# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1484151752 -3600
# Node ID d2e12678f77b16746ca126ddc53e76a3c588e1c4
# Parent  088b8ad14e33169087c728bad2e020022011d7a6
Extended hashing to tuples as well as strings. Fixed sequence comparisons by
testing for TypeError and returning NotImplemented when sequences are compared
to non-sequence objects.

diff -r 088b8ad14e33 -r d2e12678f77b lib/__builtins__/sequence.py
--- a/lib/__builtins__/sequence.py	Wed Jan 11 12:26:04 2017 +0100
+++ b/lib/__builtins__/sequence.py	Wed Jan 11 17:22:32 2017 +0100
@@ -19,6 +19,7 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
+from __builtins__.int import maxint
 from native import isinstance as _isinstance
 
 class itemaccess:
@@ -156,6 +157,30 @@
 
         return 0
 
+class hashable(itemaccess):
+
+    "An abstract class providing support for hashable sequences."
+
+    _p = maxint / 32
+    _a = 31
+
+    def _hashvalue(self, fn):
+
+        """
+        Return a value for hashing purposes for the sequence using the given
+        'fn' on each item.
+        """
+
+        result = 0
+        l = self.__len__()
+        i = 0
+
+        while i < l:
+            result = (result * self._a + fn(self.__get_single_item__(i))) % self._p
+            i += 1
+
+        return result
+
 class sequence(itemaccess):
 
     "A common base class for sequence types."
@@ -214,6 +239,18 @@
 
         "Return whether this sequence is equal to 'other'."
 
+        try:
+            return self._eq(other)
+        except TypeError:
+            return NotImplemented
+
+    def _eq(self, other):
+
+        """
+        Return whether this sequence is equal to 'other' sequence. Note that
+        this method will raise a TypeError if 'other' is not a sequence.
+        """
+
         # Sequences must have equal lengths to be equal.
 
         n = self.__len__()
diff -r 088b8ad14e33 -r d2e12678f77b lib/__builtins__/str.py
--- a/lib/__builtins__/str.py	Wed Jan 11 12:26:04 2017 +0100
+++ b/lib/__builtins__/str.py	Wed Jan 11 17:22:32 2017 +0100
@@ -19,20 +19,16 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-from __builtins__.int import maxint
 from __builtins__.operator import _negate
-from __builtins__.sequence import itemaccess
+from __builtins__.sequence import hashable, itemaccess
 from __builtins__.types import check_int
 from native import str_add, str_lt, str_gt, str_eq, str_len, str_nonempty, \
                    str_substr
 
-class basestring(itemaccess):
+class basestring(hashable):
 
     "The base class for all strings."
 
-    _p = maxint / 32
-    _a = 31
-
     def __init__(self, other=None):
 
         "Initialise the string, perhaps from 'other'."
@@ -62,15 +58,7 @@
 
         "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
+        return self._hashvalue(ord)
 
     def _binary_op(self, op, other):
 
diff -r 088b8ad14e33 -r d2e12678f77b lib/__builtins__/tuple.py
--- a/lib/__builtins__/tuple.py	Wed Jan 11 12:26:04 2017 +0100
+++ b/lib/__builtins__/tuple.py	Wed Jan 11 17:22:32 2017 +0100
@@ -20,11 +20,11 @@
 """
 
 from __builtins__.iterator import itemiterator
-from __builtins__.sequence import sequence
+from __builtins__.sequence import hashable, sequence
 from native import list_element, list_init, list_len, list_setsize, \
                    list_setelement
 
-class tuple(sequence):
+class tuple(sequence, hashable):
 
     "Implementation of tuple."
 
@@ -47,6 +47,12 @@
                 list_setelement(self.__data__, i, arg)
                 i += 1
 
+    def __hash__(self):
+
+        "Return a hashable value for the tuple."
+
+        return self._hashvalue(hash)
+
     def __getslice__(self, start, end=None):
 
         "Return a slice starting from 'start', with the optional 'end'."
diff -r 088b8ad14e33 -r d2e12678f77b tests/dict.py
--- a/tests/dict.py	Wed Jan 11 12:26:04 2017 +0100
+++ b/tests/dict.py	Wed Jan 11 17:22:32 2017 +0100
@@ -5,37 +5,56 @@
     for key, value in d.items():
         return value
 
-d = {10 : "a", 20 : "b", "c" : 30}
+d = {10 : "a", 20 : "b", "c" : 30, (1, 2) : "d"}
+print "# d: ",
 print d
 print d[10]                             # a
 print d[20]                             # b
 print d["c"]                            # 30
+print d[(1, 2)]                         # d
 try:
     print d[30]                         # should fail with an exception
 except KeyError, exc:
     print "d[30]: key not found", exc.key
 
 l = f(d)
+print "# l: ",
 print l
 print 10 in l                          	# True
 print 20 in l                          	# True
 print "c" in l                          # True
+print "d" in l                          # False
 print 30 in l                          	# False
+print (1, 2) in l                       # True
 
 l = d.values()
+print "# l: ",
 print l
 print "a" in l                          # True
 print "b" in l                          # True
+print "c" in l                          # False
+print "d" in l                          # True
 print 30 in l                           # True
-print "c" in l                          # False
+print (1, 2) in l                       # False
 
-v = g(d) # either "a" or "b" or 30
+v = g(d) # either "a" or "b" or 30 or "d"
+print "# v: ",
 print v
-print v == "a" or v == "b" or v == 30   # True
-print v == 10 or v == 20 or v == "c"    # False
+print v == "a" or v == "b" or v == 30 or v == "d"   # True
+print v == 10 or v == 20 or v == "c" or v == (1, 2) # False
 
 l = d.items()
+print "# l: ",
 print l
 print (10, "a") in l                    # True
 print ("c", 30) in l                    # True
+print ((1, 2), "d") in l                # True
 print (10, "b") in l                    # False
+
+# Try to put a list key in a dictionary.
+
+try:
+    d[[1, 2]] = "e"
+    print d[[1, 2]]
+except TypeError:
+    print "d[[1, 2]]: key not appropriate"