Map Rust enums with inner fields
[ldk-java] / genbindings.py
index e0b2e184b03e77ec26ec9d3b2ca46fb10c6e88c5..be317e8f455d3eca87b728134ac0b0f0b26dd99e 100755 (executable)
@@ -1,8 +1,8 @@
 #!/usr/bin/env python3
 import sys, re
 
-if len(sys.argv) != 5:
-    print("USAGE: /path/to/lightning.h /path/to/bindings/output.java /path/to/bindings/output.c debug")
+if len(sys.argv) != 6:
+    print("USAGE: /path/to/lightning.h /path/to/bindings/output.java /path/to/bindings/enums/ /path/to/bindings/output.c debug")
     print("debug should be true or false and indicates whether to track allocations and ensure we don't leak")
     sys.exit(1)
 
@@ -43,11 +43,37 @@ class ConvInfo:
             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:
+with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.argv[4], "w") as out_c:
     opaque_structs = set()
     trait_structs = set()
     unitary_enums = set()
 
+    def camel_to_snake(s):
+        # Convert camel case to snake case, in a way that appears to match cbindgen
+        con = "_"
+        ret = ""
+        lastchar = ""
+        lastund = False
+        for char in s:
+            if lastchar.isupper():
+                if not char.isupper() and not lastund:
+                    ret = ret + "_"
+                    lastund = True
+                else:
+                    lastund = False
+                ret = ret + lastchar.lower()
+            else:
+                ret = ret + lastchar
+                if char.isupper() and not lastund:
+                    ret = ret + "_"
+                    lastund = True
+                else:
+                    lastund = False
+            lastchar = char
+            if char.isnumeric():
+                lastund = True
+        return (ret + lastchar.lower()).strip("_")
+
     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):
@@ -105,7 +131,7 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
             if ma.group(1).strip() in unitary_enums:
                 java_ty = ma.group(1).strip()
                 c_ty = "jclass"
-                fn_ty_arg = "Lorg/ldk/impl/bindings$" + ma.group(1).strip() + ";"
+                fn_ty_arg = "Lorg/ldk/enums/" + ma.group(1).strip() + ";"
                 fn_arg = ma.group(2).strip()
                 rust_obj = ma.group(1).strip()
                 take_by_ptr = True
@@ -239,7 +265,7 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
                         # 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 + "), \"" + ty_info.rust_obj + "\");\n*ret = ", ";\nassert(ret->is_owned);\nret->is_owned = false;"),
+                            ret_conv = (ty_info.rust_obj + "* ret = MALLOC(sizeof(" + ty_info.rust_obj + "), \"" + ty_info.rust_obj + "\");\n*ret = ", ";\nDO_ASSERT(ret->is_owned);\nret->is_owned = false;"),
                             ret_conv_name = "(long)ret",
                             arg_conv = None, arg_conv_name = None)
                     else:
@@ -314,7 +340,7 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
     def map_trait(struct_name, field_var_lines, trait_fn_lines):
         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("\tJavaVM *vm;\n")
         out_c.write("\tjobject o;\n")
         for var_line in field_var_lines:
             if var_line.group(1) in trait_structs:
@@ -357,17 +383,19 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
                 out_java.write(");\n")
                 out_c.write(") {\n")
                 out_c.write("\t" + struct_name + "_JCalls *j_calls = (" + struct_name + "_JCalls*) this_arg;\n")
+                out_c.write("\tJNIEnv *env;\n")
+                out_c.write("\tDO_ASSERT((*j_calls->vm)->GetEnv(j_calls->vm, (void**)&env, JNI_VERSION_1_8) == JNI_OK);\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("\t" + arg_info.ret_conv[0].replace('\n', '\n\t').replace("_env", "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")
+                        out_c.write(arg_info.ret_conv[1].replace('\n', '\n\t').replace("_env", "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")
+                    out_c.write("\treturn (*env)->Call" + ret_ty_info.java_ty.title() + "Method(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");
+                    out_c.write("\t" + fn_line.group(1).strip() + "* ret = (" + fn_line.group(1).strip() + "*)(*env)->CallLongMethod(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:
@@ -385,7 +413,9 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
                 out_c.write("static 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\tJNIEnv *env;\n")
+                out_c.write("\t\tDO_ASSERT((*j_calls->vm)->GetEnv(j_calls->vm, (void**)&env, JNI_VERSION_1_8) == JNI_OK);\n")
+                out_c.write("\t\t(*env)->DeleteGlobalRef(env, j_calls->o);\n")
                 out_c.write("\t\tFREE(j_calls);\n")
                 out_c.write("\t}\n}\n")
 
