graphqljs.node.txt

                                  ┏━━━━━━━━━━━━━━━┓
                                  ┃   GRAPHQLJS   ┃
                                  ┗━━━━━━━━━━━━━━━┛

VERSION ==>                       #0.10.1
                                  #Node.js server-side implementation of GraphQL
                                  #Only includes the bare minimum
                                  #Core:
                                  #  - performs operation according to spec
                                  #  - must:
                                  #     - provide definition as SCHEMA:
                                  #        - using either:
                                  #           - JavaScript (e.g. GraphQLInt)
                                  #           - 'DEFINITIONS' string
                                  #           - DOCUMENT_NODE
                                  #        - can be printed back to 'DEFINITIONS'
                                  #     - provide 'QUERY' (and VARIABLES, 'OPNAME'), which is lexed and parsed into
                                  #       plain object DOCUMENT_NODE (which includes AST_NODEs)
                                  #  - resolvers:
                                  #     - default one returns RPARENT.FIELD[(ARGS, CONTEXT, RESINFO)]
                                  #     - can provide ROOTVAL, CONTEXT
                                  #     - provides fourth argument RESINFO with extra info
                                  #  - lots of validation:
                                  #     - including anything that can be done before performing operation
                                  #     - can perform it manually
                                  #     - can validate against deprecation
                                  #  - can check if schema changes introduce breaking changes

                                  ┌────────────┐
                                  │   LEXING   │
                                  └────────────┘

new Source('QUERY'[, 'FILE'])     #'FILE' is for debugging (def: 'GraphQL')

getLocation(SOURCE, NUM)->OBJ     #Converts NUM of characters into OBJ: line NUM, column NUM
                                  #I.e. after taking into account newlines as formatting

lex(SOURCE)->LEXER                #
LEXER([NUM])->AST_TOKEN           #Returns next AST_TOKEN, or EOF if none
                                  #NUM is position to seek (def: next one)
AST_TOKEN.kind                    #Among Kind.*:
                                  #  - SOF|EOF (start|end)
                                  #  - BANG: !
                                  #  - DOLLAR: $
                                  #  - COLON: :
                                  #  - EQUALS: =
                                  #  - AT: @
                                  #  - PIPE: |
                                  #  - BRACKET_L|BRACKET_R: [ ]
                                  #  - BRACE_L|BRACE_R: { }
                                  #  - PAREN_L|PAREN_R: ( )
                                  #  - SPREAD: ...
                                  #  - COMMENT: #COMMENT
                                  #  - NAME: 'ATTR', etc.
                                  #  - INT|FLOAT|STRING
AST_TOKEN.value                   #STR
AST_TOKEN.start|end               #Position NUM (in characters)
AST_TOKEN.line|column             #NUM
AST_TOKEN.prev|next               #AST_TOKEN2|null

                                  ┌─────────────┐
                                  │   PARSING   │
                                  └─────────────┘

parse(STR|SOURCE[, POPTS])
 ->DOCUMENT_NODE
parseType(STR|SOURCE[, POPTS])
 ->TYPE_NODE
parse[Const]Value
 (STR|SOURCE[, POPTS])            #Internally creates LEXER
 ->VALUE_NODE                     #If "Const", do not allow $VARs

POPTS.maxTokens                   #Throws if more than NUM tokens

getOperationAST
 (DOCUMENT_NODE[, 'OPNAME'])
 ->OPERATION_DEFINITION_NODE      #

valueFromAST(VALUE_NODE,
 INPUT_TYPE[, VARIABLES])->VAL    #
astFromValue(VAL, INPUT_TYPE)
 ->VALUE_NODE                     #
typeFromAST
 (SCHEMA, TYPE_NODE)->TYPE        #

gql`QUERY`->DOCUMENT_NODE        ##Like parse('QUERY') except:
                                 ##  - memoized
                                 ##  - can use ${AST_NODE}
                                 ##  - remove AST_NODE.loc
                                 ##Package graphql-tag (1.2.4)
GRAPHQL-LOADER                   ##Loads 'QUERY' files as DOCUMENT_NODE, using gql`QUERY`
                                 ##QUERY can contain #import "FILE" to include another file (must contain top-level operation)
                                 ##Package graphql-tag (1.2.4)

