// sds尾部隐含有一个‘\0‘；sds是以len字段来判断是否到达字符串末尾// 所以sds存储的字符串中间可以出现‘\0‘，即sds字符串是二进制安全的// 分配一个新sds，buf数组存储内容initsds sdsnewlen(const void *init, size_t initlen) {    void *sh;    sds s;    char type = sdsReqType(initlen); // 根据长度大小选择合适的sds头部    /* Empty strings are usually created in order to append. Use type 8     * since type 5 is not good at this. */    if (type == SDS_TYPE_5 && initlen == 0) type = SDS_TYPE_8;    int hdrlen = sdsHdrSize(type); // 获取sds头部大小    unsigned char *fp; /* flags pointer. */    // 为sds分配内存，总大小为：头部大小+存储字符串的长度+末尾隐含的空字符大小    sh = s_malloc(hdrlen+initlen+1);     if (!init)        memset(sh, 0, hdrlen+initlen+1); // 内存初始化为0    if (sh == NULL) return NULL;    s = (char*)sh+hdrlen; // buf数组的起始地址    fp = ((unsigned char*)s)-1; // 指向flags字段    // 初始化sds头部的len,alloc,flags字段    switch(type) {        case SDS_TYPE_5: {            *fp = type | (initlen << SDS_TYPE_BITS);            break;        }        case SDS_TYPE_8: {            SDS_HDR_VAR(8,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }        case SDS_TYPE_16: {            SDS_HDR_VAR(16,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }        case SDS_TYPE_32: {            SDS_HDR_VAR(32,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }        case SDS_TYPE_64: {            SDS_HDR_VAR(64,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }    }    // 初始化buf数组    if (initlen && init)        memcpy(s, init, initlen); // 拷贝init到buf数组    s[initlen] = ‘\0‘; // 添加末尾的空字符    return s;}

 // 为sds的len字段增加addlen个字节，剩余空间不足时会引起空间重新分配sds sdsMakeRoomFor(sds s, size_t addlen) {    void *sh, *newsh;    size_t avail = sdsavail(s);    size_t len, newlen;    char type, oldtype = s[-1] & SDS_TYPE_MASK;    int hdrlen;    /* Return ASAP if there is enough space left. */    if (avail >= addlen) return s; // sds剩余空间足够    len = sdslen(s);    sh = (char*)s-sdsHdrSize(oldtype);    newlen = (len+addlen); // sds剩余空间不够，新的len为len+addlen        // 下面两步实现空间预分配    if (newlen < SDS_MAX_PREALLOC) // 新长度小于1M，则len设为2*(len+addlen)大小        newlen *= 2;    else        newlen += SDS_MAX_PREALLOC; // 新长度大于1M，则len设为 len+1M 大小    type = sdsReqType(newlen); // 新len对应的sds头部    /* Don‘t use type 5: the user is appending to the string and type 5 is     * not able to remember empty space, so sdsMakeRoomFor() must be called     * at every appending operation. */    if (type == SDS_TYPE_5) type = SDS_TYPE_8;    hdrlen = sdsHdrSize(type);    if (oldtype==type) {        newsh = s_realloc(sh, hdrlen+newlen+1);        if (newsh == NULL) return NULL;        s = (char*)newsh+hdrlen;    } else {        /* Since the header size changes, need to move the string forward,         * and can‘t use realloc */        newsh = s_malloc(hdrlen+newlen+1);        if (newsh == NULL) return NULL;        memcpy((char*)newsh+hdrlen, s, len+1);        s_free(sh);        s = (char*)newsh+hdrlen;        s[-1] = type;        sdssetlen(s, len);    }    sdssetalloc(s, newlen);    return s;}

/* SDSLib 2.0 -- A C dynamic strings library * 简单动态字符串 */#ifndef __SDS_H#define __SDS_H#define SDS_MAX_PREALLOC (1024*1024) // 1M，空间预分配使用#include <sys/types.h>#include <stdarg.h>#include <stdint.h>// 指向存储数据的起始地址typedef char *sds;/* Note: sdshdr5 is never used, we just access the flags byte directly. * However is here to document the layout of type 5 SDS strings. */// sds由两部分组成：sds头部(即下面的各种结构体)、真正存储字符串的字符数组// 这两部分在内存上连续 // len : 已存储的字符串长度// alloc : 能存储的字符串的最大容量，不包括sds头部和结尾的NULL字符// flags : 标志位，最低三位代表了sds头部类型// buf[] : 字符数组，存储字符串// __attribute__ ((__packed__)) : // 使得编译器不会因为内存对齐而在结构体中填充字节，以保证内存的紧凑，使得下面的s[-1]得到正确的地址// char buf[] : 初始时不占用内存，而且使得头部内存和存储字符串的内存地址连续。