@@ -411,15 +441,15 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
         out_c.write(") {\n")
 
         out_c.write("\tjclass c = (*env)->GetObjectClass(env, o);\n")
-        out_c.write("\tassert(c != NULL);\n")
+        out_c.write("\tDO_ASSERT(c != NULL);\n")
         out_c.write("\t" + struct_name + "_JCalls *calls = MALLOC(sizeof(" + struct_name + "_JCalls), \"" + struct_name + "_JCalls\");\n")
         out_c.write("\tatomic_init(&calls->refcnt, 1);\n")
-        out_c.write("\tcalls->env = env;\n")
+        out_c.write("\tDO_ASSERT((*env)->GetJavaVM(env, &calls->vm) == 0);\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("\tDO_ASSERT(calls->" + fn_line.group(2) + "_meth != NULL);\n")
         out_c.write("\n\t" + struct_name + " ret = {\n")
         out_c.write("\t\t.this_arg = (void*) calls,\n")
         for fn_line in trait_fn_lines:
@@ -465,18 +495,9 @@ with open(sys.argv[1]) as in_h, open(sys.argv[2], "w") as out_java, open(sys.arg
                 dummy_line = fn_line.group(1) + struct_name + "_call_" + fn_line.group(2) + " " + struct_name + "* arg" + fn_line.group(4) + "\n"
                 map_fn(dummy_line, re.compile("([A-Za-z_0-9]*) *([A-Za-z_0-9]*) *(.*)").match(dummy_line), None, "(arg_conv->" + fn_line.group(2) + ")(arg_conv->this_arg")
 
-    out_java.write("""package org.ldk.impl;
-
-public class bindings {
-       static {
-               System.loadLibrary(\"lightningjni\");
-               init(java.lang.Enum.class);
-       }
-""")
     out_c.write("""#include \"org_ldk_impl_bindings.h\"
 #include <rust_types.h>
 #include <lightning.h>
-#include <assert.h>
 #include <string.h>
 #include <stdatomic.h>
 """)
@@ -484,13 +505,16 @@ public class bindings {
     if sys.argv[4] == "false":
         out_c.write("#define MALLOC(a, _) malloc(a)\n")
         out_c.write("#define FREE free\n")
+        out_c.write("#define DO_ASSERT(a) (void)(a)\n")
     else:
-        out_c.write("""
+        out_c.write("""#include <assert.h>
+#define DO_ASSERT(a) do { bool _assert_val = (a); assert(_assert_val); } while(0)
+
 #include <threads.h>
 static mtx_t allocation_mtx;
 
 void __attribute__((constructor)) init_mtx() {
-       assert(mtx_init(&allocation_mtx, mtx_plain) == thrd_success);
+       DO_ASSERT(mtx_init(&allocation_mtx, mtx_plain) == thrd_success);
 }
 
 typedef struct allocation {
@@ -505,45 +529,69 @@ void* MALLOC(size_t len, const char* struct_name) {
        allocation* new_alloc = malloc(sizeof(allocation));
        new_alloc->ptr = res;
        new_alloc->struct_name = struct_name;
-       assert(mtx_lock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(mtx_lock(&allocation_mtx) == thrd_success);
        new_alloc->next = allocation_ll;
        allocation_ll = new_alloc;
-       assert(mtx_unlock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(mtx_unlock(&allocation_mtx) == thrd_success);
        return res;
 }
 