                                  ┌───────────┐
                                  │   NODES   │
                                  └───────────┘

AST_NODE                          #Parsed node of a client operation
                                  #Any of following *_NODE
                                  #  - kind: CamelCase, e.g. OPERATION_DEFINITION_NODE has kind 'OperationDefinition'
                                  #  - loc (absent if POPTS.noLocation true)
                                  #     - start|end NUM
                                  #     - start|endToken AST_TOKEN
                                  #     - source SOURCE

NAME_NODE                         #OBJ: value STR

TYPE_NODE                         #Any of the following *_TYPE_NODE
NAMED_TYPE_NODE                   #OBJ: name NAME_NODE
LIST_TYPE_NODE                    #OBJ: type TYPE_NODE
NON_NULL_TYPE_NODE                #OBJ: type NAMED_TYPE_NODE|LIST_TYPE_NODE

VALUE_NODE                        #Any of the following *_VALUE_NODE or VARIABLE_NODE
VARIABLE_NODE                     #OBJ: name NAME_NODE
INT_VALUE_NODE                    #OBJ: value STR
FLOAT_VALUE_NODE                  #OBJ: value STR
STRING_VALUE_NODE                 #OBJ:
                                  #  - value STR
                                  #  - block BOOL
BOOLEAN_VALUE_NODE                #OBJ: value BOOL
NULL_VALUE_NODE                   #OBJ.
ENUM_VALUE_NODE                   #OBJ: value STR
LIST_VALUE_NODE                   #OBJ: values VALUE_NODE_ARR
OBJECT_VALUE_NODE                 #OBJ: fields OBJECT_FIELD_NODE_ARR
                                  #  - name NAME_NODE
                                  #  - value VALUE_NODE

CONST_VALUE|LIST|OBJECT[_FIELD]|
 DIRECTIVE|ARGUMENT_NODE          #Exclude VARIABLE_NODE

ARGUMENT_NODE                     #OBJ:
                                  #  - name NAME_NODE
                                  #  - value VALUE_NODE

INPUT_VALUE_DEFINITION_NODE_ARR   #OBJ:
                                  #  - name NAME_NODE
                                  #  - type TYPE_NODE
                                  #  - defaultValue VALUE_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - description STRING_VALUE_NODE

DIRECTIVE_NODE                    #OBJ:
                                  #  - name NAME_NODE
                                  #  - arguments ARGUMENT_NODE_ARR

DOCUMENT_NODE                     #OBJ: definitions OBJ_ARR, of either:
                                  #  (OPERATION_DEFINITION_NODE)
                                  #  (FRAGMENT_DEFINITION_NODE)
                                  #  (TYPE_SYSTEM_DEFINITION_NODE), of either
                                  #     (SCHEMA_DEFINITION_NODE)
                                  #     (TYPE_DEFINITION_NODE), of either
                                  #       (SCALAR_TYPE_DEFINITION_NODE)
                                  #       (OBJECT_TYPE_DEFINITION_NODE)
                                  #       (INTERFACE_TYPE_DEFINITION_NODE)
                                  #       (UNION_TYPE_DEFINITION_NODE)
                                  #       (ENUM_TYPE_DEFINITION_NODE)
                                  #       (INPUT_OBJECT_TYPE_DEFINITION_NODE)
                                  #    (DIRECTIVE_DEFINITION_NODE)
                                  #  (TYPE_EXTENSION_DEFINITION_NODE)

OPERATION_DEFINITION_NODE         #OBJ:
                                  #  - operation 'OPTYPE'
                                  #  - name NAME_NODE
                                  #  - variableDefinitions VARIABLE_DEFINITION_NODE_ARR
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - selectionSet SELECTION_SET_NODE

