Tests for pointer slicing.

tests/run/slice_ptr.pyx

+from libc.stdlib cimport malloc, free
+from cpython.object cimport Py_EQ, Py_NE
+
+def double_ptr_slice(x, L, int a, int b):
+    """
+    >>> L = range(10)
+    >>> double_ptr_slice(5, L, 0, 10)
+    >>> double_ptr_slice(6, L, 0, 10)
+    >>> double_ptr_slice(None, L, 0, 10)
+    >>> double_ptr_slice(0, L, 3, 7)
+    >>> double_ptr_slice(5, L, 3, 7)
+    >>> double_ptr_slice(9, L, 3, 7)
+    
+    >>> double_ptr_slice(EqualsEvens(), L, 0, 10)
+    >>> double_ptr_slice(EqualsEvens(), L, 1, 10)
+    """
+    cdef double *L_c = NULL
+    try:
+        L_c = <double*>malloc(len(L) * sizeof(double))
+        for i, a in enumerate(L):
+            L_c[i] = L[i]
+        assert (x in L_c[:b]) == (x in L[:b])
+        assert (x in L_c[a:b]) == (x in L[a:b])
+        assert (x in L_c[a:b:2]) == (x in L[a:b:2])
+    finally:
+        free(L_c)
+
+def void_ptr_slice(py_x, L, int a, int b):
+    """
+    >>> L = range(10)
+    >>> void_ptr_slice(5, L, 0, 10)
+    >>> void_ptr_slice(6, L, 0, 10)
+    >>> void_ptr_slice(None, L, 0, 10)
+    >>> void_ptr_slice(0, L, 3, 7)
+    >>> void_ptr_slice(5, L, 3, 7)
+    >>> void_ptr_slice(9, L, 3, 7)
+    """
+    # I'm using the fact that small Python ints are cached.
+    cdef void **L_c = NULL
+    cdef void *x = <void*>py_x
+    try:
+        L_c = <void**>malloc(len(L) * sizeof(void*))
+        for i, a in enumerate(L):
+            L_c[i] = <void*>L[i]
+        assert (x in L_c[:b]) == (py_x in L[:b])
+        assert (x in L_c[a:b]) == (py_x in L[a:b])
+#        assert (x in L_c[a:b:2]) == (py_x in L[a:b:2])
+    finally:
+        free(L_c)
+
+cdef class EqualsEvens:
+    """
+    >>> e = EqualsEvens()
+    >>> e == 2
+    True
+    >>> e == 5
+    False
+    >>> [e == k for k in range(4)]
+    [True, False, True, False]
+    """
+    def __richcmp__(self, other, int op):
+        if op == Py_EQ:
+            return other % 2 == 0
+        elif op == Py_NE:
+            return other % 2 == 1
+        else:
+            return False
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