Optimize IcaoDecoder.isMilitary() by eliminating regex recompilation

[kevinelliott]

Fixed a critical performance issue where 30+ regex patterns were being compiled on every call to isMilitary(). The patterns are now compiled once as static readonly class fields and reused via .test() method.

Performance impact:

• Before: 30+ regex compilations per isMilitary() call
• After: Zero regex compilations (patterns compiled once at class load)

This significantly improves performance for high-throughput ACARS message processing scenarios.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Refactor
  • Optimized military ICAO address detection with improved pattern matching performance.
  • Expanded coverage to recognize military aircraft across additional countries and ICAO ranges.

[jazzberry-ai]

Bug Report

Name	Severity	Example test case	Description
Missing Spain Military Range End Anchor	Medium	Input: '3500001'	The code uses a range check (i >= '350000' && i <= '37ffff') for the Spain military range. The new regex implementation doesn't have an equivalent range check, which could lead to missed identifications if the input isn't exactly 6 characters long.
Incorrect Australia Military Regex	Critical	Input: '7c822e'	The regex `i.match(/^7c8([2-4]

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[coderabbitai]

Walkthrough

The IcaoDecoder class was refactored to use precompiled regex patterns for military ICAO address detection. Inline regex checks were replaced with lookups into a new MILITARY_PATTERNS map, and local aliases were introduced for improved readability and performance.

Changes

Cohort / File(s)	Summary
Military Pattern Optimization lib/IcaoDecoder.ts	Added MILITARY_PATTERNS static map with precompiled regex patterns for country-specific military ICAO ranges. Refactored isMilitary() method to use pattern lookups via local aliases (i for this.icao, p for MILITARY_PATTERNS) and .test() method instead of inline .match() calls. Expanded pattern coverage across multiple countries.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

The changes follow a consistent, mechanical refactoring pattern applied to a single file. Review effort is minimal due to homogeneity, though verification of regex pattern correctness and expanded military ICAO coverage is recommended.

Poem

A rabbit hops through patterns neat,
Where military codes now beat,
Precompiled, swift, and lean—
The fastest ICAO screen! 🐰✈️
No more inline, just maps so keen!

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The PR title "Optimize IcaoDecoder.isMilitary() by eliminating regex recompilation" directly and accurately describes the main change in the changeset. It specifically identifies the method being optimized and the optimization strategy—moving from inline regex patterns that recompile on every call to precompiled static patterns. The title is clear, concise, and specific enough that a teammate scanning history would immediately understand the primary change addresses performance optimization. This aligns perfectly with the PR objectives, which confirm the intent to fix a performance issue where 30+ regex patterns were being recompiled on every isMilitary() call.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch claude/optimize-performance-011CUKrd1cCWeWVtfk7c2xnW

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

lib/IcaoDecoder.ts (1)

108-109: Consider more descriptive variable names.

While the local aliases reduce verbosity, single-letter names like i and p reduce clarity. Consider using more descriptive names:

-    const i = this.icao;
-    const p = IcaoDecoder.MILITARY_PATTERNS;
+    const icaoAddress = this.icao;
+    const patterns = IcaoDecoder.MILITARY_PATTERNS;

Then update the references in the return statement accordingly (e.g., patterns.US_MIL_1.test(icaoAddress)).

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b4b2d1f and 5a6ea2e.

📒 Files selected for processing (1)

• lib/IcaoDecoder.ts (2 hunks)

🔇 Additional comments (2)

lib/IcaoDecoder.ts (2)

5-100: Excellent performance optimization!

The refactoring to static readonly pre-compiled patterns is exactly the right approach. This eliminates 30+ regex compilations per method call and improves performance for high-throughput scenarios.

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111-229: Pattern usage is correct and efficient.

The refactored code correctly uses .test() method with the pre-compiled patterns. The logic flow and control structure are preserved while achieving the performance optimization goals.

Note: Some ranges still use string comparisons (lines 133, 212), which is fine and was present in the original code. String comparison works correctly for hex address ranges due to lexicographic ordering.

[makrsmark]

Make MILITARY_PATTERNS an array of regexp instead of a dictionary and then just return MILITARY_PATTERNS.some((p) => p.test(i));

all the comments can move up to the definition

[makrsmark]

If you take my other comment, remove as it's not saving anything