Create 'TokenKindEnum' type.

Author: IvanGoncharov

src/index.js

@@ -248,6 +248,7 @@ export type {
   ObjectTypeExtensionNode,
   DirectiveDefinitionNode,
   KindEnum,
+  TokenKindEnum,
   DirectiveLocationEnum,
 } from './language';
 

src/language/ast.js

@@ -8,6 +8,7 @@
  */
 
 import type { Source } from './source';
+import type { TokenKindEnum } from './lexer';
 
 /**
  * Contains a range of UTF-8 character offsets and token references that
@@ -40,35 +41,6 @@ export type Location = {
   +source: Source,
 };
 
-/**
- * Represents the different kinds of tokens in a GraphQL document.
- * This type is not inlined in `Token` to fix syntax highlighting on GitHub
- * *only*.
- */
-type TokenKind =
-  | '<SOF>'
-  | '<EOF>'
-  | '!'
-  | '$'
-  | '&'
-  | '('
-  | ')'
-  | '...'
-  | ':'
-  | '='
-  | '@'
-  | '['
-  | ']'
-  | '{'
-  | '|'
-  | '}'
-  | 'Name'
-  | 'Int'
-  | 'Float'
-  | 'String'
-  | 'BlockString'
-  | 'Comment';
-
 /**
  * Represents a range of characters represented by a lexical token
  * within a Source.
@@ -77,7 +49,7 @@ export type Token = {
   /**
    * The kind of Token.
    */
-  +kind: TokenKind,
+  +kind: TokenKindEnum,
 
   /**
    * The character offset at which this Node begins.

src/language/directiveLocation.js

@@ -10,7 +10,7 @@
 /**
  * The set of allowed directive location values.
  */
-export const DirectiveLocation = {
+export const DirectiveLocation = Object.freeze({
   // Request Definitions
   QUERY: 'QUERY',
   MUTATION: 'MUTATION',
@@ -31,9 +31,9 @@ export const DirectiveLocation = {
   ENUM_VALUE: 'ENUM_VALUE',
   INPUT_OBJECT: 'INPUT_OBJECT',
   INPUT_FIELD_DEFINITION: 'INPUT_FIELD_DEFINITION',
-};
+});
 
 /**
  * The enum type representing the directive location values.
  */
-export type DirectiveLocationEnum = $Keys<typeof DirectiveLocation>;
+export type DirectiveLocationEnum = $Values<typeof DirectiveLocation>;

src/language/index.js

@@ -24,7 +24,7 @@ export {
 } from './visitor';
 export type { ASTVisitor, Visitor, VisitFn, VisitorKeyMap } from './visitor';
 
-export type { Lexer } from './lexer';
+export type { Lexer, TokenKindEnum } from './lexer';
 export type { ParseOptions } from './parser';
 
 export type {

src/language/lexer.js

@@ -24,7 +24,7 @@ export function createLexer<TOptions>(
   source: Source,
   options: TOptions,
 ): Lexer<TOptions> {
-  const startOfFileToken = new Tok(SOF, 0, 0, 0, 0, null);
+  const startOfFileToken = new Tok(TokenKind.SOF, 0, 0, 0, 0, null);
   const lexer: Lexer<TOptions> = {
     source,
     options,
@@ -46,11 +46,11 @@ function advanceLexer() {
 
 function lookahead() {
   let token = this.token;
-  if (token.kind !== EOF) {
+  if (token.kind !== TokenKind.EOF) {
     do {
       // Note: next is only mutable during parsing, so we cast to allow this.
       token = token.next || ((token: any).next = readToken(this, token));
-    } while (token.kind === COMMENT);
+    } while (token.kind === TokenKind.COMMENT);
   }
   return token;
 }
@@ -94,58 +94,39 @@ export type Lexer<TOptions> = {
   lookahead(): Token,
 };
 
-// Each kind of token.
-const SOF = '<SOF>';
-const EOF = '<EOF>';
-const BANG = '!';
-const DOLLAR = '$';
-const AMP = '&';
-const PAREN_L = '(';
-const PAREN_R = ')';
-const SPREAD = '...';
-const COLON = ':';
-const EQUALS = '=';
-const AT = '@';
-const BRACKET_L = '[';
-const BRACKET_R = ']';
-const BRACE_L = '{';
-const PIPE = '|';
-const BRACE_R = '}';
-const NAME = 'Name';
-const INT = 'Int';
-const FLOAT = 'Float';
-const STRING = 'String';
-const BLOCK_STRING = 'BlockString';
-const COMMENT = 'Comment';
-
 /**
  * An exported enum describing the different kinds of tokens that the
  * lexer emits.
  */
-export const TokenKind = {
-  SOF,
-  EOF,
-  BANG,
-  DOLLAR,
-  AMP,
-  PAREN_L,
-  PAREN_R,
-  SPREAD,
-  COLON,
-  EQUALS,
-  AT,
-  BRACKET_L,
-  BRACKET_R,
-  BRACE_L,
-  PIPE,
-  BRACE_R,
-  NAME,
-  INT,
-  FLOAT,
-  STRING,
-  BLOCK_STRING,
-  COMMENT,
-};
+export const TokenKind = Object.freeze({
+  SOF: '<SOF>',
+  EOF: '<EOF>',
+  BANG: '!',
+  DOLLAR: '$',
+  AMP: '&',
+  PAREN_L: '(',
+  PAREN_R: ')',
+  SPREAD: '...',
+  COLON: ':',
+  EQUALS: '=',
+  AT: '@',
+  BRACKET_L: '[',
+  BRACKET_R: ']',
+  BRACE_L: '{',
+  PIPE: '|',
+  BRACE_R: '}',
+  NAME: 'Name',
+  INT: 'Int',
+  FLOAT: 'Float',
+  STRING: 'String',
+  BLOCK_STRING: 'BlockString',
+  COMMENT: 'Comment',
+});
+
+/**
+ * The enum type representing the token kinds values.
+ */
+export type TokenKindEnum = $Values<typeof TokenKind>;
 
