first commit

sring.py

@@ -0,0 +1,71 @@
+class sring:
+    
+    #don't mess with defaults when creating a new sring
+    def __init__(self, dat, size=1, eprev=None, enext=None):
+        self.dat = dat
+        self.size = size
+        if eprev is None:
+            self.eprev = self
+            self.enext = self
+        else:
+            self.eprev = eprev
+            self.enext = enext
+    
+    def __getitem__(self, index):
+        return self.rotate(index).dat
+    
+    def __delitem__(self, index):
+        loc = self.rotate(index)
+        loc.eprev.enext = loc.enext
+        loc.enext.eprev = loc.eprev
+        self.propsize(self.size-1)
+    
+    def __str__(self):
+        return str(self.cut())
+    
+    def __len__(self):
+        return self.size
+    
+    def rotate(self, index):
+        if not isinstance(index, int):
+            raise TypeError('index must be an integer')
+        ind = ((index + self.size / 2) % self.size) - self.size / 2
+        if ind == 0:
+            return self
+        elif ind < 0:
+            loc = self
+            while ind != 0:
+                loc = loc.eprev
+                ind += 1
+            return loc
+        elif index > 0:
+            loc = self
+            while ind != 0:
+                loc = loc.enext
+                ind -= 1
+            return loc
+    
+    #inserts AFTER the given index
+    def insert(self, dat, index=-1):
+        target = self.rotate(index)
+        tarnext = target.enext
+        enew = sring(dat, eprev=target, enext = tarnext)
+        target.enext = enew
+        tarnext.eprev = enew
+        self.propsize(self.size+1)
+    
+    def cut(self, index=0):
+        loc = self.rotate(index)
+        data = [loc.dat]
+        nex = loc.enext
+        while nex != loc:
+            data += [nex.dat]
+            nex = nex.enext
+        return data
+
+    def propsize(self, nsize):
+        self.size = nsize
+        loc = self.enext
+        while loc != self:
+            loc.size = nsize
+            loc = loc.enext