Test current state of things, which actually doesn't crash!
[ldk-java] / genbindings.py
index 9f7e136980d1e2787563e2476c79a3a4c737e64e..cf033916ee719da00482740e0f8f33fd109f63f1 100755 (executable)
 #!/usr/bin/env python3
 import sys, re
 
-if len(sys.argv) != 3:
-    print("USAGE: /path/to/lightning.h /path/to/bindings.java")
+if len(sys.argv) != 4:
+    print("USAGE: /path/to/lightning.h /path/to/bindings/output.java /path/to/bindings/output.c")
     sys.exit(1)
 
-with open(sys.argv[1]) as f, open(sys.argv[2], "w") as out_f:
-    var_is_arr_regex = re.compile("\(\*([A-za-z_]*)\)\[[0-9]*\]");
-    def map_type(fn_arg, print_void):
+class TypeInfo:
+    def __init__(self, rust_obj, java_ty, java_fn_ty_arg, c_ty, passed_as_ptr, is_ptr, var_name, arr_len):
+        self.rust_obj = rust_obj
+        self.java_ty = java_ty
+        self.java_fn_ty_arg = java_fn_ty_arg
+        self.c_ty = c_ty
+        self.passed_as_ptr = passed_as_ptr
+        self.is_ptr = is_ptr
+        self.var_name = var_name
+        self.arr_len = arr_len
+
+class ConvInfo:
+    def __init__(self, ty_info, arg_name, arg_conv, arg_conv_name, ret_conv, ret_conv_name):
+        assert(ty_info.c_ty is not None)
+        assert(ty_info.java_ty is not None)
+        assert(arg_name is not None)
+        self.c_ty = ty_info.c_ty
+        self.java_ty = ty_info.java_ty
+        self.java_fn_ty_arg = ty_info.java_fn_ty_arg
+        self.arg_name = arg_name
+        self.arg_conv = arg_conv
+        self.arg_conv_name = arg_conv_name
+        self.ret_conv = ret_conv
+        self.ret_conv_name = ret_conv_name
+
+    def print_ty(self):
+        out_c.write(self.c_ty)
+        out_java.write(self.java_ty)
+
+    def print_name(self):
+        if self.arg_name != "":
+            out_java.write(" " + self.arg_name)
+            out_c.write(" " + self.arg_name)
+        else:
+            out_java.write(" arg")
+            out_c.write(" arg")
+
+with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.argv[3], "w") as out_c:
+    opaque_structs = set()
+    trait_structs = set()
+
+    var_is_arr_regex = re.compile("\(\*([A-za-z_]*)\)\[([0-9]*)\]")
+    var_ty_regex = re.compile("([A-za-z_0-9]*)(.*)")
+    def java_c_types(fn_arg, ret_arr_len):
         fn_arg = fn_arg.strip()
         if fn_arg.startswith("MUST_USE_RES "):
             fn_arg = fn_arg[13:]
+        is_const = False
         if fn_arg.startswith("const "):
             fn_arg = fn_arg[6:]
+            is_const = True
+
+        is_ptr = False
+        take_by_ptr = False
+        rust_obj = None
         if fn_arg.startswith("void"):
-            if print_void:
-                out_f.write("void")
-            else:
-                return
-            fn_arg = fn_arg.strip("void ")
+            java_ty = "void"
+            c_ty = "void"
+            fn_ty_arg = "V"
+            fn_arg = fn_arg[4:].strip()
         elif fn_arg.startswith("bool"):
-            out_f.write("boolean")
-            fn_arg = fn_arg.strip("bool ")
+            java_ty = "boolean"
+            c_ty = "jboolean"
+            fn_ty_arg = "Z"
+            fn_arg = fn_arg[4:].strip()
         elif fn_arg.startswith("uint8_t"):
-            out_f.write("byte")
-            fn_arg = fn_arg.strip("uint8_t ")
+            java_ty = "byte"
+            c_ty = "jbyte"
+            fn_ty_arg = "B"
+            fn_arg = fn_arg[7:].strip()
+        elif fn_arg.startswith("uint16_t"):
+            java_ty = "short"
+            c_ty = "jshort"
+            fn_ty_arg = "S"
+            fn_arg = fn_arg[8:].strip()
         elif fn_arg.startswith("uint32_t"):
-            out_f.write("int")
-            fn_arg = fn_arg.strip("uint32_t ")
+            java_ty = "int"
+            c_ty = "jint"
+            fn_ty_arg = "I"
+            fn_arg = fn_arg[8:].strip()
         elif fn_arg.startswith("uint64_t"):
-            out_f.write("long")
-            fn_arg = fn_arg.strip("uint64_t ")
+            java_ty = "long"
+            c_ty = "jlong"
+            fn_ty_arg = "J"
+            fn_arg = fn_arg[8:].strip()
+        elif is_const and fn_arg.startswith("char *"):
+            java_ty = "String"
+            c_ty = "const char*"
+            fn_ty_arg = "Ljava/lang/String;"
+            fn_arg = fn_arg[6:].strip()
         else:
-            out_f.write("long")
-            fn_arg = "".join([e + " " for e in fn_arg.split(" ")[1:]]).strip()
+            ma = var_ty_regex.match(fn_arg)
+            java_ty = "long"
+            c_ty = "jlong"
+            fn_ty_arg = "J"
+            fn_arg = ma.group(2).strip()
+            rust_obj = ma.group(1).strip()
+            take_by_ptr = True
+
+        if fn_arg.startswith(" *") or fn_arg.startswith("*"):
+            fn_arg = fn_arg.replace("*", "").strip()
+            is_ptr = True
+            c_ty = "jlong"
+            java_ty = "long"
+
         var_is_arr = var_is_arr_regex.match(fn_arg)
-        if var_is_arr is not None:
-            out_f.write("[] " + var_is_arr.group(1))
-        elif fn_arg.strip() != "":
-            out_f.write(" " + fn_arg.replace('*', '').strip())
+        if var_is_arr is not None or ret_arr_len is not None:
+            assert(not take_by_ptr)
+            assert(not is_ptr)
+            java_ty = java_ty + "[]"
+            c_ty = c_ty + "Array"
+            if var_is_arr is not None:
+                return TypeInfo(rust_obj=None, java_ty=java_ty, java_fn_ty_arg="[" + fn_ty_arg, c_ty=c_ty,
+                    passed_as_ptr=False, is_ptr=False, var_name=var_is_arr.group(1), arr_len=var_is_arr.group(2))
+        return TypeInfo(rust_obj=rust_obj, java_ty=java_ty, java_fn_ty_arg=fn_ty_arg, c_ty=c_ty, passed_as_ptr=is_ptr or take_by_ptr,
+            is_ptr=is_ptr, var_name=fn_arg, arr_len=None)
+
+    def map_type(fn_arg, print_void, ret_arr_len, is_free):
+        ty_info = java_c_types(fn_arg, ret_arr_len)
+
+        if ty_info.c_ty == "void":
+            if not print_void:
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = None, arg_conv_name = None, ret_conv = None, ret_conv_name = None)
+
+        if ty_info.c_ty.endswith("Array"):
+            arr_len = ty_info.arr_len
+            if arr_len is not None:
+                arr_name = ty_info.var_name
+            else:
+                arr_name = "ret"
+                arr_len = ret_arr_len
+            assert(ty_info.c_ty == "jbyteArray")
+            return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                arg_conv = "unsigned char " + arr_name + "_arr[" + arr_len + "];\n" +
+                    "(*_env)->GetByteArrayRegion (_env, """ + arr_name + ", 0, " + arr_len + ", " + arr_name + "_arr);\n" +
+                    "unsigned char (*""" + arr_name + "_ref)[" + arr_len + "] = &" + arr_name + "_arr;",
+                arg_conv_name = arr_name + "_ref",
+                ret_conv = ("jbyteArray " + arr_name + "_arr = (*_env)->NewByteArray(_env, " + arr_len + ");\n" +
+                    "(*_env)->SetByteArrayRegion(_env, " + arr_name + "_arr, 0, " + arr_len + ", *",
+                    ");"),
+                ret_conv_name = arr_name + "_arr")
+        elif ty_info.var_name != "":
+            # If we have a parameter name, print it (noting that it may indicate its a pointer)
+            if ty_info.rust_obj is not None:
+                assert(ty_info.passed_as_ptr)
+                if not ty_info.is_ptr:
+                    if ty_info.rust_obj in trait_structs:
+                        base_conv = ty_info.rust_obj + " *" + ty_info.var_name + "_conv = (" + ty_info.rust_obj + "*)" + ty_info.var_name + ";"
+                        if not is_free:
+                            base_conv = base_conv + "\n" + ty_info.rust_obj + "_JCalls_clone(" + ty_info.var_name + "_conv->this_arg);"
+                        return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                            arg_conv = base_conv,
+                            arg_conv_name = "*" + ty_info.var_name + "_conv",
+                            ret_conv = None, ret_conv_name = None)
+                    base_conv = ty_info.rust_obj + " " + ty_info.var_name + "_conv = *(" + ty_info.rust_obj + "*)" + ty_info.var_name + ";\nfree((void*)" + ty_info.var_name + ");";
+                    if ty_info.rust_obj in opaque_structs:
+                        return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                            arg_conv = base_conv + "\n" + ty_info.var_name + "_conv._underlying_ref = false;",
+                            arg_conv_name = ty_info.var_name + "_conv",
+                            ret_conv = None, ret_conv_name = None)