 /**
  * A helper function to describe a token as a string for debugging
@@ -162,7 +143,7 @@ const slice = String.prototype.slice;
  * Helper function for constructing the Token object.
  */
 function Tok(
-  kind,
+  kind: TokenKindEnum,
   start: number,
   end: number,
   line: number,
@@ -194,7 +175,7 @@ function printCharCode(code) {
   return (
     // NaN/undefined represents access beyond the end of the file.
     isNaN(code)
-      ? EOF
+      ? TokenKind.EOF
       : // Trust JSON for ASCII.
         code < 0x007f
         ? JSON.stringify(String.fromCharCode(code))
@@ -220,7 +201,7 @@ function readToken(lexer: Lexer<*>, prev: Token): Token {
   const col = 1 + position - lexer.lineStart;
 
   if (position >= bodyLength) {
-    return new Tok(EOF, bodyLength, bodyLength, line, col, prev);
+    return new Tok(TokenKind.EOF, bodyLength, bodyLength, line, col, prev);
   }
 
   const code = charCodeAt.call(body, position);
@@ -234,58 +215,62 @@ function readToken(lexer: Lexer<*>, prev: Token): Token {
     );
   }
 
+  function literalTok(kind: TokenKindEnum) {
+    return new Tok(kind, position, position + kind.length, line, col, prev);
+  }
+
   switch (code) {
     // !
     case 33:
-      return new Tok(BANG, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.BANG);
     // #
     case 35:
       return readComment(source, position, line, col, prev);
     // $
     case 36:
-      return new Tok(DOLLAR, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.DOLLAR);
     // &
     case 38:
-      return new Tok(AMP, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.AMP);
     // (
     case 40:
-      return new Tok(PAREN_L, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.PAREN_L);
     // )
     case 41:
-      return new Tok(PAREN_R, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.PAREN_R);
     // .
     case 46:
       if (
         charCodeAt.call(body, position + 1) === 46 &&
         charCodeAt.call(body, position + 2) === 46
       ) {
-        return new Tok(SPREAD, position, position + 3, line, col, prev);
+        return literalTok(TokenKind.SPREAD);
       }
       break;
     // :
     case 58:
-      return new Tok(COLON, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.COLON);
     // =
     case 61:
-      return new Tok(EQUALS, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.EQUALS);
     // @
     case 64:
-      return new Tok(AT, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.AT);
     // [
     case 91:
-      return new Tok(BRACKET_L, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.BRACKET_L);
     // ]
     case 93:
-      return new Tok(BRACKET_R, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.BRACKET_R);
     // {
     case 123:
-      return new Tok(BRACE_L, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.BRACE_L);
     // |
     case 124:
-      return new Tok(PIPE, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.PIPE);
     // }
     case 125:
-      return new Tok(BRACE_R, position, position + 1, line, col, prev);
+      return literalTok(TokenKind.BRACE_R);
     // A-Z _ a-z
     case 65:
     case 66:
@@ -440,7 +425,7 @@ function readComment(source, start, line, col, prev): Token {
   );
 
   return new Tok(
-    COMMENT,
+    TokenKind.COMMENT,
     start,
     position,
     line,
@@ -505,7 +490,7 @@ function readNumber(source, start, firstCode, line, col, prev): Token {
   }
 
   return new Tok(
-    isFloat ? FLOAT : INT,
+    isFloat ? TokenKind.FLOAT : TokenKind.INT,
     start,
     position,
     line,
@@ -558,7 +543,15 @@ function readString(source, start, line, col, prev): Token {
     // Closing Quote (")
     if (code === 34) {
       value += slice.call(body, chunkStart, position);
-      return new Tok(STRING, start, position + 1, line, col, prev, value);
+      return new Tok(
+        TokenKind.STRING,
+        start,
+        position + 1,
+        line,
+        col,
+        prev,
+        value,
+      );
     }
 
     // SourceCharacter
@@ -659,7 +652,7 @@ function readBlockString(source, start, line, col, prev): Token {
     ) {
       rawValue += slice.call(body, chunkStart, position);
       return new Tok(
-        BLOCK_STRING,
+        TokenKind.BLOCK_STRING,
         start,
         position + 3,
         line,
@@ -756,7 +749,7 @@ function readName(source, position, line, col, prev): Token {
     ++end;
   }
   return new Tok(
-    NAME,
+    TokenKind.NAME,
     position,
     end,
     line,