VARIABLE_DEFINITION_NODE          #OBJ:
                                  #  - variable VARIABLE_NODE
                                  #  - type TYPE_NODE
                                  #  - defaultValue VALUE_NODE
                                  #  - directives DIRECTIVE_NODE_ARR

SELECTION_SET_NODE                #OBJ: selections SELECTION_NODE_ARR, of either
                                  #  (FIELD_NODE)
                                  #  (FRAGMENT_SPREAD_NODE)
                                  #  (INLINE_FRAGMENT_NODE)

FIELD_NODE                        #OBJ:
                                  #  - alias NAME_NODE
                                  #  - name NAME_NODE
                                  #  - arguments ARGUMENT_NODE_ARR
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - selectionSet SELECTION_SET_NODE

FRAGMENT_SPREAD_NODE              #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR

INLINE_FRAGMENT_NODE              #OBJ:
                                  #  - typeCondition NAMED_TYPE_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - selectionSet SELECTION_SET_NODE

FRAGMENT_DEFINITION_NODE          #OBJ:
                                  #  - name NAME_NODE
                                  #  - typeCondition NAMED_TYPE_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - selectionSet SELECTION_SET_NODE

SCHEMA_DEFINITION_NODE            #OBJ:
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - operationTypes OPERATION_TYPE_DEFINITION_NODE_ARR
                                  #  - description STRING_VALUE_NODE

OPERATION_TYPE_DEFINITION_NODE    #OBJ:
                                  #  - operation 'OPTYPE'
                                  #  - type NAMED_TYPE_NODE

SCALAR_TYPE_DEFINITION_NODE       #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - description STRING_VALUE_NODE

OBJECT_TYPE_DEFINITION_NODE       #OBJ:
                                  #  - name NAME_NODE
                                  #  - interfaces NAMED_TYPE_NODE_ARR
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - fields FIELD_DEFINITION_NODE_ARR
                                  #  - description STRING_VALUE_NODE

FIELD_DEFINITION_NODE             #OBJ:
                                  #  - name NAME_NODE
                                  #  - arguments INPUT_VALUE_DEFINITION_NODE_ARR
                                  #  - type TYPE_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - description STRING_VALUE_NODE

INTERFACE_TYPE_DEFINITION_NODE    #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - fields FIELD_DEFINITION_NODE_ARR
                                  #  - interfaces NAMED_TYPE_NODE_ARR
                                  #  - description STRING_VALUE_NODE

UNION_TYPE_DEFINITION_NODE        #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - types NAMED_TYPE_NODE_ARR
                                  #  - description STRING_VALUE_NODE

ENUM_TYPE_DEFINITION_NODE         #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - values ENUM_VALUE_DEFINITION_NODE_ARR
                                  #  - description STRING_VALUE_NODE

ENUM_VALUE_DEFINITION_NODE        #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - description STRING_VALUE_NODE

INPUT_OBJECT_TYPE_DEFINITION_NODE #OBJ:
                                  #  - name NAME_NODE
                                  #  - directives DIRECTIVE_NODE_ARR
                                  #  - fields INPUT_VALUE_DEFINITION_NODE_ARR
                                  #  - description STRING_VALUE_NODE

DIRECTIVE_DEFINITION_NODE         #OBJ:
                                  #  - name NAME_NODE
                                  #  - arguments INPUT_VALUE_DEFINITION_NODE_ARR
                                  #  - locations NAME_NODE_ARR
                                  #  - repeatable BOOL
                                  #  - description STRING_VALUE_NODE

isNode(VAL)->BOOL                 #

                                  ┌────────────────┐
                                  │   DEFINITION   │
                                  └────────────────┘

