Merge lp:~stefanor/ibid/calc-336195 into lp:~ibid-core/ibid/old-trunk-pack-0.92

[Stefano Rivera]

[Stefano Rivera (stefanor)]

Rip it to shreds! (Or accept)

[Stefano Rivera (stefanor)]

Come on Vhata, don't be afraid

[lp:~stefanor/ibid/calc-336195]

597. By Stefano Rivera on 2009-04-18

Use ast / compiler instead of expression munging

598. By Stefano Rivera on 2009-04-18

Comments

599. By Stefano Rivera on 2009-04-18

Timeout bc

Unmerged revisions

=== modified file 'ibid/plugins/math.py'
--- ibid/plugins/math.py	2009-03-11 11:49:44 +0000
+++ ibid/plugins/math.py	2009-04-16 08:14:59 +0000
@@ -1,3 +1,4 @@
+import logging
 import re
 from subprocess import Popen, PIPE
 
@@ -7,6 +8,7 @@
 from ibid.utils import file_in_path, unicode_output
 
 help = {}
+log = logging.getLogger('math')
 
 help['bc'] = u'Calculate mathematical expressions using bc'
 class BC(Processor):
@@ -42,13 +44,22 @@
             raise Exception("BC Error: %s" % error)
 
 help['calc'] = u'Returns the anwser to mathematical expressions'
+class LimitException(Exception):
+    pass
+
+def limited_pow(*args):
+    for arg, limit in zip(args, (1e100, 200)):
+        if isinstance(arg, int) and (arg > limit or arg < -limit):
+            raise LimitException
+    return pow(*args)
+
 class Calc(Processor):
     u"""[calc] <expression>"""
     feature = 'calc'
 
     priority = 500
 
-    extras = ('abs', 'pow', 'round', 'min', 'max')
+    extras = ('abs', 'round', 'min', 'max')
     banned = ('for', 'yield', 'lambda')
 
     # Create a safe dict to pass to eval() as locals
@@ -57,6 +68,7 @@
     del safe['__builtins__']
     for function in extras:
         safe[function] = eval(function)
+    safe['pow'] = limited_pow
 
     @match(r'^(?:calc\s+)?(.+?)$')
     def calculate(self, event, expression):
@@ -64,6 +76,44 @@
             if term in expression:
                 return
 
+        # Replace the power operator with our limited pow function
+        # Due to its binding, we try to match from right to left, but respect brackets
+        pow_re = re.compile(r'^(.*\)|(.*?)((?:[0-9.]+[eE]-?)?\d+))\s*\*\*\s*(\w*\(.*|[+-~]?\s*[0-9.]+(?:[eE]-?\d+)?)(.*?)$')
+        func_re = re.compile(r'^(.*?[\s(])(\w+)$')
+        while '**' in expression:
+            brleft, prefix, left, right, suffix = pow_re.match(expression).groups()
+            if left == None and prefix == None:
+                left = brleft
+                prefix = u''
+
+            if ')' in left:
+                brackets = 0
+                for pos, c in enumerate(reversed(left)):
+                    if c == ')':
+                        brackets += 1
+                    elif c == '(':
+                        brackets -= 1
+                        if brackets == 0:
+                            prefix, left = prefix + left[:-pos - 1], left[-pos - 1:]
+                            # The open bracket may have been preceeded by a function name
+                            m = func_re.match(prefix)
+                            if m:
+                                prefix, left = m.group(1), m.group(2) + left
+
+            if '(' in right:
+                brackets = 0
+                for pos, c in enumerate(right):
+                    if c == '(':
+                        brackets += 1
+                    elif c == ')':
+                        brackets -= 1
+                        if brackets == 0:
+                            right, suffix = right[:pos + 1], right[pos + 1:]
+
+            expression = u'%s pow(%s, %s) %s' % (prefix, left, right, suffix)
+
+        #log.debug('Normalised expression to %s', expression)
+
         try:
             result = eval(expression, {'__builtins__': None}, self.safe)
         except ZeroDivisionError, e:
@@ -76,6 +126,9 @@
             if unicode(e) == u"math domain error":
                 event.addresponse(u"I can't do that: %s", unicode(e))
                 return
+        except LimitException, e:
+            event.addresponse(u"I'm afraid I'm not allowed to play with big numbers")
+            return
         except Exception, e:
             return