bind: support for custom java package name and objective-c prefix.

Introduce options -javapkg and -prefix for gobind command.

The following generates java class Testpkg with package name com.example.

gobind -lang=java -javapkg=com.example testpkg

The following generates objective-c files where function and type names
are prefixed with ExampleTestpkg.

gobind -lang=objc -prefix=Example testpkg

As discussed in golang/go#9660 and golang/go#12245.

Gomobile support is not yet implemented.

Change-Id: Ib9e39997ce915580a5a2e25643c0c28373f27ee1
Reviewed-on: https://go-review.googlesource.com/13969
Reviewed-by: David Crawshaw <crawshaw@golang.org>

bind/bind.go

@@ -21,12 +21,16 @@ import (
 )
 
 // GenJava generates a Java API from a Go package.
-func GenJava(w io.Writer, fset *token.FileSet, pkg *types.Package) error {
+func GenJava(w io.Writer, fset *token.FileSet, pkg *types.Package, javaPkg string) error {
+	if javaPkg == "" {
+		javaPkg = javaPkgName(pkg.Name())
+	}
 	buf := new(bytes.Buffer)
 	g := &javaGen{
 		printer: &printer{buf: buf, indentEach: []byte("    ")},
 		fset:    fset,
 		pkg:     pkg,
+		javaPkg: javaPkg,
 	}
 	if err := g.gen(); err != nil {
 		return err
@@ -57,12 +61,17 @@ func GenGo(w io.Writer, fset *token.FileSet, pkg *types.Package) error {
 }
 
 // GenObjc generates the Objective-C API from a Go package.
-func GenObjc(w io.Writer, fset *token.FileSet, pkg *types.Package, isHeader bool) error {
+func GenObjc(w io.Writer, fset *token.FileSet, pkg *types.Package, prefix string, isHeader bool) error {
+	if prefix == "" {
+		prefix = "Go"
+	}
+
 	buf := new(bytes.Buffer)
 	g := &objcGen{
 		printer: &printer{buf: buf, indentEach: []byte("\t")},
 		fset:    fset,
 		pkg:     pkg,
+		prefix:  prefix,
 	}
 	var err error
 	if isHeader {

bind/bind_test.go

@@ -7,6 +7,7 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
@@ -96,7 +97,7 @@ func TestGenObjc(t *testing.T) {
 
 		for isHeader, suffix := range suffixes {
 			var buf bytes.Buffer
-			if err := GenObjc(&buf, fset, pkg, isHeader); err != nil {
+			if err := GenObjc(&buf, fset, pkg, "", isHeader); err != nil {
 				t.Errorf("%s: %v", filename, err)
 				continue
 			}
@@ -121,7 +122,7 @@ func TestGenJava(t *testing.T) {
 	for _, filename := range tests {
 		var buf bytes.Buffer
 		pkg := typeCheck(t, filename)
-		if err := GenJava(&buf, fset, pkg); err != nil {
+		if err := GenJava(&buf, fset, pkg, ""); err != nil {
 			t.Errorf("%s: %v", filename, err)
 			continue
 		}
@@ -165,3 +166,47 @@ func TestGenGo(t *testing.T) {
 		}
 	}
 }
+
+func TestCustomPrefix(t *testing.T) {
+	const datafile = "testdata/customprefix.go"
+	const isHeader = true
+	pkg := typeCheck(t, datafile)
+
+	testCases := []struct {
+		golden string
+		gen    func(w io.Writer) error
+	}{
+		{
+			"testdata/customprefix.java.golden",
+			func(w io.Writer) error { return GenJava(w, fset, pkg, "com.example") },
+		},
+		{
+			"testdata/customprefix.objc.h.golden",
+			func(w io.Writer) error { return GenObjc(w, fset, pkg, "EX", isHeader) },
+		},
+		{
+			"testdata/customprefix.objc.m.golden",
+			func(w io.Writer) error { return GenObjc(w, fset, pkg, "EX", !isHeader) },
+		},
+	}
+
+	for _, tc := range testCases {
+		var buf bytes.Buffer
+		if err := tc.gen(&buf); err != nil {
+			t.Errorf("generating %s: %v", tc.golden, err)
+			continue
+		}
+		out := writeTempFile(t, "generated", buf.Bytes())
+		defer os.Remove(out)
+		if diffstr := diff(tc.golden, out); diffstr != "" {
+			t.Errorf("%s: generated file does not match:\b%s", tc.golden, diffstr)
+			if *updateFlag {
+				t.Logf("Updating %s...", tc.golden)
+				err := exec.Command("/bin/cp", out, tc.golden).Run()
+				if err != nil {
+					t.Errorf("Update failed: %s", err)
+				}
+			}
+		}
+	}
+}

