var noop = function() {};
|
|
function ensureFunction(value) {
|
return typeof value === 'function' ? value : noop;
|
}
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|
module.exports = function(node, options, context) {
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function walk(node) {
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enter.call(context, node);
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|
switch (node.type) {
|
case 'Group':
|
node.terms.forEach(walk);
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break;
|
|
case 'Multiplier':
|
walk(node.term);
|
break;
|
|
case 'Type':
|
case 'Property':
|
case 'Keyword':
|
case 'AtKeyword':
|
case 'Function':
|
case 'String':
|
case 'Token':
|
case 'Comma':
|
break;
|
|
default:
|
throw new Error('Unknown type: ' + node.type);
|
}
|
|
leave.call(context, node);
|
}
|
|
var enter = noop;
|
var leave = noop;
|
|
if (typeof options === 'function') {
|
enter = options;
|
} else if (options) {
|
enter = ensureFunction(options.enter);
|
leave = ensureFunction(options.leave);
|
}
|
|
if (enter === noop && leave === noop) {
|
throw new Error('Neither `enter` nor `leave` walker handler is set or both aren\'t a function');
|
}
|
|
walk(node, context);
|
};
|
