strbuf.h

#ifndef STRBUF_H
#define STRBUF_H

#include <stddef.h>

/*
 * Minimal strbuf implementation for standalone graph.c
 * Only implements functions actually used by graph.c
 */

struct strbuf {
	size_t alloc;
	size_t len;
	char *buf;
};

extern char strbuf_slopbuf[];

#define STRBUF_INIT { 0, 0, strbuf_slopbuf }

/* Initialize a strbuf. Optionally pre-allocate 'hint' bytes. */
void strbuf_init(struct strbuf *sb, size_t hint);

/* Release the buffer memory. Safe to call multiple times. */
void strbuf_release(struct strbuf *sb);

/* Ensure at least 'extra' more bytes can be added without realloc */
void strbuf_grow(struct strbuf *sb, size_t extra);

/* Set length, ensuring NUL termination. Use for truncating or after manual writes. */
static inline void strbuf_setlen(struct strbuf *sb, size_t len)
{
	if (len > (sb->alloc ? sb->alloc - 1 : 0)) {
		/* Caller is responsible for not exceeding allocated space */
		return;
	}
	sb->len = len;
	if (sb->buf != strbuf_slopbuf)
		sb->buf[len] = '\0';
}

/* Reset to empty string (keeps allocated memory) */
static inline void strbuf_reset(struct strbuf *sb)
{
	strbuf_setlen(sb, 0);
}

/* Add a single character */
void strbuf_addch(struct strbuf *sb, int c);

/* Add 'n' copies of character 'c' */
void strbuf_addchars(struct strbuf *sb, int c, size_t n);

/* Add a NUL-terminated string */
void strbuf_addstr(struct strbuf *sb, const char *s);

/* Add 'len' bytes from buffer */
void strbuf_add(struct strbuf *sb, const void *data, size_t len);

/* Return number of bytes that can be added without realloc */
static inline size_t strbuf_avail(const struct strbuf *sb)
{
	return sb->alloc ? sb->alloc - sb->len - 1 : 0;
}

#endif /* STRBUF_H */