stage2 大量优化代码使其自举编译时间大幅缩短

stage2/parser.spl

@@ -42,11 +42,8 @@ fn new(ast: *Ast, toks: Vec, diag: *Diag): Parser {
 // ---- token 访问 ----
 
 fn token_ptr(self: *Parser, index: usize): *Token {
-    match Vec.get(&self.toks, index) {
-        .Ok(ptr) => { ret ptr as *Token; },
-        .Err(error) => { ret null; },
-    }
-    ret null;
+    if index >= self.toks.len { ret null; }
+    ret (self.toks.data as *Token) + index;
 }
 
 fn is_trivia(kind: TokenKind): bool {
@@ -61,16 +58,17 @@ fn is_trivia(kind: TokenKind): bool {
 // 跳过 trivia；返回当前 token（含 EOF）。越界返回 null。
 fn peek(self: *Parser): *Token {
     var n = self.toks.len;
+    var base = self.toks.data as *Token;
     var i = self.pos;
     while i < n {
-        var t = token_ptr(self, i);
-        if t == null { break; }
+        if base == null { break; }
+        var t = base + i;
         if !is_trivia(t.kind) { break; }
         i = i + 1;
     }
     self.pos = i;
-    if i >= n { ret null; }
-    ret token_ptr(self, i);
+    if i >= n || base == null { ret null; }
+    ret base + i;
 }
 
 fn advance(self: *Parser): *Token {