graphql
Version:
A Query Language and Runtime which can target any service.
300 lines (273 loc) • 8.2 kB
JavaScript
/**
* Copyright (c) 2015, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
;
var _slicedToArray = require('babel-runtime/helpers/sliced-to-array')['default'];
var _Object$defineProperty = require('babel-runtime/core-js/object/define-property')['default'];
_Object$defineProperty(exports, '__esModule', {
value: true
});
exports.visit = visit;
exports.getVisitFn = getVisitFn;
var VisitorKeys = {
Name: [],
Document: ['definitions'],
OperationDefinition: ['name', 'variableDefinitions', 'directives', 'selectionSet'],
VariableDefinition: ['variable', 'type', 'defaultValue'],
Variable: ['name'],
SelectionSet: ['selections'],
Field: ['alias', 'name', 'arguments', 'directives', 'selectionSet'],
Argument: ['name', 'value'],
FragmentSpread: ['name', 'directives'],
InlineFragment: ['typeCondition', 'directives', 'selectionSet'],
FragmentDefinition: ['name', 'typeCondition', 'directives', 'selectionSet'],
IntValue: [],
FloatValue: [],
StringValue: [],
BooleanValue: [],
EnumValue: [],
ArrayValue: ['values'],
ObjectValue: ['fields'],
ObjectField: ['name', 'value'],
Directive: ['name', 'value'],
ListType: ['type'],
NonNullType: ['type']
};
exports.VisitorKeys = VisitorKeys;
var BREAK = {};
exports.BREAK = BREAK;
/**
* visit() will walk through an AST using a depth first traversal, calling
* the visitor's enter function at each node in the traveral, and calling the
* leave function after visiting that node and all of it's 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.
*
* var 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
* // 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
* }
* }
* })
*/
function visit(root, visitor) {
var visitorKeys = visitor.keys || VisitorKeys;
var stack;
var inArray = Array.isArray(root);
var keys = [root];
var index = -1;
var edits = [];
var parent;
var path = [];
var ancestors = [];
var newRoot = root;
do {
index++;
var isLeaving = index === keys.length;
var key;
var node;
var isEdited = isLeaving && edits.length !== 0;
if (isLeaving) {
key = ancestors.length === 0 ? undefined : path.pop();
node = parent;
parent = ancestors.pop();
if (isEdited) {
if (inArray) {
node = node.slice();
} else {
var clone = {};
for (var k in node) {
if (node.hasOwnProperty(k)) {
clone[k] = node[k];
}
}
node = clone;
}
var editOffset = 0;
for (var ii = 0; ii < edits.length; ii++) {
var _edits$ii = _slicedToArray(edits[ii], 2);
var editKey = _edits$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 = undefined;
if (!Array.isArray(node)) {
if (!isNode(node)) {
throw new Error('Invalid AST Node: ' + JSON.stringify(node));
}
var visitFn = getVisitFn(visitor, isLeaving, node.kind);
if (visitFn) {
result = visitFn.call(visitor, node, key, parent, path, ancestors);
if (result === BREAK) {
break;
}
if (!isLeaving && result === false) {
path.pop();
continue;
}
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) {
stack = { inArray: inArray, index: index, keys: keys, edits: 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[0][1];
}
return newRoot;
}
function isNode(maybeNode) {
return maybeNode && typeof maybeNode.kind === 'string';
}
function getVisitFn(visitor, isLeaving, kind) {
if (!visitor) {
return;
}
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;
}
return;
}
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;
}
}
}