bind/genjava.go

@@ -33,9 +33,10 @@ func (list ErrorList) Error() string {
 
 type javaGen struct {
 	*printer
-	fset *token.FileSet
-	pkg  *types.Package
-	err  ErrorList
+	fset    *token.FileSet
+	pkg     *types.Package
+	javaPkg string
+	err     ErrorList
 }
 
 func (g *javaGen) genStruct(obj *types.TypeName, T *types.Struct) {
@@ -545,11 +546,19 @@ func (g *javaGen) errorf(format string, args ...interface{}) {
 	g.err = append(g.err, fmt.Errorf(format, args...))
 }
 
-const javaPreamble = `// Java Package %s is a proxy for talking to a Go program.
-//   gobind -lang=java %s
+func (g *javaGen) gobindOpts() string {
+	opts := []string{"-lang=java"}
+	if g.javaPkg != javaPkgName(g.pkg.Name()) {
+		opts = append(opts, "-javapkg="+g.javaPkg)
+	}
+	return strings.Join(opts, " ")
+}
+
+const javaPreamble = `// Java class %[1]s.%[2]s is a proxy for talking to a Go program.
+//   gobind %[3]s %[4]s
 //
 // File is generated by gobind. Do not edit.
-package go.%s;
+package %[1]s;
 
 import go.Seq;
 
@@ -560,8 +569,8 @@ var javaNameReplacer = strings.NewReplacer(
 	".", "_",
 )
 
-func (g *javaGen) javaPkgName() string {
-	s := javaNameReplacer.Replace(g.pkg.Name())
+func javaPkgName(pkgName string) string {
+	s := javaNameReplacer.Replace(pkgName)
 	// Look for Java keywords that are not Go keywords, and avoid using
 	// them as a package name.
 	//
@@ -579,7 +588,7 @@ func (g *javaGen) javaPkgName() string {
 		"void", "volatile", "while":
 		s += "_"
 	}
-	return s
+	return "go." + s
 }
 
 func (g *javaGen) className() string {
@@ -587,7 +596,7 @@ func (g *javaGen) className() string {
 }
 
 func (g *javaGen) gen() error {
-	g.Printf(javaPreamble, g.javaPkgName(), g.pkg.Path(), g.javaPkgName())
+	g.Printf(javaPreamble, g.javaPkg, g.className(), g.gobindOpts(), g.pkg.Path())
 
 	g.Printf("public abstract class %s {\n", g.className())
 	g.Indent()

bind/genobjc.go

@@ -9,8 +9,6 @@ import (
 	"go/token"
 	"go/types"
 	"strings"
-	"unicode"
-	"unicode/utf8"
 )
 
 // TODO(hyangah): error code/domain propagation
@@ -21,6 +19,8 @@ type objcGen struct {
 	pkg  *types.Package
 	err  ErrorList
 
+	prefix string // prefix arg passed by flag.
+
 	// fields set by init.
 	pkgName    string
 	namePrefix string
@@ -28,14 +28,9 @@ type objcGen struct {
 	names      []*types.TypeName
 }
 
-func capitalize(n string) string {
-	firstRune, size := utf8.DecodeRuneInString(n)
-	return string(unicode.ToUpper(firstRune)) + n[size:]
-}
-
 func (g *objcGen) init() {
 	g.pkgName = g.pkg.Name()
-	g.namePrefix = "Go" + capitalize(g.pkgName)
+	g.namePrefix = g.prefix + strings.Title(g.pkgName)
 	g.funcs = nil
 	g.names = nil
 
@@ -57,8 +52,8 @@ func (g *objcGen) init() {
 	}
 }
 
-const objcPreamble = `// Objective-C API for talking to %s Go package.
-//   gobind -lang=objc %s
+const objcPreamble = `// Objective-C API for talking to %[1]s Go package.
+//   gobind %[2]s %[3]s
 //
 // File is generated by gobind. Do not edit.
 
