feat: Add filterStrict() and flatten() methods to ArrayList

[endou-mame]

Add filterStrict() and flatten() methods to ArrayList

Changes

• Add filterStrict() method that returns static (preserves exact type)
• Modify filter() method to return self (ArrayList) instead of static
• Add flatten() method to convert 2D arrays to 1D
• Update IArrayList interface with new method signatures
• Add comprehensive tests for all new methods

Fixes #40

Generated with Claude Code

[claude]

Claude finished @endou-mame's task —— View job

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Code Review Complete ✅

I've thoroughly reviewed the PR implementation. Here's my comprehensive feedback:

Todo List:

• Read and analyze changed files
• Review ArrayList.php implementation
• Review IArrayList.php interface changes
• Review test coverage in ArrayListTest.php
• Check for potential bugs and security issues
• Evaluate performance considerations
• Provide comprehensive feedback

---

Review Findings

✅ Positive Aspects

1. Well-tested implementation - Comprehensive test coverage with edge cases
2. Proper immutability - All methods maintain immutable behavior
3. Type safety - Good use of generics and PHPDoc annotations
4. Interface consistency - Changes properly reflected in both interface and implementation

⚠️ Areas for Improvement

1. Breaking Change in filter() Method (src/Collection/ArrayList.php:341-344)

The change from static to self return type is a breaking change that may affect type inference:

// Before: returned static<TValue>
// After: returns self<TValue>
public function filter(Closure $closure): self

Recommendation: Consider if this breaking change is intentional. If maintaining strict typing is important, you might want to keep filter() returning static and only use self where specifically needed.

2. flatten() Method Limitations (src/Collection/ArrayList.php:446-461)

The current implementation only flattens one level:

// Current: [[1, [2, 3]], 4] → [1, [2, 3], 4]
// Doesn't handle: [[1, [2, 3]], 4] → [1, 2, 3, 4] (deep flatten)

Recommendations:

• Consider adding an optional $depth parameter for multi-level flattening
• Add documentation clarifying it only flattens one level
• Consider recursive flattening for nested arrays

Improved implementation example:

public function flatten(int $depth = 1): self
{
    $result = [];
    
    foreach ($this->elements as $item) {
        if (is_array($item) && $depth > 0) {
            $flattened = (new self($item))->flatten($depth - 1);
            foreach ($flattened as $subItem) {
                $result[] = $subItem;
            }
        } else {
            $result[] = $item;
        }
    }
    
    return new self($result);
}

3. Performance Considerations

• flatten() uses nested loops which is fine for moderate-sized arrays
• filterStrict() implementation is efficient using native array_filter
• No significant performance concerns for typical use cases

4. Type Safety Analysis

The distinction between filter() and filterStrict() is clear:

• filter(): Returns self<TValue> (ArrayList instance)
• filterStrict(): Returns static<TValue> (exact subclass type)

This provides flexibility for different inheritance scenarios.

🔒 Security Assessment

• ✅ No security concerns identified
• ✅ Proper input validation through existing type constraints
• ✅ No external data exposure or injection risks

📋 Test Coverage

Excellent test coverage including:

• ✅ Basic functionality tests
• ✅ Edge cases (empty arrays, mixed types)
• ✅ Type verification for both filter methods
• ✅ Immutability verification
• ✅ Various data types and scenarios

📝 Minor Suggestions

1. Consider adding PHPDoc examples for the flatten() method
2. Add test cases for deeply nested arrays to clarify current behavior
3. Consider performance benchmarks for large arrays if this will be used extensively

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Overall Assessment

This is a well-implemented feature with good test coverage and proper adherence to the existing codebase patterns. The main considerations are the breaking change in filter() and the single-level limitation of flatten().

Recommendation: ✅ Approve with minor considerations - The implementation is solid, but consider the breaking change impact and document the flatten() behavior clearly.

[endou-mame]

@claude PHPUnit と PHPStan でエラーが発生しています。
修正してください。

[claude]

Claude finished @endou-mame's task —— View job

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PHPUnit and PHPStan Errors Fixed ✅

I've successfully identified and resolved the type inconsistency issues that were causing the PHPUnit and PHPStan errors.

Issues Found and Fixed:

Type Inconsistencies in ArrayList.php:

1. sole() method (line 256): Mixed types between new static() and filter() return types
2. reject() method (line 355): Declared to return static but called filter() which returns self

Type Inconsistencies in ValueObjectList.php:

3. remove() method (line 30): Returns static but called filter() which returns self
4. diff() method (line 48): Returns static but called filter() which returns self

Root Cause:

The change from filter() returning static to returning self created type mismatches in methods that need to return static but were calling filter().