TYPE                              #Parsed node of a server operations definitions
TYPE.name                         #'TYPE'.
                                  #Not with GraphQLList|GraphQLNonNull
TYPE.toString|toJSON()->STR       #Returns TYPE.name, with also ! [] for GraphQLList|GraphQLNonNull
TYPE.description                  #STR
                                  #Not with GraphQLList|GraphQLNonNull
TYPE.ofType                       #TYPE2
                                  #Only with GraphQLList|GraphQLNonNull

new GraphQL*(...)                 #Create new TYPEs, not TYPE instances
                                  #E.g. GraphQLInt is not constructor
                                  #If argument is OPTS, always have:
                                  #  - name STR
                                  #  - description STR

new GraphQLList(TYPE)             #ARR modifier
getNamedType(TYPE)->TYPE2         #Removes NonNull|ARR modifiers, if present

new GraphQLNonNull(TYPE)          #NonNull (!) modifier
getNullableType(TYPE)->TYPE2      #Removes NonNull modifier, if present

new GraphQLScalarType(OPTS)       #SCALARTYPE. Constructor is used for custom ones
                                  #OPTS:
                                  #  - name STR
                                  #  - description STR (def: none)
                                  #  - specifiedByUrl STR (def: none): documentation URL
                                  #  (server -> client)
                                  #  - serialize(VAL)->STR (def: identity)
                                  #  (client -> server)
                                  #  - parseLiteral(VALUE_NODE[, OBJ])->VAL
                                  #     - OBJ are variables
                                  #     - def:
                                  #        - use VALUE_NODE.value transtyped to STR|NUM|BOOL
                                  #        - deeply for ARR|OBJ
                                  #        - replace $VAR
                                  #        - then call parseValue()
                                  #  - parseValue(VAL)->VAL
                                  #     - def: identity
                                  #     - called after parseLiteral()
                                  #VAL is of any type
                                  #Should throw TypeError if wrong input
GraphQLInt                        #INT TYPE
GraphQLFloat                      #FLOAT TYPE
GraphQLString                     #STR TYPE
GraphQLBoolean                    #BOOL TYPE
GraphQLID                         #ID TYPE

GraphQLJSON                      ##'JSON' [non-]OBJ|ARR TYPE
GraphQLJSONObject                ##'JSON' OBJ|ARR TYPE
                                 ##Package graphql-type-json (version 0.3.2)

PACKAGE ==>                      ##Package graphql-iso-date (version 3.6.1)
GraphQLDate                      ##Serialized as 'YYYY-MM-DD' (ISO-8601), parsed as DATE
GraphQLTime                      ##Same for 'HH:MM:SSZ' (ISO-8601), parsed as DATE
GraphQLDateTime                  ##Same for 'YYYY-MM-DDTHH:MM:SSZ' (ISO-8601), parsed as DATE

PACKAGE ==>                      ##Package graphql-custom-types (version 1.7.0)
GraphQLDateTime                  ##Of type string, validating using Date.parse()
GraphQLEmail                     ##Of type string, using regexp validation
                                 ##Checks:
                                 ##  - characters are not among <>()[\]\.,;:\s@\", unless surrounded by "..." (username only)
                                 ##  - @ in middle
                                 ##  - possible subdomains
                                 ##  - TLD with min 2 characters
GraphQLURL                       ##Of type string, using regexp validation
                                 ##Only for HTTP[S] and FTP
GraphQLUUID                      ##Of type string, using regexp validation. Any UUID version, i.e. just check AAAAAAAA-BBBB-CDDD-EEFF-GGGGGGGGGGGG with hexs
new GraphQLLimitedString         ##Of type string. Must:
(MIN[, MAX][, 'ALPHABET'])       ##  - have length between MIN and MAX (inclusive)
                                 ##  - only contains characters from 'ALPHABET'
new GraphQLPassword              ##Same but must also contain at least:
(MIN[, MAX][, 'ALPHABET'][,OPTS])##  - one number and one letter, if OPTS.alphaNumeric true
                                 ##  - one uppercase and one lowercase letter, if OPTS.mixedCase true
                                 ##  - one non-alphanumeric, if OPTS.specialChars true
Factory.getRegexScalar(OPTS)     ##Creates SCALARTYPE of type string, using OPTS:
                                 ##  - name, description
                                 ##  - regex REGEXP: for validation
                                 ##  - error 'ERROR' (def: 'Query error: NAME'): message from the GraphQLError exception thrown on validation
Factory.getCustomScalar          ##Creates SCALARTYPE using:
 ('NAME', 'DESCRIPTION',         ##  - serialize(): identity
 FUNC(AST_NODE)->VAL)            ##  - parseLiteral: FUNC
 ->SCALARTYPE                    ##  - parseValue: FUNC({ kind: Kind.STRING, value: VAL })