+
+                    return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                        arg_conv = base_conv, arg_conv_name = ty_info.var_name + "_conv",
+                        ret_conv = None, ret_conv_name = None)
+                else:
+                    assert(not is_free)
+                    return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                        arg_conv = ty_info.rust_obj + "* " + ty_info.var_name + "_conv = (" + ty_info.rust_obj + "*)" + ty_info.var_name + ";",
+                        arg_conv_name = ty_info.var_name + "_conv",
+                        ret_conv = None, ret_conv_name = None)
+            elif ty_info.is_ptr:
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = None, arg_conv_name = ty_info.var_name, ret_conv = None, ret_conv_name = None)
+            elif ty_info.java_ty == "String":
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = None, arg_conv_name = None,
+                    ret_conv = ("jstring " + ty_info.var_name + "_conv = (*_env)->NewStringUTF(_env, ", ");"), ret_conv_name = ty_info.var_name + "_conv")
+            else:
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = None, arg_conv_name = ty_info.var_name, ret_conv = None, ret_conv_name = None)
         elif not print_void:
-            out_f.write(" arg");
+            # We don't have a parameter name, and want one, just call it arg
+            if ty_info.rust_obj is not None:
+                assert(not is_free or ty_info.rust_obj not in opaque_structs);
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = ty_info.rust_obj + " arg_conv = *(" + ty_info.rust_obj + "*)arg;\nfree((void*)arg);",
+                    arg_conv_name = "arg_conv",
+                    ret_conv = None, ret_conv_name = None)
+            else:
+                assert(not is_free)
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = None, arg_conv_name = "arg", ret_conv = None, ret_conv_name = None)
+        else:
+            # We don't have a parameter name, and don't want one (cause we're returning)
+            if ty_info.rust_obj is not None:
+                if not ty_info.is_ptr:
+                    if ty_info.rust_obj in opaque_structs:
+                        # If we're returning a newly-allocated struct, we don't want Rust to ever
+                        # free, instead relying on the Java GC to lose the ref. We undo this in
+                        # any _free function.
+                        # To avoid any issues, we first assert that the incoming object is non-ref.
+                        return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                            ret_conv = (ty_info.rust_obj + "* ret = malloc(sizeof(" + ty_info.rust_obj + "));\n*ret = ", ";\nassert(!ret->_underlying_ref);\nret->_underlying_ref = true;"),
+                            ret_conv_name = "(long)ret",
+                            arg_conv = None, arg_conv_name = None)
+                    else:
+                        return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                            ret_conv = (ty_info.rust_obj + "* ret = malloc(sizeof(" + ty_info.rust_obj + "));\n*ret = ", ";"),
+                            ret_conv_name = "(long)ret",
+                            arg_conv = None, arg_conv_name = None)
+                else:
+                    return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                        ret_conv = ("long ret = (long)", ";"), ret_conv_name = "ret",
+                        arg_conv = None, arg_conv_name = None)
+            else:
+                return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                    arg_conv = None, arg_conv_name = None, ret_conv = None, ret_conv_name = None)
+
+    def map_fn(re_match, ret_arr_len):
+        out_java.write("\t/// " + line)
+        out_java.write("\tpublic static native ")
+        out_c.write("JNIEXPORT ")
+
+        ret_info = map_type(re_match.group(1), True, ret_arr_len, False)
+        ret_info.print_ty()
+        if ret_info.ret_conv is not None:
+            ret_conv_pfx, ret_conv_sfx = ret_info.ret_conv
 
-    def map_fn_args(fn_args):
-        for idx, arg in enumerate(fn_args.split(',')):
+        out_java.write(" " + re_match.group(2) + "(")
