1 files changed, 122 insertions, 0 deletions
diff --git a/libgo/go/sort/genzfunc.go b/libgo/go/sort/genzfunc.go
new file mode 100644
index 00000000000..6d2b471b62e
--- /dev/null
+++ b/libgo/go/sort/genzfunc.go
@@ -0,0 +1,122 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+// This program is run via "go generate" (via a directive in sort.go)
+// to generate zfuncversion.go.
+//
+// It copies sort.go to zfuncversion.go, only retaining funcs which
+// take a "data Interface" parameter, and renaming each to have a
+// "_func" suffix and taking a "data lessSwap" instead. It then rewrites
+// each internal function call to the appropriate _func variants.
+
+package main
+
+import (
+	"bytes"
+	"go/ast"
+	"go/format"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"log"
+	"regexp"
+)
+
+var fset = token.NewFileSet()
+
+func main() {
+	af, err := parser.ParseFile(fset, "sort.go", nil, 0)
+	if err != nil {
+		log.Fatal(err)
+	}
+	af.Doc = nil
+	af.Imports = nil
+	af.Comments = nil
+
+	var newDecl []ast.Decl
+	for _, d := range af.Decls {
+		fd, ok := d.(*ast.FuncDecl)
+		if !ok {
+			continue
+		}
+		if fd.Recv != nil || fd.Name.IsExported() {
+			continue
+		}
+		typ := fd.Type
+		if len(typ.Params.List) < 1 {
+			continue
+		}
+		arg0 := typ.Params.List[0]
+		arg0Name := arg0.Names[0].Name
+		arg0Type := arg0.Type.(*ast.Ident)
+		if arg0Name != "data" || arg0Type.Name != "Interface" {
+			continue
+		}
+		arg0Type.Name = "lessSwap"
+
+		newDecl = append(newDecl, fd)
+	}
+	af.Decls = newDecl
+	ast.Walk(visitFunc(rewriteCalls), af)
+
+	var out bytes.Buffer
+	if err := format.Node(&out, fset, af); err != nil {
+		log.Fatalf("format.Node: %v", err)
+	}
+
+	// Get rid of blank lines after removal of comments.
+	src := regexp.MustCompile(`\n{2,}`).ReplaceAll(out.Bytes(), []byte("\n"))
+
+	// Add comments to each func, for the lost reader.
+	// This is so much easier than adding comments via the AST
+	// and trying to get position info correct.
+	src = regexp.MustCompile(`(?m)^func (\w+)`).ReplaceAll(src, []byte("\n// Auto-generated variant of sort.go:$1\nfunc ${1}_func"))
+
+	// Final gofmt.
+	src, err = format.Source(src)
+	if err != nil {
+		log.Fatalf("format.Source: %v on\n%s", err, src)
+	}
+
+	out.Reset()
+	out.WriteString(`// DO NOT EDIT; AUTO-GENERATED from sort.go using genzfunc.go
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+`)
+	out.Write(src)
+
+	const target = "zfuncversion.go"
+	if err := ioutil.WriteFile(target, out.Bytes(), 0644); err != nil {
+		log.Fatal(err)
+	}
+}
+
+type visitFunc func(ast.Node) ast.Visitor
+
+func (f visitFunc) Visit(n ast.Node) ast.Visitor { return f(n) }
+
+func rewriteCalls(n ast.Node) ast.Visitor {
+	ce, ok := n.(*ast.CallExpr)
+	if ok {
+		rewriteCall(ce)
+	}
+	return visitFunc(rewriteCalls)
+}
+
+func rewriteCall(ce *ast.CallExpr) {
+	ident, ok := ce.Fun.(*ast.Ident)
+	if !ok {
+		// e.g. skip SelectorExpr (data.Less(..) calls)
+		return
+	}
+	if len(ce.Args) < 1 {
+		return
+	}
+	ident.Name += "_func"
+}