new GraphQLEnumType(OPTS)         #OPTS.values.ENUM_VAL:
                                  #  - value ENUM_INTERNAL_NUM
                                  #  - description STR
                                  #  - deprecationReason STR

new GraphQLObjectType(OPTS)       #OPTS:
                                  #  - fields[()].FIELD:
                                  #     - type OUTPUTTYPE
                                  #     - args.ARG:
                                  #        - type INPUTTYPE
                                  #        - defaultValue VAL
                                  #        - description STR
                                  #     - resolve(RPARENT, ARGS, CONTEXT, RESINFO)->[PROMISE_]RATTR
                                  #        - resolve function
                                 ##        - can validate all resolvers are defined, using GraphQL-tools (see its doc)
                                  #     - subscribe(RPARENT, ARGS, CONTEXT, RESINFO)->SPAYLOAD_ASYNC_ITERABLE: subscribe function
                                  #     - description STR
                                  #     - deprecationReason STR
                                  #  - interfaces[()] INTERFACETYPE_ARR
                                  #  - isTypeOf(VAL, RESINFO)->[PROMISE_]BOOL:
                                  #     - VAL is RESOLVER return value
                                  #     - def: VAL.__typename === 'TYPE'

new GraphQLInputObjectType(OPTS)  #OPTS.fields[()].FIELD:
                                  #  - type INPUTTYPE
                                  #  - defaultValue VAL
                                  #  - description STR

new GraphQLInterfaceType(OPTS)    #OPTS:
                                  #  - fields: like OBJTYPE
                                  #  - resolveType(VAL, RESINFO)->OBJTYPE
                                  #     - used to determine which child type to pick
                                  #     - def: call each defined OBJTYPE.isTypeOf()

new GraphQLUnionType(OPTS)        #OPTS:
                                  #  - types OBJTYPE_ARR[()]
                                  #  - resolveType: like INTERFACETYPE

new GraphQLDirective(OPTS)        #OPTS:
                                  #  - locations ARR: among DirectiveLocation.*
                                  #  - args.ARG:
                                  #     - type INPUTTYPE
                                  #     - description STR
                                  #     - defaultValue VAL
                                  #  - isRepeatable BOOL (def: false)
GraphQLInclude|SkipDirective      #Possible locations: FIELD, FRAGMENT_SPREAD, INLINE_FRAGMENT
GraphQLDeprecatedDirective        #Possible locations: FIELD_DEFINITION, ENUM_VALUE
GraphQLSpecifiedByDirective       #Possible locations: SCALAR
GraphQLDeferDirective             #Possible locations: FRAGMENT_SPREAD, INLINE_FRAGMENT
GraphQLStreamDirective            #Possible locations: FIELD

new GraphQLSchema(OPTS)           #OPTS:
                                  #  - query|mutation|subscription OBJTYPE
                                  #  - types NAMEDTYPE_ARR:
                                  #     - all possible types, used by introspection __schema.types
                                  #     - def: guessed by going through schema
                                  #     - useful to specify when SCHEMA uses INTERFACE|UNIONs, i.e. subtypes might be missing
                                  #       from definition, but usable by clients
                                  #  - directives DIRECTIVE_ARR
specifiedDirectives               #Def value of GraphQLSchema OPTS.directives.
                                  #Includes: @include|skip|deprecated|specifiedBy
                                  #To add new ones (such as @defer|@stream), must be passed together with specifiedDirectives
                                  #to new GraphQLSchema() OPTS.directives