+        out_c.write(" JNICALL Java_org_ldk_impl_bindings_" + re_match.group(2).replace('_', '_1') + "(JNIEnv * _env, jclass _b")
+
+        arg_names = []
+        for idx, arg in enumerate(re_match.group(3).split(',')):
             if idx != 0:
-                out_f.write(", ")
-            map_type(arg, False)
+                out_java.write(", ")
+            if arg != "void":
+                out_c.write(", ")
+            arg_conv_info = map_type(arg, False, None, re_match.group(2).endswith("_free"))
+            if arg_conv_info.c_ty != "void":
+                arg_conv_info.print_ty()
+                arg_conv_info.print_name()
+            arg_names.append(arg_conv_info)
 
-    def map_fn(re_match, ret_ty_suffix):
-        out_f.write("\t/// " + line)
-        out_f.write("\tpublic static native ")
-        map_type(re_match.group(1), True)
-        out_f.write(ret_ty_suffix + " " + re_match.group(2).replace('_', '') + "(")
-        map_fn_args(re_match.group(3))
-        out_f.write(");\n")
+        out_java.write(");\n")
+        out_c.write(") {\n")
 
-    out_f.write("""package org.ldk;
+        for info in arg_names:
+            if info.arg_conv is not None:
+                out_c.write("\t" + info.arg_conv.replace('\n', "\n\t") + "\n");
+
+        if ret_info.ret_conv is not None:
+            out_c.write("\t" + ret_conv_pfx.replace('\n', '\n\t'));
+        else:
+            out_c.write("\treturn ");
+
+        out_c.write(re_match.group(2) + "(")
+        for idx, info in enumerate(arg_names):
+            if info.arg_conv_name is not None:
+                if idx != 0:
+                    out_c.write(", ")
+                out_c.write(info.arg_conv_name)
+        out_c.write(")")
+        if ret_info.ret_conv is not None:
+            out_c.write(ret_conv_sfx.replace('\n', '\n\t'))
+            out_c.write("\n\treturn " + ret_info.ret_conv_name + ";")
+        else:
+            out_c.write(";")
+        out_c.write("\n}\n\n")
+
+    out_java.write("""package org.ldk.impl;
 
 public class bindings {
        static {
-               System.loadLibrary(\"lightning\");
+               System.loadLibrary(\"lightningjni\");
        }
 
 """)
+    out_c.write("#include \"org_ldk_impl_bindings.h\"\n")
+    out_c.write("#include <rust_types.h>\n")
+    out_c.write("#include <lightning.h>\n")
+    out_c.write("#include <assert.h>\n")
+    out_c.write("#include <string.h>\n")
+    out_c.write("#include <stdatomic.h>\n\n")
+
+    # XXX: Temporarily write out a manual SecretKey_new() for testing, we should auto-gen this kind of thing
+    out_java.write("\tpublic static native long LDKSecretKey_new();\n\n") # TODO: rm me
+    out_c.write("JNIEXPORT jlong JNICALL Java_org_ldk_impl_bindings_LDKSecretKey_1new(JNIEnv * _env, jclass _b) {\n") # TODO: rm me
+    out_c.write("\tLDKSecretKey* key = (LDKSecretKey*)malloc(sizeof(LDKSecretKey));\n") # TODO: rm me
+    out_c.write("\treturn (long)key;\n") # TODO: rm me
+    out_c.write("}\n") # TODO: rm me
 
     in_block_comment = False
     in_block_enum = False
-    in_block_struct = False
+    cur_block_struct = None
     in_block_union = False
 
     fn_ptr_regex = re.compile("^extern const ([A-Za-z_0-9\* ]*) \(\*(.*)\)\((.*)\);$")
-    fn_ret_arr_regex = re.compile("(.*) \(\*(.*)\((.*)\)\)\[.*\];$")
-    reg_fn_regex = re.compile("([A-Za-z_0-9\* ]*) \*?([a-zA-Z_0-9]*)\((.*)\);$")
+    fn_ret_arr_regex = re.compile("(.*) \(\*(.*)\((.*)\)\)\[([0-9]*)\];$")
+    reg_fn_regex = re.compile("([A-Za-z_0-9\* ]* \*?)([a-zA-Z_0-9]*)\((.*)\);$")
+    const_val_regex = re.compile("^extern const ([A-Za-z_0-9]*) ([A-Za-z_0-9]*);$")
+
+    line_indicates_opaque_regex = re.compile("^   bool _underlying_ref;$")
+    line_indicates_trait_regex = re.compile("^   ([A-Za-z_0-9]* \*?)\(\*([A-Za-z_0-9]*)\)\((const )?void \*this_arg(.*)\);$")
+    assert(line_indicates_trait_regex.match("   uintptr_t (*send_data)(void *this_arg, LDKu8slice data, bool resume_read);"))
+    assert(line_indicates_trait_regex.match("   LDKCVec_MessageSendEventZ (*get_and_clear_pending_msg_events)(const void *this_arg);"))
+    assert(line_indicates_trait_regex.match("   void *(*clone)(const void *this_arg);"))
+    line_field_var_regex = re.compile("^   ([A-Za-z_0-9]*) ([A-Za-z_0-9]*);$")
+    assert(line_field_var_regex.match("   LDKMessageSendEventsProvider MessageSendEventsProvider;"))
