Hi,
This adds a method to binary search in a sorted array_slice.
The implementation is direct copy of vec:bsearch. Moreover, to only
copy it once and not twice, I used const_cast in the non-const
variants to be able to use the const variants. I hope that is
acceptable abuse of const_cast but I'll be happy to change that if
not.
Bootstrapped and tested along code that actually uses it on
x86_64-linux. OK for trunk?
Thanks,
Martin
gcc/ChangeLog:
2022-08-08 Martin Jambor <mjam...@suse.cz>
* vec.h (array_slice::bsearch): New methods.
---
gcc/vec.h | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 94 insertions(+)
diff --git a/gcc/vec.h b/gcc/vec.h
index b0477e1044c..61ebdc4ca13 100644
--- a/gcc/vec.h
+++ b/gcc/vec.h
@@ -2301,6 +2301,14 @@ public:
// True if the array is valid, false if it is an array like INVALID.
bool is_valid () const { return m_base || m_size == 0; }
+ /* Methods for binary search in sorted array_slice. */
+ const T *bsearch (const void *key, int (*compar)(const void *,
+ const void *)) const;
+ T *bsearch (const void *key, int (*compar)(const void *, const void *));
+ const T *bsearch (const void *key,
+ int (*compar)(const void *, const void *, void *), void *) const;
+ T *bsearch (const void *key,
+ int (*compar)(const void *, const void *, void *), void *);
private:
iterator m_base;
unsigned int m_size;
@@ -2361,6 +2369,92 @@ make_array_slice (T *base, unsigned int size)
return array_slice<T> (base, size);
}
+/* Search the contents of the sorted array_slice with a binary search. CMP is
+ the comparison function to pass to bsearch. */
+
+template<typename T>
+inline const T *
+array_slice<T>::bsearch (const void *key,
+ int (*compar) (const void *, const void *)) const
+{
+ const void *base = this->m_base;
+ size_t nmemb = this->size ();
+ size_t size = sizeof (T);
+ /* The following is a copy of glibc stdlib-bsearch.h. */
+ size_t l, u, idx;
+ const void *p;
+ int comparison;
+
+ l = 0;
+ u = nmemb;
+ while (l < u)
+ {
+ idx = (l + u) / 2;
+ p = (const void *) (((const char *) base) + (idx * size));
+ comparison = (*compar) (key, p);
+ if (comparison < 0)
+ u = idx;
+ else if (comparison > 0)
+ l = idx + 1;
+ else
+ return (T *)const_cast<void *>(p);
+ }
+
+ return NULL;
+}
+
+template<typename T>
+inline T *
+array_slice<T>::bsearch (const void *key,
+ int (*compar) (const void *, const void *))
+{
+ return const_cast<T>(bsearch (key, compar));
+}
+
+/* Search the contents of the sorted array_slice with a binary search. CMP is
+ the comparison function to pass to bsearch. */
+
+template<typename T>
+inline const T *
+array_slice<T>::bsearch (const void *key,
+ int (*compar) (const void *, const void *, void *),
+ void *data) const
+{
+ const void *base = this->m_base;
+ size_t nmemb = this->size ();
+ size_t size = sizeof (T);
+ /* The following is a copy of glibc stdlib-bsearch.h. */
+ size_t l, u, idx;
+ const void *p;
+ int comparison;
+
+ l = 0;
+ u = nmemb;
+ while (l < u)
+ {
+ idx = (l + u) / 2;
+ p = (const void *) (((const char *) base) + (idx * size));
+ comparison = (*compar) (key, p, data);
+ if (comparison < 0)
+ u = idx;
+ else if (comparison > 0)
+ l = idx + 1;
+ else
+ return (T *)const_cast<void *>(p);
+ }
+
+ return NULL;
+}
+
+template<typename T>
+inline T *
+array_slice<T>::bsearch (const void *key,
+ int (*compar) (const void *, const void *, void *),
+ void *data)
+{
+ return const_cast<T> (bsearch (key, compar, data));
+}
+
#if (GCC_VERSION >= 3000)
# pragma GCC poison m_vec m_vecpfx m_vecdata
#endif
--
2.37.2
