()
_searchIndexForMusicBlock()
setupActivityAbcParser()

The exported setup function attaches:

parseABC()

to the Activity instance during initialization.

---

Activity Integration

The previous inline parser implementation was removed from:

js/activity.js

and replaced with:

setupActivityAbcParser(this);

This preserves existing behavior while reducing constructor complexity.

---

Loader Updates

Updated:

js/loader.js

to:

• Register the new activity/abc-parser path alias
• Add activity/abc-parser as a dependency of the Activity shim

This ensures the parser module is available before Activity initialization.

---

Test Updates

Updated:

js/__tests__/activity_startup_recovery.test.js

The test executes a sliced portion of activity.js inside a VM sandbox.

Because the new call:

setupActivityAbcParser(this);

appears inside the tested slice, a no-op implementation was added:

setupActivityAbcParser: () => {}

to preserve existing test behavior.

---

What is preserved

The following remain completely unchanged:

Public API

this.parseABC(tune)

remains available on the Activity instance exactly as before.

---

ABC Import Workflow

The complete ABC import pipeline remains unchanged:

abcReader.onload
    ↓
ensureABCJS
    ↓
ABCJS.parseOnly
    ↓
this.parseABC

---

Generated Block Structure

The generated Music Blocks structure remains identical.

No parsing logic was modified.

No algorithmic behavior was changed.

---

User Experience

There are:

• No UI changes
• No workflow changes
• No import behavior changes

Users will experience identical functionality before and after this refactor.

---

Why this is safe

This PR is a pure code organization refactor.

It:

• Extracts existing code without changing logic
• Preserves all public interfaces
• Preserves Activity initialization behavior
• Preserves ABC import functionality
• Maintains compatibility with existing tests

The only goal is improved maintainability and clearer separation of concerns within the Activity subsystem.
-[x] Documentation

[github-actions]

🧪 Jest Test Results

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Statements: 48.36% | Branches: 40.05% | Functions: 53.02% | Lines: 48.74%
Master Coverage: Statements: 48.36% | Branches: 40.07% | Functions: 53.05% | Lines: 48.75%

[github-actions]

This PR has merge conflicts with master.

Please rebase your branch:

# Add upstream remote (one-time setup)
git remote add upstream https://github.com/sugarlabs/musicblocks.git

# Fetch latest master and rebase
git fetch upstream
git rebase upstream/master

# Resolve any conflicts, then:
git push --force-with-lease origin YOUR_BRANCH

Tip: Enable "Allow edits from maintainers" on this PR so we can auto-rebase for you next time. This only grants access to your PR branch. Your fork's other branches are not affected.

[github-actions]

🧪 Jest Test Results

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Statements: 48.53% | Branches: 40.3% | Functions: 53.24% | Lines: 48.92%
Master Coverage: Statements: 48.36% | Branches: 40.06% | Functions: 53.04% | Lines: 48.75%

[github-actions]

🧪 Jest Test Results

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Statements: 48.53% | Branches: 40.31% | Functions: 53.25% | Lines: 48.93%
Master Coverage: Statements: 48.36% | Branches: 40.06% | Functions: 53.04% | Lines: 48.75%

[github-actions]

🧪 Jest Test Results

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Statements: 48.53% | Branches: 40.3% | Functions: 53.25% | Lines: 48.92%
Master Coverage: Statements: 48.36% | Branches: 40.06% | Functions: 53.04% | Lines: 48.75%

[github-actions]

🧪 Jest Test Results

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Statements: 48.53% | Branches: 40.3% | Functions: 53.25% | Lines: 48.92%
Master Coverage: Statements: 48.36% | Branches: 40.06% | Functions: 53.04% | Lines: 48.75%