+    struct_name_regex = re.compile("^typedef struct (MUST_USE_STRUCT )?(LDK[A-Za-z_0-9]*) {$")
+    assert(struct_name_regex.match("typedef struct LDKCVecTempl_u8 {"))
 
-    for line in f:
+    for line in in_h:
         if in_block_comment:
-            #out_f.write("\t" + line)
+            #out_java.write("\t" + line)
             if line.endswith("*/\n"):
                 in_block_comment = False
-        elif in_block_struct:
+        elif cur_block_struct is not None:
+            cur_block_struct  = cur_block_struct + line
             if line.startswith("} "):
-                in_block_struct = False
+                field_lines = []
+                struct_name = None
+                struct_lines = cur_block_struct.split("\n")
+                is_opaque = False
+                trait_fn_lines = []
+                field_var_lines = []
+
+                for idx, struct_line in enumerate(struct_lines):
+                    if struct_line.strip().startswith("/*"):
+                        in_block_comment = True
+                    if in_block_comment:
+                        if struct_line.endswith("*/"):
+                            in_block_comment = False
+                    else:
+                        struct_name_match = struct_name_regex.match(struct_line)
+                        if struct_name_match is not None:
+                            struct_name = struct_name_match.group(2)
+                        if line_indicates_opaque_regex.match(struct_line):
+                            is_opaque = True
+                        trait_fn_match = line_indicates_trait_regex.match(struct_line)
+                        if trait_fn_match is not None:
+                            trait_fn_lines.append(trait_fn_match)
+                        field_var_match = line_field_var_regex.match(struct_line)
+                        if field_var_match is not None:
+                            field_var_lines.append(field_var_match)
+                        field_lines.append(struct_line)
+
+                assert(struct_name is not None)
+                assert(len(trait_fn_lines) == 0 or not is_opaque)
+                if is_opaque:
+                    opaque_structs.add(struct_name)
+                if len(trait_fn_lines) > 0:
+                    trait_structs.add(struct_name)
+                    out_c.write("typedef struct " + struct_name + "_JCalls {\n")
+                    out_c.write("\tatomic_size_t refcnt;\n")
+                    out_c.write("\tJNIEnv *env;\n")
+                    out_c.write("\tjobject o;\n")
+                    for var_line in field_var_lines:
+                        if var_line.group(1) in trait_structs:
+                            out_c.write("\t" + var_line.group(1) + "_JCalls* " + var_line.group(2) + ";\n")
+                    for fn_line in trait_fn_lines:
+                        if fn_line.group(2) != "free" and fn_line.group(2) != "clone":
+                            out_c.write("\tjmethodID " + fn_line.group(2) + "_meth;\n")
+                    out_c.write("} " + struct_name + "_JCalls;\n")
+
+                    out_java.write("\tpublic interface " + struct_name + " {\n")
+                    java_meths = []
+                    for fn_line in trait_fn_lines:
+                        java_meth_descr = "("
+                        if fn_line.group(2) != "free" and fn_line.group(2) != "clone":
+                            ret_ty_info = java_c_types(fn_line.group(1), None)
+
+                            out_java.write("\t\t " + ret_ty_info.java_ty + " " + fn_line.group(2) + "(")
+                            is_const = fn_line.group(3) is not None
+                            out_c.write(fn_line.group(1) + fn_line.group(2) + "_jcall(")
+                            if is_const:
+                                out_c.write("const void* this_arg")
+                            else:
+                                out_c.write("void* this_arg")
+
+                            arg_names = []
+                            for idx, arg in enumerate(fn_line.group(4).split(',')):
+                                if arg == "":
+                                    continue
+                                if idx >= 2:
+                                    out_java.write(", ")
