57 lines
1.7 KiB
JavaScript
57 lines
1.7 KiB
JavaScript
export const TRAVERSAL_PATH = {
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ArrayExpression: ['elements'],
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ArrayPattern: ['elements'],
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AssignmentExpression: ['left', 'right'],
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AwaitExpression: ['argument'],
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BinaryExpression: ['left', 'right'],
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BlockStatement: ['body'],
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BreakStatement: [],
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CallExpression: ['arguments', 'callee'],
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ChainExpression: ['expression'],
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ConditionalExpression: ['alternate', 'consequent', 'test'],
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DoWhileStatement: ['body', 'test'],
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ExpressionStatement: ['expression'],
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ForOfStatement: ['body', 'left', 'right'],
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ForStatement: ['body', 'init', 'test', 'update'],
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Identifier: [],
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IfStatement: ['alternate', 'consequent', 'test'],
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MemberExpression: ['object', 'property'],
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NewExpression: ['arguments', 'callee'],
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Literal: [],
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LogicalExpression: ['left', 'right'],
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ObjectExpression: ['properties'],
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ObjectPattern: ['properties'],
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Program: ['body'],
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Property: ['key', 'value'],
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ReturnStatement: ['argument'],
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SpreadElement: ['argument'],
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UnaryExpression: ['argument'],
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UpdateExpression: ['argument'],
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VariableDeclaration: ['declarations'],
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VariableDeclarator: ['id', 'init'],
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WhileStatement: ['body', 'test'],
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};
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export default function traverse(node, visitor) {
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/* v8 ignore next 3 */
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if (!(node.type in TRAVERSAL_PATH)) {
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throw new Error(`node type ${node.type} not traversable. (${Object.keys(node).join(', ')})`);
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}
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visitor(node, 'enter');
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for (const key of TRAVERSAL_PATH[node.type]) {
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if (Array.isArray(node[key])) {
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for (const child of node[key]) {
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if (child) {
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traverse(child, visitor);
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}
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}
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}
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else {
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if (node[key]) {
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traverse(node[key], visitor);
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}
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}
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}
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visitor(node, 'exit');
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}
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