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@category Visiting */\n\nimport { devAssert } from '../jsutils/devAssert.ts';\nimport { inspect } from '../jsutils/inspect.ts';\n\nimport type { ASTNode } from './ast.ts';\nimport { isNode, QueryDocumentKeys } from './ast.ts';\nimport { Kind } from './kinds.ts';\n\n/** A visitor defines the callbacks called during AST traversal. */\nexport type ASTVisitor = EnterLeaveVisitor<ASTNode> | KindVisitor;\n\ntype KindVisitor = {\n  readonly [NodeT in ASTNode as NodeT['kind']]?:\n    | ASTVisitFn<NodeT>\n    | EnterLeaveVisitor<NodeT>;\n};\n\ninterface EnterLeaveVisitor<TVisitedNode extends ASTNode> {\n  readonly enter?: ASTVisitFn<TVisitedNode> | undefined;\n  readonly leave?: ASTVisitFn<TVisitedNode> | undefined;\n}\n\n/**\n * A visitor is composed of visit functions called for each node during traversal.\n * @typeParam TVisitedNode - AST node type handled by this visitor function.\n */\nexport type ASTVisitFn<TVisitedNode extends ASTNode> = (\n  /** Current node being visited. */\n  node: TVisitedNode,\n  /** Index or key for this node within the parent node or array. */\n  key: string | number | undefined,\n  /** Parent immediately above this node, which may be an array. */\n  parent: ASTNode | ReadonlyArray<ASTNode> | undefined,\n  /** Key path from the root node to this node. */\n  path: ReadonlyArray<string | number>,\n  /**\n   * All nodes and arrays visited before reaching this node's parent.\n   * These correspond to array indices in `path`.\n   * Note: ancestors includes arrays that contain the visited node's parent.\n   */\n  ancestors: ReadonlyArray<ASTNode | ReadonlyArray<ASTNode>>,\n) => any;\n\n/**\n * A reducer is composed of reducer functions that convert AST nodes into another form.\n *\n * @internal\n */\nexport type ASTReducer<R> = {\n  readonly [NodeT in ASTNode as NodeT['kind']]?: {\n    readonly enter?: ASTVisitFn<NodeT>;\n    readonly leave: ASTReducerFn<NodeT, R>;\n  };\n};\n\ntype ASTReducerFn<TReducedNode extends ASTNode, R> = (\n  /**\n   * Current node being visited.\n   * @internal\n   */\n  node: { [K in keyof TReducedNode]: ReducedField<TReducedNode[K], R> },\n  /**\n   * Index or key for this node within the parent node or array.\n   * @internal\n   */\n  key: string | number | undefined,\n  /**\n   * Parent immediately above this node, which may be an array.\n   * @internal\n   */\n  parent: ASTNode | ReadonlyArray<ASTNode> | undefined,\n  /**\n   * Key path from the root node to this node.\n   * @internal\n   */\n  path: ReadonlyArray<string | number>,\n  /**\n   * All nodes and arrays visited before reaching this node's parent.\n   * These correspond to array indices in `path`.\n   * Note: ancestors includes arrays that contain the visited node's parent.\n   * @internal\n   */\n  ancestors: ReadonlyArray<ASTNode | ReadonlyArray<ASTNode>>,\n) => R;\n\ntype ReducedField<T, R> = T extends ASTNode\n  ? R\n  : T extends ReadonlyArray<ASTNode>\n    ? ReadonlyArray<R>\n    : T;\n\n/** A visitor key map describes the traversable child properties for each node kind. */\nexport type ASTVisitorKeyMap = {\n  [NodeT in ASTNode as NodeT['kind']]?: ReadonlyArray<keyof NodeT>;\n};\n\n/** A value that can be returned from a visitor function to stop traversal. */\nexport const BREAK: unknown = Object.freeze({});\n\n/**\n * visit() will walk through an AST using a depth-first traversal, calling\n * the visitor's enter function at each node in the traversal, and calling the\n * leave function after visiting that node and all of its child nodes.\n *\n * By returning different values from the enter and leave functions, the\n * behavior of the visitor can be altered, including skipping over a sub-tree of\n * the AST (by returning false), editing the AST by returning a value or null\n * to remove the value, or to stop the whole traversal by returning BREAK.