re-do of description support

uses blockstrings2 re-do and matches closer to canonical js approach. cleaned up test names.  update tests.

Author: haikusw

Sources/GraphQL/Language/AST.swift

@@ -57,7 +57,6 @@ final public class Token {
         case string = "String"
         case blockstring = "BlockString"
         case comment = "Comment"
-        case description = "Description"    // string in a description position
 
         public var description: String {
             return rawValue
@@ -134,19 +133,6 @@ extension Token : CustomStringConvertible {
     }
 }
 
-extension Token {
-    convenience init(from token: Token, as kind: Kind ) {
-        self.init(kind: kind,
-                  start: token.start,
-                  end: token.end,
-                  line: token.line,
-                  column: token.column,
-                  value: token.value,
-                  prev: token.prev,
-                  next: token.next)
-    }
-}
-
 public enum NodeResult {
     case node(Node)
     case array([Node])
@@ -825,16 +811,18 @@ public final class StringValue {
     public let kind: Kind = .stringValue
     public let loc: Location?
     public let value: String
+    public let block: Bool?
 
-    init(loc: Location? = nil, value: String) {
+    init(loc: Location? = nil, value: String, block: Bool? = nil) {
         self.loc = loc
         self.value = value
+        self.block = block
     }
 }
 
 extension StringValue : Equatable {
     public static func == (lhs: StringValue, rhs: StringValue) -> Bool {
-        return lhs.value == rhs.value
+        return lhs.value == rhs.value && lhs.block == rhs.block
     }
 }
 
@@ -1090,11 +1078,11 @@ public func == (lhs: TypeSystemDefinition, rhs: TypeSystemDefinition) -> Bool {
 public final class SchemaDefinition {
     public let kind: Kind = .schemaDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let directives: [Directive]
     public let operationTypes: [OperationTypeDefinition]
 
-    init(loc: Location? = nil, description: String? = nil, directives: [Directive], operationTypes: [OperationTypeDefinition]) {
+    init(loc: Location? = nil, description: StringValue? = nil, directives: [Directive], operationTypes: [OperationTypeDefinition]) {
         self.loc = loc
         self.description = description
         self.directives = directives
@@ -1174,11 +1162,11 @@ public func == (lhs: TypeDefinition, rhs: TypeDefinition) -> Bool {
 public final class ScalarTypeDefinition {
     public let kind: Kind = .scalarTypeDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let directives: [Directive]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, directives: [Directive] = []) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, directives: [Directive] = []) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1197,13 +1185,13 @@ extension ScalarTypeDefinition : Equatable {
 public final class ObjectTypeDefinition {
     public let kind: Kind = .objectTypeDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let interfaces: [NamedType]
     public let directives: [Directive]
     public let fields: [FieldDefinition]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, interfaces: [NamedType] = [], directives: [Directive] = [], fields: [FieldDefinition] = []) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, interfaces: [NamedType] = [], directives: [Directive] = [], fields: [FieldDefinition] = []) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1226,13 +1214,13 @@ extension ObjectTypeDefinition : Equatable {
 public final class FieldDefinition {
     public let kind: Kind = .fieldDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let arguments: [InputValueDefinition]
     public let type: Type
     public let directives: [Directive]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, arguments: [InputValueDefinition] = [], type: Type, directives: [Directive] = []) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, arguments: [InputValueDefinition] = [], type: Type, directives: [Directive] = []) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1255,13 +1243,13 @@ extension FieldDefinition : Equatable {
 public final class InputValueDefinition {
     public let kind: Kind = .inputValueDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let type: Type
     public let defaultValue: Value?
     public let directives: [Directive]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, type: Type, defaultValue: Value? = nil, directives: [Directive] = []) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, type: Type, defaultValue: Value? = nil, directives: [Directive] = []) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1300,15 +1288,15 @@ extension InputValueDefinition : Equatable {
 public final class InterfaceTypeDefinition {
     public let kind: Kind = .interfaceTypeDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let interfaces: [NamedType]
     public let directives: [Directive]
     public let fields: [FieldDefinition]
 
     init(
         loc: Location? = nil,
-        description: String? = nil,
+        description: StringValue? = nil,
         name: Name,
         interfaces: [NamedType] = [],
         directives: [Directive] = [],
@@ -1335,12 +1323,12 @@ extension InterfaceTypeDefinition : Equatable {
 public final class UnionTypeDefinition {
     public let kind: Kind = .unionTypeDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let directives: [Directive]
     public let types: [NamedType]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, directives: [Directive] = [], types: [NamedType]) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, directives: [Directive] = [], types: [NamedType]) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1361,12 +1349,12 @@ extension UnionTypeDefinition : Equatable {
 public final class EnumTypeDefinition {
     public let kind: Kind = .enumTypeDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let directives: [Directive]
     public let values: [EnumValueDefinition]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, directives: [Directive] = [], values: [EnumValueDefinition]) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, directives: [Directive] = [], values: [EnumValueDefinition]) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1387,11 +1375,11 @@ extension EnumTypeDefinition : Equatable {
 public final class EnumValueDefinition {
     public let kind: Kind = .enumValueDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let directives: [Directive]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, directives: [Directive] = []) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, directives: [Directive] = []) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1410,12 +1398,12 @@ extension EnumValueDefinition : Equatable {
 public final class InputObjectTypeDefinition {
     public let kind: Kind = .inputObjectTypeDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let directives: [Directive]
     public let fields: [InputValueDefinition]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, directives: [Directive] = [], fields: [InputValueDefinition]) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, directives: [Directive] = [], fields: [InputValueDefinition]) {
         self.loc = loc
         self.description = description
         self.name = name
@@ -1453,12 +1441,12 @@ extension TypeExtensionDefinition : Equatable {
 public final class DirectiveDefinition {
     public let kind: Kind = .directiveDefinition
     public let loc: Location?
-    public let description: String?
+    public let description: StringValue?
     public let name: Name
     public let arguments: [InputValueDefinition]
     public let locations: [Name]
 
-    init(loc: Location? = nil, description: String? = nil, name: Name, arguments: [InputValueDefinition] = [], locations: [Name]) {
+    init(loc: Location? = nil, description: StringValue? = nil, name: Name, arguments: [InputValueDefinition] = [], locations: [Name]) {
         self.loc = loc
         self.name = name
         self.description = description

Sources/GraphQL/Language/Lexer.swift

@@ -91,6 +91,33 @@ final class Lexer {
     func advance() throws -> Token {
         return try advanceFunction(self)
     }
+    
+    /**
+     * Looks ahead and returns the next non-ignored token, but does not change
+     * the state of Lexer.
+     */
+    func lookahead() throws -> Token {
+        var startToken = token
+        let savedLine = self.line
+        let savedLineStart = self.lineStart
+        
+        guard startToken.kind != .eof else { return startToken }
+        repeat {
+            startToken = try startToken.next ??
+                {
+                    startToken.next = try readToken(lexer: self, prev: startToken)
+                    return startToken.next!
+                }()
+        } while startToken.kind == .comment
+        
+        // restore these since both `positionAfterWhitespace` & `readBlockString`
+        // can potentially modify them and commment for `lookahead` says no lexer modification.
+        // (the latter is true in the canonical js lexer also and is likely a bug)
+        self.line = savedLine
+        self.lineStart = savedLineStart
+        
+        return startToken
+    }
 }
 
 /**