some code to get started

lib/causal.py

@@ -0,0 +1,90 @@
+import sys
+
+if sys.version_info[0] < 3:
+    raise "Must be using Python 3"
+
+class Causal:
+    def __init__(self, causalcode=""):
+        self.causalcode = causalcode
+        self._description = ""
+        self._title = ""
+        self._prechac = ""
+        self._sequence = ""
+        self._fourhanded = ""
+
+    # https://docs.python.org/3/library/functions.html#property
+
+    @property
+    def description(self):
+        return self._description
+
+    @description.setter
+    def description(self, value):
+        self._description = value
+
+    @property
+    def title(self):
+        return self._title
+
+    @title.setter
+    def title(self, value):
+        self._title = value
+
+    @property
+    def prechac(self):
+        return self._prechac
+
+    @prechac.setter
+    def prechac(self, value):
+        self._prechac = value
+
+    @property
+    def sequence(self):
+        return self._sequence
+
+    @sequence.setter
+    def sequence(self, value):
+        self._sequence = value
+
+    @property
+    def fourhanded(self):
+        return self._fourhanded
+
+    @fourhanded.setter
+    def fourhanded(self, value):
+        if self.isvalid_fourhanded(value):
+            self._fourhanded = str(value)
+        else:
+            raise Exception("Can't parse as fourhanded siteswap")
+        # convert to prechac and fill prechac value
+
+    def isvalid_fourhanded(self, value):
+        if type(value) == int:
+            value = str(value)
+        elif type(value) == str:
+            if value.isdigit():
+                next
+            else:
+                return False
+        else:
+            return False
+
+        # inspired by https://icculus.org/jugglemaster/docs/validate.txt
+        lst = [1] * len(value)
+        for i, c in enumerate(value):
+            j = ( i + int(c) ) % len(value)
+            lst[j] = lst[j] - 1
+        for i in lst:
+            if i != 0:
+                return False
+        return True
+
+    def fourhanded_to_local(self, value):
+        # local notation from https://jonglieren-jena.de/ppa/anthology.pdf
+        # This is the local siteswap of the pattern accompanying a global siteswap. Subscripts
+        # indicate the starting positions of the different jugglers. So than in
+        # A7B65 the juggler A starts with a 7 while B starts with a 6
+
+        if not self.isvalid_fourhanded(value):
+            raise Exception("Can't parse as fourhanded siteswap")
+        return