feat(Struct)

src/ConstString.js

@@ -0,0 +1,33 @@
+import { memcpy } from "./mem"
+import { Type } from "./Type"
+
+export function ConstString(size) {
+  const obj = { _size: size }
+  Object.setPrototypeOf(obj, ConstString.prototype)
+  obj.new(ConstString, arguments)
+  return obj
+}
+ConstString.prototype.serialize = function(dv, src) {
+  const encoder = new TextEncoder('utf-8')
+  const encoded = new DataView(encoder.encode(src).buffer, 0, this._size)
+
+  if (dv.byteLength < encoded.byteLength) {
+    throw new Error('too small buffer')
+  }
+
+  memcpy(dv, encoded)
+  return
+}
+ConstString.prototype.parse = function(dv) {
+  const frame = new DataView(dv.buffer, dv.byteOffset, this._size)
+  const decoder = new TextDecoder('utf-8')
+  return decoder.decode(frame)
+}
+ConstString.prototype.isHeadless = function() {
+  return false
+}
+ConstString.prototype.sizeof = function() {
+  return this._size
+}
+Object.setPrototypeOf(ConstString.prototype, Type.prototype)
+Object.freeze(ConstString.prototype)