On 4/15/20 11:16 AM, Richard W.M. Jones wrote:
Can be used for building up lists of things, especially
lists of strings.
---
common/include/Makefile.am | 6 +++
common/include/test-vector.c | 90 +++++++++++++++++++++++++++++++++
common/include/vector.h | 96 ++++++++++++++++++++++++++++++++++++
.gitignore | 1 +
4 files changed, 193 insertions(+)
+++ b/common/include/vector.h
+/* Simple implementation of appendable vector. There are two main
+ * use-cases we consider: lists of strings (either with a defined
+ * length, or NULL-terminated), and lists of numbers. It is generic
+ * so could be used for lists of anything (eg. structs) where being
+ * able to append easily is important.
+ */
+
+#ifndef NBDKIT_VECTOR_H
+#define NBDKIT_VECTOR_H
+
+#include <assert.h>
+
+#define DEFINE_VECTOR_TYPE(name, type) \
+ struct name { \
+ type *ptr; /* Pointer to array of items. */ \
+ size_t size; /* Number of valid items in the array. */ \
+ size_t alloc; /* Number of items allocated. */ \
+ }; \
+ typedef struct name name; \
+ static inline int \
+ name##_extend (name *v, size_t n) \
+ { \
+ return generic_vector_extend ((struct generic_vector *)v, n, \
+ sizeof (type)); \
+ } \
+ static inline int \
+ name##_append (name *v, type elem) \
+ { \
+ if (v->size >= v->alloc) { \
+ if (name##_extend (v, 1) == -1) return -1; \
+ } \
+ v->ptr[v->size++] = elem; \
+ return 0; \
+ } \
+ static inline void \
+ name##_iter (name *v, void (*f) (type elem)) \
Do we want an iterator that can take a void* opaque argument, as in:
name##_iter_arg (name *v, void (*f) (type elem, void *o), void *o)
Of course, since you want to pass 'free' to string_vector, you'll still
want the form without an opaque argument as well.
+ { \
+ size_t i; \
+ for (i = 0; i < v->size; ++i) \
+ f (v->ptr[i]); \
+ }
Should we allow the callback to return a value, where returning 0 can
abort the iteration early?
+
+#define empty_vector { .ptr = NULL, .size = 0, .alloc = 0 }
Nice that this initializer is type-agnostic.
+
+struct generic_vector {
+ void *ptr;
+ size_t size;
+ size_t alloc;
+};
+
+static int
+generic_vector_extend (struct generic_vector *v, size_t n, size_t itemsize)
+{
+ void *newptr;
+
+ newptr = realloc (v->ptr, (n + v->alloc) * itemsize);
+ if (newptr == NULL)
+ return -1;
+ v->ptr = newptr;
+ v->alloc += n;
+ return 0;
+}
Do we really want this implemented in the header?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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