// sdshdr5比较特殊,flags字段低3位代表sds头部类型，高5位代表已存储的字符串长度// 分为不同类型的头部，目的是为了存储不同长度的字符串使用不同类型，从而节省内存 struct __attribute__ ((__packed__)) sdshdr5 {    unsigned char flags; /* 3 lsb of type, and 5 msb of string length */    char buf[];};struct __attribute__ ((__packed__)) sdshdr8 {    uint8_t len; /* used */    uint8_t alloc; /* excluding the header and null terminator */    unsigned char flags; /* 3 lsb of type, 5 unused bits */    char buf[];};struct __attribute__ ((__packed__)) sdshdr16 {    uint16_t len; /* used */    uint16_t alloc; /* excluding the header and null terminator */    unsigned char flags; /* 3 lsb of type, 5 unused bits */    char buf[];};struct __attribute__ ((__packed__)) sdshdr32 {    uint32_t len; /* used */    uint32_t alloc; /* excluding the header and null terminator */    unsigned char flags; /* 3 lsb of type, 5 unused bits */    char buf[];};struct __attribute__ ((__packed__)) sdshdr64 {    uint64_t len; /* used */    uint64_t alloc; /* excluding the header and null terminator */    unsigned char flags; /* 3 lsb of type, 5 unused bits */    char buf[];};// flags的低三位代表不同类型的sds头部：#define SDS_TYPE_5  0#define SDS_TYPE_8  1#define SDS_TYPE_16 2#define SDS_TYPE_32 3#define SDS_TYPE_64 4#define SDS_TYPE_MASK 7#define SDS_TYPE_BITS 3// 返回一个指向sds头部的起始地址的指针#define SDS_HDR_VAR(T,s) struct sdshdr##T *sh = (void*)((s)-(sizeof(struct sdshdr##T)));// 返回sds头部的起始地址#define SDS_HDR(T,s) ((struct sdshdr##T *)((s)-(sizeof(struct sdshdr##T))))// 获取sdshdr5类型的sds存储的字符串长度#define SDS_TYPE_5_LEN(f) ((f)>>SDS_TYPE_BITS)// 获取buf数组中sds存储的字符串长度static inline size_t sdslen(const sds s) {    unsigned char flags = s[-1]; // 内存空间连续，所以往后移1个字节，便是flags字段    switch(flags&SDS_TYPE_MASK) { // 和flags低3位相与，得到sds头部类型        case SDS_TYPE_5:            return SDS_TYPE_5_LEN(flags);        case SDS_TYPE_8:            return SDS_HDR(8,s)->len; // 先移动到sds头部的起始地址，进而可以直接获取len字段的值。下同        case SDS_TYPE_16:            return SDS_HDR(16,s)->len;        case SDS_TYPE_32:            return SDS_HDR(32,s)->len;        case SDS_TYPE_64:            return SDS_HDR(64,s)->len;    }    return 0;}// 获取buf数组中剩余可用的内存大小static inline size_t sdsavail(const sds s) {    unsigned char flags = s[-1]; // 后移1字节，得到flags字段    switch(flags&SDS_TYPE_MASK) { // 得到sds头部类型        case SDS_TYPE_5: {            return 0;        }        case SDS_TYPE_8: {            SDS_HDR_VAR(8,s);            return sh->alloc - sh->len; // 总大小减去已使用大小        }        case SDS_TYPE_16: {            SDS_HDR_VAR(16,s);            return sh->alloc - sh->len;        }        case SDS_TYPE_32: {            SDS_HDR_VAR(32,s);            return sh->alloc - sh->len;        }        case SDS_TYPE_64: {            SDS_HDR_VAR(64,s);            return sh->alloc - sh->len;        }    }    return 0;}// 设置sds头部的len字段static inline void sdssetlen(sds s, size_t newlen) {    unsigned char flags = s[-1];    switch(flags&SDS_TYPE_MASK) {        case SDS_TYPE_5:            {                // 对于sdshdr5，则是设置flags的高5位                unsigned char *fp = ((unsigned char*)s)-1;                *fp = SDS_TYPE_5 | (newlen << SDS_TYPE_BITS);            }            break;        case SDS_TYPE_8:            SDS_HDR(8,s)->len = newlen;            break;        case SDS_TYPE_16:            SDS_HDR(16,s)->len = newlen;            break;        case SDS_TYPE_32:            SDS_HDR(32,s)->len = newlen;            break;        case SDS_TYPE_64:            SDS_HDR(64,s)->len = newlen;            break;    }}// 将sds头部的len字段增加incstatic inline void sdsinclen(sds s, size_t inc) {    unsigned char flags = s[-1];    switch(flags&SDS_TYPE_MASK) {        case SDS_TYPE_5:            {                // 对于sdshdr5，则是设置flags的高5位                unsigned char *fp = ((unsigned char*)s)-1;                unsigned char newlen = SDS_TYPE_5_LEN(flags)+inc;                *fp = SDS_TYPE_5 | (newlen << SDS_TYPE_BITS);            }            break;        case SDS_TYPE_8:            SDS_HDR(8,s)->len += inc;            break;        case SDS_TYPE_16:            SDS_HDR(16,s)->len += inc;            break;        case SDS_TYPE_32:            SDS_HDR(32,s)->len += inc;            break;        case SDS_TYPE_64:            SDS_HDR(64,s)->len += inc;            break;    }}/* sdsalloc() = sdsavail() + sdslen() */// 获取sds的buf数组总的大小static inline size_t sdsalloc(const sds s) {    unsigned char flags = s[-1];    switch(flags&SDS_TYPE_MASK) {        case SDS_TYPE_5:            return SDS_TYPE_5_LEN(flags);        case SDS_TYPE_8:            return SDS_HDR(8,s)->alloc;        case SDS_TYPE_16:            return SDS_HDR(16,s)->alloc;        case SDS_TYPE_32:            return SDS_HDR(32,s)->alloc;        case SDS_TYPE_64:            return SDS_HDR(64,s)->alloc;    }    return 0;}// 设置sds的buf数组总的大小static inline void sdssetalloc(sds s, size_t newlen) {    unsigned char flags = s[-1];    switch(flags&SDS_TYPE_MASK) {        case SDS_TYPE_5:            /* Nothing to do, this type has no total allocation info. */            break;        case SDS_TYPE_8:            SDS_HDR(8,s)->alloc = newlen;            break;        case SDS_TYPE_16:            SDS_HDR(16,s)->alloc = newlen;            break;        case SDS_TYPE_32:            SDS_HDR(32,s)->alloc = newlen;            break;        case SDS_TYPE_64:            SDS_HDR(64,s)->alloc = newlen;            break;    }}sds sdsnewlen(const void *init, size_t initlen);sds sdsnew(const char *init);sds sdsempty(void);sds sdsdup(const sds s);void sdsfree(sds s);sds sdsgrowzero(sds s, size_t len);sds sdscatlen(sds s, const void *t, size_t len);sds sdscat(sds s, const char *t);sds sdscatsds(sds s, const sds t);sds sdscpylen(sds s, const char *t, size_t len);sds sdscpy(sds s, const char *t);sds sdscatvprintf(sds s, const char *fmt, va_list ap);#ifdef __GNUC__sds sdscatprintf(sds s, const char *fmt, ...)    __attribute__((format(printf, 2, 3)));#elsesds sdscatprintf(sds s, const char *fmt, ...);#endifsds sdscatfmt(sds s, char const *fmt, ...);sds sdstrim(sds s, const char *cset);void sdsrange(sds s, int start, int end);void sdsupdatelen(sds s);void sdsclear(sds s);int sdscmp(const sds s1, const sds s2);sds *sdssplitlen(const char *s, int len, const char *sep, int seplen, int *count);void sdsfreesplitres(sds *tokens, int count);void sdstolower(sds s);void sdstoupper(sds s);sds sdsfromlonglong(long long value);sds sdscatrepr(sds s, const char *p, size_t len);sds *sdssplitargs(const char *line, int *argc);sds sdsmapchars(sds s, const char *from, const char *to, size_t setlen);sds sdsjoin(char **argv, int argc, char *sep);sds sdsjoinsds(sds *argv, int argc, const char *sep, size_t seplen);/* Low level functions exposed to the user API */sds sdsMakeRoomFor(sds s, size_t addlen);void sdsIncrLen(sds s, int incr);sds sdsRemoveFreeSpace(sds s);size_t sdsAllocSize(sds s);void *sdsAllocPtr(sds s);/* Export the allocator used by SDS to the program using SDS. * Sometimes the program SDS is linked to, may use a different set of * allocators, but may want to allocate or free things that SDS will * respectively free or allocate. */void *sds_malloc(size_t size);void *sds_realloc(void *ptr, size_t size);void sds_free(void *ptr);#ifdef REDIS_TESTint sdsTest(int argc, char *argv[]);#endif#endif

/* SDSLib 2.0 -- A C dynamic strings library */#include <stdio.h>#include <stdlib.h>#include <string.h>#include <ctype.h>#include <assert.h>#include "sds.h"#include "sdsalloc.h"// 获取type类型的sds对应的头部类型大小static inline int sdsHdrSize(char type) {    switch(type&SDS_TYPE_MASK) {        case SDS_TYPE_5:            return sizeof(struct sdshdr5);        case SDS_TYPE_8:            return sizeof(struct sdshdr8);        case SDS_TYPE_16:            return sizeof(struct sdshdr16);        case SDS_TYPE_32:            return sizeof(struct sdshdr32);        case SDS_TYPE_64:            return sizeof(struct sdshdr64);    }    return 0;}// 根据不同大小选用不同类型的sds头部static inline char sdsReqType(size_t string_size) {    if (string_size < 1<<5) // 0~2^5-1        return SDS_TYPE_5;    if (string_size < 1<<8) // 2^5~2^8-1        return SDS_TYPE_8;    if (string_size < 1<<16) // 2^8~2^16-1        return SDS_TYPE_16;    if (string_size < 