bind: generate Java constructors for every exported struct

A recent CL added Java constructors to generated classes that extends
or implements other Java classes and interfaces. Constructors for a
struct S are Go functions on the form

func NewS...(...) *S

If no such constructors exists, a default empty constructor is
generated.

Expand that to cover every exported Go struct.

Fixes golang/go#17086

Change-Id: I910aba13d5884c3f67c946c62a8ac4a3db8e2ea7
Reviewed-on: https://go-review.googlesource.com/29710
Reviewed-by: David Crawshaw <crawshaw@golang.org>

bind/genjava.go

@@ -26,6 +26,10 @@ type JavaGen struct {
 
 	jstructs map[*types.TypeName]*javaClassInfo
 	clsMap   map[string]*java.Class
+	// Constructors is a map from Go struct types to a list
+	// of exported constructor functions for the type, on the form
+	// func New<Type>(...) *Type
+	constructors map[*types.TypeName][]*types.Func
 }
 
 type javaClassInfo struct {
@@ -36,9 +40,6 @@ type javaClassInfo struct {
 	methods map[string]*java.Func
 	// Does the class need a default no-arg constructor
 	genNoargCon bool
-	// Constructors for the type, on the form
-	// func New<Type>(...) *Type
-	cons []*types.Func
 }
 
 // Init intializes the embedded Generator and initializes the Java class information
@@ -50,6 +51,7 @@ func (g *JavaGen) Init(classes []*java.Class) {
 		g.clsMap[cls.Name] = cls
 	}
 	g.jstructs = make(map[*types.TypeName]*javaClassInfo)
+	g.constructors = make(map[*types.TypeName][]*types.Func)
 	for _, s := range g.structs {
 		classes := embeddedJavaClasses(s.t)
 		if len(classes) == 0 {
@@ -87,8 +89,8 @@ func (g *JavaGen) Init(classes []*java.Class) {
 			if jinf != nil {
 				sig := f.Type().(*types.Signature)
 				jinf.genNoargCon = jinf.genNoargCon && sig.Params().Len() > 0
-				jinf.cons = append(jinf.cons, f)
 			}
+			g.constructors[t] = append(g.constructors[t], f)
 		}
 	}
 }
@@ -178,23 +180,22 @@ func (g *JavaGen) genStruct(s structInfo) {
 
 	g.Printf("static { %s.touch(); }\n\n", g.className())
 	g.genProxyImpl(n)
-	if jinf != nil {
+	cons := g.constructors[s.obj]
-		for _, f := range jinf.cons {
+	for _, f := range cons {
-			if !g.isSigSupported(f.Type()) {
+		if !g.isSigSupported(f.Type()) {
-				g.Printf("// skipped constructor %s.%s with unsupported parameter or return types\n\n", n, f.Name())
+			g.Printf("// skipped constructor %s.%s with unsupported parameter or return types\n\n", n, f.Name())
-				continue
+			continue
-			}
-			g.genConstructor(f, n)
 		}
-		if jinf.genNoargCon {
+		g.genConstructor(f, n, jinf != nil)
-			// Generate constructor for Go instantiated instances.
+	}
-			g.Printf("%s(Seq.Ref ref) { this.ref = ref; }\n\n", n)
+	if jinf == nil || jinf.genNoargCon {
+		// constructor for Go instantiated instances.
+		g.Printf("%s(Seq.Ref ref) { this.ref = ref; }\n\n", n)
+		if len(cons) == 0 {
 			// Generate default no-arg constructor
 			g.Printf("public %s() { this.ref = __New(); }\n\n", n)
 			g.Printf("private static native Seq.Ref __New();\n\n")
 		}
-	} else {
-		g.Printf("%s(Seq.Ref ref) { this.ref = ref; }\n\n", n)
 	}
 
 	for _, f := range fields {
@@ -266,22 +267,25 @@ func (g *JavaGen) genStruct(s structInfo) {
 	g.Printf("}\n\n")
 }
 