\n *\n * When using visit() to edit an AST, the original AST will not be modified, and\n * a new version of the AST with the changes applied will be returned from the\n * visit function.\n * @param root - The AST node at which to start traversal.\n * @param visitor - The visitor or reducer functions to call while traversing.\n * @param visitorKeys - Optional map of child keys to visit for each AST node kind.\n * @returns The original AST, an edited AST, or a reduced value depending on the visitor.\n * @typeParam N - The root AST node type returned when visiting without reducing.\n * @example\n * ```ts\n * // Return values control traversal: undefined makes no change, false skips\n * // a subtree, BREAK stops traversal, null removes a node, and any other\n * // value replaces the current node.\n * import { Kind, parse, print, visit } from 'graphql/language';\n *\n * const document = parse('{ hero { name } }');\n * const editedAST = visit(document, {\n *   Field: (node) => {\n *     if (node.name.value === 'hero') {\n *       return {\n *         ...node,\n *         name: { kind: Kind.NAME, value: 'human' },\n *       };\n *     }\n *   },\n * });\n *\n * print(editedAST); // => '{\\n  human {\\n    name\\n  }\\n}'\n * ```\n * @example\n * ```ts\n * // A named visitor function runs when entering nodes of that kind.\n * import { parse, visit } from 'graphql/language';\n *\n * const document = parse('{ hero { name } }');\n * const fieldNames = [];\n *\n * visit(document, {\n *   Field: (node) => {\n *     fieldNames.push(node.name.value);\n *   },\n * });\n *\n * fieldNames; // => ['hero', 'name']\n * ```\n * @example\n * ```ts\n * // A named visitor object can provide separate enter and leave handlers for\n * // nodes of that kind.\n * import { parse, visit } from 'graphql/language';\n *\n * const document = parse('{ hero { name } }');\n * const events = [];\n *\n * visit(document, {\n *   Field: {\n *     enter: (node) => {\n *       events.push(`enter:${node.name.value}`);\n *     },\n *     leave: (node) => {\n *       events.push(`leave:${node.name.value}`);\n *     },\n *   },\n * });\n *\n * events; // => ['enter:hero', 'enter:name', 'leave:name', 'leave:hero']\n * ```\n * @example\n * ```ts\n * // Generic enter and leave handlers run for every node.\n * import { parse, visit } from 'graphql/language';\n *\n * const document = parse('{ hero { name } }');\n * let enterCount = 0;\n * let leaveCount = 0;\n *\n * visit(document, {\n *   enter: (node) => {\n *     enterCount += 1;\n *   },\n *   leave: (node) => {\n *     leaveCount += 1;\n *   },\n * });\n *\n * enterCount; // => leaveCount\n * enterCount > 0; // => true\n * ```\n */\nexport function visit<N extends ASTNode>(\n  root: N,\n  visitor: ASTVisitor,\n  visitorKeys?: ASTVisitorKeyMap,\n): N;\n/**\n * Traverses an AST with reducer callbacks and returns the reduced value.\n * @param root - The AST node where traversal starts.\n * @param visitor - Reducer callbacks to invoke during traversal.\n * @param visitorKeys - Optional mapping of child keys for each AST node kind.\n * @returns The value produced by the reducer visitor.\n * @typeParam R - The value produced by reducer visitor callbacks.\n * @example\n * ```ts\n * // A reducer visitor returns values from leave handlers to build a reduced\n * // result instead of returning an edited AST.\n * import { parse, visit } from 'graphql/language';\n *\n * const document = parse('{ hero { name } }');\n * const printed = visit(document, {\n *   Name: {\n *     leave: (node) => {\n *       return node.value;\n *     },\n *   },\n *   Field: {\n *     leave: (node) => {\n *       return node.selectionSet == null\n *         ? node.name\n *         : `${node.name} { ${node.selectionSet} }`;\n *     },\n *   },\n *   SelectionSet: {\n *     leave: (node) => {\n *       return node.selections.join(' ');\n *     },\n *   },\n *   OperationDefinition: {\n *     leave: (node) => {\n *       return node.selectionSet;\n *     },\n *   },\n *   Document: {\n *     leave: (node) => {\n *       return node.definitions.join('\\n');\n *     },\n *   },\n * });\n *\n * printed; // => 'hero { name }'\n * ```\n */\nexport function visit<R>(\n  root: ASTNode,\n  visitor: ASTReducer<R>,\n  visitorKeys?: ASTVisitorKeyMap,\n): R;\n/**\n * Traverses an AST with visitor or reducer callbacks.