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383 lines
11 KiB
TypeScript
383 lines
11 KiB
TypeScript
// Loaded from https://deno.land/x/graphql_deno@v15.0.0/lib/language/visitor.js
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import inspect from '../jsutils/inspect.js';
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import { isNode } from './ast.js';
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/**
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* A visitor is provided to visit, it contains the collection of
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* relevant functions to be called during the visitor's traversal.
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*/
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export const QueryDocumentKeys = {
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Name: [],
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Document: ['definitions'],
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OperationDefinition: ['name', 'variableDefinitions', 'directives', 'selectionSet'],
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VariableDefinition: ['variable', 'type', 'defaultValue', 'directives'],
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Variable: ['name'],
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SelectionSet: ['selections'],
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Field: ['alias', 'name', 'arguments', 'directives', 'selectionSet'],
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Argument: ['name', 'value'],
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FragmentSpread: ['name', 'directives'],
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InlineFragment: ['typeCondition', 'directives', 'selectionSet'],
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FragmentDefinition: ['name', // Note: fragment variable definitions are experimental and may be changed
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// or removed in the future.
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'variableDefinitions', 'typeCondition', 'directives', 'selectionSet'],
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IntValue: [],
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FloatValue: [],
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StringValue: [],
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BooleanValue: [],
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NullValue: [],
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EnumValue: [],
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ListValue: ['values'],
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ObjectValue: ['fields'],
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ObjectField: ['name', 'value'],
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Directive: ['name', 'arguments'],
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NamedType: ['name'],
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ListType: ['type'],
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NonNullType: ['type'],
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SchemaDefinition: ['description', 'directives', 'operationTypes'],
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OperationTypeDefinition: ['type'],
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ScalarTypeDefinition: ['description', 'name', 'directives'],
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ObjectTypeDefinition: ['description', 'name', 'interfaces', 'directives', 'fields'],
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FieldDefinition: ['description', 'name', 'arguments', 'type', 'directives'],
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InputValueDefinition: ['description', 'name', 'type', 'defaultValue', 'directives'],
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InterfaceTypeDefinition: ['description', 'name', 'interfaces', 'directives', 'fields'],
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UnionTypeDefinition: ['description', 'name', 'directives', 'types'],
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EnumTypeDefinition: ['description', 'name', 'directives', 'values'],
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EnumValueDefinition: ['description', 'name', 'directives'],
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InputObjectTypeDefinition: ['description', 'name', 'directives', 'fields'],
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DirectiveDefinition: ['description', 'name', 'arguments', 'locations'],
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SchemaExtension: ['directives', 'operationTypes'],
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ScalarTypeExtension: ['name', 'directives'],
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ObjectTypeExtension: ['name', 'interfaces', 'directives', 'fields'],
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InterfaceTypeExtension: ['name', 'interfaces', 'directives', 'fields'],
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UnionTypeExtension: ['name', 'directives', 'types'],
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EnumTypeExtension: ['name', 'directives', 'values'],
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InputObjectTypeExtension: ['name', 'directives', 'fields']
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};
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export const BREAK = Object.freeze({});
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/**
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* visit() will walk through an AST using a depth first traversal, calling
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* the visitor's enter function at each node in the traversal, and calling the
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* leave function after visiting that node and all of its child nodes.
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*
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* By returning different values from the enter and leave functions, the
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* behavior of the visitor can be altered, including skipping over a sub-tree of
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* the AST (by returning false), editing the AST by returning a value or null
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* to remove the value, or to stop the whole traversal by returning BREAK.
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*
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* When using visit() to edit an AST, the original AST will not be modified, and
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* a new version of the AST with the changes applied will be returned from the
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* visit function.
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*
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* const editedAST = visit(ast, {
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* enter(node, key, parent, path, ancestors) {
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* // @return
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* // undefined: no action
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* // false: skip visiting this node
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* // visitor.BREAK: stop visiting altogether
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* // null: delete this node
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* // any value: replace this node with the returned value
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* },
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* leave(node, key, parent, path, ancestors) {
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* // @return
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* // undefined: no action
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* // false: no action
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* // visitor.BREAK: stop visiting altogether
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* // null: delete this node
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* // any value: replace this node with the returned value
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* }
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* });
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*
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* Alternatively to providing enter() and leave() functions, a visitor can
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* instead provide functions named the same as the kinds of AST nodes, or
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* enter/leave visitors at a named key, leading to four permutations of
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* visitor API:
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*
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* 1) Named visitors triggered when entering a node a specific kind.
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*
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* visit(ast, {
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* Kind(node) {
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* // enter the "Kind" node
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* }
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* })
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*
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* 2) Named visitors that trigger upon entering and leaving a node of
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* a specific kind.
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*
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* visit(ast, {
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* Kind: {
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* enter(node) {
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* // enter the "Kind" node
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* }
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* leave(node) {
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* // leave the "Kind" node
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* }
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* }
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* })
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*
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* 3) Generic visitors that trigger upon entering and leaving any node.
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*
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* visit(ast, {
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* enter(node) {
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* // enter any node
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* },
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* leave(node) {
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* // leave any node
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* }
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* })
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*
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* 4) Parallel visitors for entering and leaving nodes of a specific kind.
