feat: add stake program methods; refactor instruction type handling

web3.js/src/instruction.js

@@ -0,0 +1,27 @@
+// @flow
+
+import * as BufferLayout from 'buffer-layout';
+
+import * as Layout from './layout';
+
+/**
+ * @typedef {Object} InstructionType
+ * @property (index} The Instruction index (from solana upstream program)
+ * @property (BufferLayout} The BufferLayout to use to build data
+ */
+export type InstructionType = {|
+  index: number,
+  layout: typeof BufferLayout,
+|};
+
+/**
+ * Populate a buffer of instruction data using an InstructionType
+ */
+export function encodeData(type: InstructionType, fields: Object): Buffer {
+  const allocLength =
+    type.layout.span >= 0 ? type.layout.span : Layout.getAlloc(type, fields);
+  const data = Buffer.alloc(allocLength);
+  const layoutFields = Object.assign({instruction: type.index}, fields);
+  type.layout.encode(layoutFields, data);
+  return data;
+}