// @flow
// @module SyntaxTree
import { typeOf } from './types'
import { print, parse } from 'graphql'
// Shorthand for the key storing the internal AST
// @prop
const AST_KEY = Symbol.for('Internal AST Storage Key');
/**
* A parser and processor of GraphQL IDL Abstract Syntax Trees. Used to combine
* a set of {@link GQLBase} class instances.
*
* @class SyntaxTree
*/
export class SyntaxTree
{
/**
* Constructs a new `SyntaxTree` object. If a string schema is supplied or
* an already parsed AST object, either of which is valid GraphQL IDL, then
* its parsed AST will be the internals of this object.
*
* @instance
* @memberof SyntaxTree
* @method ⎆⠀constructor
*
* @param {string|Object|SyntaxTree} schemaOrASTOrST if supplied the tree
* will be constructed with the contents of the data. If a string of IDL is
* given, it will be parsed. If an AST is given, it will be verified. If a
* SyntaxTree is supplied, it will be copied.
*/
constructor(schemaOrASTOrST: string | Object | SyntaxTree | undefined) {
this[Symbol.toStringTag] = this.constructor.name;
this[AST_KEY] = {};
if (schemaOrASTOrST) {
this.setAST(schemaOrASTOrST);
}
}
/**
* Getter that retrieves the abstract syntax tree created by `graphql.parse`
* when it is presented with a valid string of IDL.
*
* @instance
* @memberof SyntaxTree
* @method ⬇︎⠀ast
*
* @return {Object} a GraphQL AST object
*/
get ast(): Object {
return this[AST_KEY];
}
/**
* Setter that assigns the abstract syntax tree, typically created by
* `graphql.parse` when given a valid string of IDL.
*
* @instance
* @memberof SyntaxTree
* @method ⬆︎⠀ast
*
* @param {Object} value a valid AST object. Other operations will act
* in an undefined manner should this object not be a valid AST
*/
set ast(value: Object): void {
this[AST_KEY] = value;
}
/**
* Sets the underlying AST object with either schema which will be parsed
* into a valid AST or an existing AST. Previous ast values will be erased.
*
* @instance
* @memberof SyntaxTree
* @method ⌾⠀setAST
*
* @param {string|Object} schemaOrAST a valid GraphQL IDL schema or a
* previosuly parsed or compatible GraphQL IDL AST object.
* @return {SyntaxTree} this for inlining.
*/
setAST(schemaOrASTOrST: string|Object|SyntaxTree): SyntaxTree {
this[AST_KEY] = {};
const type = typeOf(schemaOrASTOrST);
let schema;
let ast;
let st;
switch (type) {
case String.name:
try {
ast = parse(schemaOrASTOrST);
Object.assign(this.ast, ast);
}
catch (ignore) { /* Ignore this error */ }
break;
case Object.name:
ast = schemaOrASTOrST;
try {
ast = parse(print(ast));
Object.assign(this.ast, ast);
}
catch (ignore) { /* Ignore this error */ }
break;
case SyntaxTree.name:
st = schemaOrASTOrST;
Object.assign(this.ast, st.ast);
break;
}
return this;
}
/**
* As passthru update method that works on the internal AST object. If
* an error occurs, the update is skipped. An error can occur if adding the
* changes would make the AST invalid. In such a case, the error is logged
* to the error console.
*
* @instance
* @memberof SyntaxTree
* @method ⌾⠀updateAST
*
* @param {Object} ast an existing GraphQL IDL AST object that will be
* merged on top of the existing tree using Object.assign()
* @return {SyntaxTree} this for inlining.
*/
updateAST(ast: Object): SyntaxTree {
if (typeOf(ast) === Object.name) {
let newAST = Object.assign({}, this.ast, ast);
try {
print(newAST);
this.ast = Object.assign(this.ast, ast);
}
catch (error) {
console.error('[SyntaxTree] Failed to updateAST with %o', ast);
console.error('Resulting object would be %o', newAST);
console.error(error.message);
console.error(error.stack);
}
}
return this;
}
/**
* Appends all definitions from another AST to this one. The method will
* actually create a copy using SyntaxTree.from() so the input types can
* be any one of a valid GraphQL IDL schema string, a GraphQL IDL AST or
* another SyntaxTree object instance.
