Merge pull request #189 from allanjoseph98/rolechar

add `RoleChar` type
niklasf · Dec 14, 2024 · edd0823 · edd0823
2 parents bd1449c + 70bfa4e
commit edd0823
Show file tree

Hide file tree

Showing 3 changed files with 11 additions and 3 deletions.
diff --git a/src/fen.ts b/src/fen.ts
@@ -227,7 +227,7 @@ export const parsePiece = (str: string): Piece | undefined => {
 };
 
 export const makePiece = (piece: Piece): string => {
-  let r = roleToChar(piece.role);
+  let r: string = roleToChar(piece.role);
   if (piece.color === 'white') r = r.toUpperCase();
   if (piece.promoted) r += '~';
   return r;

diff --git a/src/types.ts b/src/types.ts
@@ -10,6 +10,12 @@ export type Square = number;
 
 export type SquareName = `${FileName}${RankName}`;
 
+export const ROLE_CHARS = ['q', 'n', 'r', 'b', 'p', 'k'] as const;
+
+export type LowerCaseRoleChar = (typeof ROLE_CHARS)[number];
+
+export type RoleChar = LowerCaseRoleChar | Uppercase<LowerCaseRoleChar>;
+
 /**
  * Indexable by square indices.
  */

diff --git a/src/util.ts b/src/util.ts
@@ -4,9 +4,11 @@ import {
   FILE_NAMES,
   isDrop,
   isNormal,
+  type LowerCaseRoleChar,
   Move,
   RANK_NAMES,
   Role,
+  type RoleChar,
   Square,
   SquareName,
 } from './types.js';
@@ -22,7 +24,7 @@ export const squareFile = (square: Square): number => square & 0x7;
 export const squareFromCoords = (file: number, rank: number): Square | undefined =>
   0 <= file && file < 8 && 0 <= rank && rank < 8 ? file + 8 * rank : undefined;
 
-export const roleToChar = (role: Role): string => {
+export const roleToChar = (role: Role): LowerCaseRoleChar => {
   switch (role) {
     case 'pawn':
       return 'p';
@@ -39,7 +41,7 @@ export const roleToChar = (role: Role): string => {
   }
 };
 
-export function charToRole(ch: 'p' | 'n' | 'b' | 'r' | 'q' | 'k' | 'P' | 'N' | 'B' | 'R' | 'Q' | 'K'): Role;
+export function charToRole(ch: RoleChar): Role;
 export function charToRole(ch: string): Role | undefined;
 export function charToRole(ch: string): Role | undefined {
   switch (ch.toLowerCase()) {