Implement basic integer math operations

src/vm/commands/plus.ts

@@ -0,0 +1,29 @@
+import {Command, ParseContext, StrTerm} from "./command.js";
+import {LexInput} from "../lexer.js";
+import {StrVM} from "../vm.js";
+
+export type PlusData = {
+    val: StrTerm,
+}
+
+export class Plus extends Command<PlusData> {
+    async attemptParse(context: ParseContext): Promise<PlusData> {
+        return {
+            val: await context.popTerm(),
+        }
+    }
+
+    getDisplayName(): string {
+        return 'plus'
+    }
+
+    isParseCandidate(token: LexInput): boolean {
+        return this.isKeyword(token, 'plus')
+    }
+
+    async execute(vm: StrVM, data: PlusData): Promise<StrVM> {
+        return vm.replaceContextMatchingTerm(ctx => ({
+            int: sub => sub + ctx.resolveInt(data.val),
+        }))
+    }
+}