node.js - 如何访问 LESS 生成的 AST？

Question

我想通过访问 AST 对 LESS 样式表执行一些代码分析。 programmatic usage文档仅介绍如何渲染文件或字符串。

如何访问less.js谷草转氨 enzyme ？

Answer 1

Github user Vecerek had a similar need 。 less.parse 可以与回调一起使用来访问 AST:

...I'm putting the actual code here, that works to get the AST, in case someone will be facing the same hurdle and comes across this issue.

var less = require('less')
  , fs = require('fs')
  , path = require('path');

var src = './test_import.less'; //some less source file
var result = less.parse(fs.readFileSync(src).toString(), {
  filename: path.resolve(src)
}, function(e, tree) {
  console.log(JSON.stringify(tree, null, 2));
});

这个片段可以合理地调整以使用 promise 结构，我发现它更有用:

function lessAST(filename, options) {
    options = options || {};
    options.filename = path.resolve(filename);
    return new Promise(function (res, rej) {
        less.parse(fs.readFileSync(filename).toString(), options, function (e, tree) {
            if (e) {
                rej(e);
            } else {
                res(tree);
            }
        });
    });
}

使用示例:

lessAST('styles.less', {
    ...options...
}).then(function (tree) {
    ...do stuff with the AST...
});