1<<32) // 2^16~2^32-1        return SDS_TYPE_32;    return SDS_TYPE_64; // 2^32~}/* Create a new sds string with the content specified by the ‘init‘ pointer * and ‘initlen‘. * If NULL is used for ‘init‘ the string is initialized with zero bytes. * * The string is always null-termined (all the sds strings are, always) so * even if you create an sds string with: * * mystring = sdsnewlen("abc",3); * * You can print the string with printf() as there is an implicit \0 at the * end of the string. However the string is binary safe and can contain * \0 characters in the middle, as the length is stored in the sds header. */ // sds尾部隐含有一个‘\0‘；sds是以len字段来判断是否到达字符串末尾// 所以sds存储的字符串中间可以出现‘\0‘，即sds字符串是二进制安全的// 分配一个新sds，buf数组存储内容initsds sdsnewlen(const void *init, size_t initlen) {    void *sh;    sds s;    char type = sdsReqType(initlen); // 根据长度大小选择合适的sds头部    /* Empty strings are usually created in order to append. Use type 8     * since type 5 is not good at this. */    if (type == SDS_TYPE_5 && initlen == 0) type = SDS_TYPE_8;    int hdrlen = sdsHdrSize(type); // 获取sds头部大小    unsigned char *fp; /* flags pointer. */    // 为sds分配内存，总大小为：头部大小+存储字符串的长度+末尾隐含的空字符大小    sh = s_malloc(hdrlen+initlen+1);     if (!init)        memset(sh, 0, hdrlen+initlen+1); // 内存初始化为0    if (sh == NULL) return NULL;    s = (char*)sh+hdrlen; // buf数组的起始地址    fp = ((unsigned char*)s)-1; // 指向flags字段    // 初始化sds头部的len,alloc,flags字段    switch(type) {        case SDS_TYPE_5: {            *fp = type | (initlen << SDS_TYPE_BITS);            break;        }        case SDS_TYPE_8: {            SDS_HDR_VAR(8,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }        case SDS_TYPE_16: {            SDS_HDR_VAR(16,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }        case SDS_TYPE_32: {            SDS_HDR_VAR(32,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }        case SDS_TYPE_64: {            SDS_HDR_VAR(64,s);            sh->len = initlen;            sh->alloc = initlen;            *fp = type;            break;        }    }    // 初始化buf数组    if (initlen && init)        memcpy(s, init, initlen); // 拷贝init到buf数组    s[initlen] = ‘\0‘; // 添加末尾的空字符    return s;}/* Create an empty (zero length) sds string. Even in this case the string * always has an implicit null term. */// 分配一个空的sdssds sdsempty(void) {    return sdsnewlen("",0);}/* Create a new sds string starting from a null terminated C string. */// 分配一个新sds，以c字符串初始化其buf数组sds sdsnew(const char *init) {    size_t initlen = (init == NULL) ? 0 : strlen(init);    return sdsnewlen(init, initlen);}/* Duplicate an sds string. */// 复制一个sdssds sdsdup(const sds s) {    return sdsnewlen(s, sdslen(s));}/* Free an sds string. No operation is performed if ‘s‘ is NULL. */// 释放一个sdsvoid sdsfree(sds s) {    if (s == NULL) return;    s_free((char*)s-sdsHdrSize(s[-1])); // 先移动到sds头部起始地址，再释放}/* Set the sds string length to the length as obtained with strlen(), so * considering as content only up to the first null term character. * * This function is useful when the sds string is hacked manually in some * way, like in the following example: * * s = sdsnew("foobar"); * s[2] = ‘\0‘; * sdsupdatelen(s); * printf("%d\n", sdslen(s)); * * The output will be "2", but if we comment out the call to sdsupdatelen() * the output will be "6" as the string was modified but the logical length * remains 6 bytes. */  // 以第1个‘\0‘位置为sds长度，重新设置sds长度 // 这样做目的是将第一个‘\0‘后面的部分全部截断void sdsupdatelen(sds s) {    int reallen = strlen(s); // 以strlen()来计算长度，到第1个‘\0‘截止    sdssetlen(s, reallen);}/* Modify an sds string in-place to make it empty (zero length). * However all the existing buffer is not discarded but set as free space * so that next append operations will not require allocations up to the * number of bytes previously available. */  // 清空sds内容，len字段清为0 // 但之前的空间并未释放，可避免以后的重新分配内存。