fix parsing of range-like expressions

Author: ColinEberhardt

assembly/__tests__/range-quantifiers.spec.ts

@@ -25,3 +25,11 @@ it("handles quantifiers within alternates", () => {
   expectMatch("a{2}|b{2}", ["bb", "aa"]);
   expectNotMatch("a{2}|b{2}", ["cc"]);
 });
+
+it("handles imcomplete quantifier ", () => {
+  expectMatch("a{2", ["a{2"]);
+  expectMatch("a{2,", ["a{2,"]);
+  expectMatch("a{2,3", ["a{2,3"]);
+  expectMatch("a{2,3a", ["a{2,3a"]);
+  expectMatch("a{2,3a}", ["a{2,3a}"]);
+});

assembly/parser/parser.ts

@@ -136,7 +136,7 @@ export class Parser {
     return new CharacterNode(this.eatToken());
   }
 
-  private maybeParseRepetitionRange(): Range {
+  private maybeParseRepetitionRange(): Range | null {
     // snapshot
     const iteratorCopy = this.iterator.copy();
     this.eatToken(Char.LeftCurlyBrace);
@@ -191,7 +191,7 @@ export class Parser {
     // repetition not found - reset state
     this.iterator = iteratorCopy;
 
-    return range;
+    return null;
   }
 
   // parses a sequence of chars
@@ -213,12 +213,12 @@ export class Parser {
         // @ts-ignore
       } else if (token == Char.LeftCurlyBrace) {
         const range = this.maybeParseRepetitionRange();
-        if (range.from == -1) {
-          // this is not the start of a repetition, it's just a char!
-          nodes.push(this.parseCharacter());
-        } else {
+        if (range != null) {
           const expression = nodes.pop();
           nodes.push(new RangeRepetitionNode(expression, range.from, range.to));
+        } else {
+          // this is not the start of a repetition, it's just a char!
+          nodes.push(this.parseCharacter());
         }
       } else if (isQuantifier(token)) {
         const expression = nodes.pop();

package.json

@@ -6,8 +6,8 @@
   "scripts": {
     "test": "npm run test:generate && npm run asbuild:untouched && npm run prettier && npm run eslint && npm run asp",
     "test:generate": "node spec/test-generator.js",
-    "asp": "asp --verbose",
-    "asp:ci": "asp",
+    "asp": "asp --verbose --nologo",
+    "asp:ci": "asp --nologo",
     "prettier": "prettier --check .",
     "prettier:write": "prettier --write .",
     "eslint:write": "npm run eslint -- --fix ",

ts/index.ts

@@ -5,7 +5,7 @@ globalAny.log = console.log;
 
 import { RegExp } from "../assembly/regexp";
 
-const regexObj = new RegExp("((a)(b)c)(d)");
-const match = regexObj.exec("abcd");
+const regexObj = new RegExp("a{3,");
+const match = regexObj.exec("a{3,");
 
 console.log(match);