graphql
Version:
A Query Language and Runtime which can target any service.
195 lines (194 loc) • 6.38 kB
TypeScript
import type { ASTNode } from './ast';
import { Kind } from './kinds';
/**
* A visitor is provided to visit, it contains the collection of
* relevant functions to be called during the visitor's traversal.
*/
export declare type ASTVisitor = EnterLeaveVisitor<ASTNode> | KindVisitor;
declare type KindVisitor = {
readonly [NodeT in ASTNode as NodeT['kind']]?:
| ASTVisitFn<NodeT>
| EnterLeaveVisitor<NodeT>;
};
interface EnterLeaveVisitor<TVisitedNode extends ASTNode> {
readonly enter?: ASTVisitFn<TVisitedNode>;
readonly leave?: ASTVisitFn<TVisitedNode>;
}
/**
* A visitor is comprised of visit functions, which are called on each node
* during the visitor's traversal.
*/
export declare type ASTVisitFn<TVisitedNode extends ASTNode> = (
/** The current node being visiting. */
node: TVisitedNode,
/** The index or key to this node from the parent node or Array. */
key: string | number | undefined,
/** The parent immediately above this node, which may be an Array. */
parent: ASTNode | ReadonlyArray<ASTNode> | undefined,
/** The key path to get to this node from the root node. */
path: ReadonlyArray<string | number>,
/**
* All nodes and Arrays visited before reaching parent of this node.
* These correspond to array indices in `path`.
* Note: ancestors includes arrays which contain the parent of visited node.
*/
ancestors: ReadonlyArray<ASTNode | ReadonlyArray<ASTNode>>,
) => any;
/**
* A reducer is comprised of reducer functions which convert AST nodes into
* another form.
*/
export declare type ASTReducer<R> = {
readonly [NodeT in ASTNode as NodeT['kind']]?: {
readonly enter?: ASTVisitFn<NodeT>;
readonly leave: ASTReducerFn<NodeT, R>;
};
};
declare type ASTReducerFn<TReducedNode extends ASTNode, R> = (
/** The current node being visiting. */
node: {
[K in keyof TReducedNode]: ReducedField<TReducedNode[K], R>;
},
/** The index or key to this node from the parent node or Array. */
key: string | number | undefined,
/** The parent immediately above this node, which may be an Array. */
parent: ASTNode | ReadonlyArray<ASTNode> | undefined,
/** The key path to get to this node from the root node. */
path: ReadonlyArray<string | number>,
/**
* All nodes and Arrays visited before reaching parent of this node.
* These correspond to array indices in `path`.
* Note: ancestors includes arrays which contain the parent of visited node.
*/
ancestors: ReadonlyArray<ASTNode | ReadonlyArray<ASTNode>>,
) => R;
declare type ReducedField<T, R> = T extends null | undefined
? T
: T extends ReadonlyArray<any>
? ReadonlyArray<R>
: R;
/**
* A KeyMap describes each the traversable properties of each kind of node.
*
* @deprecated Please inline it. Will be removed in v17
*/
export declare type ASTVisitorKeyMap = {
[NodeT in ASTNode as NodeT['kind']]?: ReadonlyArray<keyof NodeT>;
};
export declare const BREAK: unknown;
/**
* visit() will walk through an AST using a depth-first traversal, calling
* the visitor's enter function at each node in the traversal, and calling the
* leave function after visiting that node and all of its child nodes.
*
* By returning different values from the enter and leave functions, the
* behavior of the visitor can be altered, including skipping over a sub-tree of
* the AST (by returning false), editing the AST by returning a value or null
* to remove the value, or to stop the whole traversal by returning BREAK.
*
* When using visit() to edit an AST, the original AST will not be modified, and
* a new version of the AST with the changes applied will be returned from the
* visit function.
*
* ```ts
* const editedAST = visit(ast, {
* enter(node, key, parent, path, ancestors) {
* // @return
* // undefined: no action
* // false: skip visiting this node
* // visitor.BREAK: stop visiting altogether
* // null: delete this node
* // any value: replace this node with the returned value
* },
* leave(node, key, parent, path, ancestors) {
* // @return
* // undefined: no action
* // false: no action
* // visitor.BREAK: stop visiting altogether
* // null: delete this node
* // any value: replace this node with the returned value
* }
* });
* ```
*
* Alternatively to providing enter() and leave() functions, a visitor can
* instead provide functions named the same as the kinds of AST nodes, or
* enter/leave visitors at a named key, leading to three permutations of the
* visitor API:
*
* 1) Named visitors triggered when entering a node of a specific kind.
*
* ```ts
* visit(ast, {
* Kind(node) {
* // enter the "Kind" node
* }
* })
* ```
*
* 2) Named visitors that trigger upon entering and leaving a node of a specific kind.
*
* ```ts
* visit(ast, {
* Kind: {
* enter(node) {
* // enter the "Kind" node
* }
* leave(node) {
* // leave the "Kind" node
* }
* }
* })
* ```
*
* 3) Generic visitors that trigger upon entering and leaving any node.
*
* ```ts
* visit(ast, {
* enter(node) {
* // enter any node
* },
* leave(node) {
* // leave any node
* }
* })
* ```
*/
export declare function visit<N extends ASTNode>(
root: N,
visitor: ASTVisitor,
visitorKeys?: ASTVisitorKeyMap,
): N;
export declare function visit<R>(
root: ASTNode,
visitor: ASTReducer<R>,
visitorKeys?: ASTVisitorKeyMap,
): R;
/**
* Creates a new visitor instance which delegates to many visitors to run in
* parallel. Each visitor will be visited for each node before moving on.
*
* If a prior visitor edits a node, no following visitors will see that node.
*/
export declare function visitInParallel(
visitors: ReadonlyArray<ASTVisitor>,
): ASTVisitor;
/**
* Given a visitor instance and a node kind, return EnterLeaveVisitor for that kind.
*/
export declare function getEnterLeaveForKind(
visitor: ASTVisitor,
kind: Kind,
): EnterLeaveVisitor<ASTNode>;
/**
* Given a visitor instance, if it is leaving or not, and a node kind, return
* the function the visitor runtime should call.
*
* @deprecated Please use `getEnterLeaveForKind` instead. Will be removed in v17
*/
export declare function getVisitFn(
visitor: ASTVisitor,
kind: Kind,
isLeaving: boolean,
): ASTVisitFn<ASTNode> | undefined;
export {};