+                                out_c.write(", ")
+                                arg_conv_info = map_type(arg, True, None, False)
+                                out_c.write(arg.strip())
+                                out_java.write(arg_conv_info.java_ty + " " + arg_conv_info.arg_name)
+                                arg_names.append(arg_conv_info)
+                                java_meth_descr = java_meth_descr + arg_conv_info.java_fn_ty_arg
+                            java_meth_descr = java_meth_descr + ")" + ret_ty_info.java_fn_ty_arg
+                            java_meths.append(java_meth_descr)
+
+                            out_java.write(");\n")
+                            out_c.write(") {\n")
+                            out_c.write("\t" + struct_name + "_JCalls *j_calls = (" + struct_name + "_JCalls*) this_arg;\n")
+
+                            for arg_info in arg_names:
+                                if arg_info.ret_conv is not None:
+                                    out_c.write("\t" + arg_info.ret_conv[0].replace('\n', '\n\t').replace("_env", "j_calls->env"));
+                                    out_c.write(arg_info.arg_name)
+                                    out_c.write(arg_info.ret_conv[1].replace('\n', '\n\t').replace("_env", "j_calls->env") + "\n")
+
+                            if not ret_ty_info.passed_as_ptr:
+                                out_c.write("\treturn (*j_calls->env)->Call" + ret_ty_info.java_ty.title() + "Method(j_calls->env, j_calls->o, j_calls->" + fn_line.group(2) + "_meth")
+                            else:
+                                out_c.write("\t" + fn_line.group(1).strip() + "* ret = (" + fn_line.group(1).strip() + "*)(*j_calls->env)->CallLongMethod(j_calls->env, j_calls->o, j_calls->" + fn_line.group(2) + "_meth");
+
+                            for arg_info in arg_names:
+                                if arg_info.ret_conv is not None:
+                                    out_c.write(", " + arg_info.ret_conv_name)
+                                else:
+                                    out_c.write(", " + arg_info.arg_name)
+                            out_c.write(");\n");
+
+                            if ret_ty_info.passed_as_ptr:
+                                out_c.write("\t" + fn_line.group(1).strip() + " res = *ret;\n")
+                                out_c.write("\tfree(ret);\n")
+                                out_c.write("\treturn res;\n")
+                            out_c.write("}\n")
+                        elif fn_line.group(2) == "free":
+                            out_c.write("void " + struct_name + "_JCalls_free(void* this_arg) {\n")
+                            out_c.write("\t" + struct_name + "_JCalls *j_calls = (" + struct_name + "_JCalls*) this_arg;\n")
+                            out_c.write("\tif (atomic_fetch_sub_explicit(&j_calls->refcnt, 1, memory_order_acquire) == 1) {\n")
+                            out_c.write("\t\t(*j_calls->env)->DeleteGlobalRef(j_calls->env, j_calls->o);\n")
+                            out_c.write("\t\tfree(j_calls);\n")
+                            out_c.write("\t}\n}\n")
+
+                    # Write out a clone function whether we need one or not, as we use them in moving to rust
+                    out_c.write("void* " + struct_name + "_JCalls_clone(const void* this_arg) {\n")
+                    out_c.write("\t" + struct_name + "_JCalls *j_calls = (" + struct_name + "_JCalls*) this_arg;\n")
+                    out_c.write("\tatomic_fetch_add_explicit(&j_calls->refcnt, 1, memory_order_release);\n")
+                    for var_line in field_var_lines:
+                        if var_line.group(1) in trait_structs:
+                            out_c.write("\tatomic_fetch_add_explicit(&j_calls->" + var_line.group(2) + "->refcnt, 1, memory_order_release);\n")
+                    out_c.write("\treturn (void*) this_arg;\n")
+                    out_c.write("}\n")
+
+                    out_java.write("\t}\n")
+
+                    out_java.write("\tpublic static native long " + struct_name + "_new(" + struct_name + " impl")
+                    out_c.write("JNIEXPORT long JNICALL Java_org_ldk_impl_bindings_" + struct_name.replace("_", "_1") + "_1new (JNIEnv * env, jclass _a, jobject o")
