Start lipsum command

src/vm/commands/command.ts

@@ -1,10 +1,15 @@
 import {LexInput} from '../lexer.js'
-import {ExpectedEndOfInputError, InvalidVariableNameError, UnexpectedEndOfInputError} from "../parse.js";
+import {
+    ExpectedEndOfInputError,
+    InvalidVariableNameError,
+    IsNotKeywordError,
+    UnexpectedEndOfInputError
+} from "../parse.js";
 
 export type StrLVal = { term: 'variable', name: string }
 
 export type StrTerm =
-    { term: 'string', value: string }
+    { term: 'string', value: string, literal?: true }
     | StrLVal
 
 export class ParseContext {
@@ -25,7 +30,7 @@ export class ParseContext {
 
     popTerm(): StrTerm {
         if ( !this.inputs.length ) {
-            throw new UnexpectedEndOfInputError('Unexpected end of input. Expected term.');
+            throw new UnexpectedEndOfInputError('Unexpected end of input. Expected term.')
         }
 
         const input = this.inputs.shift()!
@@ -40,7 +45,19 @@ export class ParseContext {
         }
 
         // Otherwise, parse it as a string literal:
-        return { term: 'string', value: input.value }
+        return { term: 'string', value: input.value, literal: input.literal }
+    }
+
+    popKeywordInSet<T extends string[]>(options: T) {
+        if ( !this.inputs.length ) {
+            throw new UnexpectedEndOfInputError('Unexpected end of input. Expected one of: ' + options.join(', '))
+        }
+
+        const input = this.inputs.shift()!
+
+        if ( input.literal || !options.includes(input.value) ) {
+            throw new IsNotKeywordError('Unexpected term: ' + input.value + ' (expected one of: ' + options.join(', ') + ')')
+        }
     }
 
     popLVal(): StrLVal {

src/vm/commands/lipsum.ts

@@ -0,0 +1,18 @@
+import {Command, ParseContext, StrTerm} from './command.js'
+import {LexInput} from '../lexer.js'
+
+export class Lipsum extends Command<{ length: StrTerm }> {
+    attemptParse(context: ParseContext): { length: StrTerm } {
+        return {
+            length: context.popTerm(),
+        }
+    }
+
+    getDisplayName(): string {
+        return 'lipsum'
+    }
+
+    isParseCandidate(token: LexInput): boolean {
+        return this.isKeyword(token, 'lipsum')
+    }
+}