feat(struct): add missing int8 and int16 types

packages/struct/src/struct.ts

@@ -215,18 +215,18 @@ export default class Struct<
      * Merges (flats) another `Struct`'s fields and extra fields into this one.
      */
     public fields<TOther extends Struct<any, any, any, any>>(
-        struct: TOther
+        other: TOther
     ): Struct<
         TValue & TOther['valueType'],
         TInit & TOther['initType'],
         TExtra & TOther['extraType'],
         TPostDeserialized
     > {
-        for (const field of struct._fields) {
+        for (const field of other._fields) {
             this._fields.push(field);
         }
-        this._size += struct._size;
-        Object.assign(this._extra, struct._extra);
+        this._size += other._size;
+        Object.assign(this._extra, other._extra);
         return this as any;
     }
 
@@ -245,6 +245,23 @@ export default class Struct<
         );
     }
 
+    /**
+     * Appends an `int8` field to the `Struct`
+     */
+    public int8<
+        TName extends PropertyKey,
+        TTypeScriptType = (typeof NumberFieldType)['Uint8']['valueType']
+    >(
+        name: TName,
+        _typescriptType?: TTypeScriptType,
+    ) {
+        return this.number(
+            name,
+            NumberFieldType.Int8,
+            _typescriptType
+        );
+    }
+
     /**
      * Appends an `uint8` field to the `Struct`
      */
@@ -262,6 +279,23 @@ export default class Struct<
         );
     }
 
+    /**
+     * Appends an `int16` field to the `Struct`
+     */
+    public int16<
+        TName extends PropertyKey,
+        TTypeScriptType = (typeof NumberFieldType)['Uint16']['valueType']
+    >(
+        name: TName,
+        _typescriptType?: TTypeScriptType,
+    ) {
+        return this.number(
+            name,
+            NumberFieldType.Int16,
+            _typescriptType
+        );
+    }
+
     /**
      * Appends an `uint16` field to the `Struct`
      */
@@ -409,11 +443,14 @@ export default class Struct<
         };
 
     /**
-     * Adds some extra fields into every Struct instance.
+     * Adds some extra fields into every Struct value.
      *
      * Extra fields will not affect serialize or deserialize process.
      *
      * Multiple calls to `extra` will merge all values together.
+     *
+     * @param value
+     * An object containing anything you want to add to the result object. Accessors and methods are also allowed.
      */
     public extra<T extends Record<
         // This trick disallows any keys that are already in `TValue`

packages/struct/src/types/number.ts

@@ -7,8 +7,12 @@ export type DataViewSetters =
     { [TKey in keyof DataView]: TKey extends `set${string}` ? TKey : never }[keyof DataView];
 
 export class NumberFieldType<TTypeScriptType extends number | bigint = number | bigint> {
+    public static readonly Int8 = new NumberFieldType<number>(1, 'getInt8', 'setInt8');
+
     public static readonly Uint8 = new NumberFieldType<number>(1, 'getUint8', 'setUint8');
 
+    public static readonly Int16 = new NumberFieldType<number>(2, 'getInt16', 'setUint16');
+
     public static readonly Uint16 = new NumberFieldType<number>(2, 'getUint16', 'setUint16');
 
     public static readonly Int32 = new NumberFieldType<number>(4, 'getInt32', 'setInt32');

packages/struct/src/types/utils.ts

@@ -33,15 +33,15 @@ export type Overwrite<TBase extends object, TNew extends object> =
  */
 export type OmitNever<T> = Pick<T, { [K in keyof T]: [T[K]] extends [never] ? never : K }[keyof T]>;
 
-/**
- * Generates a type. Useful in generic type inference.
- */
-export function placeholder<T>(): T {
-    return undefined as unknown as T;
-}
-
 /**
  * Extract keys of fields in `T` that has type `TValue`
  */
 export type KeysOfType<T, TValue> =
     { [TKey in keyof T]: T[TKey] extends TValue ? TKey : never }[keyof T];
+
+/**
+ * Returns a (fake) value of the given type.
+ */
+export function placeholder<T>(): T {
+    return undefined as unknown as T;
+}