+                    for var_line in field_var_lines:
+                        if var_line.group(1) in trait_structs:
+                            out_java.write(", " + var_line.group(1) + " " + var_line.group(2))
+                            out_c.write(", jobject " + var_line.group(2))
+                    out_java.write(");\n")
+                    out_c.write(") {\n")
+
+                    out_c.write("\tjclass c = (*env)->GetObjectClass(env, o);\n")
+                    out_c.write("\tassert(c != NULL);\n")
+                    out_c.write("\t" + struct_name + "_JCalls *calls = malloc(sizeof(" + struct_name + "_JCalls));\n")
+                    out_c.write("\tatomic_init(&calls->refcnt, 1);\n")
+                    out_c.write("\tcalls->env = env;\n")
+                    out_c.write("\tcalls->o = (*env)->NewGlobalRef(env, o);\n")
+                    for (fn_line, java_meth_descr) in zip(trait_fn_lines, java_meths):
+                        if fn_line.group(2) != "free" and fn_line.group(2) != "clone":
+                            out_c.write("\tcalls->" + fn_line.group(2) + "_meth = (*env)->GetMethodID(env, c, \"" + fn_line.group(2) + "\", \"" + java_meth_descr + "\");\n")
+                            out_c.write("\tassert(calls->" + fn_line.group(2) + "_meth != NULL);\n")
+                    out_c.write("\n\t" + struct_name + " *ret = malloc(sizeof(" + struct_name + "));\n")
+                    out_c.write("\tret->this_arg = (void*) calls;\n")
+                    for fn_line in trait_fn_lines:
+                        if fn_line.group(2) != "free" and fn_line.group(2) != "clone":
+                            out_c.write("\tret->" + fn_line.group(2) + " = " + fn_line.group(2) + "_jcall;\n")
+                        elif fn_line.group(2) == "free":
+                            out_c.write("\tret->free = " + struct_name + "_JCalls_free;\n")
+                        else:
+                            out_c.write("\tret->clone = " + struct_name + "_JCalls_clone;\n")
+                    for var_line in field_var_lines:
+                        if var_line.group(1) in trait_structs:
+                            out_c.write("\tret->" + var_line.group(2) + " = *(" + var_line.group(1) + "*)Java_org_ldk_impl_bindings_" + var_line.group(1) + "_1new(env, _a, " + var_line.group(2) + ");\n")
+                            out_c.write("\tcalls->" + var_line.group(2) + " = ret->" + var_line.group(2) + ".this_arg;\n")
+                    out_c.write("\treturn (long)ret;\n")
+                    out_c.write("}\n\n")
+
+                    #out_java.write("/* " + "\n".join(field_lines) + "*/\n")
+                cur_block_struct = None
         elif in_block_union:
             if line.startswith("} "):
                 in_block_union = False
@@ -92,28 +494,32 @@ public class bindings {
             fn_ptr = fn_ptr_regex.match(line)
             fn_ret_arr = fn_ret_arr_regex.match(line)
             reg_fn = reg_fn_regex.match(line)
+            const_val = const_val_regex.match(line)
 
             if line.startswith("#include <"):
                 pass
             elif line.startswith("/*"):
-                #out_f.write("\t" + line)
+                #out_java.write("\t" + line)
                 if not line.endswith("*/\n"):
                     in_block_comment = True
             elif line.startswith("typedef enum "):
                 in_block_enum = True
             elif line.startswith("typedef struct "):
-                in_block_struct = True
+                cur_block_struct = line
             elif line.startswith("typedef union "):
                 in_block_union = True
             elif line.startswith("typedef "):
                 pass
             elif fn_ptr is not None:
-                map_fn(fn_ptr, "")
+                map_fn(fn_ptr, None)
             elif fn_ret_arr is not None:
-                map_fn(fn_ret_arr, "[]")
+                map_fn(fn_ret_arr, fn_ret_arr.group(4))
             elif reg_fn is not None:
-                map_fn(reg_fn, "")
+                map_fn(reg_fn, None)
+            elif const_val_regex is not None:
+                # TODO Map const variables
+                pass
             else:
                 assert(line == "\n")
 
-    out_f.write("}\n");
+    out_java.write("}\n")