 void FREE(void* ptr) {
        allocation* p = NULL;
-       assert(mtx_lock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(mtx_lock(&allocation_mtx) == thrd_success);
        allocation* it = allocation_ll;
        while (it->ptr != ptr) { p = it; it = it->next; }
        if (p) { p->next = it->next; } else { allocation_ll = it->next; }
-       assert(mtx_unlock(&allocation_mtx) == thrd_success);
-       assert(it->ptr == ptr);
+       DO_ASSERT(mtx_unlock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(it->ptr == ptr);
        free(it);
        free(ptr);
 }
 
 void __attribute__((destructor)) check_leaks() {
        for (allocation* a = allocation_ll; a != NULL; a = a->next) { fprintf(stderr, "%s %p remains\\n", a->struct_name, a->ptr); }
-       assert(allocation_ll == NULL);
+       DO_ASSERT(allocation_ll == NULL);
 }
 """)
+    out_java.write("""package org.ldk.impl;
+import org.ldk.enums.*;
 
-    out_java.write("""
-       static native void init(java.lang.Class c);
+public class bindings {
+       public static class VecOrSliceDef {
+               public long dataptr;
+               public long datalen;
+               public long stride;
+               public VecOrSliceDef(long dataptr, long datalen, long stride) {
+                       this.dataptr = dataptr; this.datalen = datalen; this.stride = stride;
+               }
+       }
+       static {
+               System.loadLibrary(\"lightningjni\");
+               init(java.lang.Enum.class, VecOrSliceDef.class);
+       }
+       static native void init(java.lang.Class c, java.lang.Class slicedef);
 
        public static native boolean deref_bool(long ptr);
        public static native long deref_long(long ptr);
        public static native void free_heap_ptr(long ptr);
-       public static native long u8_vec_len(long vec);
+       public static native byte[] read_bytes(long ptr, long len);
+       public static native byte[] get_u8_slice_bytes(long slice_ptr);
+       public static native long bytes_to_u8_vec(byte[] bytes);
+       public static native long vec_slice_len(long vec);
+       public static native long new_empty_slice_vec();
 
 """)
     out_c.write("""
 jmethodID ordinal_meth = NULL;
-JNIEXPORT void Java_org_ldk_impl_bindings_init(JNIEnv * env, jclass _b, jclass enum_class) {
+jmethodID slicedef_meth = NULL;
+jclass slicedef_cls = NULL;
+JNIEXPORT void Java_org_ldk_impl_bindings_init(JNIEnv * env, jclass _b, jclass enum_class, jclass slicedef_class) {
        ordinal_meth = (*env)->GetMethodID(env, enum_class, "ordinal", "()I");
-       assert(ordinal_meth != NULL);
+       DO_ASSERT(ordinal_meth != NULL);
+       slicedef_meth = (*env)->GetMethodID(env, slicedef_class, "<init>", "(JJJ)V");
+       DO_ASSERT(slicedef_meth != NULL);
+       slicedef_cls = (*env)->NewGlobalRef(env, slicedef_class);
+       DO_ASSERT(slicedef_cls != NULL);
 }
 
