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/*
* upb - a minimalist implementation of protocol buffers.
*
* Copyright (c) 2009 Joshua Haberman. See LICENSE for details.
* Defines a delimited (as opposed to null-terminated) string type and some
* library functions for manipulating them.
*
* There are two primary reasons upb uses delimited strings. One is that they
* can be more efficient for some operations because they do not have to scan
* the string to find its length. For example, streql can start by just
* comparing the lengths (very efficient) and scan the strings themselves only
* if the lengths are equal.
*
* More importantly, using delimited strings makes it possible for strings to
* reference substrings of other strings. For example, if I am parsing a
* protobuf I can create a string that references the original protobuf's
* string data. With NULL-termination I would be forced to write a NULL
* into the middle of the protobuf's data, which is less than ideal and in
* some cases not practical or possible.
*/
#ifndef UPB_STRING_H_
#define UPB_STRING_H_
#ifdef __cplusplus
extern "C" {
#endif
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
/* inline if possible, emit standalone code if required. */
#ifndef INLINE
#define INLINE static inline
#endif
#define UPB_MAX(x, y) ((x) > (y) ? (x) : (y))
#define UPB_MIN(x, y) ((x) < (y) ? (x) : (y))
struct upb_string {
/* We expect the data to be 8-bit clean (uint8_t), but char* is such an
* ingrained convention that we follow it. */
char *ptr;
uint32_t byte_len;
uint32_t byte_size; /* How many bytes of ptr we own. */
};
INLINE void upb_strinit(struct upb_string *str)
{
str->ptr = NULL;
str->byte_len = 0;
str->byte_size = 0;
}
INLINE void upb_struninit(struct upb_string *str)
{
if(str->byte_size) free(str->ptr);
}
INLINE struct upb_string *upb_strnew(void)
{
struct upb_string *str = (struct upb_string*)malloc(sizeof(*str));
upb_strinit(str);
return str;
}
INLINE void upb_strfree(struct upb_string *str)
{
upb_struninit(str);
free(str);
}
INLINE void upb_stralloc(struct upb_string *str, uint32_t size)
{
if(str->byte_size < size) {
/* Need to resize. */
str->byte_size = size;
void *oldptr = str->byte_size == 0 ? NULL : str->ptr;
str->ptr = (char*)realloc(oldptr, str->byte_size);
}
}
INLINE void upb_strdrop(struct upb_string *str)
{
upb_struninit(str);
}
INLINE bool upb_streql(struct upb_string *s1, struct upb_string *s2) {
return s1->byte_len == s2->byte_len &&
memcmp(s1->ptr, s2->ptr, s1->byte_len) == 0;
}
INLINE int upb_strcmp(struct upb_string *s1, struct upb_string *s2) {
size_t common_length = UPB_MIN(s1->byte_len, s2->byte_len);
int common_diff = memcmp(s1->ptr, s2->ptr, common_length);
return common_diff == 0 ? (int)s1->byte_len - (int)s2->byte_len : common_diff;
}
INLINE void upb_strcpy(struct upb_string *dest, struct upb_string *src) {
dest->byte_len = src->byte_len;
upb_stralloc(dest, dest->byte_len);
memcpy(dest->ptr, src->ptr, src->byte_len);
}
INLINE struct upb_string *upb_strdup(struct upb_string *s) {
struct upb_string *copy = upb_strnew();
upb_strcpy(copy, s);
return copy;
}
INLINE struct upb_string *upb_strdupc(char *s) {
struct upb_string *copy = upb_strnew();
copy->byte_len = strlen(s);
upb_stralloc(copy, copy->byte_len);
memcpy(copy->ptr, s, copy->byte_len);
return copy;
}
/* Reads an entire file into a newly-allocated string. */
bool upb_strreadfile(const char *filename, struct upb_string *data);
/* Allows defining upb_strings as literals, ie:
* struct upb_string str = UPB_STRLIT("Hello, World!\n");
* Doesn't work with C++ due to lack of struct initializer syntax.
*/
#define UPB_STRLIT(strlit) {.ptr=strlit, .byte_len=sizeof(strlit)-1}
/* Allows using upb_strings in printf, ie:
* struct upb_string str = UPB_STRLIT("Hello, World!\n");
* printf("String is: " UPB_STRFMT, UPB_STRARG(str)); */
#define UPB_STRARG(str) (str)->byte_len, (str)->ptr
#define UPB_STRFMT "%.*s"
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* UPB_H_ */
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