Add overload decorator in ltypes

Author: Smit-create

src/runtime/ltypes/ltypes.py

@@ -1,6 +1,53 @@
+from inspect import getfullargspec, getcallargs
+
+# data-types
+
 i32 = []
 i64 = []
 f32 = []
 f64 = []
 c32 = []
 c64 = []
+
+# overloading support
+
+class OverloadedFunction:
+    """
+    A wrapper class for allowing overloading.
+    """
+    global_map = {}
+
+    def __init__(self, func):
+        self.func_name = func.__name__
+        f_list = self.global_map.get(func.__name__, [])
+        f_list.append((func, getfullargspec(func)))
+        self.global_map[func.__name__] = f_list
+
+    def __call__(self, *args, **kwargs):
+        func_map_list = self.global_map.get(self.func_name, False)
+        if not func_map_list:
+            raise Exception("Function not defined")
+        for item in func_map_list:
+            func, key = item
+            try:
+                # This might fail for the cases when arguments don't match
+                ann_dict = getcallargs(func, *args, **kwargs)
+            except TypeError:
+                continue
+            flag = True
+            for k, v in ann_dict.items():
+                if not key.annotations.get(k, False):
+                    flag = False
+                    break
+                else:
+                    if type(v) != key.annotations.get(k):
+                        flag = False
+                        break
+            if flag:
+                return func(*args, **kwargs)
+        raise Exception("Function not found with matching signature")
+
+
+def overload(f):
+    overloaded_f = OverloadedFunction(f)
+    return overloaded_f