 JNIEXPORT jboolean JNICALL Java_org_ldk_impl_bindings_deref_1bool (JNIEnv * env, jclass _a, jlong ptr) {
@@ -555,10 +603,44 @@ JNIEXPORT jlong JNICALL Java_org_ldk_impl_bindings_deref_1long (JNIEnv * env, jc
 JNIEXPORT void JNICALL Java_org_ldk_impl_bindings_free_1heap_1ptr (JNIEnv * env, jclass _a, jlong ptr) {
        FREE((void*)ptr);
 }
-JNIEXPORT jlong JNICALL Java_org_ldk_impl_bindings_u8_1vec_1len (JNIEnv * env, jclass _a, jlong ptr) {
+JNIEXPORT jbyteArray JNICALL Java_org_ldk_impl_bindings_read_1bytes (JNIEnv * _env, jclass _b, jlong ptr, jlong len) {
+       jbyteArray ret_arr = (*_env)->NewByteArray(_env, len);
+       (*_env)->SetByteArrayRegion(_env, ret_arr, 0, len, (unsigned char*)ptr);
+       return ret_arr;
+}
+JNIEXPORT jbyteArray JNICALL Java_org_ldk_impl_bindings_get_1u8_1slice_1bytes (JNIEnv * _env, jclass _b, jlong slice_ptr) {
+       LDKu8slice *slice = (LDKu8slice*)slice_ptr;
+       jbyteArray ret_arr = (*_env)->NewByteArray(_env, slice->datalen);
+       (*_env)->SetByteArrayRegion(_env, ret_arr, 0, slice->datalen, slice->data);
+       return ret_arr;
+}
+JNIEXPORT long JNICALL Java_org_ldk_impl_bindings_bytes_1to_1u8_1vec (JNIEnv * _env, jclass _b, jbyteArray bytes) {
+       LDKCVec_u8Z *vec = (LDKCVec_u8Z*)MALLOC(sizeof(LDKCVec_u8Z), "LDKCVec_u8");
+       vec->datalen = (*_env)->GetArrayLength(_env, bytes);
+       vec->data = (uint8_t*)malloc(vec->datalen); // May be freed by rust, so don't track allocation
+       (*_env)->GetByteArrayRegion (_env, bytes, 0, vec->datalen, vec->data);
+       return (long)vec;
+}
+JNIEXPORT jlong JNICALL Java_org_ldk_impl_bindings_vec_1slice_1len (JNIEnv * env, jclass _a, jlong ptr) {
+        // Check offsets of a few Vec types are all consistent as we're meant to be generic across types
+       _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKCVec_SignatureZ, datalen), "Vec<*> needs to be mapped identically");
+       _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKCVec_MessageSendEventZ, datalen), "Vec<*> needs to be mapped identically");
+       _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKCVec_EventZ, datalen), "Vec<*> needs to be mapped identically");
+       _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKCVec_C2Tuple_usizeTransactionZZ, datalen), "Vec<*> needs to be mapped identically");
        LDKCVec_u8Z *vec = (LDKCVec_u8Z*)ptr;
        return (long)vec->datalen;
 }
+JNIEXPORT long JNICALL Java_org_ldk_impl_bindings_new_1empty_1slice_1vec (JNIEnv * _env, jclass _b) {
+        // Check sizes of a few Vec types are all consistent as we're meant to be generic across types
+       _Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKCVec_SignatureZ), "Vec<*> needs to be mapped identically");
+       _Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKCVec_MessageSendEventZ), "Vec<*> needs to be mapped identically");
+       _Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKCVec_EventZ), "Vec<*> needs to be mapped identically");
+       _Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKCVec_C2Tuple_usizeTransactionZZ), "Vec<*> needs to be mapped identically");
+       LDKCVec_u8Z *vec = (LDKCVec_u8Z*)MALLOC(sizeof(LDKCVec_u8Z), "Empty LDKCVec");
+       vec->data = NULL;
+       vec->datalen = 0;
+       return (long)vec;
+}
 
 // We assume that CVec_u8Z and u8slice are the same size and layout (and thus pointers to the two can be mixed)
 _Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKu8slice), "Vec<u8> and [u8] need to have been mapped identically");
@@ -583,6 +665,7 @@ _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKu8slice, datalen),
     const_val_regex = re.compile("^extern const ([A-Za-z_0-9]*) ([A-Za-z_0-9]*);$")
 
     line_indicates_result_regex = re.compile("^   bool result_ok;$")
+    line_indicates_vec_regex = re.compile("^   ([A-Za-z_0-9]*) \*data;$")
     line_indicates_opaque_regex = re.compile("^   bool is_owned;$")
     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);"))
@@ -597,6 +680,7 @@ _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKu8slice, datalen),
     assert(struct_alias_regex.match("typedef LDKCResultTempl_bool__PeerHandleError LDKCResult_boolPeerHandleErrorZ;"))
 