*
* Definitions of the same name but different kinds will be replaced by the
* new copy. Those of the same kind and name will be merged (TODO handle more
* than ObjectTypeDefinition kinds when merging; currently other types are
* overwritten).
*
* @instance
* @memberof SyntaxTree
* @method ⌾⠀appendDefinitions
*
* @param {string|Object|SyntaxTree} schemaOrASTOrST an instance of one of
* the valid types for SyntaxTree.from() that can be used to create or
* duplicate the source from which to copy definitions.
* @return {SyntaxTree} this for inlining
*/
appendDefinitions(schemaOrASTOrST: string | Object | SyntaxTree): SyntaxTree {
const source = SyntaxTree.from(schemaOrASTOrST);
const set = new Set();
this.ast.definitions.map((definition) => {
set.add(definition.name.value);
})
if (source && source.ast.definitions && this.ast.definitions) {
for (let theirs of source) {
let name = theirs.name.value;
let ours = this.find(name);
let index = ours && this.ast.definitions.indexOf(ours) || -1;
// We don't yet have one with that name
if (!set.has(name)) {
set.add(name);
this.ast.definitions.push(theirs);
}
// We do have one with that name
else {
// The kinds aren't the same, just replace theirs with ours
if (theirs.kind !== ours.kind) {
// replace with the new one
this.ast.definitions[index] = theirs;
}
// The kinds are the same, lets just merge their fields
else {
// merge the properties of the same types.
switch (theirs.kind) {
case 'ObjectTypeDefinition':
ours.interfaces = [].concat(ours.interfaces, theirs.interfaces)
ours.directives = [].concat(ours.directives, theirs.directives)
ours.fields = [].concat(ours.fields, theirs.fields)
break;
default:
// Since we don't support other types yet. Let's replace
this.ast.definitions[index] = theirs;
break;
}
}
}
}
}
return this;
}
/**
* This method finds the Query type definitions in the supplied AST or
* SyntaxTree objects, takes its defined fields and adds it to the current
* instances. If this instance does not have a Query type defined but the
* supplied object does, then the supplied one is moved over. If neither
* has a query handler, then nothing happens.
*
* NOTE this *removes* the Query type definition from the supplied AST or
* SyntaxTree object.
*
* @instance
* @memberof SyntaxTree
* @method ⌾⠀consumeDefinition
*
* @param {Object|SyntaxTree} astOrSyntaxTree a valid GraphQL IDL AST or
* an instance of SyntaxTree that represents one.
* @param {string|RegExp} definitionType a valid search input as would be
* accepted for the #find() method of this object.
* @return {SyntaxTree} returns this for inlining
*/
consumeDefinition(
astOrSyntaxTree: Object | SyntaxTree,
definitionType: string | RegExp = "Query"
): SyntaxTree {
if (!astOrSyntaxTree || !this.ast || !this.ast.definitions) { return this }
const tree = typeOf(SyntaxTree) === SyntaxTree.name
? astOrSyntaxTree
: SyntaxTree.from(astOrSyntaxTree);
let left = this.find(definitionType);
let right = tree.find(definitionType);
if (!right) { return this }
if (!left) {
console.log('Here')
console.log('Before', this.ast.definitions)
this.ast.definitions.push(right);
console.log('After', this.ast.definitions)
// Remove the copied definition from the source
tree.ast.definitions.splice(tree.ast.definitions.indexOf(right), 1);
return this;
}
// TODO support other types aside from ObjectTypeDefinitions
// TODO see if there is a better way to achieve this with built-in
// graphql code someplace
switch(left.kind) {
case 'ObjectTypeDefinition':
if (left.interfaces && right.interfaces) {
left.interfaces = [].concat(left.interfaces, right.interfaces);
}
if (left.directives && right.directives) {
left.directives = [].concat(left.directives, right.directives);
}
if (left.fields && right.fields) {
console.log('Left fields before', left.fields);
console.log('Right fields', right.fields);
left.fields = [].concat(left.fields, right.fields);
console.log('Left fields after', left.fields);
}
break;
default:
break;
}
// Remove the copied definition from the source
tree.ast.definitions.splice(tree.ast.definitions.indexOf(right), 1);
return this;
}
/**
* When iterating over an instance of SyntaxTree, you are actually
* iterating over the definitions of the SyntaxTree if there are any;
*
* @instance
* @memberof SyntaxTree
* @method *[Symbol.iterator]
*/
*[Symbol.iterator](): any {
if (this[AST_KEY].definitions) {
return yield* this[AST_KEY].definitions;
}
else {
return yield* this;
}
}
/**
* Iterate through the definitions of the AST if there are any. For each
* definition the name property's value field is compared to the supplied
* definitionName. The definitionName can be a string or a regular
* expression if finer granularity is desired.
