@cloudpss/template/src/parser.ts

Lightweight string and object templating utilities with interpolation and formula support.

import { compileSync, type VmScript } from '@mirascript/mirascript';
import { LRUCache } from 'lru-cache';

/** 字符串模板 */
export type Template =
    | string
    | {
          type: TemplateType;
          value: VmScript;
      };

/** 字符串模板类型 */
export type TemplateType = 'interpolation' | 'formula';

const CACHE_SIZE = 100;

const formula = new LRUCache<string, Template & { type: 'formula' }>({
    max: CACHE_SIZE,
    memoMethod: (template: string) => {
        const formula = template.slice(1);
        const value = compileSync(formula, { input_mode: 'Script' });
        return {
            type: 'formula',
            value: value,
        };
    },
});
const interpolation = new LRUCache<string, Template & { type: 'interpolation' }>({
    max: CACHE_SIZE,
    memoMethod: (template: string) => {
        const expr = template.slice(1);
        const value = compileSync(expr, { input_mode: 'Template' });
        return {
            type: 'interpolation',
            value: value,
        };
    },
});

/**
 * 解析字符串模板
 * - 长度大于 1
 *   - 如果模板以 `=` 开头，则表示是一个公式
 *   - 如果模板以 `$` 开头，则表示是一个插值模板
 * - 否则表示是一个普通字符串
 */
export function parseTemplate(template: string): Template {
    if (template.length <= 1) return template;
    if (template.startsWith('=')) {
        return formula.memo(template);
    }
    if (template.startsWith('$')) {
        return interpolation.memo(template);
    }
    return template;
}