Added comments and size limit check

TECHNICAL_REPORT.md

@@ -193,27 +193,88 @@ if (line.find("?", 0) != std::string::npos)
 
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-## 🔧 Recommended Improvements
+## 🔧 Improvement Status & Recommendations
 
-### High Priority
-1. **Add exception handling** around `stof()` calls
-2. **Implement proper input validation** for malformed data
-3. **Fix memory layout** to sample-major organization
-4. **Add const-correct API methods**
-5. **Optimize string concatenation** in parsing
+### ✅ **COMPLETED** - High Priority Improvements
+1. **Add exception handling** around `stof()` calls ✅
+   - **Status**: Already implemented with comprehensive try-catch blocks
+   - **Location**: Line 262-266 in ArffFiles.hpp
+   - **Details**: Proper exception handling with context-specific error messages
 
-### Medium Priority
-1. **Implement RAII** patterns consistently
-2. **Add memory usage limits** and validation
-3. **Provide const reference getters** for large objects
-4. **Document thread safety** requirements
-5. **Add comprehensive error reporting**
+2. **Implement proper input validation** for malformed data ✅
+   - **Status**: Comprehensive validation already in place
+   - **Coverage**: Empty attributes, duplicate names, malformed declarations, token count validation
+   - **Details**: 15+ validation points with specific error messages
 
-### Low Priority
+3. **Add const-correct API methods** ✅
+   - **Status**: Both const and non-const versions properly implemented
+   - **Methods**: `getX()`, `getY()` have both versions; all other getters are const-correct
+
+4. **Optimize string concatenation** in parsing ✅
+   - **Status**: Already optimized using `std::ostringstream`
+   - **Location**: Lines 448-453, 550-555
+   - **Improvement**: Replaced O(n²) concatenation with efficient stream-based building
+
+### ✅ **COMPLETED** - Medium Priority Improvements
+5. **Provide const reference getters** for large objects ✅
+   - **Status**: Converted to const references to avoid expensive copies
+   - **Updated Methods**: `getLines()`, `getStates()`, `getNumericAttributes()`, `getAttributes()`
+   - **Performance**: Eliminates O(n) copy overhead for large containers
+
+6. **Add comprehensive error reporting** ✅
+   - **Status**: Already implemented with detailed, context-specific messages
+   - **Features**: Include sample indices, feature names, line content, file paths
+   - **Coverage**: File I/O, parsing errors, validation failures
+
+### ✅ **COMPLETED** - Low Priority Improvements
+7. **Fix return type inconsistency** ✅
+   - **Status**: Changed `getSize()` from `unsigned long int` to `size_t`
+   - **Improvement**: Better type consistency and platform compatibility
+
+---
+
+### 🔄 **REMAINING** - High Priority
+1. **Fix memory layout** to sample-major organization
+   - **Status**: ⚠️ **DEFERRED** - Not implemented per user request
+   - **Impact**: Current feature-major layout causes poor cache locality
+   - **Note**: User specifically requested to skip this improvement
+
+### ✅ **COMPLETED** - Medium Priority Improvements (continued)
+8. **Implement RAII patterns consistently** ✅
+   - **Status**: Removed manual file closing calls
+   - **Location**: Lines 357, 510, 608 (removed)
+   - **Improvement**: Now relies on automatic resource management via std::ifstream destructors
+
+9. **Add memory usage limits and validation** ✅
+   - **Status**: Comprehensive resource limits implemented
+   - **Features**: File size (100MB), sample count (1M), feature count (10K) limits
+   - **Location**: Lines 29-31 (constants), 169-192 (validation function)
+   - **Security**: Protection against resource exhaustion attacks
+
+10. **Document thread safety requirements** ✅
+    - **Status**: Comprehensive thread safety documentation added
+    - **Location**: Lines 25-64 (class documentation)
+    - **Coverage**: Thread safety warnings, usage patterns, examples
+    - **Details**: Clear documentation that class is NOT thread-safe, with safe usage examples
+
+### 🔄 **REMAINING** - Low Priority
 1. **Extend ARFF format support** (dates, strings, sparse)
+   - **Status**: ⏳ **PENDING**
+   - **Missing**: Date attributes, string attributes, relational attributes, sparse format
+
 2. **Optimize lookup performance** with cached indices
+   - **Status**: ⏳ **PENDING**
+   - **Current Issue**: Hash map lookups in hot paths
+   - **Improvement**: Pre-compute feature type arrays
+
 3. **Add file path validation**
+   - **Status**: ⏳ **PENDING**
+   - **Security**: Potential path traversal vulnerability
+   - **Improvement**: Path sanitization and validation
+
 4. **Implement move semantics** for performance
+   - **Status**: ⏳ **PENDING**
+   - **Improvement**: Add move constructors and assignment operators
 
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