Merge pull request #37 from lance6716/implement_abs

Implement abs.

Compiler/types.py

@@ -456,6 +456,9 @@ class cint(_clear, _int):
     def __neg__(self):
         return 0 - self
 
+    def __abs__(self):
+        return (self >= 0).if_else(self, -self)
+
     @vectorize
     def __invert__(self):
         res = cint()
@@ -1041,6 +1044,10 @@ class sint(_secret, _int):
     def __neg__(self):
         return 0 - self
 
+    @vectorize
+    def __abs__(self):
+        return (self >= 0).if_else(self, -self)
+
     @read_mem_value
     @vectorize
     def __lt__(self, other, bit_length=None, security=None):
@@ -1956,6 +1963,7 @@ class sfloat(_number):
         s: sign bit
         """
     __slots__ = ['v', 'p', 'z', 's', 'size']
+
     # single precision
     vlen = 24
     plen = 8