     result_templ_structs = set()
+    union_enum_items = {}
     for line in in_h:
         if in_block_comment:
             #out_java.write("\t" + line)
@@ -607,6 +691,7 @@ _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKu8slice, datalen),
             if line.startswith("} "):
                 field_lines = []
                 struct_name = None
+                vec_ty = None
                 obj_lines = cur_block_obj.split("\n")
                 is_opaque = False
                 is_result = False
@@ -624,6 +709,7 @@ _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKu8slice, datalen),
                             in_block_comment = False
                     else:
                         struct_name_match = struct_name_regex.match(struct_line)
+                        vec_ty_match = line_indicates_vec_regex.match(struct_line)
                         if struct_name_match is not None:
                             struct_name = struct_name_match.group(3)
                             if struct_name_match.group(1) == "enum":
@@ -637,6 +723,8 @@ _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKu8slice, datalen),
                             is_opaque = True
                         elif line_indicates_result_regex.match(struct_line):
                             is_result = True
+                        elif vec_ty_match is not None and struct_name.startswith("LDKCVecTempl_"):
+                            vec_ty = vec_ty_match.group(1)
                         trait_fn_match = line_indicates_trait_regex.match(struct_line)
                         if trait_fn_match is not None:
                             trait_fn_lines.append(trait_fn_match)
@@ -646,55 +734,166 @@ _Static_assert(offsetof(LDKCVec_u8Z, datalen) == offsetof(LDKu8slice, datalen),
                         field_lines.append(struct_line)
 