Solution:

Updated methods that return static to use filterStrict() instead of filter():

• filterStrict() returns static (exact subclass type)
• filter() returns self (ArrayList instance)

Files Modified:

• src/Collection/ArrayList.php: Fixed sole() and reject() methods
• src/ValueObjectList.php: Fixed remove() and diff() methods

Changes Committed:

✅ Committed as: fix: Resolve type inconsistencies in filter methods (7174bb5)

The PHPUnit and PHPStan errors should now be resolved. The implementation maintains the intended behavior while ensuring type safety.

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[claude]

Claude finished @endou-mame's task —— View job

---

PR Code Review Complete ✅

I've thoroughly reviewed this PR and found both positive aspects and critical issues that need to be addressed.

Todo List:

• Read repository setup instructions (CLAUDE.md) - No file found
• Analyze ArrayList.php implementation changes
• Review IArrayList.php interface updates
• Examine ValueObjectList.php modifications
• Review test coverage in ArrayListTest.php
• Check phpunit.xml.dist configuration changes
• Identify git history issues
• Evaluate code quality and best practices
• Identify potential bugs or issues
• Assess performance considerations
• Review security concerns
• Provide comprehensive feedback

---

🚨 Critical Issues

1. Missing flatten() Method (src/Collection/ArrayList.php & IArrayList.php)

The flatten() method was implemented in commit 4cded0d but accidentally removed in the latest commit c2f0167 when flatMap() was added.

Evidence:

• PR description promises flatten() method
• Commit 4cded0d message claims to add it
• Method was present in that commit but missing in current files
• Interface declaration also removed

Impact: This is a breaking change from the PR's stated goals.

---

✅ Positive Aspects

1. filterStrict() Implementation (src/Collection/ArrayList.php:372-375)

• ✅ Correctly implemented with proper return type static
• ✅ Interface properly updated (IArrayList.php:150-155)
• ✅ Good test coverage with type verification
• ✅ Proper distinction from filter() method

2. Type Consistency Fixes (Multiple files)

• ✅ Fixed in commit 7174bb5 - resolved filter method return type issues
• ✅ ValueObjectList.php properly uses filterStrict() in remove() and diff() methods
• ✅ No type inconsistencies remain

3. flatMap() Implementation (src/Collection/ArrayList.php:345-359)

• ✅ Well-implemented with proper generic types
• ✅ Comprehensive test coverage (ArrayListTest.php:501-541)
• ✅ Proper immutability maintained
• ✅ Good performance using simple foreach loops

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📊 Code Quality Analysis

Performance: Good ⭐⭐⭐⭐

• filterStrict(): Uses native array_filter() - optimal
• flatMap(): Simple nested loops - efficient for typical use cases
• No performance concerns identified

Security: Excellent ⭐⭐⭐⭐⭐

• ✅ No security vulnerabilities identified
• ✅ Proper input validation through existing type constraints
• ✅ No data exposure risks
• ✅ Immutable operations maintained

Type Safety: Excellent ⭐⭐⭐⭐⭐

• ✅ Clear distinction between filter() (returns self) and filterStrict() (returns static)
• ✅ Proper generic annotations with @template and @param
• ✅ PHPStan compliance after type fixes

Test Coverage: Excellent ⭐⭐⭐⭐⭐

• ✅ Comprehensive tests for all implemented methods
• ✅ Edge cases covered (empty arrays, mixed types)
• ✅ Immutability verification included
• ✅ Type verification tests present

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🔧 Required Fixes

1. Restore flatten() Method

Add to ArrayList.php:

#[Override]
final public function flatten(): self
{
    $result = [];
    
    foreach ($this->elements as $item) {
        if (is_array($item)) {
            foreach ($item as $subItem) {
                $result[] = $subItem;
            }
        } else {
            $result[] = $item;
        }
    }
    
    return new self($result);
}

Add to IArrayList.php:

/**
 * 2次元配列を1次元に変換する
 * @return self
 */
public function flatten(): self;

2. Add flatten() Tests

The method needs dedicated test coverage since it was mentioned in the PR goals.

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📝 Minor Recommendations

1. Consider flatten depth parameter: Current implementation only flattens one level
2. Document flatMap vs flatten: Clarify when to use each method
3. Consistent naming: Both methods follow existing conventions well

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📋 Summary

Overall Assessment: ✅ Good implementation with critical missing piece

The PR demonstrates solid understanding of PHP type systems, immutability principles, and comprehensive testing. The filterStrict() and flatMap() methods are well-implemented. However, the missing flatten() method needs to be restored to fulfill the PR's stated objectives.

Recommendation: 🔄 Request changes - Restore the flatten() method and its tests before merging.

---

[claude]

Claude finished @endou-mame's task —— View job

---

Code Review Complete ✅

I've thoroughly reviewed this PR and identified both positive aspects and critical issues that need attention.