__Schema|__Type|__Directive|
__Field|__InputValue|__EnumValue|
__TypeKind|__Directive|           #
__DirectiveLocation               #OBJTYPE, related to introspection, with default resolvers

isLeafType(VAL)->BOOL             #GraphQLScalarType + GraphQLEnumType
isAbstractType(VAL)->BOOL         #GraphQLInterfaceType + GraphQLUnionType
isCompositeType(VAL)->BOOL        #AbstractType + GraphQLObjectType
isInputType(VAL)->BOOL            #Any type except CompositeType
isOutputType(VAL)->BOOL           #Any type except GraphQLInputObjectType
isNamedType(VAL)->BOOL            #Any type except GraphQLNonNull|GraphQLList
isType(VAL)->BOOL                 #Any type

assert*Type(VAL)                  #Throws unless is*Type(VAL)
isEqualType(TYPE, TYPE2)->BOOL    #Recursively

                                  ┌───────────┐
                                  │   BUILD   │
                                  └───────────┘

buildSchema('DEFINITIONS')        #Shortcut.
 ->SCHEMA                         #Instead of using new GraphQL*Type(...), let graphql.js create them by parsing 'DEFINITIONS' or DOCUMENT_NODE
buildASTSchema(DOCUMENT_NODE)     #Will also add:
 ->SCHEMA                         #  - comments before anything -> description
                                  #  - @deprecated REASON -> deprecationReason
                                  #Problem:
                                  #  - does not add resolvers
                                  #  - does not add resolveType|isTypeOf(), so cannot use interface|union
                                  #  - does not add serialize|parseValue|parseLiteral(), so cannot use custom scalars
                                 ##  - GraphQL-tools fixes all this (see its doc)

extendSchema(SCHEMA,DOCUMENT_NODE)#Proper way to add new definitions (DOCUMENT_NODE) to existing SCHEMA
 ->SCHEMA                         #Also the only way to use "extend type ..." definitions (GraphQL-tools fixes all this (see its doc))

                                  ┌────────────────┐
                                  │   VALIDATION   │
                                  └────────────────┘

validate(SCHEMA, DOCUMENT_NODE)   #Validates query (not against deprecation)
 ->GRAPHQLERROR_ARR|null          #Using spec-defined validation rules, also available one by one if necessary (see source)

findDeprecatedUsages
(SCHEMA, DOCUMENT_NODE)
->GRAPHQL_ERROR_ARR               #Validates against deprecation

assertValidName('TYPE'[, BOOL])   #Used internally to check against all names, including 'TYPE', 'ATTR', 'ENUM_VAL', 'DIRECTIVE', 'ARG', etc:
                                  #  - check regexp /^[_a-zA-Z][_a-zA-Z0-9]*$/
                                  #  - check does not start with __, unless BOOL true
                                  #     - can ignore error with OPTS.isIntrospection true for OBJTYPE|ENUMTYPE
                                  #  - throws exception if error
isValidJSValue(VAL, TYPE)->BOOL   #From server to client
isValidLiteralValue
(TYPE, VALUE_NODE)->BOOL          #From client to server

                                  ┌───────────────┐
                                  │   EXECUTION   │
                                  └───────────────┘

graphqlSync(OBJ)->RES_OBJ2        #Same as:
                                  #  validateSchema(OBJ.schema)
                                  #  DOCUMENT_NODE = parse(OBJ.source)
                                  #  validate(OBJ.schema, DOCUMENT_NODE)
                                  #  return execute({ document: DOCUMENT_NODE, ...OBJ })
                                  #Returns { errors } if validate*() fails
graphql(OBJ)->PROMISE_RES_OBJ2    #Same but OBJ.fieldResolver can return a PROMISE