                 assert(struct_name is not None)
-                assert(len(trait_fn_lines) == 0 or not (is_opaque or is_unitary_enum or is_union_enum or is_union))
-                assert(not is_opaque or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_union_enum or is_union))
-                assert(not is_unitary_enum or not (len(trait_fn_lines) != 0 or is_opaque or is_union_enum or is_union))
-                assert(not is_union_enum or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_opaque or is_union))
-                assert(not is_union or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_union_enum or is_opaque))
+                assert(len(trait_fn_lines) == 0 or not (is_opaque or is_unitary_enum or is_union_enum or is_union or is_result or vec_ty is not None))
+                assert(not is_opaque or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_union_enum or is_union or is_result or vec_ty is not None))
+                assert(not is_unitary_enum or not (len(trait_fn_lines) != 0 or is_opaque or is_union_enum or is_union or is_result or vec_ty is not None))
+                assert(not is_union_enum or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_opaque or is_union or is_result or vec_ty is not None))
+                assert(not is_union or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_union_enum or is_opaque or is_result or vec_ty is not None))
+                assert(not is_result or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_union_enum or is_opaque or is_union or vec_ty is not None))
+                assert(vec_ty is None or not (len(trait_fn_lines) != 0 or is_unitary_enum or is_union_enum or is_opaque or is_union or is_result))
+
                 if is_opaque:
                     opaque_structs.add(struct_name)
+                    out_java.write("\tpublic static native long " + struct_name + "_optional_none();\n")
+                    out_c.write("JNIEXPORT jlong JNICALL Java_org_ldk_impl_bindings_" + struct_name.replace("_", "_1") + "_1optional_1none (JNIEnv * env, jclass _a) {\n")
+                    out_c.write("\t" + struct_name + " *ret = MALLOC(sizeof(" + struct_name + "), \"" + struct_name + "\");\n")
+                    out_c.write("\tret->inner = NULL;\n")
+                    out_c.write("\treturn (long)ret;\n")
+                    out_c.write("}\n")
                 elif is_result:
                     result_templ_structs.add(struct_name)
-                elif is_unitary_enum:
-                    unitary_enums.add(struct_name)
-                    out_c.write("static inline " + struct_name + " " + struct_name + "_from_java(JNIEnv *env, jclass val) {\n")
-                    out_c.write("\tswitch ((*env)->CallIntMethod(env, val, ordinal_meth)) {\n")
-                    ord_v = 0
-                    for idx, struct_line in enumerate(field_lines):
+                elif vec_ty is not None:
+                    out_java.write("\tpublic static native VecOrSliceDef " + struct_name + "_arr_info(long vec_ptr);\n")
+                    out_c.write("JNIEXPORT jobject JNICALL Java_org_ldk_impl_bindings_" + struct_name.replace("_", "_1") + "_1arr_1info(JNIEnv *env, jclass _b, jlong ptr) {\n")
+                    out_c.write("\t" + struct_name + " *vec = (" + struct_name + "*)ptr;\n")
+                    out_c.write("\treturn (*env)->NewObject(env, slicedef_cls, slicedef_meth, (long)vec->data, (long)vec->datalen, sizeof(" + vec_ty + "));\n")
+                    out_c.write("}\n")
+                elif is_union_enum:
+                    assert(struct_name.endswith("_Tag"))
+                    struct_name = struct_name[:-4]
+                    union_enum_items[struct_name] = {"field_lines": field_lines}
+                elif struct_name.endswith("_Body") and struct_name.split("_")[0] in union_enum_items:
+                    enum_var_name = struct_name.split("_")
+                    union_enum_items[enum_var_name[0]][enum_var_name[1]] = field_lines
+                elif struct_name in union_enum_items:
+                    tag_field_lines = union_enum_items[struct_name]["field_lines"]
+                    init_meth_jty_strs = {}
+                    for idx, struct_line in enumerate(tag_field_lines):
                         if idx == 0:
-                            out_java.write("\tpublic enum " + struct_name + " {\n")
-                        elif idx == len(field_lines) - 3:
+                            out_java.write("\tpublic static class " + struct_name + " {\n")
+                            out_java.write("\t\tprivate " + struct_name + "() {}\n")
+                        elif idx == len(tag_field_lines) - 3:
                             assert(struct_line.endswith("_Sentinel,"))
-                        elif idx == len(field_lines) - 2:
+                        elif idx == len(tag_field_lines) - 2:
+                            out_java.write("\t\tstatic native void init();\n")
                             out_java.write("\t}\n")
-                        elif idx == len(field_lines) - 1:
+                        elif idx == len(tag_field_lines) - 1:
                             assert(struct_line == "")
                         else:
-                            out_java.write("\t" + struct_line + "\n")
-                            out_c.write("\t\tcase %d: return %s;\n" % (ord_v, struct_line.strip().strip(",")))
-                            ord_v = ord_v + 1
-                    out_c.write("\t}\n")
-                    out_c.write("\tassert(false);\n")
