stage2 修复全局变量未完成的问题 提供错误处理解析

stage2/parser.spl

@@ -282,6 +282,7 @@ fn can_start_expr(kind: TokenKind): bool {
                 .For => { ret true; },
                 .Match => { ret true; },
                 .Comptime => { ret true; },
+                .Try => { ret true; },
                 _ => { ret false; },
             }
         },
@@ -321,6 +322,7 @@ fn can_start_statement(kind: TokenKind): bool {
                 .Break => { ret true; },
                 .Continue => { ret true; },
                 .Defer => { ret true; },
+                .Errdefer => { ret true; },
                 .Var => { ret true; },
                 .Const => { ret true; },
                 .Type => { ret true; },
@@ -1237,7 +1239,19 @@ fn parse_expr_prec(self: *Parser, min_prec: i32): usize {
 }
 
 fn parse_expr(self: *Parser): usize {
-    ret parse_expr_prec(self, 1);
+    var e = parse_expr_prec(self, 1);
+    // `expr catch <pattern> <block>`：catch 用解包语法绑定错误。
+    while !self.failed {
+        var t = peek(self);
+        if t == null { break; }
+        if !kind_is_keyword(t.kind, .Catch) { break; }
+        advance(self);
+        var pat = parse_pattern(self);
+        if pat == 0 { ret e; }
+        var handler = parse_block(self);
+        e = new_node(self, .ExprCatch(.{ .value = e, .pattern = pat, .handler = handler }), t);
+    }
+    ret e;
 }
 
 fn parse_cast(self: *Parser): usize {
@@ -1444,6 +1458,12 @@ fn parse_primary(self: *Parser): usize {
             if @enum2int(k) == @enum2int(Keyword.Loop) { ret parse_loop_expr(self); }
             if @enum2int(k) == @enum2int(Keyword.For) { ret parse_for_expr(self); }
             if @enum2int(k) == @enum2int(Keyword.Match) { ret parse_match_expr(self); }
+            // `try <expr>`：错误上抛前缀。
+            if @enum2int(k) == @enum2int(Keyword.Try) {
+                advance(self);
+                var tv = parse_expr(self);
+                ret new_node(self, .ExprTry(.{ .value = tv }), t);
+            }
             // `comptime <expr>`：编译期表达式（可调用普通函数、返回类型等）。
             if @enum2int(k) == @enum2int(Keyword.Comptime) {
                 advance(self);
@@ -1958,6 +1978,22 @@ fn parse_defer_stmt(self: *Parser): usize {
     ret new_node(self, .StatementDefer(.{ .body = body }), kw);
 }
 
+fn parse_errdefer_stmt(self: *Parser): usize {
+    var kw = peek(self);
+    if kw == null || !kind_is_keyword(kw.kind, .Errdefer) { ret 0; }
+    advance(self);
+    var body: usize = 0;
+    var t = peek(self);
+    if t != null && kind_is_punct(t.kind, .LBrace) { body = parse_block(self); }
+    else if t != null && can_start_statement(t.kind) { body = parse_statement(self); }
+    else {
+        body = parse_expr(self);
+        t = peek(self);
+        if t != null && kind_is_punct(t.kind, .Semicolon) { advance(self); }
+    }
+    ret new_node(self, .StatementErrdefer(.{ .body = body }), kw);
+}
+
 fn parse_comptime_stmt(self: *Parser): usize {
     var kw = peek(self);
     if kw == null || !kind_is_keyword(kw.kind, .Comptime) { ret 0; }
@@ -1979,6 +2015,7 @@ fn parse_statement(self: *Parser): usize {
             if @enum2int(k) == @enum2int(Keyword.Break) { ret parse_break_stmt(self); }
             if @enum2int(k) == @enum2int(Keyword.Continue) { ret parse_continue_stmt(self); }
             if @enum2int(k) == @enum2int(Keyword.Defer) { ret parse_defer_stmt(self); }
+            if @enum2int(k) == @enum2int(Keyword.Errdefer) { ret parse_errdefer_stmt(self); }
             if @enum2int(k) == @enum2int(Keyword.Comptime) { ret parse_comptime_stmt(self); }
             if @enum2int(k) == @enum2int(Keyword.Var) ||
                @enum2int(k) == @enum2int(Keyword.Const) ||