[WIP] Implement save, load, over, infile, outfile, on, lipsum, help + start implementing undo, redo, exit, edit

src/vm/commands/load.ts

@@ -1,5 +1,10 @@
-import {Command, ParseContext, StrTerm} from "./command.js";
+import {Command, ParseContext, processPath, StrTerm} from "./command.js";
 import {LexInput} from "../lexer.js";
+import {StrVM} from "../vm.js";
+import {Awaitable} from "../../util/types.js";
+import os from "node:os";
+import fs from "node:fs/promises";
+import {isSaveData} from "./save.js";
 
 export class Load extends Command<{ path?: StrTerm }> {
     isParseCandidate(token: LexInput): boolean {
@@ -13,4 +18,23 @@ export class Load extends Command<{ path?: StrTerm }> {
     getDisplayName(): string {
         return 'load'
     }
+
+    execute(vm: StrVM, data: { path?: StrTerm }): Awaitable<StrVM> {
+        return vm.replaceContextMatchingTerm(ctx => ({
+            override: async () => {
+                const path = processPath(
+                    data.path
+                        ? ctx.resolveString(data.path)
+                        : `~/.str.json`)
+
+                const content = await fs.readFile(path, 'utf8')
+                const saveData = JSON.parse(content)
+                if ( !isSaveData(saveData) ) {
+                    throw new Error('Cannot load: invalid save data')
+                }
+
+                return saveData.subject
+            }
+        }))
+    }
 }