sort: add gen_sort_variants support for x/exp/slices

Also add a go:generate command to the standard library slices package.

For #61374

Change-Id: I7aae8e451b7c6c4390e0344257478d1a96a14189
Reviewed-on: https://go-review.googlesource.com/c/go/+/511660
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Eli Bendersky <eliben@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

2 files changed, 92 insertions, 35 deletions

diff --git a/src/slices/sort.go b/src/slices/sort.go
index 822f2fceb4..d5e998ce1e 100644
--- a/src/slices/sort.go
+++ b/src/slices/sort.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:generate go run $GOROOT/src/sort/gen_sort_variants.go -generic
+
 package slices
 
 import (
diff --git a/src/sort/gen_sort_variants.go b/src/sort/gen_sort_variants.go
index 2c12b98db3..89500e1c10 100644
--- a/src/sort/gen_sort_variants.go
+++ b/src/sort/gen_sort_variants.go
@@ -68,12 +68,50 @@ type Variant struct {
 	Funcs template.FuncMap
 }
 
-func main() {
-	genGeneric := flag.Bool("generic", false, "generate generic versions")
-	flag.Parse()
+var (
+	traditionalVariants = []Variant{
+		Variant{
+			Name:       "interface",
+			Path:       "zsortinterface.go",
+			Package:    "sort",
+			Imports:    "",
+			FuncSuffix: "",
+			TypeParam:  "",
+			ExtraParam: "",
+			ExtraArg:   "",
+			DataType:   "Interface",
+			Funcs: template.FuncMap{
+				"Less": func(name, i, j string) string {
+					return fmt.Sprintf("%s.Less(%s, %s)", name, i, j)
+				},
+				"Swap": func(name, i, j string) string {
+					return fmt.Sprintf("%s.Swap(%s, %s)", name, i, j)
+				},
+			},
+		},
+		Variant{
+			Name:       "func",
+			Path:       "zsortfunc.go",
+			Package:    "sort",
+			Imports:    "",
+			FuncSuffix: "_func",
+			TypeParam:  "",
+			ExtraParam: "",
+			ExtraArg:   "",
+			DataType:   "lessSwap",
+			Funcs: template.FuncMap{
+				"Less": func(name, i, j string) string {
+					return fmt.Sprintf("%s.Less(%s, %s)", name, i, j)
+				},
+				"Swap": func(name, i, j string) string {
+					return fmt.Sprintf("%s.Swap(%s, %s)", name, i, j)
+				},
+			},
+		},
+	}
 
-	if *genGeneric {
-		generate(&Variant{
+	genericVariants = []Variant{
+		Variant{
 			Name:       "generic_ordered",
 			Path:       "zsortordered.go",
 			Package:    "slices",
@@ -91,9 +129,8 @@ func main() {
 					return fmt.Sprintf("%s[%s], %s[%s] = %s[%s], %s[%s]", name, i, name, j, name, j, name, i)
 				},
 			},
-		})
-
-		generate(&Variant{
+		},
+		Variant{
 			Name:       "generic_func",
 			Path:       "zsortanyfunc.go",
 			Package:    "slices",
@@ -110,47 +147,65 @@ func main() {
 					return fmt.Sprintf("%s[%s], %s[%s] = %s[%s], %s[%s]", name, i, name, j, name, j, name, i)
 				},
 			},
-		})
-	} else {
-		generate(&Variant{
-			Name:       "interface",
-			Path:       "zsortinterface.go",
-			Package:    "sort",
-			Imports:    "",
-			FuncSuffix: "",
-			TypeParam:  "",
+		},
+	}
+
+	expVariants = []Variant{
+		Variant{
+			Name:       "exp_ordered",
+			Path:       "zsortordered.go",
+			Package:    "slices",
+			Imports:    "import \"golang.org/x/exp/constraints\"\n",
+			FuncSuffix: "Ordered",
+			TypeParam:  "[E constraints.Ordered]",
 			ExtraParam: "",
 			ExtraArg:   "",
-			DataType:   "Interface",
+			DataType:   "[]E",
 			Funcs: template.FuncMap{
 				"Less": func(name, i, j string) string {
-					return fmt.Sprintf("%s.Less(%s, %s)", name, i, j)
+					return fmt.Sprintf("cmpLess(%s[%s], %s[%s])", name, i, name, j)
 				},
 				"Swap": func(name, i, j string) string {
-					return fmt.Sprintf("%s.Swap(%s, %s)", name, i, j)
+					return fmt.Sprintf("%s[%s], %s[%s] = %s[%s], %s[%s]", name, i, name, j, name, j, name, i)
 				},
 			},
-		})
-
-		generate(&Variant{
-			Name:       "func",
-			Path:       "zsortfunc.go",
-			Package:    "sort",
-			Imports:    "",
-			FuncSuffix: "_func",
-			TypeParam:  "",
-			ExtraParam: "",
-			ExtraArg:   "",
-			DataType:   "lessSwap",
+		},
+		Variant{
+			Name:       "exp_func",
+			Path:       "zsortanyfunc.go",
+			Package:    "slices",
+			FuncSuffix: "CmpFunc",
+			TypeParam:  "[E any]",
+			ExtraParam: ", cmp func(a, b E) int",
+			ExtraArg:   ", cmp",
+			DataType:   "[]E",
 			Funcs: template.FuncMap{
 				"Less": func(name, i, j string) string {
-					return fmt.Sprintf("%s.Less(%s, %s)", name, i, j)
+					return fmt.Sprintf("(cmp(%s[%s], %s[%s]) < 0)", name, i, name, j)
 				},
 				"Swap": func(name, i, j string) string {
-					return fmt.Sprintf("%s.Swap(%s, %s)", name, i, j)
+					return fmt.Sprintf("%s[%s], %s[%s] = %s[%s], %s[%s]", name, i, name, j, name, j, name, i)
 				},
 			},
-		})
+		},
+	}
+)
+
+func main() {
+	genGeneric := flag.Bool("generic", false, "generate generic versions")
+	genExp := flag.Bool("exp", false, "generate x/exp/slices versions")
+	flag.Parse()
+
+	var variants []Variant
+	if *genExp {
+		variants = expVariants
+	} else if *genGeneric {
+		variants = genericVariants
+	} else {
+		variants = traditionalVariants
+	}
+	for i := range variants {
+		generate(&variants[i])
 	}
 }