Better template variable extraction

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@ztimson/utils",
-	"version": "0.27.20",
+	"version": "0.28.1",
 	"description": "Utility library",
 	"author": "Zak Timson",
 	"license": "MIT",

src/template.ts

@@ -5,15 +5,56 @@ import {formatDate} from './time.ts';
 
 export class TemplateError extends BadRequestError { }
 
-function findTemplateVars(html: string): Record<string, any> {
+export function findTemplateVars(html: string): Record<string, any> {
 	const variables = new Set<string>();
+	const excluded = new Set<string>(['true', 'false', 'null', 'undefined']);
+
+	// Extract & exclude loop variables
+	for (const loop of matchAll(html, /\{\{\s*?\*\s*?(.+?)\s+in\s+(.+?)\s*?}}/g)) {
+		const [element, index = 'index'] = loop[1].replaceAll(/[()\s]/g, '').split(',');
+		excluded.add(element);
+		excluded.add(index);
+		// Add the array reference (but exclude if it's a loop variable)
+		const arrayRef = loop[2].trim();
+		const arrayVar = arrayRef.split('.')[0].match(/^[a-zA-Z_$][a-zA-Z0-9_$]*/)?.[0];
+		if (arrayVar && !excluded.has(arrayVar)) variables.add(arrayVar);
+	}
+
+	// Extract variables from if/else-if conditions
+	for (const ifStmt of matchAll(html, /\{\{\s*?[!]?\?\s*?([^}]+?)\s*?}}/g)) {
+		const code = ifStmt[1].replace(/["'`][^"'`]*["'`]/g, ''); // Remove string literals
+		const vars = code.match(/[a-zA-Z_$][a-zA-Z0-9_$.]+/g) || [];
+		for (const v of vars) {
+			const root = v.split('.')[0];
+			if (!excluded.has(root)) variables.add(root);
+		}
+	}
+
+	// Extract variables from content within if blocks
+	for (const ifBlock of matchAll(html, /\{\{\s*?\?\s*?.+?\s*?}}([\s\S]*?)\{\{\s*?\/\?\s*?}}/g)) {
+		const content = ifBlock[1];
+		const regex = /\{\{\s*([^<>\*\?!/}\s][^}]*?)\s*}}/g;
+		let match;
+		while ((match = regex.exec(content)) !== null) {
+			const code = match[1].trim().replace(/["'`][^"'`]*["'`]/g, '');
+			const vars = code.match(/[a-zA-Z_$][a-zA-Z0-9_$.]+/g) || [];
+			for (const v of vars) {
+				const root = v.split('.')[0];
+				if (!excluded.has(root)) variables.add(v);
+			}
+		}
+	}
+
+	// Extract variables from regular interpolations
 	const regex = /\{\{\s*([^<>\*\?!/}\s][^}]*?)\s*}}/g;
 	let match;
-
 	while ((match = regex.exec(html)) !== null) {
-		const code = match[1].trim();
+		const code = match[1].trim().replace(/["'`][^"'`]*["'`]/g, '');
-		const varMatch = code.match(/^([a-zA-Z_$][a-zA-Z0-9_$.]*)/);
+		const vars = code.match(/[a-zA-Z_$][a-zA-Z0-9_$.]+/g) || [];
-		if (varMatch) variables.add(varMatch[1]);
+		for (const v of vars) {
+			const root = v.split('.')[0];
+			if (!excluded.has(root)) variables.add(v);
+		}
 	}
 
 	const result: Record<string, any> = {};

tests/templates.spec.ts

@@ -1,4 +1,87 @@
-import { renderTemplate, TemplateError } from '../src';
+import {findTemplateVars, renderTemplate, TemplateError} from '../src';
+
+describe('findTemplateVars', () => {
+	test('extracts simple variables', () => {
+		const result = findTemplateVars('Hello {{ name }}!');
+		expect(result).toEqual({ name: '' });
+	});
+
+	test('extracts nested object paths', () => {
+		const result = findTemplateVars('{{ user.name }} is {{ user.age }}');
+		expect(result).toEqual({ user: { name: '', age: '' } });
+	});
+
+	test('extracts variables from if statements', () => {
+		const result = findTemplateVars('{{ ? active }}{{ message }}{{ /? }}');
+		expect(result).toEqual({ active: '', message: '' });
+	});
+
+	test('extracts variables from else-if conditions', () => {
+		const result = findTemplateVars('{{ ? status == "paid" }}PAID{{ !? status == "pending" }}{{ value }}{{ /? }}');
+		expect(result).toEqual({ status: '', value: '' });
+	});
+
+	test('extracts array reference from loops', () => {
+		const result = findTemplateVars('{{ * item in items }}{{ item }}{{ /* }}');
+		expect(result).toEqual({ items: '' });
+	});
+
+	test('excludes loop element variable', () => {
+		const result = findTemplateVars('{{ * item in items }}{{ item.name }}{{ /* }}');
+		expect(result).toEqual({ items: '' });
+		expect(result).not.toHaveProperty('item');
+	});
+
+	test('excludes loop index variable', () => {
+		const result = findTemplateVars('{{ * (item, i) in items }}{{ i }}:{{ item }}{{ /* }}');
+		expect(result).toEqual({ items: '' });
+		expect(result).not.toHaveProperty('item');
+		expect(result).not.toHaveProperty('i');
+	});
+
+	test('extracts external vars used inside loops', () => {
+		const result = findTemplateVars('{{ * item in items }}{{ item }}-{{ prefix }}{{ /* }}');
+		expect(result).toEqual({ items: '', prefix: '' });
+	});
+
+	test('handles nested loops', () => {
+		const result = findTemplateVars('{{ * row in rows }}{{ * col in row.cols }}{{ col }}{{ /* }}{{ /* }}');
+		expect(result).toEqual({ rows: '' });
+		expect(result).not.toHaveProperty('row');
+		expect(result).not.toHaveProperty('col');
+	});
+
+	test('extracts from complex nested template', () => {
+		const tpl = `
+{{ ? items.length > 0 }}
+{{ * (item, i) in items }}
+{{ i }}. {{ item.name }}: {{ currency }}{{ item.price }}
+{{ /* }}
+Total: {{ total }}
+{{ !? }}
+{{ emptyMessage }}
+{{ /? }}`;
+		const result = findTemplateVars(tpl);
+		expect(result).toEqual({
+			items: '',
+			currency: '',
+			total: '',
+			emptyMessage: ''
+		});
+		expect(result).not.toHaveProperty('item');
+		expect(result).not.toHaveProperty('i');
+	});
+
+	test('ignores template control syntax', () => {
+		const result = findTemplateVars('{{ < header.html }}{{ > layout.html:content }}content{{ /> }}');
+		expect(result).toEqual({});
+	});
+
+	test('handles multiple variables in expressions', () => {
+		const result = findTemplateVars('{{ firstName + " " + lastName }}');
+		expect(result).toEqual({ firstName: '', lastName: '' });
+	});
+});
 
 describe('renderTemplate', () => {
 	test('basic variable interpolation', async () => {