-func (g *JavaGen) genConstructor(f *types.Func, n string) {
+func (g *JavaGen) genConstructor(f *types.Func, n string, jcls bool) {
 	g.Printf("public %s(", n)
 	g.genFuncArgs(f, nil)
 	g.Printf(") {\n")
 	g.Indent()
-	g.Printf("super(")
 	sig := f.Type().(*types.Signature)
 	params := sig.Params()
-	for i := 0; i < params.Len(); i++ {
+	if jcls {
-		if i > 0 {
+		g.Printf("super(")
-			g.Printf(", ")
+		for i := 0; i < params.Len(); i++ {
+			if i > 0 {
+				g.Printf(", ")
+			}
+			g.Printf(paramName(params, i))
 		}
-		g.Printf(paramName(params, i))
+		g.Printf(");\n")
 	}
-	g.Printf(");\n")
+	g.Printf("this.ref = ")
-	g.Printf("this.ref = __%s(", f.Name())
+	g.Printf("__%s(", f.Name())
 	for i := 0; i < params.Len(); i++ {
 		if i > 0 {
 			g.Printf(", ")
@@ -1330,21 +1334,20 @@ func (g *JavaGen) GenC() error {
 	}
 	for _, s := range g.structs {
 		sName := s.obj.Name()
+		cons := g.constructors[s.obj]
 		jinf := g.jstructs[s.obj]
-		if jinf != nil {
+		for _, f := range cons {
-			for _, f := range jinf.cons {
+			g.genJNIConstructor(f, sName)
-				g.genJNIConstructor(f, sName)
+		}
-			}
+		if len(cons) == 0 && (jinf == nil || jinf.genNoargCon) {
-			if jinf.genNoargCon {
+			g.Printf("JNIEXPORT jobject JNICALL\n")
-				g.Printf("JNIEXPORT jobject JNICALL\n")
+			g.Printf("Java_%s_%s_%s(JNIEnv *env, jclass clazz) {\n", g.jniPkgName(), sName, java.JNIMangle("__New"))
-				g.Printf("Java_%s_%s_%s(JNIEnv *env, jclass clazz) {\n", g.jniPkgName(), sName, java.JNIMangle("__New"))
+			g.Indent()
-				g.Indent()
+			g.Printf("int32_t refnum = new_%s_%s();\n", g.pkgPrefix, sName)
-				g.Printf("int32_t refnum = new_%s_%s();\n", g.pkgPrefix, sName)
+			// Pass no proxy class so that the Seq.Ref is returned instead.
-				// Pass no proxy class so that the Seq.Ref is returned instead.
+			g.Printf("return go_seq_from_refnum(env, refnum, NULL, NULL);\n")
-				g.Printf("return go_seq_from_refnum(env, refnum, NULL, NULL);\n")
+			g.Outdent()
-				g.Outdent()
+			g.Printf("}\n\n")
-				g.Printf("}\n\n")
-			}
 		}
 
 		for _, m := range exportedMethodSet(types.NewPointer(s.obj.Type())) {

bind/java/SeqTest.java

@@ -527,6 +527,17 @@ public class SeqTest extends InstrumentationTestCase {
     assertTrue("Go struct passed through Java should not be wrapped", Testpkg.callCDupper(cdup));
   }
 
+  public void testConstructor() {
+    Interface i = new Concrete();
+    i.f();
+    S2 s = new S2(1, 2);
+    assertEquals("new S2().sum", 3.0, s.sum());
+    assertEquals("new S2().tryTwoStrings", "gostring", s.tryTwoStrings("go", "string"));
+	new S3();
+	S4 s4 = new S4(123);
+	assertEquals("Constructor argument", 123, s4.getI());
+  }
+
   public void testEmptyError() {
     try {
       Testpkg.emptyError();

bind/testdata/ignore.java.c.golden

@@ -39,6 +39,12 @@ Java_go_ignore_Ignore__1init(JNIEnv *env, jclass _unused) {
 
 // skipped function Result with unsupported parameter or return types
 
+JNIEXPORT jobject JNICALL
+Java_go_ignore_S__1_1New(JNIEnv *env, jclass clazz) {
+    int32_t refnum = new_ignore_S();
+    return go_seq_from_refnum(env, refnum, NULL, NULL);
+}
+
 // skipped function S.Argument with unsupported parameter or return types
 
 // skipped function S.Result with unsupported parameter or return types

bind/testdata/ignore.java.golden

@@ -19,6 +19,10 @@ public final class S implements Seq.Proxy, I {
     
     S(Seq.Ref ref) { this.ref = ref; }
     
+    public S() { this.ref = __New(); }
+    
+    private static native Seq.Ref __New();
+    
     // skipped field S.F with unsupported type: *types.Interface
     
     // skipped method S.Argument with unsupported parameter or return types

bind/testdata/issue10788.java.c.golden

@@ -31,6 +31,12 @@ Java_go_issue10788_Issue10788__1init(JNIEnv *env, jclass _unused) {
     
 }
 
+JNIEXPORT jobject JNICALL
+Java_go_issue10788_TestStruct__1_1New(JNIEnv *env, jclass clazz) {
+    int32_t refnum = new_issue10788_TestStruct();
+    return go_seq_from_refnum(env, refnum, NULL, NULL);
+}
+
 JNIEXPORT void JNICALL
 Java_go_issue10788_TestStruct_setValue(JNIEnv *env, jobject this, jstring v) {
     int32_t o = go_seq_to_refnum(env, this);

bind/testdata/issue10788.java.golden

@@ -19,6 +19,10 @@ public final class TestStruct implements Seq.Proxy {
     
     TestStruct(Seq.Ref ref) { this.ref = ref; }
     
+    public TestStruct() { this.ref = __New(); }
+    
+    private static native Seq.Ref __New();
+    
     public final native String getValue();
     public final native void setValue(String v);
     

bind/testdata/issue12328.java.c.golden

@@ -20,6 +20,12 @@ Java_go_issue12328_Issue12328__1init(JNIEnv *env, jclass _unused) {
     proxy_class_issue12328_T_cons = (*env)->GetMethodID(env, clazz, "<init>", "(Lgo/Seq$Ref;)V");
 }
 
