diceroller.py: Refactored Dice object into its own library under lib/

lib/dice.py

@@ -0,0 +1,131 @@
+# dice.py
+#
+# This module contains a class to represent various RPG-style dice expressions.
+# These can then be rolled and the results, both total and individual rolls, returned.
+#
+# This module assumes that the built-in python PRNG (Mersenne Twister) is acceptable.
+# Support for real entropy is an RFE.
+
+import random
+import re
+
+class Dice():
+    # This builds dice out of a simple input format
+    # All of the dark regex magic is contained to this function,
+    # lest it corrupt innocent code
+    @classmethod
+    def from_str(cls, desc):
+        if not re.match(r'^\d+d\d+', desc):
+            raise Exception('Dice format invalid. See --help')
+
+        (n, s) = re.match(r'^(\d+)d(\d+)', desc).groups()
+        num = int(n)
+        sides = int(s)
+        mod = 0
+        drop_low = 0
+        drop_high = 0
+        reroll = 0
+        reroll_times = 0
+
+        for m in re.findall(r'[lh+-]\d+', desc):
+            if m[0] == '-':
+                mod += int(m)
+            elif m[0] == '+':
+                mod += int(m[1:])
+            elif m[0] == 'h':
+                drop_high = int(m[1:])
+            elif m[0] == 'l':
+                drop_low = int(m[1:])
+
+        m = re.search(r'r(\d+)(x\d+)?', desc)
+        if m:
+            (r, rt) = m.groups()
+            reroll = int(r)
+            if rt:
+                reroll_times = int(rt[1:])
+
+        return cls(num, sides, mod, drop_low, drop_high, reroll, reroll_times)
+
+
+    def __init__(self, num, sides, mod, drop_low=0, drop_high=0, reroll=0, reroll_times=0):
+        self.num = num
+        self.sides = sides
+        self.mod = mod
+        self.drop_low = drop_low
+        self.drop_high = drop_high
+        self.reroll = reroll
+        self.reroll_times = reroll_times
+        self.times_rolled = 0
+
+
+    def num_rolls(self):
+        return self.times_rolled
+
+        
+    # Rolls the dice, returns a structure
+    # containing the result plus metadata
+    def roll(self, verbose=False):
+        results = []
+        rerolled = []
+        dropped = []
+
+        # Roll the actual dice, handling rerolls
+        for i in range(0, self.num):
+            count = 0
+            result = 0
+            while result <= self.reroll or result == 0:
+                if self.reroll_times and count >= self.reroll_times:
+                    break
+
+                result = random.randint(1, self.sides)
+                count += 1
+                if result <= self.reroll:
+                    rerolled.append(result)
+
+            results.append(result)
+            
+
+        # Drop any high or low, if specified
+        if self.drop_low or self.drop_high:
+            results.sort()
+
+            if self.drop_low:
+                dropped.extend(results[:self.drop_low])
+                results = results[self.drop_low:]
+
+            if self.drop_high:
+                dropped.extend(results[-1 * self.drop_high:])
+                results = results[:-1 * self.drop_high]
+            
+            random.shuffle(results)
+            
+        # Get the results
+        total = sum(results) + self.mod
+
+        self.times_rolled += 1
+
+        return {'total': total, 'rolls': results, 'dropped': dropped, 'rerolled': rerolled}
+
+
+    def __str__(self):
+        reroll_info = ''
+        drop_info = ''
+        mod_info = ''
+
+        if self.reroll:
+            reroll_info = ' [reroll {}'.format(self.reroll)
+            if self.reroll_times:
+                reroll_info = reroll_info + 'x{}'.format(self.reroll_times)
+            reroll_info = reroll_info + ']'
+
+        if self.drop_low:
+            drop_info = drop_info + ' [drop low {}]'.format(self.drop_low)
+        if self.drop_high:
+            drop_info = drop_info + ' [drop high {}]'.format(self.drop_high)
+
+        if self.mod > 0:
+            mod_info = '+{}'.format(self.mod)
+        elif self.mod < 0:
+            mod_info = '-{}'.format(self.mod)
+
+        return "{num}d{sides}{mod}{drop}{reroll}".format(num=self.num, sides=self.sides, mod=mod_info, drop=drop_info, reroll=reroll_info)