execute(OBJ)->PROMISE_RES_OBJ2    #Perform query against a schema.
                                  #OBJ:
                                  #  - schema SCHEMA
                                  #  - document DOCUMENT_NODE
                                  #  - contextValue CONTEXT: request-wide object passed to resolvers. Can be anything
                                  #  - variableValues OBJ3: list of $VAR values
                                  #  - rootValue ROOTVAL
                                  #  - operationName 'OPNAME': if query contains several possible
                                  #  - fieldResolver FUNC: default value for OBJTYPE.FIELD.resolve(...)
                                  #  - subscribeFieldResolver FUNC: default value for OBJTYPE.FIELD.subscribe(...)
                                  #Can throw GraphQLError if something wrong in query
RES_OBJ                           #OBJ2: data OBJ|null[, errors OBJ_ARR][, extensions OBJ]
                                  #Use OBJTYPE.FIELD.resolve(...) if defined
                                  #Otherwise, use TYPE.serialize(VAL)

RESINFO                           #OBJ:
                                  #  - schema SCHEMA
                                  #  - rootValue ROOTVAL
                                  #  - variableValues VARIABLES: after coercion
                                  #  - operation OPERATION_DEFINITION_NODE: from DOCUMENT_NODE + 'OPNAME'
                                  #  - fragments.FRAGMENT FRAGMENT_DEFINITION_NODE: from DOCUMENT_NODE
                                  #  - fieldName 'ATTR'
                                  #  - fieldNodes FIELD_NODE_ARR (siblings, including itself)
                                  #  - returnType OUTPUTTYPE (field's type)
                                  #  - parentType COMPOSITETYPE (parent field's type)
                                  #  - path null|OBJ: prev PATH, key NUM|'VAR', typename 'OPTYPE'

                                  ┌────────────┐
                                  │   STREAM   │
                                  └────────────┘

experimentalExecuteIncrementally  #Like execute(OBJ), except can use @defer|@stream
 (OBJ)->PROMISE_OBJ2              #Must add them to new GraphQLSchema() OPTS.directives
                                  #OBJ2 is either:
                                  #  - if @defer|@stream:
                                  #     - initialResult RES_OBJ
                                  #     - subsequentResults RES_OBJ_ASYNC_ITERABLETOR
                                  #  - otherwise: RES_OBJ

                                  ┌───────────────┐
                                  │   SUBSCRIBE   │
                                  └───────────────┘

subscribe(OBJ)->PROMISE_VAL       #Like execute() but for subscriptions.
                                  #Return VAL is:
                                  #  - success: RES_OBJ_ASYNC_ITERABLE
                                  #     - iterate over OBJ_TYPE.subscribe()->SPAYLOAD_ASYNC_ITERABLE
                                  #     - then call execute(...) with SPAYLOAD as ROOTVAL
                                  #  - error: RES_OBJ
                                  #Does not implement the networking part, i.e.:
                                  #  - responding to initial subscription request
                                  #  - creating long-lived connection (like WebSocket) and pushing responses to it
createSourceEventStream(OBJ)
 ->PROMISE_VAL                    #Same except does not call execute(...), i.e. return SPAYLOAD instead of RES_OBJ

                                  ┌────────────┐
                                  │   ERRORS   │
                                  └────────────┘

ERRORS ==>                        #On exceptions inside resolvers: ouputs in return value "errors" field, as GraphQLError
                                  #On everything else: throws error
                                 ##Can use GraphQL-tools (see its doc) to use custom function

GraphQLError                      #Every exception|error is of that type, including the ones below
                                  #OBJ:
                                  #  - message STR
                                  #  - stack STR
                                  #  - originalError ERROR
                                  #  - locations OBJ_ARR: line|column
                                  #  - path 'VAR'|NUM_ARR
                                  #  - nodes AST_NODE_ARR
                                  #  - source SOURCE
                                  #  - positions NUM_ARR
syntaxError                       #On parsing|lexing
locatedError                      #During resolvers