Todo List:

• Read repository setup instructions (CLAUDE.md) - No file found
• Analyze ArrayList.php implementation changes
• Review IArrayList.php interface updates
• Check ValueObjectList.php modifications
• Review test coverage in ArrayListTest.php
• Analyze phpstan.yml workflow changes
• Evaluate code quality and best practices
• Identify potential bugs or issues
• Assess performance considerations
• Review security concerns
• Provide comprehensive feedback

---

🚨 Critical Issues

1. Missing flatten() Method

The most critical issue is that the flatten() method is completely missing from both the implementation and interface, despite being promised in the PR description.

Evidence:

• ❌ Not implemented in src/Collection/ArrayList.php
• ❌ Not declared in src/Collection/List/IArrayList.php
• ❌ No tests in tests/Unit/Collection/ArrayListTest.php
• ✅ PR description explicitly mentions: "Add flatten() method to convert 2D arrays to 1D"

Impact: This is a breaking discrepancy between the PR's stated goals and actual implementation.

Required Fix:

// Add to IArrayList.php
/**
 * 2次元配列を1次元に変換する
 * @return self<TValue>
 */
public function flatten(): self;

// Add to ArrayList.php  
#[Override]
final public function flatten(): self
{
    $result = [];
    
    foreach ($this->elements as $item) {
        if (is_array($item)) {
            foreach ($item as $subItem) {
                $result[] = $subItem;
            }
        } else {
            $result[] = $item;
        }
    }
    
    return new self($result);
}

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✅ Positive Aspects

1. filterStrict() Implementation (src/Collection/ArrayList.php:372-375)

• ✅ Correctly implemented with proper return type static
• ✅ Interface properly updated (IArrayList.php:150-155)
• ✅ Good test coverage with type verification (ArrayListTest.php:486-499)
• ✅ Clear distinction from filter() method

2. Type Consistency Fixes (Multiple files)

• ✅ Fixed in ValueObjectList.php - remove() and diff() methods now use filterStrict()
• ✅ ArrayList.php - sole() and reject() methods properly use filterStrict()
• ✅ Maintains type safety - no inconsistencies between static and self return types

3. flatMap() Implementation (src/Collection/ArrayList.php:345-359)

• ✅ Well-implemented with proper generic types
• ✅ Comprehensive test coverage (ArrayListTest.php:501-541)
• ✅ Proper immutability maintained
• ✅ Handles edge cases (empty arrays, complex transformations)

4. CI/CD Improvements (.github/workflows/phpstan.yml:71)

• ✅ Assertions enabled in PHPUnit with -d zend.assertions=1
• ✅ Better test environment for catching assertion failures

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📊 Code Quality Analysis

Performance: Excellent ⭐⭐⭐⭐⭐

• filterStrict(): Uses native array_filter() - optimal performance
• flatMap(): Simple nested loops - efficient for typical use cases
• No performance bottlenecks identified

Security: Excellent ⭐⭐⭐⭐⭐

• ✅ No security vulnerabilities identified
• ✅ Proper input validation through existing type constraints
• ✅ No data exposure risks
• ✅ Immutable operations maintained

Type Safety: Excellent ⭐⭐⭐⭐⭐

• ✅ Clear distinction between filter() (returns self) and filterStrict() (returns static)
• ✅ Proper generic annotations with @template and @param
• ✅ PHPStan compliance after type fixes

Test Coverage: Good ⭐⭐⭐⭐

• ✅ Comprehensive tests for implemented methods
• ✅ Edge cases covered (empty arrays, mixed types)
• ✅ Immutability verification included
• ❌ Missing tests for flatten() method (because method is missing)

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🔧 Additional Recommendations

1. Consider flatten() Depth Parameter

When implementing the missing flatten() method, consider adding an optional depth parameter:

public function flatten(int $depth = 1): self

2. Documentation Consistency

Ensure all new methods have proper PHPDoc examples in the interface.

3. Method Naming Clarity

The distinction between flatMap() and flatten() should be clearly documented:

• flatMap(): Transforms each element and flattens the results
• flatten(): Flattens existing nested arrays without transformation

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📋 Summary

Overall Assessment: 🔄 Requires Changes

The PR demonstrates excellent understanding of PHP type systems, immutability principles, and comprehensive testing. The filterStrict() and flatMap() implementations are high-quality and well-tested. However, the missing flatten() method is a critical issue that prevents this PR from meeting its stated objectives.

Recommendation: 🚨 Request changes - Implement the missing flatten() method and add corresponding tests before approval.

Files needing updates:

1. src/Collection/List/IArrayList.php - Add flatten() method declaration
2. src/Collection/ArrayList.php - Add flatten() method implementation
3. tests/Unit/Collection/ArrayListTest.php - Add flatten() method tests

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