实现惰性空间释放void sdsclear(sds s) {    sdssetlen(s, 0);    s[0] = ‘\0‘;}/* Enlarge the free space at the end of the sds string so that the caller * is sure that after calling this function can overwrite up to addlen * bytes after the end of the string, plus one more byte for nul term. * * Note: this does not change the *length* of the sds string as returned * by sdslen(), but only the free buffer space we have. */  // 为sds的len字段增加addlen个字节，剩余空间不足时会引起空间重新分配sds sdsMakeRoomFor(sds s, size_t addlen) {    void *sh, *newsh;    size_t avail = sdsavail(s);    size_t len, newlen;    char type, oldtype = s[-1] & SDS_TYPE_MASK;    int hdrlen;    /* Return ASAP if there is enough space left. */    if (avail >= addlen) return s; // sds剩余空间足够    len = sdslen(s);    sh = (char*)s-sdsHdrSize(oldtype);    newlen = (len+addlen); // sds剩余空间不够，新的len为len+addlen        // 下面两步实现空间预分配    if (newlen < SDS_MAX_PREALLOC) // 新长度小于1M，则len设为2*(len+addlen)大小        newlen *= 2;    else        newlen += SDS_MAX_PREALLOC; // 新长度大于1M，则len设为 len+1M 大小    type = sdsReqType(newlen); // 新len对应的sds头部    /* Don‘t use type 5: the user is appending to the string and type 5 is     * not able to remember empty space, so sdsMakeRoomFor() must be called     * at every appending operation. */    if (type == SDS_TYPE_5) type = SDS_TYPE_8;    hdrlen = sdsHdrSize(type);    if (oldtype==type) {        newsh = s_realloc(sh, hdrlen+newlen+1);        if (newsh == NULL) return NULL;        s = (char*)newsh+hdrlen;    } else {        /* Since the header size changes, need to move the string forward,         * and can‘t use realloc */        newsh = s_malloc(hdrlen+newlen+1);        if (newsh == NULL) return NULL;        memcpy((char*)newsh+hdrlen, s, len+1);        s_free(sh);        s = (char*)newsh+hdrlen;        s[-1] = type;        sdssetlen(s, len);    }    sdssetalloc(s, newlen);    return s;}/* Reallocate the sds string so that it has no free space at the end. The * contained string remains not altered, but next concatenation operations * will require a reallocation. * * After the call, the passed sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. */sds sdsRemoveFreeSpace(sds s) {    void *sh, *newsh;    char type, oldtype = s[-1] & SDS_TYPE_MASK;    int hdrlen;    size_t len = sdslen(s);    sh = (char*)s-sdsHdrSize(oldtype);    type = sdsReqType(len);    hdrlen = sdsHdrSize(type);    if (oldtype==type) {        newsh = s_realloc(sh, hdrlen+len+1);        if (newsh == NULL) return NULL;        s = (char*)newsh+hdrlen;    } else {        newsh = s_malloc(hdrlen+len+1);        if (newsh == NULL) return NULL;        memcpy((char*)newsh+hdrlen, s, len+1);        s_free(sh);        s = (char*)newsh+hdrlen;        s[-1] = type;        sdssetlen(s, len);    }    sdssetalloc(s, len);    return s;}/* Return the total size of the allocation of the specifed sds string, * including: * 1) The sds header before the pointer. * 2) The string. * 3) The free buffer at the end if any. * 4) The implicit null term. */ // 返回sds的总长度：sds头部+alloc字段+结尾的空字符size_t sdsAllocSize(sds s) {    size_t alloc = sdsalloc(s);    return sdsHdrSize(s[-1])+alloc+1;}/* Return the pointer of the actual SDS allocation (normally SDS strings * are referenced by the start of the string buffer). */ // 返回sds的起始地址void *sdsAllocPtr(sds s) {    return (void*) (s-sdsHdrSize(s[-1]));}/* Increment the sds length and decrements the left free space at the * end of the string according to ‘incr‘. Also set the null term * in the new end of the string. * * This function is used in order to fix the string length after the * user calls sdsMakeRoomFor(), writes something after the end of * the current string, and finally needs to set the new length. * * Note: it is possible to use a negative increment in order to * right-trim the string. * * Usage example: * * Using sdsIncrLen() and sdsMakeRoomFor() it is possible to mount the * following schema, to cat bytes coming from the kernel to the end of an * sds string without copying into