                                  ┌───────────────────┐
                                  │   INTROSPECTION   │
                                  └───────────────────┘

getIntrospectionQuery([OPTS])     #Returns 'query IntrospectionQuery { __schema { ... } }'
 ->'QUERY'                        #All __schema fields except:
                                  #  - queryType|mutationType|subscriptionType: name only
                                  #  - mentioned below
                                  #OPTS (all BOOL with default false):
                                  #  - schemaDescription: include __schema.description
                                  #  - directiveIsRepeatable: include __schema.directives.isRepeatable
                                  #  - specifiedByUrl: include __schema.types.specifiedByUrl
                                  #  - inputValueDeprecation: `includeDeprecated: true`
                                  #     - exception: always true with __schema.types.fields|enumValues

introspectionFromSchema           #Call executeSync() with getIntrospectionQuery(OPTS)
 (SCHEMA[, OPTS])->OBJ            #OPTS all with default true instead

                                  ┌─────────────┐
                                  │   VISITOR   │
                                  └─────────────┘

visit(AST_NODE, OPTS[, MAP])      #Iterates over AST_NODE and descendants
 ->AST_NODE2                      #OPTS visitor function return values can modify|skip part of the tree, returning new AST_NODE2
                                  #OPTS:
                                  #  - enter|leave[.KIND](AST_NODE, KEY, PARENT_AST_NODE, PATH, ANCESTORS_AST_NODE_ARR)
                                  #     - KIND is NODE.kind (def: any)
                                  #     - KEY is NUM (if iterating over ARR) or 'VAR' (if iterating over OBJ)
                                  #     - PATH is KEY_ARR, including ancestors
                                  #     - enter|leave is when starting|stopping to iterate over the AST_NODE and its descendants
                                  #     - can return:
                                  #        - undefined: no action
                                  #        - VAL: replace node by VAL
                                  #        - null: erase node
                                  #        - false: skips visiting current node, but keep it
                                  #        - BREAK: skips visiting any node
                                  #  - KIND[.enter|leave](...): same (def: enter)
                                  #MAP:
                                  #  - define which attribute each node has
                                  #  - only need to specify if adding custom AST_NODEs
                                  #  - default one is QueryDocumentKeys
                                  #  - key is KIND
                                  #  - value is 'ATTR'_ARR:
                                  #     - attributes to iterate over, in each AST_NODE
                                  #     - e.g. for 'Directive', ['name', 'value']

visitInParallel(OPTS_ARR)->OPTS   #Return OPTS that applies several OPTs
visitWithTypeInfo(OBJ, OPTS)
 ->OPTS                           #Returns OPTS that also fires OBJ.enter|leave(AST_NODE), for debugging

                                  ┌───────────────────┐
                                  │   SERIALIZATION   │
                                  └───────────────────┘

print(AST_NODE)->STR              #Serialize AST_NODE to graphQL query format

print[Introspection]Schema        #Serialize SCHEMA into graphQL query format, underlyingly using print(...)
 (SCHEMA)->STR                    #Automatically sorts
                                  #Includes:
                                  #  - no "Introspection": not @DIRECTIVE nor builtin scalar types nor introspection types
                                  #  - "Introspection": only introspection types

printType(TYPE)-STR               #

printLocation(AST_NODE.loc)->STR  #

                                  ┌───────────────┐
                                  │   MIGRATION   │
                                  └───────────────┘

findBreakingChanges               #Returns possible breaking changes from one schema to another
(OLD_SCHEMA, NEW_SCHEMA)->OBJ_ARR #OBJ:
                                  #  - type STR
                                  #  - description STR
                                  #Possible:
                                  #  - 'TYPE|ARG_REMOVED[_FROM_UNION|ENUM]'
                                  #  - 'TYPE|FIELD|ARG_CHANGED_KIND'
findDangerousChanges(...)         #Same but for non-breaking changes but still dangerous:
                                  #  - 'ARG_DEFAULT_VALUE_CHANGE'