@@ -67,9 +62,9 @@ const objcPreamble = `// Objective-C API for talking to %s Go package.
 func (g *objcGen) genH() error {
 	g.init()
 
-	g.Printf(objcPreamble, g.pkg.Path(), g.pkg.Path())
-	g.Printf("#ifndef __Go%s_H__\n", capitalize(g.pkgName))
-	g.Printf("#define __Go%s_H__\n", capitalize(g.pkgName))
+	g.Printf(objcPreamble, g.pkg.Path(), g.gobindOpts(), g.pkg.Path())
+	g.Printf("#ifndef __Go%s_H__\n", strings.Title(g.pkgName))
+	g.Printf("#define __Go%s_H__\n", strings.Title(g.pkgName))
 	g.Printf("\n")
 	g.Printf("#include <Foundation/Foundation.h>")
 	g.Printf("\n\n")
@@ -115,10 +110,18 @@ func (g *objcGen) genH() error {
 	return nil
 }
 
+func (g *objcGen) gobindOpts() string {
+	opts := []string{"-lang=objc"}
+	if g.prefix != "Go" {
+		opts = append(opts, "-prefix="+g.prefix)
+	}
+	return strings.Join(opts, " ")
+}
+
 func (g *objcGen) genM() error {
 	g.init()
 
-	g.Printf(objcPreamble, g.pkg.Path(), g.pkg.Path())
+	g.Printf(objcPreamble, g.pkg.Path(), g.gobindOpts(), g.pkg.Path())
 	g.Printf("#include %q\n", g.namePrefix+".h")
 	g.Printf("#include <Foundation/Foundation.h>\n")
 	g.Printf("#include \"seq.h\"\n")

bind/testdata/basictypes.java.golden

@@ -1,4 +1,4 @@
-// Java Package basictypes is a proxy for talking to a Go program.
+// Java class go.basictypes.Basictypes is a proxy for talking to a Go program.
 //   gobind -lang=java basictypes
 //
 // File is generated by gobind. Do not edit.

bind/testdata/customprefix.go

@@ -0,0 +1,10 @@
+// Copyright 2015 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.
+
+// Data for -pkgpath and -prefix options.
+
+package customprefix
+
+func F() {
+}

bind/testdata/customprefix.java.golden

@@ -0,0 +1,20 @@
+// Java class com.example.Customprefix is a proxy for talking to a Go program.
+//   gobind -lang=java -javapkg=com.example customprefix
+//
+// File is generated by gobind. Do not edit.
+package com.example;
+
+import go.Seq;
+
+public abstract class Customprefix {
+    private Customprefix() {} // uninstantiable
+    
+    public static void F() {
+        go.Seq _in = new go.Seq();
+        go.Seq _out = new go.Seq();
+        Seq.send(DESCRIPTOR, CALL_F, _in, _out);
+    }
+    
+    private static final int CALL_F = 1;
+    private static final String DESCRIPTOR = "customprefix";
+}

bind/testdata/customprefix.objc.h.golden

@@ -0,0 +1,13 @@
+// Objective-C API for talking to customprefix Go package.
+//   gobind -lang=objc -prefix=EX customprefix
+//
+// File is generated by gobind. Do not edit.
+
+#ifndef __GoCustomprefix_H__
+#define __GoCustomprefix_H__
+
+#include <Foundation/Foundation.h>
+
+FOUNDATION_EXPORT void EXCustomprefixF();
+
+#endif