\n * @internal\n */\nexport function visit(\n  root: ASTNode,\n  visitor: ASTVisitor | ASTReducer<any>,\n  visitorKeys: ASTVisitorKeyMap = QueryDocumentKeys,\n): any {\n  const enterLeaveMap = new Map<Kind, EnterLeaveVisitor<ASTNode>>();\n  for (const kind of Object.values(Kind)) {\n    enterLeaveMap.set(kind, getEnterLeaveForKind(visitor, kind));\n  }\n\n  /* eslint-disable no-undef-init */\n  let stack: any = undefined;\n  let inArray = Array.isArray(root);\n  let keys: any = [root];\n  let index = -1;\n  let edits = [];\n  let node: any = root;\n  let key: any = undefined;\n  let parent: any = undefined;\n  const path: any = [];\n  const ancestors = [];\n  /* eslint-enable no-undef-init */\n\n  do {\n    index++;\n    const isLeaving = index === keys.length;\n    const isEdited = isLeaving && edits.length !== 0;\n    if (isLeaving) {\n      key = ancestors.length === 0 ? undefined : path[path.length - 1];\n      node = parent;\n      parent = ancestors.pop();\n      if (isEdited) {\n        if (inArray) {\n          node = node.slice();\n\n          let editOffset = 0;\n          for (const [editKey, editValue] of edits) {\n            const arrayKey = editKey - editOffset;\n            if (editValue === null) {\n              node.splice(arrayKey, 1);\n              editOffset++;\n            } else {\n              node[arrayKey] = editValue;\n            }\n          }\n        } else {\n          node = { ...node };\n          for (const [editKey, editValue] of edits) {\n            node[editKey] = editValue;\n          }\n        }\n      }\n      index = stack.index;\n      keys = stack.keys;\n      edits = stack.edits;\n      inArray = stack.inArray;\n      stack = stack.prev;\n    } else if (parent != null) {\n      key = inArray ? index : keys[index];\n      node = parent[key];\n      if (node === null || node === undefined) {\n        continue;\n      }\n      path.push(key);\n    }\n\n    let result;\n    if (!Array.isArray(node)) {\n      devAssert(isNode(node), `Invalid AST Node: ${inspect(node)}.`);\n\n      const visitFn = isLeaving\n        ? enterLeaveMap.get(node.kind)?.leave\n        : enterLeaveMap.get(node.kind)?.enter;\n\n      result = visitFn?.call(visitor, node, key, parent, path, ancestors);\n\n      if (result === BREAK) {\n        break;\n      }\n\n      if (result === false) {\n        if (!isLeaving) {\n          path.pop();\n          continue;\n        }\n      } else if (result !== undefined) {\n        edits.push([key, result]);\n        if (!isLeaving) {\n          if (isNode(result)) {\n            node = result;\n          } else {\n            path.pop();\n            continue;\n          }\n        }\n      }\n    }\n\n    if (result === undefined && isEdited) {\n      edits.push([key, node]);\n    }\n\n    if (isLeaving) {\n      path.pop();\n    } else {\n      stack = { inArray, index, keys, edits, prev: stack };\n      inArray = Array.isArray(node);\n      keys = inArray ? node : ((visitorKeys as any)[node.kind] ?? []);\n      index = -1;\n      edits = [];\n      if (parent != null) {\n        ancestors.push(parent);\n      }\n      parent = node;\n    }\n  } while (stack !== undefined);\n\n  if (edits.length !== 0) {\n    // New root\n    return edits.at(-1)[1];\n  }\n\n  return root;\n}\n\n/**\n * Creates a new visitor instance which delegates to many visitors to run in\n * parallel. Each visitor will be visited for each node before moving on.