perf: introduce AST to avoid reparse

src/parser/parse-stream.ts

@@ -1,20 +1,21 @@
-import { Token } from '../parser/token'
+import { Token } from '../tokens/token'
 import { Template } from '../template/template'
-import { TagToken } from './tag-token'
+import { isTagToken } from '../util/type-guards'
+import { TopLevelToken } from '../tokens/toplevel-token'
 
-type ParseToken = ((token: Token, remainTokens: Token[]) => Template)
+type ParseToken<T extends Token> = ((token: T, remainTokens: T[]) => Template)
 
-export class ParseStream {
-  private tokens: Token[]
+export class ParseStream<T extends Token = TopLevelToken> {
+  private tokens: T[]
   private handlers: {[key: string]: (arg: any) => void} = {}
   private stopRequested = false
-  private parseToken: ParseToken
+  private parseToken: ParseToken<T>
 
-  public constructor (tokens: Token[], parseToken: ParseToken) {
+  public constructor (tokens: T[], parseToken: ParseToken<T>) {
     this.tokens = tokens
     this.parseToken = parseToken
   }
-  public on<T extends Template | Token | undefined> (name: string, cb: (arg: T) => void): ParseStream {
+  public on<T2 extends Template | T | undefined> (name: string, cb: (arg: T2) => void): ParseStream<T> {
     this.handlers[name] = cb
     return this
   }
@@ -24,10 +25,10 @@ export class ParseStream {
   }
   public start () {
     this.trigger('start')
-    let token: Token | undefined
+    let token: T | undefined
     while (!this.stopRequested && (token = this.tokens.shift())) {
       if (this.trigger('token', token)) continue
-      if (TagToken.is(token) && this.trigger(`tag:${token.name}`, token)) {
+      if (isTagToken(token) && this.trigger(`tag:${token.name}`, token)) {
         continue
       }
       const template = this.parseToken(token, this.tokens)