# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1480636545 -3600
# Node ID 503985ccf89356b025d382e8ed45f958ccf9fb90
# Parent  6cfa2f4aaca2ae06d5057cc392cf72910b0f79c1
Added a simple hash function for strings; expanded string and dictionary tests.

diff -r 6cfa2f4aaca2 -r 503985ccf893 lib/__builtins__/str.py
--- a/lib/__builtins__/str.py	Fri Dec 02 00:54:32 2016 +0100
+++ b/lib/__builtins__/str.py	Fri Dec 02 00:55:45 2016 +0100
@@ -27,6 +27,9 @@
 
     "The base class for all strings."
 
+    _p = 0x03ffffff
+    _a = 31
+
     def __init__(self):
 
         "Initialise the string."
@@ -37,6 +40,20 @@
 
         self.__data__ = None
 
+    def __hash__(self):
+
+        "Return a value for hashing purposes."
+
+        result = 0
+        l = self.__len__()
+        i = 0
+
+        while i < l:
+            result = (result * self._a + ord(self.__get_single_item__(i))) % self._p
+            i += 1
+
+        return result
+
     def __iadd__(self, other):
 
         "Return a new string for the operation."
diff -r 6cfa2f4aaca2 -r 503985ccf893 tests/dict.py
--- a/tests/dict.py	Fri Dec 02 00:54:32 2016 +0100
+++ b/tests/dict.py	Fri Dec 02 00:55:45 2016 +0100
@@ -5,9 +5,11 @@
     for key, value in d.items():
         return value
 
-d = {10 : "a", 20 : "b"}
+d = {10 : "a", 20 : "b", "c" : 30}
+print d
 print d[10]                             # a
 print d[20]                             # b
+print d["c"]                            # 30
 try:
     print d[30]                         # should fail with an exception
 except KeyError, exc:
@@ -17,20 +19,23 @@
 print l
 print 10 in l                          	# True
 print 20 in l                          	# True
+print "c" in l                          # True
 print 30 in l                          	# False
 
 l = d.values()
 print l
 print "a" in l                          # True
 print "b" in l                          # True
+print 30 in l                           # True
 print "c" in l                          # False
 
-v = g(d) # either "a" or "b"
+v = g(d) # either "a" or "b" or 30
 print v
-print v == "a" or v == "b"              # True
-print v == 10 or v == 20                # False
+print v == "a" or v == "b" or v == 30   # True
+print v == 10 or v == 20 or v == "c"    # False
 
 l = d.items()
 print l
 print (10, "a") in l                    # True
+print ("c", 30) in l                    # True
 print (10, "b") in l                    # False
diff -r 6cfa2f4aaca2 -r 503985ccf893 tests/string.py
--- a/tests/string.py	Fri Dec 02 00:54:32 2016 +0100
+++ b/tests/string.py	Fri Dec 02 00:55:45 2016 +0100
@@ -20,3 +20,5 @@
     print ord(s)            # should raise an exception
 except ValueError, exc:
     print "ord(s): value is not appropriate", exc.value
+
+print hash(s)