Code Metrics Analysis Overview
Measure and analyze code quality metrics to identify complexity, maintainability issues, and areas for improvement.
When to Use Code quality assessment Identifying refactoring candidates Technical debt monitoring Code review automation CI/CD quality gates Team performance tracking Legacy code analysis Key Metrics Metric Description Good Range Cyclomatic Complexity Number of linearly independent paths 1-10 Cognitive Complexity Measure of code understandability <15 Lines of Code Total lines (LOC) Function: <50 Maintainability Index Overall maintainability score >65 Code Churn Frequency of changes Low Test Coverage Percentage covered by tests >80% Implementation Examples 1. TypeScript Complexity Analyzer import * as ts from 'typescript'; import * as fs from 'fs';
interface ComplexityMetrics { cyclomaticComplexity: number; cognitiveComplexity: number; linesOfCode: number; functionCount: number; classCount: number; maxNestingDepth: number; }
class CodeMetricsAnalyzer { analyzeFile(filePath: string): ComplexityMetrics { const sourceCode = fs.readFileSync(filePath, 'utf-8'); const sourceFile = ts.createSourceFile( filePath, sourceCode, ts.ScriptTarget.Latest, true );
const metrics: ComplexityMetrics = {
cyclomaticComplexity: 0,
cognitiveComplexity: 0,
linesOfCode: sourceCode.split('\n').length,
functionCount: 0,
classCount: 0,
maxNestingDepth: 0
};
this.visit(sourceFile, metrics);
return metrics;
}
private visit(node: ts.Node, metrics: ComplexityMetrics, depth: number = 0): void { metrics.maxNestingDepth = Math.max(metrics.maxNestingDepth, depth);
// Count functions
if (
ts.isFunctionDeclaration(node) ||
ts.isMethodDeclaration(node) ||
ts.isArrowFunction(node)
) {
metrics.functionCount++;
metrics.cyclomaticComplexity++;
}
// Count classes
if (ts.isClassDeclaration(node)) {
metrics.classCount++;
}
// Cyclomatic complexity contributors
if (
ts.isIfStatement(node) ||
ts.isConditionalExpression(node) ||
ts.isWhileStatement(node) ||
ts.isForStatement(node) ||
ts.isCaseClause(node)
) {
metrics.cyclomaticComplexity++;
}
// Cognitive complexity (simplified)
if (ts.isIfStatement(node)) {
metrics.cognitiveComplexity += 1 + depth;
}
if (ts.isWhileStatement(node) || ts.isForStatement(node)) {
metrics.cognitiveComplexity += 1 + depth;
}
// Recurse
const newDepth = this.increasesNesting(node) ? depth + 1 : depth;
ts.forEachChild(node, child => {
this.visit(child, metrics, newDepth);
});
}
private increasesNesting(node: ts.Node): boolean { return ( ts.isIfStatement(node) || ts.isWhileStatement(node) || ts.isForStatement(node) || ts.isFunctionDeclaration(node) || ts.isMethodDeclaration(node) ); }
calculateMaintainabilityIndex(metrics: ComplexityMetrics): number { // Simplified maintainability index const halsteadVolume = metrics.linesOfCode * 4.5; // Simplified const cyclomaticComplexity = metrics.cyclomaticComplexity; const linesOfCode = metrics.linesOfCode;
const mi = Math.max(
0,
(171 - 5.2 * Math.log(halsteadVolume) -
0.23 * cyclomaticComplexity -
16.2 * Math.log(linesOfCode)) * 100 / 171
);
return Math.round(mi);
}
analyzeProject(directory: string): Record
const files = this.getTypeScriptFiles(directory);
for (const file of files) {
results[file] = this.analyzeFile(file);
}
return results;
}
private getTypeScriptFiles(dir: string): string[] { const files: string[] = [];
const items = fs.readdirSync(dir);
for (const item of items) {
const fullPath = `${dir}/${item}`;
const stat = fs.statSync(fullPath);
if (stat.isDirectory() && !item.startsWith('.') && item !== 'node_modules') {
files.push(...this.getTypeScriptFiles(fullPath));
} else if (item.endsWith('.ts') && !item.endsWith('.d.ts')) {
files.push(fullPath);
}
}
return files;
}
generateReport(results: Record
// Summary
const totalFiles = Object.keys(results).length;
const avgComplexity = Object.values(results).reduce(
(sum, m) => sum + m.cyclomaticComplexity, 0
) / totalFiles;
report += `## Summary\n\n`;
report += `- Total Files: ${totalFiles}\n`;
report += `- Average Complexity: ${avgComplexity.toFixed(2)}\n\n`;
// High complexity files
report += `## High Complexity Files\n\n`;
const highComplexity = Object.entries(results)
.filter(([_, m]) => m.cyclomaticComplexity > 10)
.sort((a, b) => b[1].cyclomaticComplexity - a[1].cyclomaticComplexity);
if (highComplexity.length === 0) {
report += 'None found.\n\n';
} else {
for (const [file, metrics] of highComplexity) {
report += `- ${file}\n`;
report += ` - Cyclomatic: ${metrics.cyclomaticComplexity}\n`;
report += ` - Cognitive: ${metrics.cognitiveComplexity}\n`;
report += ` - LOC: ${metrics.linesOfCode}\n\n`;
}
}
return report;
} }
// Usage const analyzer = new CodeMetricsAnalyzer(); const results = analyzer.analyzeProject('./src'); const report = analyzer.generateReport(results); console.log(report);
- Python Code Metrics (using radon) from radon.complexity import cc_visit from radon.metrics import mi_visit, h_visit from radon.raw import analyze import os from typing import Dict, List import json
class CodeMetricsAnalyzer: def analyze_file(self, file_path: str) -> Dict: """Analyze a single Python file.""" with open(file_path, 'r') as f: code = f.read()
# Cyclomatic complexity
complexity = cc_visit(code)
# Maintainability index
mi = mi_visit(code, True)
# Halstead metrics
halstead = h_visit(code)
# Raw metrics
raw = analyze(code)
return {
'file': file_path,
'complexity': [{
'name': block.name,
'complexity': block.complexity,
'lineno': block.lineno
} for block in complexity],
'maintainability_index': mi,
'halstead': {
'volume': halstead.total.volume if halstead.total else 0,
'difficulty': halstead.total.difficulty if halstead.total else 0,
'effort': halstead.total.effort if halstead.total else 0
},
'raw': {
'loc': raw.loc,
'lloc': raw.lloc,
'sloc': raw.sloc,
'comments': raw.comments,
'multi': raw.multi,
'blank': raw.blank
}
}
def analyze_project(self, directory: str) -> List[Dict]:
"""Analyze all Python files in a project."""
