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node_modules/graphql/language/visitor.js.flow

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+// @flow strict
+
+import inspect from '../jsutils/inspect';
+
+import { type TypeInfo } from '../utilities/TypeInfo';
+
+import { type ASTNode, type ASTKindToNode } from './ast';
+
+/**
+ * A visitor is provided to visit, it contains the collection of
+ * relevant functions to be called during the visitor's traversal.
+ */
+export type ASTVisitor = Visitor<ASTKindToNode>;
+export type Visitor<KindToNode, Nodes = $Values<KindToNode>> =
+  | EnterLeave<
+      | VisitFn<Nodes>
+      | ShapeMap<KindToNode, <Node>(Node) => VisitFn<Nodes, Node>>,
+    >
+  | ShapeMap<
+      KindToNode,
+      <Node>(Node) => VisitFn<Nodes, Node> | EnterLeave<VisitFn<Nodes, Node>>,
+    >;
+type EnterLeave<T> = {| +enter?: T, +leave?: T |};
+type ShapeMap<O, F> = $Shape<$ObjMap<O, F>>;
+
+/**
+ * A visitor is comprised of visit functions, which are called on each node
+ * during the visitor's traversal.
+ */
+export type VisitFn<TAnyNode, TVisitedNode: TAnyNode = TAnyNode> = (
+  // The current node being visiting.
+  node: TVisitedNode,
+  // The index or key to this node from the parent node or Array.
+  key: string | number | void,
+  // The parent immediately above this node, which may be an Array.
+  parent: TAnyNode | $ReadOnlyArray<TAnyNode> | void,
+  // 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<TAnyNode | $ReadOnlyArray<TAnyNode>>,
+) => any;
+
+/**
+ * A KeyMap describes each the traversable properties of each kind of node.
+ */
+export type VisitorKeyMap<KindToNode> = $ObjMap<
+  KindToNode,
+  <T>(T) => $ReadOnlyArray<$Keys<T>>,
+>;
+
+export const QueryDocumentKeys = {
+  Name: [],
+
+  Document: ['definitions'],
+  OperationDefinition: [
+    'name',
+    'variableDefinitions',
+    'directives',
+    'selectionSet',
+  ],
+  VariableDefinition: ['variable', 'type', 'defaultValue', 'directives'],
+  Variable: ['name'],
+  SelectionSet: ['selections'],
+  Field: ['alias', 'name', 'arguments', 'directives', 'selectionSet'],
+  Argument: ['name', 'value'],
+
+  FragmentSpread: ['name', 'directives'],
+  InlineFragment: ['typeCondition', 'directives', 'selectionSet'],
+  FragmentDefinition: [
+    'name',
+    // Note: fragment variable definitions are experimental and may be changed
+    // or removed in the future.
+    'variableDefinitions',
+    'typeCondition',
+    'directives',
+    'selectionSet',
+  ],
+
+  IntValue: [],
+  FloatValue: [],
+  StringValue: [],
+  BooleanValue: [],
+  NullValue: [],
+  EnumValue: [],
+  ListValue: ['values'],
+  ObjectValue: ['fields'],
+  ObjectField: ['name', 'value'],
+
+  Directive: ['name', 'arguments'],
+
+  NamedType: ['name'],
+  ListType: ['type'],
+  NonNullType: ['type'],
+
+  SchemaDefinition: ['directives', 'operationTypes'],
+  OperationTypeDefinition: ['type'],
+
+  ScalarTypeDefinition: ['description', 'name', 'directives'],
+  ObjectTypeDefinition: [
+    'description',
+    'name',
+    'interfaces',
+    'directives',
+    'fields',
+  ],
+  FieldDefinition: ['description', 'name', 'arguments', 'type', 'directives'],
+  InputValueDefinition: [
+    'description',
+    'name',
+    'type',
+    'defaultValue',
+    'directives',
+  ],
+  InterfaceTypeDefinition: ['description', 'name', 'directives', 'fields'],
+  UnionTypeDefinition: ['description', 'name', 'directives', 'types'],
+  EnumTypeDefinition: ['description', 'name', 'directives', 'values'],
+  EnumValueDefinition: ['description', 'name', 'directives'],
+  InputObjectTypeDefinition: ['description', 'name', 'directives', 'fields'],
+
+  DirectiveDefinition: ['description', 'name', 'arguments', 'locations'],
+
+  SchemaExtension: ['directives', 'operationTypes'],
+
+  ScalarTypeExtension: ['name', 'directives'],
+  ObjectTypeExtension: ['name', 'interfaces', 'directives', 'fields'],
+  InterfaceTypeExtension: ['name', 'directives', 'fields'],
+  UnionTypeExtension: ['name', 'directives', 'types'],
+  EnumTypeExtension: ['name', 'directives', 'values'],
+  InputObjectTypeExtension: ['name', 'directives', 'fields'],
+};
+
+export const BREAK = Object.freeze({});
+
+/**
+ * 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.