bind/testdata/customprefix.objc.m.golden

@@ -0,0 +1,27 @@
+// Objective-C API for talking to customprefix Go package.
+//   gobind -lang=objc -prefix=EX customprefix
+//
+// File is generated by gobind. Do not edit.
+
+#include "EXCustomprefix.h"
+#include <Foundation/Foundation.h>
+#include "seq.h"
+
+static NSString* errDomain = @"go.customprefix";
+
+@protocol goSeqRefInterface
+-(GoSeqRef*) ref;
+@end
+
+#define _DESCRIPTOR_ "customprefix"
+
+#define _CALL_F_ 1
+
+void EXCustomprefixF() {
+	GoSeq in_ = {};
+	GoSeq out_ = {};
+	go_seq_send(_DESCRIPTOR_, _CALL_F_, &in_, &out_);
+	go_seq_free(&in_);
+	go_seq_free(&out_);
+}
+

bind/testdata/interfaces.java.golden

@@ -1,4 +1,4 @@
-// Java Package interfaces is a proxy for talking to a Go program.
+// Java class go.interfaces.Interfaces is a proxy for talking to a Go program.
 //   gobind -lang=java interfaces
 //
 // File is generated by gobind. Do not edit.

bind/testdata/issue10788.java.golden

@@ -1,4 +1,4 @@
-// Java Package issue10788 is a proxy for talking to a Go program.
+// Java class go.issue10788.Issue10788 is a proxy for talking to a Go program.
 //   gobind -lang=java issue10788
 //
 // File is generated by gobind. Do not edit.

bind/testdata/issue12328.java.golden

@@ -1,4 +1,4 @@
-// Java Package issue12328 is a proxy for talking to a Go program.
+// Java class go.issue12328.Issue12328 is a proxy for talking to a Go program.
 //   gobind -lang=java issue12328
 //
 // File is generated by gobind. Do not edit.

bind/testdata/structs.java.golden

@@ -1,4 +1,4 @@
-// Java Package structs is a proxy for talking to a Go program.
+// Java class go.structs.Structs is a proxy for talking to a Go program.
 //   gobind -lang=java structs
 //
 // File is generated by gobind. Do not edit.

bind/testdata/try.java.golden

@@ -1,4 +1,4 @@
-// Java Package try_ is a proxy for talking to a Go program.
+// Java class go.try_.Try is a proxy for talking to a Go program.
 //   gobind -lang=java try
 //
 // File is generated by gobind. Do not edit.

cmd/gobind/gen.go

@@ -53,7 +53,7 @@ func genPkg(pkg *build.Package) {
 	switch *lang {
 	case "java":
 		w, closer := writer(fname, p)
-		processErr(bind.GenJava(w, fset, p))
+		processErr(bind.GenJava(w, fset, p, *javaPkg))
 		closer()
 	case "go":
 		w, closer := writer(fname, p)
@@ -61,15 +61,15 @@ func genPkg(pkg *build.Package) {
 		closer()
 	case "objc":
 		if fname == "" {
-			processErr(bind.GenObjc(os.Stdout, fset, p, true))
-			processErr(bind.GenObjc(os.Stdout, fset, p, false))
+			processErr(bind.GenObjc(os.Stdout, fset, p, *prefix, true))
+			processErr(bind.GenObjc(os.Stdout, fset, p, *prefix, false))
 		} else {
 			hname := fname[:len(fname)-2] + ".h"
 			w, closer := writer(hname, p)
-			processErr(bind.GenObjc(w, fset, p, true))
+			processErr(bind.GenObjc(w, fset, p, *prefix, true))
 			closer()
 			w, closer = writer(fname, p)
-			processErr(bind.GenObjc(w, fset, p, false))
+			processErr(bind.GenObjc(w, fset, p, *prefix, false))
 			closer()
 		}
 	default:

cmd/gobind/main.go

@@ -13,8 +13,10 @@ import (
 )
 