results = []
for root, dirs, files in os.walk(directory):
# Skip common directories
dirs[:] = [d for d in dirs if d not in ['.git', '__pycache__', 'venv', 'node_modules']]
for file in files:
if file.endswith('.py'):
file_path = os.path.join(root, file)
try:
result = self.analyze_file(file_path)
results.append(result)
except Exception as e:
print(f"Error analyzing {file_path}: {e}")
return results
def generate_report(self, results: List[Dict]) -> str:
"""Generate a markdown report."""
report = "# Code Metrics Report\n\n"
# Summary
total_files = len(results)
avg_mi = sum(r['maintainability_index'] for r in results) / total_files if total_files > 0 else 0
total_loc = sum(r['raw']['loc'] for r in results)
report += "## Summary\n\n"
report += f"- Total Files: {total_files}\n"
report += f"- Total LOC: {total_loc}\n"
report += f"- Average Maintainability Index: {avg_mi:.2f}\n\n"
# High complexity functions
report += "## High Complexity Functions\n\n"
high_complexity = []
for result in results:
for func in result['complexity']:
if func['complexity'] > 10:
high_complexity.append({
'file': result['file'],
**func
})
high_complexity.sort(key=lambda x: x['complexity'], reverse=True)
if not high_complexity:
report += "None found.\n\n"
else:
for func in high_complexity[:10]: # Top 10
report += f"- {func['file']}:{func['lineno']} - {func['name']}\n"
report += f" Complexity: {func['complexity']}\n\n"
# Low maintainability files
report += "## Low Maintainability Files\n\n"
low_mi = [r for r in results if r['maintainability_index'] < 65]
low_mi.sort(key=lambda x: x['maintainability_index'])
if not low_mi:
report += "None found.\n\n"
else:
for file in low_mi[:10]:
report += f"- {file['file']}\n"
report += f" MI: {file['maintainability_index']:.2f}\n"
report += f" LOC: {file['raw']['loc']}\n\n"
return report
def export_json(self, results: List[Dict], output_file: str):
"""Export results as JSON."""
with open(output_file, 'w') as f:
json.dump(results, f, indent=2)
Usage
analyzer = CodeMetricsAnalyzer() results = analyzer.analyze_project('./src') report = analyzer.generate_report(results) print(report)
Export to JSON
analyzer.export_json(results, 'metrics.json')
-
ESLint Plugin for Complexity // eslint-plugin-complexity.js module.exports = { rules: { 'max-complexity': { create(context) { const maxComplexity = context.options[0] || 10; let complexity = 0;
function increaseComplexity(node) { complexity++; } function checkComplexity(node) { if (complexity > maxComplexity) { context.report({ node, message: `Function has complexity of ${complexity}. Maximum allowed is ${maxComplexity}.` }); } } return { FunctionDeclaration(node) { complexity = 1; }, 'FunctionDeclaration:exit': checkComplexity, IfStatement: increaseComplexity, SwitchCase: increaseComplexity, ForStatement: increaseComplexity, WhileStatement: increaseComplexity, DoWhileStatement: increaseComplexity, ConditionalExpression: increaseComplexity, LogicalExpression(node) { if (node.operator === '&&' || node.operator === '||') { increaseComplexity(); } } };} } } };
-
CI/CD Quality Gates
.github/workflows/code-quality.yml
name: Code Quality
on: [pull_request]
jobs: metrics: runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Setup Node.js
uses: actions/setup-node@v2
with:
node-version: '18'
- name: Install dependencies
run: npm install
- name: Run complexity analysis
run: npx ts-node analyze-metrics.ts
- name: Check quality gates
run: |
COMPLEXITY=$(cat metrics.json | jq '.avgComplexity')
if (( $(echo "$COMPLEXITY > 10" | bc -l) )); then
echo "Average complexity too high: $COMPLEXITY"
exit 1
fi
- name: Upload metrics
uses: actions/upload-artifact@v2
with:
name: code-metrics
path: metrics.json
Best Practices ✅ DO Monitor metrics over time Set reasonable thresholds Focus on trends, not absolute numbers Automate metric collection Use metrics to guide refactoring Combine multiple metrics Include metrics in code reviews ❌ DON'T Use metrics as sole quality indicator Set unrealistic thresholds Ignore context and domain Punish developers for metrics Focus only on one metric Skip documentation Tools TypeScript/JavaScript: ESLint, ts-morph, complexity-report Python: radon, mccabe, pylint Java: PMD, Checkstyle, SonarQube C#: NDepend, SonarQube Multi-language: SonarQube, CodeClimate Resources Cyclomatic Complexity Cognitive Complexity SonarQube