Add expect() & startOfWord() helpers to new parser

src/parser2.ts

@@ -22,15 +22,11 @@ export function parse(
   try {
     const parser = new Parser(code);
     const script = parser.parseScript();
-
-    // TODO: report error with error position
-
-    if (parser.lastIndex != code.length) {
-      return [false, "Couldn't parse full script"];
-    }
+    parser.expect("EOF");
 
     return [true, script];
   } catch (ex) {
+    // TODO: report error with error position
     return [false, String(ex)];
   }
 }
@@ -77,8 +73,12 @@ class WipScript {
   wordPos: number | undefined = undefined;
   // TODO: thing to fail {}a & ""a
 
+  startOfWord(): boolean {
+    return this.wipWord.length == 0;
+  }
+
   addWordPiece(piece: InterpolatedPiece, pos?: number) {
-    if (this.wipWord.length == 0) {
+    if (this.startOfWord()) {
       this.wordPos = pos;
     }
     this.wipWord.push(piece);
@@ -129,6 +129,14 @@ class Parser {
     return (this.next = ["ERROR", "Token not matched", startPos]);
   }
 
+  expect(type: TokenType) {
+    if (this.next[0] != type) {
+      throw new Error(
+        `Expected ${type}, found ${this.next[0]} (${this.next[1]})`
+      );
+    }
+  }
+
   parseScript(): Script {
     const wip = new WipScript();