\n *\n * If a prior visitor edits a node, no following visitors will see that node.\n * @param visitors - The visitors to merge into one parallel visitor.\n * @returns A visitor that delegates traversal to each provided visitor.\n * @example\n * ```ts\n * import { parse, visit, visitInParallel } from 'graphql/language';\n *\n * const document = parse('{ hero { name } }');\n * const events = [];\n *\n * visit(\n *   document,\n *   visitInParallel([\n *     {\n *       Field: (node) => {\n *         events.push(`field:${node.name.value}`);\n *       },\n *     },\n *     {\n *       Name: (node) => {\n *         events.push(`name:${node.value}`);\n *       },\n *     },\n *   ]),\n * );\n *\n * events; // => ['field:hero', 'name:hero', 'field:name', 'name:name']\n * ```\n */\nexport function visitInParallel(\n  visitors: ReadonlyArray<ASTVisitor>,\n): ASTVisitor {\n  const skipping = new Array(visitors.length).fill(null);\n  const mergedVisitor = Object.create(null);\n\n  for (const kind of Object.values(Kind)) {\n    let hasVisitor = false;\n    const enterList = new Array(visitors.length).fill(undefined);\n    const leaveList = new Array(visitors.length).fill(undefined);\n\n    for (let i = 0; i < visitors.length; ++i) {\n      const { enter, leave } = getEnterLeaveForKind(visitors[i], kind);\n      hasVisitor ||= enter != null || leave != null;\n      enterList[i] = enter;\n      leaveList[i] = leave;\n    }\n\n    if (!hasVisitor) {\n      continue;\n    }\n\n    const mergedEnterLeave: EnterLeaveVisitor<ASTNode> = {\n      enter(...args) {\n        const node = args[0];\n        for (let i = 0; i < visitors.length; i++) {\n          if (skipping[i] === null) {\n            const result = enterList[i]?.apply(visitors[i], args);\n            if (result === false) {\n              skipping[i] = node;\n            } else if (result === BREAK) {\n              skipping[i] = BREAK;\n            } else if (result !== undefined) {\n              return result;\n            }\n          }\n        }\n      },\n      leave(...args) {\n        const node = args[0];\n        for (let i = 0; i < visitors.length; i++) {\n          if (skipping[i] === null) {\n            const result = leaveList[i]?.apply(visitors[i], args);\n            if (result === BREAK) {\n              skipping[i] = BREAK;\n            } else if (result !== undefined && result !== false) {\n              return result;\n            }\n          } else if (skipping[i] === node) {\n            skipping[i] = null;\n          }\n        }\n      },\n    };\n\n    mergedVisitor[kind] = mergedEnterLeave;\n  }\n\n  return mergedVisitor;\n}\n\n/**\n * Given a visitor instance and a node kind, return EnterLeaveVisitor for that kind.\n * @param visitor - The visitor object to inspect.\n * @param kind - The AST node kind to resolve handlers for.\n * @returns The enter and leave handlers that apply for the given node kind.\n * @example\n * ```ts\n * import { Kind, getEnterLeaveForKind } from 'graphql/language';\n *\n * const handlers = getEnterLeaveForKind({ Field: () => {} }, Kind.FIELD);\n *\n * typeof handlers.enter; // => 'function'\n * handlers.leave; // => undefined\n * ```\n */\nexport function getEnterLeaveForKind(\n  visitor: ASTVisitor,\n  kind: Kind,\n): EnterLeaveVisitor<ASTNode> {\n  const kindVisitor:\n    | ASTVisitFn<ASTNode>\n    | EnterLeaveVisitor<ASTNode>\n    | undefined = (visitor as any)[kind];\n\n  if (typeof kindVisitor === 'object') {\n    // { Kind: { enter() {}, leave() {} } }\n    return kindVisitor;\n  } else if (typeof kindVisitor === 'function') {\n    // { Kind() {} }\n    return { enter: kindVisitor, leave: undefined };\n  }\n\n  // { enter() {}, leave() {} }\n  return { enter: (visitor as any).enter, leave: (visitor as any).leave };\n}\n"]}