scanner: clean up scanning of `>` (#11943)

vlib/v/scanner/scanner.v

@@ -919,56 +919,34 @@ fn (mut s Scanner) text_scan() token.Token {
 					return s.new_token(.ge, '', 2)
 				} else if nextc == `>` {
 					if s.pos + 2 < s.text.len {
-						if s.text[s.pos + 2] == `=` {
+						// an algorithm to decide it's generic or non-generic
-							s.pos += 2
-							return s.new_token(.right_shift_assign, '', 3)
-						} else if s.last_lt >= 0 && s.pos - s.last_lt < 100 {
-							// an algorithm to discriminate two-level generic call and shift-right patterns
 						// such as `foo<Baz, Bar<int>>(a)` vs `a, b := Foo{}<Foo{}, bar>>(baz)`
 						// @SleepyRoy if you have smarter algorithm :-)
-							// almost correct heuristics: 2-level generic call's last <T> cannot be extremely long
+						// almost correct heuristics: last <T> of generic cannot be extremely long
 						// here we set the limit 100 which should be nice for real cases
-							// ...Bar<int, []Foo, [20]f64, map[string][]bool>> =>
+						// e.g. ...Bar<int, []Foo<int>, Baz_, [20]f64, map[string][]bool>> =>
-							// int, []Foo, [20]f64, map[string][]bool =>
+						// <int, Baz_, [20]f64, map[string][]bool => int, Baz_, f64, bool
-							// int, Foo, f64, bool
+						mut is_generic := true
+						if s.last_lt >= 0 && s.pos - s.last_lt < 100 {
 							typs := s.text[s.last_lt + 1..s.pos].split(',').map(it.trim_space().trim_right('>').after(']'))
-							// if any typ is neither Type nor builtin, then the case is shift-right
+							// if any typ is neither Type nor builtin, then the case is non-generic
 							for typ in typs {
-								// TODO: combine two ifs once logic shortcut with `.all()` is fixed
+								if typ.len == 0
-								if typ.len == 0 {
+									|| (!(typ[0].is_capital() && typ[1..].bytes().all(it.is_alnum()
-									if s.text[s.pos + 2] == `>` {
+									|| it == `_`)) && typ !in ast.builtin_type_names) {
-										if s.pos + 3 < s.text.len && s.text[s.pos + 3] == `=` {
+									is_generic = false
-											s.pos += 3
+									break
-											return s.new_token(.unsigned_right_shift_assign,
-												'', 4)
-										}
-										s.pos += 2
-										return s.new_token(.unsigned_right_shift, '',
-											3)
-									}
-									s.pos++
-									return s.new_token(.right_shift, '', 2)
-								}
-								if !(typ[0].is_capital() && typ[1..].bytes().all(it.is_alnum()))
-									&& typ !in ast.builtin_type_names {
-									if s.text[s.pos + 2] == `>` {
-										if s.pos + 3 < s.text.len && s.text[s.pos + 3] == `=` {
-											s.pos += 3
-											return s.new_token(.unsigned_right_shift_assign,
-												'', 4)
-										}
-										s.pos += 2
-										return s.new_token(.unsigned_right_shift, '',
-											3)
-									}
-									s.pos++
-									return s.new_token(.right_shift, '', 2)
 								}
 							}
+						} else {
+							is_generic = false
+						}
+						if is_generic {
 							return s.new_token(.gt, '', 1)
-						}
+						} else if s.text[s.pos + 2] == `=` {
-					}
+							s.pos += 2
-					if s.text[s.pos + 2] == `>` {
+							return s.new_token(.right_shift_assign, '', 3)
+						} else if s.text[s.pos + 2] == `>` {
 							if s.pos + 3 < s.text.len && s.text[s.pos + 3] == `=` {
 								s.pos += 3
 								return s.new_token(.unsigned_right_shift_assign, '', 4)
@@ -976,6 +954,7 @@ fn (mut s Scanner) text_scan() token.Token {
 							s.pos += 2
 							return s.new_token(.unsigned_right_shift, '', 3)
 						}
+					}
 					s.pos++
 					return s.new_token(.right_shift, '', 2)
 				}

vlib/v/tests/generics_test.v

@@ -510,9 +510,9 @@ fn test_multi_level_generics() {
 		two) == 20
 }
 
-struct Empty {}
+struct Empty_ {}
 
-fn (e1 Empty) < (e2 Empty) bool {
+fn (e1 Empty_) < (e2 Empty_) bool {
 	return true
 }
 
@@ -551,11 +551,11 @@ fn test_generic_detection() {
 	res1, res2 := foo < bar, baz >> (foo + 1 - 1)
 	assert res1
 	assert res2 == 8
-	res3, res4 := Empty{} < Empty{}, baz >> (foo + 1 - 1)
+	res3, res4 := Empty_{} < Empty_{}, baz >> (foo + 1 - 1)
 	assert res3
 	assert res4 == 8
-	assert boring_function<TandU<Empty, int>>(TandU<Empty, int>{
+	assert boring_function<TandU<Empty_, int>>(TandU<Empty_, int>{
-		t: Empty{}
+		t: Empty_{}
 		u: 10
 	})
 
@@ -573,11 +573,11 @@ fn test_generic_detection() {
 	})
 
 	// this final case challenges your scanner :-)
-	assert boring_function<TandU<TandU<int,MultiLevel<Empty>>, map[string][]int>>(TandU<TandU<int,MultiLevel<Empty>>, map[string][]int>{
+	assert boring_function<TandU<TandU<int,MultiLevel<Empty_>>, map[string][]int>>(TandU<TandU<int,MultiLevel<Empty_>>, map[string][]int>{
-		t: TandU<int,MultiLevel<Empty>>{
+		t: TandU<int,MultiLevel<Empty_>>{
 			t: 20
-			u: MultiLevel<Empty>{
+			u: MultiLevel<Empty_>{
-				foo: Empty{}
+				foo: Empty_{}
 			}
 		}
 		u: {