+ *
+ *     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 four permutations of
+ * visitor API:
+ *
+ * 1) Named visitors triggered when entering a node a specific kind.
+ *
+ *     visit(ast, {
+ *       Kind(node) {
+ *         // enter the "Kind" node
+ *       }
+ *     })
+ *
+ * 2) Named visitors that trigger upon entering and leaving a node of
+ *    a specific kind.
+ *
+ *     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.
+ *
+ *     visit(ast, {
+ *       enter(node) {
+ *         // enter any node
+ *       },
+ *       leave(node) {
+ *         // leave any node
+ *       }
+ *     })
+ *
+ * 4) Parallel visitors for entering and leaving nodes of a specific kind.
+ *
+ *     visit(ast, {
+ *       enter: {
+ *         Kind(node) {
+ *           // enter the "Kind" node
+ *         }
+ *       },
+ *       leave: {
+ *         Kind(node) {
+ *           // leave the "Kind" node
+ *         }
+ *       }
+ *     })
+ */
+export function visit(
+  root: ASTNode,
+  visitor: Visitor<ASTKindToNode>,
+  visitorKeys: VisitorKeyMap<ASTKindToNode> = QueryDocumentKeys,
+): any {
+  /* eslint-disable no-undef-init */
+  let stack: any = undefined;
+  let inArray = Array.isArray(root);
+  let keys: any = [root];
+  let index = -1;
+  let edits = [];
+  let node: any = undefined;
+  let key: any = undefined;
+  let parent: any = undefined;
+  const path: any = [];
+  const ancestors = [];
+  let newRoot = root;
+  /* eslint-enable no-undef-init */
+
+  do {
+    index++;
+    const isLeaving = index === keys.length;
+    const isEdited = isLeaving && edits.length !== 0;
+    if (isLeaving) {
+      key = ancestors.length === 0 ? undefined : path[path.length - 1];
+      node = parent;
+      parent = ancestors.pop();
+      if (isEdited) {
+        if (inArray) {
+          node = node.slice();
+        } else {
+          const clone = {};
+          for (const k of Object.keys(node)) {
+            clone[k] = node[k];
+          }
+          node = clone;
+        }
+        let editOffset = 0;
+        for (let ii = 0; ii < edits.length; ii++) {
+          let editKey: any = edits[ii][0];
+          const editValue = edits[ii][1];
+          if (inArray) {
+            editKey -= editOffset;
+          }
+          if (inArray && editValue === null) {
+            node.splice(editKey, 1);
+            editOffset++;
+          } else {
+            node[editKey] = editValue;
+          }
+        }
+      }
+      index = stack.index;
+      keys = stack.keys;
+      edits = stack.edits;
+      inArray = stack.inArray;
+      stack = stack.prev;
+    } else {
+      key = parent ? (inArray ? index : keys[index]) : undefined;
+      node = parent ? parent[key] : newRoot;
+      if (node === null || node === undefined) {
+        continue;
+      }
+      if (parent) {
+        path.push(key);
+      }
+    }
+
+    let result;
+    if (!Array.isArray(node)) {
+      if (!isNode(node)) {
+        throw new Error('Invalid AST Node: ' + inspect(node));
+      }
+      const visitFn = getVisitFn(visitor, node.kind, isLeaving);
+      if (visitFn) {
+        result = visitFn.call(visitor, node, key, parent, path, ancestors);
+
+        if (result === BREAK) {
+          break;
+        }
+
+        if (result === false) {
+          if (!isLeaving) {
+            path.pop();
+            continue;
+          }
+        } else if (result !== undefined) {
+          edits.push([key, result]);
+          if (!isLeaving) {
+            if (isNode(result)) {
+              node = result;
+            } else {
+              path.pop();
+              continue;
+            }
+          }
+        }
+      }
+    }
+
+    if (result === undefined && isEdited) {
+      edits.push([key, node]);
+    }
+
+    if (isLeaving) {
+      path.pop();
+    } else {
+      stack = { inArray, index, keys, edits, prev: stack };