 var (
-	lang   = flag.String("lang", "java", "target language for bindings, either java, go, or objc (experimental).")
-	outdir = flag.String("outdir", "", "result will be written to the directory instead of stdout.")
+	lang    = flag.String("lang", "java", "target language for bindings, either java, go, or objc (experimental).")
+	outdir  = flag.String("outdir", "", "result will be written to the directory instead of stdout.")
+	javaPkg = flag.String("javapkg", "", "custom Java package path used instead of the default 'go.<go package name>'. Valid only with -lang=java.")
+	prefix  = flag.String("prefix", "", "custom Objective-C name prefix used instead of the default 'Go'. Valid only with -lang=objc.")
 )
 
 var usage = `The Gobind tool generates Java language bindings for Go.
@@ -24,6 +26,12 @@ For usage details, see doc.go.`
 func main() {
 	flag.Parse()
 
+	if *lang != "java" && *javaPkg != "" {
+		log.Fatalf("Invalid option -javapkg for gobind -lang=%s", *lang)
+	} else if *lang != "objc" && *prefix != "" {
+		log.Fatalf("Invalid option -prefix for gobind -lang=%s", *lang)
+	}
+
 	cwd, err := os.Getwd()
 	if err != nil {
 		log.Fatal(err)

cmd/gomobile/bind.go

@@ -119,14 +119,16 @@ func (b *binder) GenObjc(outdir string) error {
 		printcmd("gobind -lang=objc %s > %s", b.pkg.Path(), mfile)
 	}
 
+	const objcPrefix = "" // TODO(hyangah): -prefix
+
 	generate := func(w io.Writer) error {
-		return bind.GenObjc(w, b.fset, b.pkg, false)
+		return bind.GenObjc(w, b.fset, b.pkg, objcPrefix, false)
 	}
 	if err := writeFile(mfile, generate); err != nil {
 		return err
 	}
 	generate = func(w io.Writer) error {
-		return bind.GenObjc(w, b.fset, b.pkg, true)
+		return bind.GenObjc(w, b.fset, b.pkg, objcPrefix, true)
 	}
 	if err := writeFile(hfile, generate); err != nil {
 		return err
@@ -147,8 +149,9 @@ func (b *binder) GenJava(outdir string) error {
 		printcmd("gobind -lang=java %s > %s", b.pkg.Path(), javaFile)
 	}
 
+	const javaPkg = "" // TODO(hyangah): -javapkg
 	generate := func(w io.Writer) error {
-		return bind.GenJava(w, b.fset, b.pkg)
+		return bind.GenJava(w, b.fset, b.pkg, javaPkg)
 	}
 	if err := writeFile(javaFile, generate); err != nil {
 		return err

cmd/gomobile/init_test.go

@@ -126,7 +126,7 @@ mkdir -p $GOMOBILE/android-{{.NDK}}/openal
 mv $WORK/openal/lib $GOMOBILE/android-{{.NDK}}/openal/lib{{if eq .GOOS "darwin"}}
 go install -p={{.NumCPU}} -x golang.org/x/mobile/gl
 go install -p={{.NumCPU}} -x golang.org/x/mobile/app
-go install -p={{.NumCPU}} -x golang.org/x/mobile/exp/app/debug {{end}}
+go install -p={{.NumCPU}} -x golang.org/x/mobile/exp/app/debug{{end}}
 GOOS=android GOARCH=arm GOARM=7 CC=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-gcc{{.EXE}} CXX=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-g++{{.EXE}} CGO_ENABLED=1 go install -p={{.NumCPU}} -pkgdir=$GOMOBILE/pkg_android_arm -x std
 {{if eq .GOOS "darwin"}}GOOS=darwin GOARCH=arm GOARM=7 CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -arch armv7 CGO_LDFLAGS=-isysroot=iphoneos -arch armv7 CGO_ENABLED=1 go install -p={{.NumCPU}} -pkgdir=$GOMOBILE/pkg_darwin_arm -x std
 GOOS=darwin GOARCH=arm64 CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -arch arm64 CGO_LDFLAGS=-isysroot=iphoneos -arch arm64 CGO_ENABLED=1 go install -p={{.NumCPU}} -pkgdir=$GOMOBILE/pkg_darwin_arm64 -x std