Improve identification of BlockState

The previous heuristic broke in 20w21a.

burger/toppings/entitymetadata.py

@@ -352,6 +352,8 @@ def identify_serializer(classloader, cls, classes, verbose):
             name = "Chat"
         elif inner_type == classes["position"]:
             name = "BlockPos"
+        elif inner_type == classes["blockstate"]:
+            name = "BlockState"
         else:
             # Try some more tests, based on the class itself:
             try:
@@ -360,18 +362,12 @@ def identify_serializer(classloader, cls, classes, verbose):
                     name = "Rotations"
                 elif content_cf.constants.find_one(type_=String, f=lambda c: c == "down"):
                     name = "Facing"
-                elif content_cf.constants.find_one(type_=String, f=lambda c: c == "minecraft:air"):
-                    # This method only works in 1.14, where BlockState isn't an interface
-                    name = "BlockState"
                 elif content_cf.constants.find_one(type_=String, f=lambda c: c == "FALL_FLYING"):
                     assert content_cf.access_flags.acc_enum
                     name = "Pose"
                 elif content_cf.access_flags.acc_interface:
                     # Make some _very_ bad assumptions here; both of these are hard to identify:
-                    if name_prefix == "Opt":
-                        name = "BlockState"
-                    else:
-                        name = "Particle"
+                    name = "Particle"
             except:
                 if verbose:
                     print("Failed to determine name of metadata content type %s" % inner_type)

burger/toppings/identify.py

@@ -196,6 +196,21 @@ def is_protected_final(m):
             if cf:
                 return 'position', cf.this.name.value
 
+        if value == 'Getting block state':
+            # This message is found in Chunk, in the method getBlockState.
+            # We could also theoretically identify BlockPos from this method,
+            # but currently identify only allows marking one class at a time.
+            class_file = classloader[path]
+
+            for method in class_file.methods:
+                for ins in method.code.disassemble():
+                    if ins.mnemonic in ("ldc", "ldc_w"):
+                        if ins.operands[0] == 'Getting block state':
+                            return 'blockstate', method.returns.name
+            else:
+                if verbose:
+                    print("Found chunk, but didn't find the method that returns blockstate")
+
 
 class IdentifyTopping(Topping):
     """Finds important superclasses needed by other toppings."""
@@ -207,6 +222,7 @@ class IdentifyTopping(Topping):
         "identify.block.list",
         "identify.block.register",
         "identify.blockstatecontainer",
+        "identify.blockstate",
         "identify.chatcomponent",
         "identify.entity.list",
         "identify.entity.trackerentry",