an intermediate buffer: * * oldlen = sdslen(s); * s = sdsMakeRoomFor(s, BUFFER_SIZE); * nread = read(fd, s+oldlen, BUFFER_SIZE); * ... check for nread <= 0 and handle it ... * sdsIncrLen(s, nread); */  // 更新sds的len字段，incr可以为负，表示减少lenvoid sdsIncrLen(sds s, int incr) {    unsigned char flags = s[-1];    size_t len;    switch(flags&SDS_TYPE_MASK) {        case SDS_TYPE_5: {            unsigned char *fp = ((unsigned char*)s)-1;            unsigned char oldlen = SDS_TYPE_5_LEN(flags);            assert((incr > 0 && oldlen+incr < 32) || (incr < 0 && oldlen >= (unsigned int)(-incr)));            *fp = SDS_TYPE_5 | ((oldlen+incr) << SDS_TYPE_BITS);            len = oldlen+incr;            break;        }        case SDS_TYPE_8: {            SDS_HDR_VAR(8,s);            assert((incr >= 0 && sh->alloc-sh->len >= incr) || (incr < 0 && sh->len >= (unsigned int)(-incr)));            len = (sh->len += incr);            break;        }        case SDS_TYPE_16: {            SDS_HDR_VAR(16,s);            assert((incr >= 0 && sh->alloc-sh->len >= incr) || (incr < 0 && sh->len >= (unsigned int)(-incr)));            len = (sh->len += incr);            break;        }        case SDS_TYPE_32: {            SDS_HDR_VAR(32,s);            assert((incr >= 0 && sh->alloc-sh->len >= (unsigned int)incr) || (incr < 0 && sh->len >= (unsigned int)(-incr)));            len = (sh->len += incr);            break;        }        case SDS_TYPE_64: {            SDS_HDR_VAR(64,s);            assert((incr >= 0 && sh->alloc-sh->len >= (uint64_t)incr) || (incr < 0 && sh->len >= (uint64_t)(-incr)));            len = (sh->len += incr);            break;        }        default: len = 0; /* Just to avoid compilation warnings. */    }    s[len] = ‘\0‘;}/* Grow the sds to have the specified length. Bytes that were not part of * the original length of the sds will be set to zero. * * if the specified length is smaller than the current length, no operation * is performed. */  // 为sds分配len大小的空间，len小于目前的len字段，则什么都不做sds sdsgrowzero(sds s, size_t len) {    size_t curlen = sdslen(s);    if (len <= curlen) return s;    s = sdsMakeRoomFor(s,len-curlen);    if (s == NULL) return NULL;    /* Make sure added region doesn‘t contain garbage */    memset(s+curlen,0,(len-curlen+1)); /* also set trailing \0 byte */    sdssetlen(s, len);    return s;}/* Append the specified binary-safe string pointed by ‘t‘ of ‘len‘ bytes to the * end of the specified sds string ‘s‘. * * After the call, the passed sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. */  // 在原sds后追加内容*tsds sdscatlen(sds s, const void *t, size_t len) {    size_t curlen = sdslen(s);    s = sdsMakeRoomFor(s,len);    if (s == NULL) return NULL;    memcpy(s+curlen, t, len);    sdssetlen(s, curlen+len);    s[curlen+len] = ‘\0‘;    return s;}/* Append the specified null termianted C string to the sds string ‘s‘. * * After the call, the passed sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. */  // 在原sds后追加字符串sds sdscat(sds s, const char *t) {    return sdscatlen(s, t, strlen(t));}/* Append the specified sds ‘t‘ to the existing sds ‘s‘. * * After the call, the modified sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. */   // 在原sds后追加sdssds sdscatsds(sds s, const sds t) {    return sdscatlen(s, t, sdslen(t));}/* Destructively modify the sds string ‘s‘ to hold the specified binary * safe string pointed by ‘t‘ of length ‘len‘ bytes. */  // 将长度为len的字符串*t拷贝到sdssds sdscpylen(sds s, const char *t, size_t len) {    if (sdsalloc(s) < len) {        s = sdsMakeRoomFor(s,len-sdslen(s));        if (s == NULL) return NULL;    }    memcpy(s, t, len);    s[len] = ‘\0‘;    sdssetlen(s, len);    return s;}/* Like sdscpylen() but ‘t‘ must be a null-termined string so that the length * of the string is obtained with strlen(). */  // 将字符串*t拷贝到sdssds sdscpy(sds s, const char *t) {    return sdscpylen(s, t, strlen(t));}/* Helper for sdscatlonglong() doing