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*
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* visit(ast, {
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* enter: {
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* Kind(node) {
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* // enter the "Kind" node
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* }
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* },
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* leave: {
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* Kind(node) {
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* // leave the "Kind" node
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* }
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* }
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* })
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*/
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export function visit(root, visitor, visitorKeys = QueryDocumentKeys) {
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/* eslint-disable no-undef-init */
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let stack = undefined;
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let inArray = Array.isArray(root);
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let keys = [root];
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let index = -1;
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let edits = [];
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let node = undefined;
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let key = undefined;
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let parent = undefined;
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const path = [];
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const ancestors = [];
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let newRoot = root;
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/* eslint-enable no-undef-init */
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do {
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index++;
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const isLeaving = index === keys.length;
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const isEdited = isLeaving && edits.length !== 0;
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if (isLeaving) {
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key = ancestors.length === 0 ? undefined : path[path.length - 1];
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node = parent;
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parent = ancestors.pop();
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if (isEdited) {
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if (inArray) {
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node = node.slice();
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} else {
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const clone = {};
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for (const k of Object.keys(node)) {
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clone[k] = node[k];
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}
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node = clone;
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}
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let editOffset = 0;
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for (let ii = 0; ii < edits.length; ii++) {
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let editKey = edits[ii][0];
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const editValue = edits[ii][1];
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if (inArray) {
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editKey -= editOffset;
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}
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if (inArray && editValue === null) {
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node.splice(editKey, 1);
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editOffset++;
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} else {
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node[editKey] = editValue;
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}
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}
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}
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index = stack.index;
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keys = stack.keys;
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edits = stack.edits;
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inArray = stack.inArray;
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stack = stack.prev;
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} else {
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key = parent ? inArray ? index : keys[index] : undefined;
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node = parent ? parent[key] : newRoot;
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if (node === null || node === undefined) {
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continue;
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}
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if (parent) {
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path.push(key);
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}
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}
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let result;
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if (!Array.isArray(node)) {
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if (!isNode(node)) {
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throw new Error(`Invalid AST Node: ${inspect(node)}.`);
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}
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const visitFn = getVisitFn(visitor, node.kind, isLeaving);
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if (visitFn) {
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result = visitFn.call(visitor, node, key, parent, path, ancestors);
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if (result === BREAK) {
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break;
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}
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if (result === false) {
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if (!isLeaving) {
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path.pop();
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continue;
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}
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} else if (result !== undefined) {
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edits.push([key, result]);
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if (!isLeaving) {
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if (isNode(result)) {
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node = result;
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} else {
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path.pop();
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continue;
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}
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}
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}
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}
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}
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if (result === undefined && isEdited) {
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edits.push([key, node]);
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}
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if (isLeaving) {
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path.pop();
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} else {
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stack = {
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inArray,
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index,
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keys,
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edits,
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prev: stack
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};
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inArray = Array.isArray(node);
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keys = inArray ? node : visitorKeys[node.kind] ?? [];
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index = -1;
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edits = [];
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if (parent) {
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ancestors.push(parent);
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}
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parent = node;
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}
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} while (stack !== undefined);
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if (edits.length !== 0) {
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newRoot = edits[edits.length - 1][1];
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}
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return newRoot;
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}
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/**
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* Creates a new visitor instance which delegates to many visitors to run in
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* parallel. Each visitor will be visited for each node before moving on.
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*
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* If a prior visitor edits a node, no following visitors will see that node.
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*/
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export function visitInParallel(visitors) {
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const skipping = new Array(visitors.length);
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return {
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enter(node) {
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for (let i = 0; i < visitors.length; i++) {
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if (skipping[i] == null) {
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const fn = getVisitFn(visitors[i], node.kind,
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/* isLeaving */
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false);
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if (fn) {
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const result = fn.apply(visitors[i], arguments);
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if (result === false) {
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skipping[i] = node;
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} else if (result === BREAK) {
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skipping[i] = BREAK;
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} else if (result !== undefined) {
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return result;
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}
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}
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}
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}
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},
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leave(node) {
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for (let i = 0; i < visitors.length; i++) {
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if (skipping[i] == null) {
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const fn = getVisitFn(visitors[i], node.kind,
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/* isLeaving */
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true);
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if (fn) {
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const result = fn.apply(visitors[i], arguments);
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if (result === BREAK) {
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skipping[i] = BREAK;
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} else if (result !== undefined && result !== false) {
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return result;
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}
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}
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} else if (skipping[i] === node) {
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skipping[i] = null;
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}
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}
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}
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};
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}
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/**
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* Given a visitor instance, if it is leaving or not, and a node kind, return
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* the function the visitor runtime should call.
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*/
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export function getVisitFn(visitor, kind, isLeaving) {
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const kindVisitor = visitor[kind];
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if (kindVisitor) {
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if (!isLeaving && typeof kindVisitor === 'function') {
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// { Kind() {} }
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return kindVisitor;
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}
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const kindSpecificVisitor = isLeaving ? kindVisitor.leave : kindVisitor.enter;
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if (typeof kindSpecificVisitor === 'function') {
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// { Kind: { enter() {}, leave() {} } }
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return kindSpecificVisitor;
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}
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} else {
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const specificVisitor = isLeaving ? visitor.leave : visitor.enter;
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if (specificVisitor) {
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if (typeof specificVisitor === 'function') {
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// { enter() {}, leave() {} }
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return specificVisitor;
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}
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const specificKindVisitor = specificVisitor[kind];
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if (typeof specificKindVisitor === 'function') {
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// { enter: { Kind() {} }, leave: { Kind() {} } }
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return specificKindVisitor;
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}
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}
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}
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} |