From aef83bae62d53de1c0e4957f7cb6ecda27d1dcf6 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@vlang.io>
Date: Fri, 18 Aug 2023 18:28:57 +0300
Subject: [PATCH] all: `@[attr]` syntax

---
 vlib/v/ast/attr.v             |  1 +
 vlib/v/fmt/attrs.v            |  6 ++++++
 vlib/v/parser/parser.v        | 28 +++++++++++++++++++++++-----
 vlib/v/parser/struct.v        |  2 +-
 vlib/v/scanner/scanner.v      |  4 ++++
 vlib/v/tests/enum_attr_test.v |  4 ++--
 6 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/vlib/v/ast/attr.v b/vlib/v/ast/attr.v
index 76a1e91634..dc55539075 100644
--- a/vlib/v/ast/attr.v
+++ b/vlib/v/ast/attr.v
@@ -23,6 +23,7 @@ pub:
 	kind    AttrKind
 	ct_opt  bool // true for [if user_defined_name?]
 	pos     token.Pos
+	has_at  bool // new syntax `@[attr]`
 pub mut:
 	ct_expr   Expr // .kind == comptime_define, for [if !name]
 	ct_evaled bool // whether ct_skip has been evaluated already
diff --git a/vlib/v/fmt/attrs.v b/vlib/v/fmt/attrs.v
index 9ea265ccc9..75c612e526 100644
--- a/vlib/v/fmt/attrs.v
+++ b/vlib/v/fmt/attrs.v
@@ -17,6 +17,9 @@ pub fn (mut f Fmt) attrs(attrs []ast.Attr) {
 			f.single_line_attrs(sorted_attrs[i..])
 			break
 		}
+		if attr.has_at {
+			f.write('@')
+		}
 		f.writeln('[${attr}]')
 	}
 }
@@ -35,6 +38,9 @@ pub fn (mut f Fmt) single_line_attrs(attrs []ast.Attr, options AttrsOptions) {
 	if options.inline {
 		f.write(' ')
 	}
+	if attrs[0].has_at {
+		f.write('@')
+	}
 	f.write('[')
 	for i, attr in sorted_attrs {
 		if i > 0 {
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index ba9f3616e5..13cdde633f 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -723,6 +723,14 @@ fn (mut p Parser) top_stmt() ast.Stmt {
 					}
 				}
 			}
+			.at {
+				if p.peek_tok.kind == .lsbr {
+					p.attributes()
+					continue
+				} else {
+					return p.error('@[attr] expected')
+				}
+			}
 			.lsbr {
 				// attrs are stored in `p.attrs`
 				p.attributes()
@@ -1769,11 +1777,20 @@ fn (mut p Parser) is_attributes() bool {
 
 // when is_top_stmt is true attrs are added to p.attrs
 fn (mut p Parser) attributes() {
-	p.check(.lsbr)
+	mut is_at := false
+	if p.tok.kind == .lsbr {
+		// [attr]
+		p.check(.lsbr)
+	} else if p.tok.kind == .at {
+		// @[attr]
+		p.check(.at)
+		p.check(.lsbr)
+		is_at = true
+	}
 	mut has_ctdefine := false
 	for p.tok.kind != .rsbr {
 		start_pos := p.tok.pos()
-		attr := p.parse_attr()
+		attr := p.parse_attr(is_at)
 		if p.attrs.contains(attr.name) && attr.name != 'wasm_export' {
 			p.error_with_pos('duplicate attribute `${attr.name}`', start_pos.extend(p.prev_tok.pos()))
 			return
@@ -1809,7 +1826,7 @@ fn (mut p Parser) attributes() {
 	}
 }
 
-fn (mut p Parser) parse_attr() ast.Attr {
+fn (mut p Parser) parse_attr(is_at bool) ast.Attr {
 	mut kind := ast.AttrKind.plain
 	apos := p.prev_tok.pos()
 	if p.tok.kind == .key_unsafe {
@@ -1882,6 +1899,7 @@ fn (mut p Parser) parse_attr() ast.Attr {
 		ct_expr: comptime_cond
 		ct_opt: comptime_cond_opt
 		pos: apos.extend(p.tok.pos())
+		has_at: is_at
 	}
 }
 
@@ -3431,7 +3449,7 @@ fn (mut p Parser) parse_number_literal() ast.Expr {
 fn (mut p Parser) module_decl() ast.Module {
 	mut module_attrs := []ast.Attr{}
 	mut attrs_pos := p.tok.pos()
-	for p.tok.kind == .lsbr {
+	for p.tok.kind == .lsbr || p.tok.kind == .at {
 		p.attributes()
 	}
 	module_attrs << p.attrs
@@ -3959,7 +3977,7 @@ fn (mut p Parser) enum_decl() ast.EnumDecl {
 			uses_exprs = true
 		}
 		mut attrs := []ast.Attr{}
-		if p.tok.kind == .lsbr {
+		if p.tok.kind == .lsbr || p.tok.kind == .at {
 			p.attributes()
 			attrs << p.attrs
 			enum_attrs[val] = attrs
diff --git a/vlib/v/parser/struct.v b/vlib/v/parser/struct.v
index 41336a74e5..caead54cad 100644
--- a/vlib/v/parser/struct.v
+++ b/vlib/v/parser/struct.v
@@ -269,7 +269,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 			// Comments after type (same line)
 			prev_attrs := p.attrs
 			p.attrs = []
-			if p.tok.kind == .lsbr {
+			if p.tok.kind == .lsbr || p.tok.kind == .at {
 				p.inside_struct_attr_decl = true
 				// attrs are stored in `p.attrs`
 				p.attributes()
diff --git a/vlib/v/scanner/scanner.v b/vlib/v/scanner/scanner.v
index cc880f129a..c429731e66 100644
--- a/vlib/v/scanner/scanner.v
+++ b/vlib/v/scanner/scanner.v
@@ -886,6 +886,10 @@ fn (mut s Scanner) text_scan() token.Token {
 				return s.new_token(.comma, '', 1)
 			}
 			`@` {
+				// @[attr]
+				if s.text[s.pos + 1] == `[` {
+					return s.new_token(.at, '', 1)
+				}
 				mut name := ''
 				if nextc != `\0` {
 					s.pos++
diff --git a/vlib/v/tests/enum_attr_test.v b/vlib/v/tests/enum_attr_test.v
index d2595214b3..f55dbe7b8a 100644
--- a/vlib/v/tests/enum_attr_test.v
+++ b/vlib/v/tests/enum_attr_test.v
@@ -1,8 +1,8 @@
 import json
 
 enum Foo {
-	yay  [json: 'A'; yay]
-	foo  [foo; json: 'B']
+	yay  @[json: 'A'; yay]
+	foo  @[foo; json: 'B']
 }
 
 struct FooStruct {