feat: restructured code

pjvm/stackframe.py

@@ -0,0 +1,45 @@
+import struct
+from typing import List
+
+from .clazz import Class, Method, Code
+from .exceptions import PJVMException
+from .old_jtypes import JObj
+
+
+class Frame:
+    ip: int = 0
+    clazz: Class
+    method: Method
+    code: Code
+    stack: List[JObj]
+    this: JObj
+    local_variables: List
+
+    def __init__(self, clazz: Class, method: Method):
+        self.clazz = clazz
+        self.method = method
+        self.code = self.method.code
+        self.stack = []
+        self.local_variables = [None for _ in range(self.code.max_locals)]
+
+    def get_byte(self, idx: int) -> int:
+        return struct.unpack('>b', self.code.code[idx:idx + 1])[0]
+
+    def get_short(self, idx: int) -> int:
+        return struct.unpack('>h', self.code.code[idx:idx + 2])[0]
+
+    def get_int(self, idx: int) -> int:
+        return struct.unpack('>i', self.code.code[idx:idx + 4])[0]
+
+    def set_local(self, val: JObj, index: int):
+        if index > self.code.max_locals:
+            raise PJVMException("Local out of bound!")
+        self.local_variables[index] = val
+
+    def get_local(self, index: int) ->JObj:
+        if index > self.code.max_locals:
+            raise PJVMException("Local out of bound!")
+        val = self.local_variables[index]
+        if val is None:
+            raise PJVMException("Local not set")
+        return val