perf: introduce AST to avoid reparse

src/tokens/range-token.ts

@@ -0,0 +1,16 @@
+import { Token } from './token'
+import { ValueToken } from './value-token'
+import { TokenKind } from '../parser/token-kind'
+
+export class RangeToken extends Token {
+  constructor (
+    public input: string,
+    public begin: number,
+    public end: number,
+    public lhs: ValueToken,
+    public rhs: ValueToken,
+    public file?: string
+  ) {
+    super(TokenKind.Range, input, begin, end, file)
+  }
+}