+      inArray = Array.isArray(node);
+      keys = inArray ? node : visitorKeys[node.kind] || [];
+      index = -1;
+      edits = [];
+      if (parent) {
+        ancestors.push(parent);
+      }
+      parent = node;
+    }
+  } while (stack !== undefined);
+
+  if (edits.length !== 0) {
+    newRoot = edits[edits.length - 1][1];
+  }
+
+  return newRoot;
+}
+
+function isNode(maybeNode): boolean %checks {
+  return Boolean(maybeNode && typeof maybeNode.kind === 'string');
+}
+
+/**
+ * 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 function visitInParallel(
+  visitors: $ReadOnlyArray<Visitor<ASTKindToNode>>,
+): Visitor<ASTKindToNode> {
+  const skipping = new Array(visitors.length);
+
+  return {
+    enter(node) {
+      for (let i = 0; i < visitors.length; i++) {
+        if (!skipping[i]) {
+          const fn = getVisitFn(visitors[i], node.kind, /* isLeaving */ false);
+          if (fn) {
+            const result = fn.apply(visitors[i], arguments);
+            if (result === false) {
+              skipping[i] = node;
+            } else if (result === BREAK) {
+              skipping[i] = BREAK;
+            } else if (result !== undefined) {
+              return result;
+            }
+          }
+        }
+      }
+    },
+    leave(node) {
+      for (let i = 0; i < visitors.length; i++) {
+        if (!skipping[i]) {
+          const fn = getVisitFn(visitors[i], node.kind, /* isLeaving */ true);
+          if (fn) {
+            const result = fn.apply(visitors[i], arguments);
+            if (result === BREAK) {
+              skipping[i] = BREAK;
+            } else if (result !== undefined && result !== false) {
+              return result;
+            }
+          }
+        } else if (skipping[i] === node) {
+          skipping[i] = null;
+        }
+      }
+    },
+  };
+}
+
+/**
+ * Creates a new visitor instance which maintains a provided TypeInfo instance
+ * along with visiting visitor.
+ */
+export function visitWithTypeInfo(
+  typeInfo: TypeInfo,
+  visitor: Visitor<ASTKindToNode>,
+): Visitor<ASTKindToNode> {
+  return {
+    enter(node) {
+      typeInfo.enter(node);
+      const fn = getVisitFn(visitor, node.kind, /* isLeaving */ false);
+      if (fn) {
+        const result = fn.apply(visitor, arguments);
+        if (result !== undefined) {
+          typeInfo.leave(node);
+          if (isNode(result)) {
+            typeInfo.enter(result);
+          }
+        }
+        return result;
+      }
+    },
+    leave(node) {
+      const fn = getVisitFn(visitor, node.kind, /* isLeaving */ true);
+      let result;
+      if (fn) {
+        result = fn.apply(visitor, arguments);
+      }
+      typeInfo.leave(node);
+      return result;
+    },
+  };
+}
+
+/**
+ * Given a visitor instance, if it is leaving or not, and a node kind, return
+ * the function the visitor runtime should call.
+ */
+export function getVisitFn(
+  visitor: Visitor<any>,
+  kind: string,
+  isLeaving: boolean,
+): ?VisitFn<any> {
+  const kindVisitor = visitor[kind];
+  if (kindVisitor) {
+    if (!isLeaving && typeof kindVisitor === 'function') {
+      // { Kind() {} }
+      return kindVisitor;
+    }
+    const kindSpecificVisitor = isLeaving
+      ? kindVisitor.leave
+      : kindVisitor.enter;
+    if (typeof kindSpecificVisitor === 'function') {
+      // { Kind: { enter() {}, leave() {} } }
+      return kindSpecificVisitor;
+    }
+  } else {
+    const specificVisitor = isLeaving ? visitor.leave : visitor.enter;
+    if (specificVisitor) {
+      if (typeof specificVisitor === 'function') {
+        // { enter() {}, leave() {} }
+        return specificVisitor;
+      }
+      const specificKindVisitor = specificVisitor[kind];
+      if (typeof specificKindVisitor === 'function') {
+        // { enter: { Kind() {} }, leave: { Kind() {} } }
+        return specificKindVisitor;
+      }
+    }
+  }
+}