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traverse.js
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Mon, Feb 24, 19:04

traverse.js
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import { createPath } from "./node-path";
import { unionTypesMap, nodeAndUnionTypes } from "./nodes"; // recursively walks the AST starting at the given node. The callback is invoked for
// and object that has a 'type' property.
function walk(context, callback) {
var stop = false;
function innerWalk(context, callback) {
if (stop) {
return;
}
var node = context.node;
if (node === undefined) {
console.warn("traversing with an empty context");
return;
}
if (node._deleted === true) {
return;
}
var path = createPath(context);
callback(node.type, path);
if (path.shouldStop) {
stop = true;
return;
}
Object.keys(node).forEach(function (prop) {
var value = node[prop];
if (value === null || value === undefined) {
return;
}
var valueAsArray = Array.isArray(value) ? value : [value];
valueAsArray.forEach(function (childNode) {
if (typeof childNode.type === "string") {
var childContext = {
node: childNode,
parentKey: prop,
parentPath: path,
shouldStop: false,
inList: Array.isArray(value)
};
innerWalk(childContext, callback);
}
});
});
}
innerWalk(context, callback);
}
var noop = function noop() {};
export function traverse(node, visitors) {
var before = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : noop;
var after = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : noop;
Object.keys(visitors).forEach(function (visitor) {
if (!nodeAndUnionTypes.includes(visitor)) {
throw new Error("Unexpected visitor ".concat(visitor));
}
});
var context = {
node: node,
inList: false,
shouldStop: false,
parentPath: null,
parentKey: null
};
walk(context, function (type, path) {
if (typeof visitors[type] === "function") {
before(type, path);
visitors[type](path);
after(type, path);
}
var unionTypes = unionTypesMap[type];
if (!unionTypes) {
throw new Error("Unexpected node type ".concat(type));
}
unionTypes.forEach(function (unionType) {
if (typeof visitors[unionType] === "function") {
before(unionType, path);
visitors[unionType](path);
after(unionType, path);
}
});
});
}

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