wx2/src/util/view/stringify.js

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/**
 * 视图ast序列化插件
 *
 * @file 视图ast序列化插件
 */

'use strict';

const FAKE_ROOT = Symbol.for('fake-root');
const SINGLE_QUOTE = '\'';
const DOUBLE_QUOTE = '"';

// 把标签名、属性片段join起来
const join = (...args) => args.filter(arg => !!arg).join(' ');

module.exports = function ({context}) {

    const viewConfig = context.rules.view;
    this.Compiler = compiler;

    function compiler(tree, file) {
        if (!tree) {
            return '';
        }
        else if (Array.isArray(tree)) {
            return tree
                .map(node => compiler(node, file))
                .join('');
        }

        const {type, children, data} = tree;
        switch (type) {
            case 'tag': {
                // 跳过虚假的根节点
                if (tree.name === FAKE_ROOT) {
                    return compiler(children, file);
                }
                const content = children
                    .map(node => compiler(node, file))
                    .join('');
                return nodeToString(tree, content, viewConfig, file);
            }
            case 'text':
                return data;
            case 'comment':
                return `<!--${data}-->`;
        }
    }
};


/**
     * 生成tag节点的字符串
     *
     * @param {Object} node tag节点
     * @param {string} content 子元素字符串
     * @param {VFile} file 文件描述
     * @param {Object} viewConfig view层的转换规则
     * @return {string}
     */
function nodeToString(node, content, viewConfig, file) {
    const {name, attribs, singleQuoteAttribs = {}, selfclose} = node;
    const stringAttribs = attributesToString(attribs, singleQuoteAttribs, viewConfig, file);
    return selfclose
        ? `<${join(name, stringAttribs)} />`
        : `<${join(name, stringAttribs)}>${content}</${name}>`;
}


/**
     * 生成tag节点属性的字符串
     *
     * @param {Object} attribs tag节点属性集合
     * @param {Object} singleQuoteAttribs tag节点使用单引号的属性集合
     * @param {VFile} file 文件描述
     * @param {Object} viewConfig view层的转换规则
     * @return {string}
     */
function attributesToString(attribs, singleQuoteAttribs, viewConfig, file) {
    if (!attribs) {
        return '';
    }

    return Object.keys(attribs).map(key => {
        let value = attribs[key];
        if (value === '') {
            if (viewConfig && viewConfig.boolAttr && viewConfig.boolAttr.indexOf(key) > -1) {
                return `${key}="false"`;
            }
            return key;
        }
        const quote = singleQuoteAttribs[key] ? SINGLE_QUOTE : DOUBLE_QUOTE;
        if (quote === DOUBLE_QUOTE && value.indexOf('\\"') >= 0) {
            value = value.replace(/\\"/g, '\'');
            file.message('Danger \\" in attribute value');
        }
        if (key !== '') {
            return `${key}=${quote}${value}${quote}`;
        }
        return `${key}`;
    }).join(' ');
}