iconFont/node_modules/css-tree/lib/lexer/trace.js

export function getTrace(node) {
    function shouldPutToTrace(syntax) {
        if (syntax === null) {
            return false;
        }

        return (
            syntax.type === 'Type' ||
            syntax.type === 'Property' ||
            syntax.type === 'Keyword'
        );
    }

    function hasMatch(matchNode) {
        if (Array.isArray(matchNode.match)) {
            // use for-loop for better perfomance
            for (let i = 0; i < matchNode.match.length; i++) {
                if (hasMatch(matchNode.match[i])) {
                    if (shouldPutToTrace(matchNode.syntax)) {
                        result.unshift(matchNode.syntax);
                    }

                    return true;
                }
            }
        } else if (matchNode.node === node) {
            result = shouldPutToTrace(matchNode.syntax)
                ? [matchNode.syntax]
                : [];

            return true;
        }

        return false;
    }

    let result = null;

    if (this.matched !== null) {
        hasMatch(this.matched);
    }

    return result;
}

export function isType(node, type) {
    return testNode(this, node, match => match.type === 'Type' && match.name === type);
}

export function isProperty(node, property) {
    return testNode(this, node, match => match.type === 'Property' && match.name === property);
}

export function isKeyword(node) {
    return testNode(this, node, match => match.type === 'Keyword');
}

function testNode(match, node, fn) {
    const trace = getTrace.call(match, node);

    if (trace === null) {
        return false;
    }

    return trace.some(fn);
}