+JNIEXPORT jobject JNICALL
+Java_go_issue12328_T__1_1New(JNIEnv *env, jclass clazz) {
+    int32_t refnum = new_issue12328_T();
+    return go_seq_from_refnum(env, refnum, NULL, NULL);
+}
+
 JNIEXPORT void JNICALL
 Java_go_issue12328_T_setErr(JNIEnv *env, jobject this, jobject v) {
     int32_t o = go_seq_to_refnum(env, this);

bind/testdata/issue12328.java.golden

@@ -19,6 +19,10 @@ public final class T implements Seq.Proxy {
     
     T(Seq.Ref ref) { this.ref = ref; }
     
+    public T() { this.ref = __New(); }
+    
+    private static native Seq.Ref __New();
+    
     public final native java.lang.Exception getErr();
     public final native void setErr(java.lang.Exception v);
     

bind/testdata/structs.java.c.golden

@@ -52,6 +52,12 @@ Java_go_structs_Structs_identityWithError(JNIEnv* env, jclass _clazz, jobject s)
     return _r0;
 }
 
+JNIEXPORT jobject JNICALL
+Java_go_structs_S__1_1New(JNIEnv *env, jclass clazz) {
+    int32_t refnum = new_structs_S();
+    return go_seq_from_refnum(env, refnum, NULL, NULL);
+}
+
 JNIEXPORT jobject JNICALL
 Java_go_structs_S_identity(JNIEnv* env, jobject __this__) {
     int32_t o = go_seq_to_refnum(env, __this__);
@@ -100,6 +106,12 @@ Java_go_structs_S_getY(JNIEnv *env, jobject this) {
     return _r0;
 }
 
+JNIEXPORT jobject JNICALL
+Java_go_structs_S2__1_1New(JNIEnv *env, jclass clazz) {
+    int32_t refnum = new_structs_S2();
+    return go_seq_from_refnum(env, refnum, NULL, NULL);
+}
+
 JNIEXPORT void JNICALL
 Java_go_structs_S2_m(JNIEnv* env, jobject __this__) {
     int32_t o = go_seq_to_refnum(env, __this__);

bind/testdata/structs.java.golden

@@ -19,6 +19,10 @@ public final class S implements Seq.Proxy {
     
     S(Seq.Ref ref) { this.ref = ref; }
     
+    public S() { this.ref = __New(); }
+    
+    private static native Seq.Ref __New();
+    
     public final native double getX();
     public final native void setX(double v);
     
@@ -79,6 +83,10 @@ public final class S2 implements Seq.Proxy, I {
     
     S2(Seq.Ref ref) { this.ref = ref; }
     
+    public S2() { this.ref = __New(); }
+    
+    private static native Seq.Ref __New();
+    
     public native void m();
     public native String string();
     @Override public boolean equals(Object o) {

bind/testdata/vars.java.c.golden

@@ -27,6 +27,12 @@ Java_go_vars_Vars__1init(JNIEnv *env, jclass _unused) {
     
 }
 
+JNIEXPORT jobject JNICALL
+Java_go_vars_S__1_1New(JNIEnv *env, jclass clazz) {
+    int32_t refnum = new_vars_S();
+    return go_seq_from_refnum(env, refnum, NULL, NULL);
+}
+
 JNIEXPORT void JNICALL
 Java_go_vars_Vars_setABool(JNIEnv *env, jclass clazz, jboolean v) {
     char _v = (char)v;

bind/testdata/vars.java.golden

@@ -19,6 +19,10 @@ public final class S implements Seq.Proxy, I {
     
     S(Seq.Ref ref) { this.ref = ref; }
     
+    public S() { this.ref = __New(); }
+    
+    private static native Seq.Ref __New();
+    
     @Override public boolean equals(Object o) {
         if (o == null || !(o instanceof S)) {
             return false;

bind/testpkg/testpkg.go

@@ -547,3 +547,14 @@ var GlobalErr error = errors.New("global err")
 func IsGlobalErr(err error) bool {
 	return GlobalErr == err
 }
+
+type S3 struct {
+}
+
+type S4 struct {
+	I int
+}
+
+func NewS4WithInt(i int) *S4 {
+	return &S4{i}
+}