agentsqripts/lib/performance/stringConcatLoopDetector.js

Comprehensive static code analysis toolkit for identifying technical debt, security vulnerabilities, performance issues, and code quality problems

/**
 * @file String concatenation in loops detector
 * @description Detects inefficient string concatenation in loops
 */

/**
 * Detects string concatenation in loops
 * @param {string} content - File content
 * @param {string} filePath - Path to the file
 * @returns {Array} Array of string concatenation issues
 */
function detectStringConcatInLoops(content, filePath) {
  const issues = [];
  const lines = content.split('\n');
  
  // Define default pattern if performance patterns aren't available
  const defaultPattern = {
    severity: 'MEDIUM',
    category: 'String',
    effort: 1,
    impact: 6
  };
  
  let pattern;
  try {
    const { PERFORMANCE_PATTERNS } = require('./performancePatterns');
    pattern = PERFORMANCE_PATTERNS['string_concat_loop'] || defaultPattern;
  } catch (error) {
    pattern = defaultPattern;
  }
  
  // Simplified approach: look for concatenation patterns in proximity to loop keywords
  for (let i = 0; i < lines.length; i++) {
    const line = lines[i];
    const lineNumber = i + 1;
    
    // More specific concatenation patterns to reduce false positives
    const concatPatterns = [
      /\w+\s*\+=\s*['"``]/, // Direct string concatenation like str += "text"
      /\w+\s*\+=\s*\w+\[.*\]/, // Array access concatenation like str += array[i]
      /\w+\s*\+=\s*\w+\.render\(/, // Template rendering like str += template.render(data)
      /\w+\s*\+=\s*\w+\[.*\]\s*\+/, // Complex array concatenation like str += items[i] + something
    ];
    
    const hasConcatenation = concatPatterns.some(pat => pat.test(line));
    
    if (hasConcatenation) {
      // Check nearby lines (within 5 lines) for loop patterns - reduced range for better accuracy
      let isInLoop = false;
      const checkRange = 5; // Reduced from 10 to be more strict
      
      for (let j = Math.max(0, i - checkRange); j <= Math.min(lines.length - 1, i + checkRange); j++) {
        const nearbyLine = lines[j];
        // More specific loop patterns to reduce false positives
        if (/\b(?:for\s*\(|while\s*\(|\.forEach\s*\(|do\s*\{)\b/.test(nearbyLine)) {
          isInLoop = true;
          break;
        }
      }
      
      if (isInLoop) {
        issues.push({
          type: 'string_concat_loop',
          severity: pattern.severity,
          category: pattern.category,
          location: `${filePath}:${lineNumber}`,
          line: lineNumber,
          code: line.trim(),
          description: 'String concatenation in loop creates new strings each iteration',
          summary: 'Inefficient string concatenation in loop',
          recommendation: 'Use array.push() and join() instead of string concatenation',
          effort: pattern.effort,
          impact: pattern.impact,
          estimatedSavings: '20-40% performance gain for string operations'
        });
      }
    }
  }
  
  return issues;
}

module.exports = {
  detectStringConcatInLoops
};