*
* @instance
* @memberof SyntaxTree
* @method ⌾⠀find
*
* @param {string|RegExp} definitionName a string or regular expression used
* to match against the definition name field in a given AST.
* @return {Object|null} a reference to the internal definition field or
* null if one with a matching name could not be found.
*/
find(definitionName: string|RegExp): Object | null {
const isRegExp = /RegExp/.test(typeOf(definitionName));
const regex = !isRegExp
? new RegExp(RegExp.escape(definitionName.toString()))
: definitionName;
const flags = regex.flags;
const source = regex.source;
const reducer = (last,cur,i) => {
if (last !== -1) return last;
return new RegExp(source, flags).test(cur.name.value) ? i : -1
}
const index = this[AST_KEY].definitions.reduce(reducer, -1);
return (~index) ? this[AST_KEY].definitions[index] : null;
}
/**
* SyntaxTree instances that are toString()'ed will have the graphql method
* print() called on them to convert their internal structures back to a
* GraphQL IDL schema syntax. If the object is in an invalid state, it WILL
* throw an error.
*
* @instance
* @memberof SyntaxTree
* @method ⌾⠀toString
*
* @return {string} the AST for the tree parsed back into a string
*/
toString(): string {
return print(this[AST_KEY]);
}
/**
* A runtime constant denoting a query type.
*
* @type {string}
* @static
* @memberof SyntaxTree
* @method ⬇︎⠀QUERY
* @readonly
* @const
*/
static get QUERY(): string { return 'Query' }
/**
* A runtime constant denoting a mutation type.
*
* @type {string}
* @static
* @memberof SyntaxTree
* @method ⬇︎⠀MUTATION
* @readonly
* @const
*/
static get MUTATION(): string { return 'Mutation' }
/**
* Ensures that the object type reported by Object.prototype.toString()
* for SyntaxTree objects returns as [object SyntaxTree]. Used by
* {@link utils#typeOf}
*
* @type {string}
* @static
* @memberof SyntaxTree
* @method ⬇︎⠀QUERY
* @readonly
* @const
*/
static get [Symbol.toStringTag](): string { return SyntaxTree.name; }
/**
* Given one of, a valid GraphQL IDL schema string, a valid GraphQL AST or
* an instance of SyntaxTree, the static from() method will create a new
* instance of the SyntaxTree with the values you provide.
*
* @static
* @memberof SyntaxTree
* @method ⌾⠀from
*
* @param {String|Object|SyntaxTree} mixed an instance of one of the valid
* types specified above. Everything else will result in a null value.
* @return {SyntaxTree} a newly created and populated instance of SyntaxTree
* or null if an invalid type was supplied for mixed.
*/
static from(mixed: string | Object | SyntaxTree): SyntaxTree | null {
let schema;
let ast;
switch (typeOf(mixed)) {
case String.name:
schema = mixed;
try { parse(schema) } catch(error) { console.log(error); return null; }
return SyntaxTree.fromSchema(schema);
case Object.name:
ast = mixed;
try { print(ast) } catch(error) { return null; }
return SyntaxTree.fromAST(ast);
case SyntaxTree.name:
schema = mixed.toString();
return SyntaxTree.from(schema);
default:
return null;
}
}
/**
* Generates a new instance of SyntaxTree from the supplied, valid, GraphQL
* schema. This method does not perform try/catch validation and if an
* invalid GraphQL schema is supplied an error will be thrown.