+                            var_name = struct_line.strip(' ,')[len(struct_name) + 1:]
+                            out_java.write("\t\tpublic final static class " + var_name + " extends " + struct_name + " {\n")
+                            out_c.write("jclass " + struct_name + "_" + var_name + "_class = NULL;\n")
+                            out_c.write("jmethodID " + struct_name + "_" + var_name + "_meth = NULL;\n")
+                            init_meth_jty_str = ""
+                            init_meth_params = ""
+                            init_meth_body = ""
+                            if "LDK" + var_name in union_enum_items[struct_name]:
+                                enum_var_lines = union_enum_items[struct_name]["LDK" + var_name]
+                                for idx, field in enumerate(enum_var_lines):
+                                    if idx != 0 and idx < len(enum_var_lines) - 2:
+                                        field_ty = java_c_types(field.strip(' ;'), None)
+                                        out_java.write("\t\t\tpublic " + field_ty.java_ty + " " + field_ty.var_name + ";\n")
+                                        init_meth_jty_str = init_meth_jty_str + field_ty.java_fn_ty_arg
+                                        if idx > 1:
+                                            init_meth_params = init_meth_params + ", "
+                                        init_meth_params = init_meth_params + field_ty.java_ty + " " + field_ty.var_name
+                                        init_meth_body = init_meth_body + "this." + field_ty.var_name + " = " + field_ty.var_name + "; "
+                                out_java.write("\t\t\t" + var_name + "(" + init_meth_params + ") { ")
+                                out_java.write(init_meth_body)
+                                out_java.write("}\n")
+                            out_java.write("\t\t}\n")
+                            init_meth_jty_strs[var_name] = init_meth_jty_str
+                    out_java.write("\tstatic { " + struct_name + ".init(); }\n")
+                    out_java.write("\tpublic static native " + struct_name + " " + struct_name + "_ref_from_ptr(long ptr);\n");
+
+                    out_c.write("JNIEXPORT void JNICALL Java_org_ldk_impl_bindings_00024" + struct_name.replace("_", "_1") + "_init (JNIEnv * env, jclass _a) {\n")
+                    for idx, struct_line in enumerate(tag_field_lines):
+                        if idx != 0 and idx < len(tag_field_lines) - 3:
+                            var_name = struct_line.strip(' ,')[len(struct_name) + 1:]
+                            out_c.write("\t" + struct_name + "_" + var_name + "_class =\n")
+                            out_c.write("\t\t(*env)->NewGlobalRef(env, (*env)->FindClass(env, \"Lorg/ldk/impl/bindings$" + struct_name + "$" + var_name + ";\"));\n")
+                            out_c.write("\tDO_ASSERT(" + struct_name + "_" + var_name + "_class != NULL);\n")
+                            out_c.write("\t" + struct_name + "_" + var_name + "_meth = (*env)->GetMethodID(env, " + struct_name + "_" + var_name + "_class, \"<init>\", \"(" + init_meth_jty_strs[var_name] + ")V\");\n")
+                            out_c.write("\tDO_ASSERT(" + struct_name + "_" + var_name + "_meth != NULL);\n")
                     out_c.write("}\n")
-
-                    ord_v = 0
-                    out_c.write("static inline jclass " + struct_name + "_to_java(JNIEnv *env, " + struct_name + " val) {\n")
-                    out_c.write("\t// TODO: This is pretty inefficient, we really need to cache the field IDs and class\n")
-                    out_c.write("\tjclass enum_class = (*env)->FindClass(env, \"Lorg/ldk/impl/bindings$" + struct_name + ";\");\n")
-                    out_c.write("\tassert(enum_class != NULL);\n")
-                    out_c.write("\tswitch (val) {\n")
-                    for idx, struct_line in enumerate(field_lines):
-                        if idx > 0 and idx < len(field_lines) - 3:
-                            variant = struct_line.strip().strip(",")
-                            out_c.write("\t\tcase " + variant + ": {\n")
-                            out_c.write("\t\t\tjfieldID field = (*env)->GetStaticFieldID(env, enum_class, \"" + variant + "\", \"Lorg/ldk/impl/bindings$" + struct_name + ";\");\n")
-                            out_c.write("\t\t\tassert(field != NULL);\n")
-                            out_c.write("\t\t\treturn (*env)->GetStaticObjectField(env, enum_class, field);\n")
-                            out_c.write("\t\t}\n")
-                            ord_v = ord_v + 1
-                    out_c.write("\t\tdefault: assert(false);\n")
-                    out_c.write("\t}\n")
-                    out_c.write("}\n\n")
+                    out_c.write("JNIEXPORT jobject JNICALL Java_org_ldk_impl_bindings_" + struct_name.replace("_", "_1") + "_1ref_1from_1ptr (JNIEnv * env, jclass _c, jlong ptr) {\n")
+                    out_c.write("\t" + struct_name + " *obj = (" + struct_name + "*)ptr;\n")
+                    out_c.write("\tswitch(obj->tag) {\n")
+                    for idx, struct_line in enumerate(tag_field_lines):
+                        if idx != 0 and idx < len(tag_field_lines) - 3:
+                            var_name = struct_line.strip(' ,')[len(struct_name) + 1:]
+                            out_c.write("\t\tcase " + struct_name + "_" + var_name + ":\n")
+                            out_c.write("\t\t\treturn (*env)->NewObject(env, " + struct_name + "_" + var_name + "_class, " + struct_name + "_" + var_name + "_meth")
