graphql/language/visitor.mjs

import inspect from "../jsutils/inspect.mjs";
import { isNode } from "./ast.mjs";
/**
 * A visitor is provided to visit, it contains the collection of
 * relevant functions to be called during the visitor's traversal.
 */

export var 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: ['description', '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', 'interfaces', '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', 'interfaces', 'directives', 'fields'],
  UnionTypeExtension: ['name', 'directives', 'types'],
  EnumTypeExtension: ['name', 'directives', 'values'],
  InputObjectTypeExtension: ['name', 'directives', 'fields']
};
export var 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 the
 * visitor API:
 *
 * 1) Named visitors triggered when entering a node of 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, visitor) {
  var visitorKeys = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : QueryDocumentKeys;

  /* eslint-disable no-undef-init */
  var stack = undefined;
  var inArray = Array.isArray(root);
  var keys = [root];
  var index = -1;
  var edits = [];
  var node = undefined;
  var key = undefined;
  var parent = undefined;
  var path = [];
  var ancestors = [];
  var newRoot = root;
  /* eslint-enable no-undef-init */

  do {
    index++;
    var isLeaving = index === keys.length;
    var 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 {
          var clone = {};

          for (var _i2 = 0, _Object$keys2 = Object.keys(node); _i2 < _Object$keys2.length; _i2++) {
            var k = _Object$keys2[_i2];
            clone[k] = node[k];
          }

          node = clone;
        }

        var editOffset = 0;

        for (var ii = 0; ii < edits.length; ii++) {
          var editKey = edits[ii][0];
          var 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);
      }
    }

    var result = void 0;

    if (!Array.isArray(node)) {
      if (!isNode(node)) {
        throw new Error("Invalid AST Node: ".concat(inspect(node), "."));
      }

      var 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 {
      var _visitorKeys$node$kin;

      stack = {
        inArray: inArray,
        index: index,
        keys: keys,
        edits: edits,
        prev: stack
      };
      inArray = Array.isArray(node);
      keys = inArray ? node : (_visitorKeys$node$kin = visitorKeys[node.kind]) !== null && _visitorKeys$node$kin !== void 0 ? _visitorKeys$node$kin : [];
      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;
}
/**
 * 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) {
  var skipping = new Array(visitors.length);
  return {
    enter: function enter(node) {
      for (var i = 0; i < visitors.length; i++) {
        if (skipping[i] == null) {
          var fn = getVisitFn(visitors[i], node.kind,
          /* isLeaving */
          false);

          if (fn) {
            var 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: function leave(node) {
      for (var i = 0; i < visitors.length; i++) {
        if (skipping[i] == null) {
          var fn = getVisitFn(visitors[i], node.kind,
          /* isLeaving */
          true);

          if (fn) {
            var 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;
        }
      }
    }
  };
}
/**
 * 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, kind, isLeaving) {
  var kindVisitor = visitor[kind];

  if (kindVisitor) {
    if (!isLeaving && typeof kindVisitor === 'function') {
      // { Kind() {} }
      return kindVisitor;
    }

    var kindSpecificVisitor = isLeaving ? kindVisitor.leave : kindVisitor.enter;

    if (typeof kindSpecificVisitor === 'function') {
      // { Kind: { enter() {}, leave() {} } }
      return kindSpecificVisitor;
    }
  } else {
    var specificVisitor = isLeaving ? visitor.leave : visitor.enter;

    if (specificVisitor) {
      if (typeof specificVisitor === 'function') {
        // { enter() {}, leave() {} }
        return specificVisitor;
      }

      var specificKindVisitor = specificVisitor[kind];

      if (typeof specificKindVisitor === 'function') {
        // { enter: { Kind() {} }, leave: { Kind() {} } }
        return specificKindVisitor;
      }
    }
  }
}