*
* @static
* @memberof SyntaxTree
* @method ⌾⠀fromSchema
*
* @param {string} schema a valid GraphQL IDL schema string.
* @return {SyntaxTree} a new instance of SyntaxTree initialized with a
* parsed response from require('graphql').parse().
*/
static fromSchema(schema: string): SyntaxTree {
const ast = parse(schema);
let tree = new SyntaxTree(ast);
return tree;
}
/**
* Generates a new instance of SyntaxTree from the supplied, valid, GraphQL
* schema. This method does not perform try/catch validation and if an
* invalid GraphQL schema is supplied an error will be thrown.
*
* @static
* @memberof SyntaxTree
* @method ⌾⠀fromAST
*
* @param {object} ast a valid GraphQL AST object.
* @return {SyntaxTree} a new instance of SyntaxTree initialized with a
* supplied abstract syntax tree generated by require('graphql').parse() or
* other compatible method.
*/
static fromAST(ast: Object): SyntaxTree | null {
const source = parse(print(ast));
let tree = new SyntaxTree(source);
return source ? tree : null;
}
/**
* Query types in GraphQL are an ObjectTypeDefinition of importance for
* placement on the root object. There is utility in creating an empty
* one that can be injected with the fields of other GraphQL object query
* entries.
*
* @static
* @memberof SyntaxTree
* @method ⌾⠀EmptyQuery
*
* @return {SyntaxTree} an instance of SyntaxTree with a base AST generated
* by parsing the graph query, "type Query {}"
*/
static EmptyQuery(): SyntaxTree {
return SyntaxTree.from(`type ${this.QUERY} {}`);
}
/**
* Mutation types in GraphQL are an ObjectTypeDefinition of importance for
* placement on the root object. There is utility in creating an empty
* one that can be injected with the fields of other GraphQL object mutation
* entries.
*
* @static
* @memberof SyntaxTree
* @method ⌾⠀EmptyMutation
*
* @return {SyntaxTree} an instance of SyntaxTree with a base AST generated
* by parsing the graph query, "type Mutation {}"
*/
static EmptyMutation(): SyntaxTree {
return SyntaxTree.from(`type ${this.MUTATION} {}`);
}
/**
* The starting point for a SyntaxTree that will be built up programmatically.
*
* @static
* @memberof SyntaxTree
* @method ⌾⠀EmptyDocument
*
* @param {string|Object|SyntaxTree} schemaOrASTOrST any valid type taken by
* SyntaxTree.from() used to further populate the new empty document
* @return {SyntaxTree} an instance of SyntaxTree with no definitions and a
* kind set to 'Document'
*/
static EmptyDocument(
schemaOrASTOrST: string | Object | SyntaxTree | undefined
): SyntaxTree {
let tree = new SyntaxTree();
// Due to normal validation methods with ASTs (i.e. converting to string
// and then back to an AST object), doing this with an empty document
// fails. Therefore, we manually set the document contents here. This allows
// toString(), consumeDefinition() and similar methods to still work.
tree.ast = {
kind: 'Document',
definitions: [],
loc: {start: 0, end: 0}
};
if (schemaOrASTOrST) {
tree.appendDefinitions(schemaOrASTOrST);
}
return tree;
}
}
export default SyntaxTree;
// repl testing
// require('./bootstrap'); let typeOf = require('./lib/utils').typeOf, GQL=require('graphql'), ST = require('./lib/GraphQL/SyntaxTree').SyntaxTree, schema = `input MessageInput { content: String author: String } type Message { id: ID! content: String author: String } type Query { getMessage(id: ID!): Message } type Mutation { createMessage(input: MessageInput): Message updateMessage(id: ID!, input: MessageInput): Message }`, ast = GQL.parse(schema), st = ST.fromSchema(schema), query = ST.EmptyQuery(), mutation = ST.EmptyMutation()