+                            if "LDK" + var_name in union_enum_items[struct_name]:
+                                enum_var_lines = union_enum_items[struct_name]["LDK" + var_name]
+                                out_c.write(",\n\t\t\t\t")
+                                for idx, field in enumerate(enum_var_lines):
+                                    if idx != 0 and idx < len(enum_var_lines) - 2:
+                                        field_ty = java_c_types(field.strip(' ;'), None)
+                                        if idx >= 2:
+                                            out_c.write(", ")
+                                        if field_ty.is_ptr:
+                                            out_c.write("(long)")
+                                        elif field_ty.passed_as_ptr or field_ty.arr_len is not None:
+                                            out_c.write("(long)&")
+                                        out_c.write("obj->" + camel_to_snake(var_name) + "." + field_ty.var_name)
+                                out_c.write("\n\t\t\t")
+                            out_c.write(");\n")
+                    out_c.write("\t\tdefault: abort();\n")
+                    out_c.write("\t}\n}\n")
+                elif is_unitary_enum:
+                    with open(sys.argv[3] + "/" + struct_name + ".java", "w") as out_java_enum:
+                        out_java_enum.write("package org.ldk.enums;\n\n")
+                        unitary_enums.add(struct_name)
+                        out_c.write("static inline " + struct_name + " " + struct_name + "_from_java(JNIEnv *env, jclass val) {\n")
+                        out_c.write("\tswitch ((*env)->CallIntMethod(env, val, ordinal_meth)) {\n")
+                        ord_v = 0
+                        for idx, struct_line in enumerate(field_lines):
+                            if idx == 0:
+                                out_java_enum.write("public enum " + struct_name + " {\n")
+                            elif idx == len(field_lines) - 3:
+                                assert(struct_line.endswith("_Sentinel,"))
+                            elif idx == len(field_lines) - 2:
+                                out_java_enum.write("\t; static native void init();\n")
+                                out_java_enum.write("\tstatic { init(); }\n")
+                                out_java_enum.write("}")
+                                out_java.write("\tstatic { " + struct_name + ".values(); /* Force enum statics to run */ }\n")
+                            elif idx == len(field_lines) - 1:
+                                assert(struct_line == "")
+                            else:
+                                out_java_enum.write(struct_line + "\n")
+                                out_c.write("\t\tcase %d: return %s;\n" % (ord_v, struct_line.strip().strip(",")))
+                                ord_v = ord_v + 1
+                        out_c.write("\t}\n")
+                        out_c.write("\tabort();\n")
+                        out_c.write("}\n")
+
+                        ord_v = 0
+                        out_c.write("static jclass " + struct_name + "_class = NULL;\n")
+                        for idx, struct_line in enumerate(field_lines):
+                            if idx > 0 and idx < len(field_lines) - 3:
+                                variant = struct_line.strip().strip(",")
+                                out_c.write("static jfieldID " + struct_name + "_" + variant + " = NULL;\n")
+                        out_c.write("JNIEXPORT void JNICALL Java_org_ldk_enums_" + struct_name.replace("_", "_1") + "_init (JNIEnv * env, jclass clz) {\n")
+                        out_c.write("\t" + struct_name + "_class = (*env)->NewGlobalRef(env, clz);\n")
+                        out_c.write("\tDO_ASSERT(" + struct_name + "_class != NULL);\n")
+                        for idx, struct_line in enumerate(field_lines):
+                            if idx > 0 and idx < len(field_lines) - 3:
+                                variant = struct_line.strip().strip(",")
+                                out_c.write("\t" + struct_name + "_" + variant + " = (*env)->GetStaticFieldID(env, " + struct_name + "_class, \"" + variant + "\", \"Lorg/ldk/enums/" + struct_name + ";\");\n")
+                                out_c.write("\tDO_ASSERT(" + struct_name + "_" + variant + " != NULL);\n")
+                        out_c.write("}\n")
+                        out_c.write("static inline jclass " + struct_name + "_to_java(JNIEnv *env, " + struct_name + " val) {\n")
+                        out_c.write("\tswitch (val) {\n")
+                        for idx, struct_line in enumerate(field_lines):
+                            if idx > 0 and idx < len(field_lines) - 3:
+                                variant = struct_line.strip().strip(",")
+                                out_c.write("\t\tcase " + variant + ":\n")
+                                out_c.write("\t\t\treturn (*env)->GetStaticObjectField(env, " + struct_name + "_class, " + struct_name + "_" + variant + ");\n")
+                                ord_v = ord_v + 1
+                        out_c.write("\t\tdefault: abort();\n")
+                        out_c.write("\t}\n")
+                        out_c.write("}\n\n")
                 elif len(trait_fn_lines) > 0:
                     trait_structs.add(struct_name)
                     map_trait(struct_name, field_var_lines, trait_fn_lines)