the actual number -> string * conversion. ‘s‘ must point to a string with room for at least * SDS_LLSTR_SIZE bytes. * * The function returns the length of the null-terminated string * representation stored at ‘s‘. */#define SDS_LLSTR_SIZE 21// 将一个long long类型的值转换为一个字符串int sdsll2str(char *s, long long value) {    char *p, aux;    unsigned long long v;    size_t l;    /* Generate the string representation, this method produces     * an reversed string. */    v = (value < 0) ? -value : value;    p = s;    do {        *p++ = ‘0‘+(v%10);        v /= 10;    } while(v);    if (value < 0) *p++ = ‘-‘;    /* Compute length and add null term. */    l = p-s;    *p = ‘\0‘;    /* Reverse the string. */    p--;    while(s < p) {        aux = *s;        *s = *p;        *p = aux;        s++;        p--;    }    return l;}/* Identical sdsll2str(), but for unsigned long long type. */// 将一个unsigned long long类型的值转换为一个字符串int sdsull2str(char *s, unsigned long long v) {    char *p, aux;    size_t l;    /* Generate the string representation, this method produces     * an reversed string. */    p = s;    do {        *p++ = ‘0‘+(v%10);        v /= 10;    } while(v);    /* Compute length and add null term. */    l = p-s;    *p = ‘\0‘;    /* Reverse the string. */    p--;    while(s < p) {        aux = *s;        *s = *p;        *p = aux;        s++;        p--;    }    return l;}/* Create an sds string from a long long value. It is much faster than: * * sdscatprintf(sdsempty(),"%lld\n", value); */  // 将一个long long类型的值以字符串的形式保存为sdssds sdsfromlonglong(long long value) {    char buf[SDS_LLSTR_SIZE];    int len = sdsll2str(buf,value);    return sdsnewlen(buf,len);}/* Like sdscatprintf() but gets va_list instead of being variadic. */// 打印不定参数的内容到sdssds sdscatvprintf(sds s, const char *fmt, va_list ap) {    va_list cpy;    char staticbuf[1024], *buf = staticbuf, *t;    size_t buflen = strlen(fmt)*2;    /* We try to start using a static buffer for speed.     * If not possible we revert to heap allocation. */    if (buflen > sizeof(staticbuf)) {        buf = s_malloc(buflen);        if (buf == NULL) return NULL;    } else {        buflen = sizeof(staticbuf);    }    /* Try with buffers two times bigger every time we fail to     * fit the string in the current buffer size. */    while(1) {        buf[buflen-2] = ‘\0‘;        va_copy(cpy,ap);        vsnprintf(buf, buflen, fmt, cpy);        va_end(cpy);        if (buf[buflen-2] != ‘\0‘) {            if (buf != staticbuf) s_free(buf);            buflen *= 2;            buf = s_malloc(buflen);            if (buf == NULL) return NULL;            continue;        }        break;    }    /* Finally concat the obtained string to the SDS string and return it. */    t = sdscat(s, buf);    if (buf != staticbuf) s_free(buf);    return t;}/* Append to the sds string ‘s‘ a string obtained using printf-alike format * specifier. * * After the call, the modified sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. * * Example: * * s = sdsnew("Sum is: "); * s = sdscatprintf(s,"%d+%d = %d",a,b,a+b). * * Often you need to create a string from scratch with the printf-alike * format. When this is the need, just use sdsempty() as the target string: * * s = sdscatprintf(sdsempty(), "... your format ...", args); */ // 打印不定参数的内容到sdssds sdscatprintf(sds s, const char *fmt, ...) {    va_list ap;    char *t;    va_start(ap, fmt);    t = sdscatvprintf(s,fmt,ap);    va_end(ap);    return t;}/* This function is similar to sdscatprintf, but much faster as it does * not rely on sprintf() family functions implemented by the libc that * are often very slow. Moreover directly handling the sds string as * new data is concatenated provides a performance improvement. * * However this function only handles an incompatible subset of printf-alike * format specifiers: * * %s - C String * %S - SDS string * %i - signed int * %I - 64 bit signed integer (long long, int64_t) * %u - unsigned int * %U - 64 bit unsigned integer (unsigned long long, uint64_t) * %% - Verbatim "%" character. */  // 格式化输出字符串到sdssds sdscatfmt(sds s, char const *fmt, ...) {    size_t initlen = sdslen(s);    const char *f = fmt;    int i;    va_list ap;    va_start(ap,fmt);    f = fmt;    /* Next format specifier byte to process. */    i = initlen; /* Position of the next byte to write to dest str. */    while(*f) {        char next, *str;        size_t l;        long long num;        unsigned long long unum;        /* Make sure there is always space for at least 1 char. */        if (sdsavail(s)==0) {            s = sdsMakeRoomFor(s,1);        }        switch(*f) {        case ‘%‘:            next = *(f+1);            f++;            switch(next) {            case ‘s‘:            case ‘S‘:                str = va_arg(ap,char*);                l = (next == ‘s‘) ? strlen(str) : sdslen(str);                if (sdsavail(s) < l) {                    s = sdsMakeRoomFor(s,l);                }                memcpy(s+i,str,l);                sdsinclen(s,l);                i += l;                break;            case ‘i‘:            case ‘I‘:                if (next == ‘i‘)                    num = va_arg(ap,int);                else                    num = va_arg(ap,long long);                {                    char buf[SDS_LLSTR_SIZE];                    l = sdsll2str(buf,num);                    if (sdsavail(s) < l) {                        s = sdsMakeRoomFor(s,l);                    }                    memcpy(s+i,buf,l);                    sdsinclen(s,l);                    i += l;                }                break;            case ‘u‘:            case ‘U‘:                if (next == ‘u‘)                    unum = va_arg(ap,unsigned int);                else                    unum = va_arg(ap,unsigned long long);                {                    char buf[SDS_LLSTR_SIZE];                    l = sdsull2str(buf,unum);                    if (sdsavail(s) < l) {                        s = sdsMakeRoomFor(s,l);                    }                    memcpy(s+i,buf,l);                    sdsinclen(s,l);                    i += l;                }                break;            default: /* Handle %% and generally %<unknown>. */                s[i++] = next;                sdsinclen(s,1);                break;            }            break;        default:            s[i++] = *f;            sdsinclen(s,1);            break;        }        f++;    }    va_end(ap);    /* Add null-term */    s[i] = ‘\0‘;    return s;}/* Remove the part of the string from left and from right composed just of * contiguous characters found in ‘cset‘, that is a null terminted C string. * * After the call, the modified sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. * * Example: * * s = sdsnew("AA...AA.a.aa.aHelloWorld     :::"); * s = sdstrim(s,"Aa. :"); * printf("%s\n", s); * * Output will be just "Hello World". */sds sdstrim(sds s, const char *cset) {    char *start, *end, *sp, *ep;    size_t len;    sp = start = s;    ep = end = s+sdslen(s)-1;    while(sp <= end && strchr(cset, *sp)) sp++;    while(ep > sp && strchr(cset, *ep)) ep--;    len = (sp > ep) ? 0 : ((ep-sp)+1);    if (s != sp) memmove(s, sp, len);    s[len] = ‘\0‘;    sdssetlen(s,len);    return s;}/* Turn the string into a smaller (or equal) string containing only the * substring specified by the ‘start‘ and ‘end‘ indexes. * * start and end can be negative, where -1 means the last character of the * string, -2 the penultimate character, and so forth. * * The interval is inclusive, so the start and end characters will be part * of the resulting string. * * The string is modified in-place. * * Example: * * s = sdsnew("Hello World"); * sdsrange(s,1,-1); => "ello World" */void sdsrange(sds s, int start, int end) {    size_t newlen, len = sdslen(s);    if (len == 0) return;    if (start < 0) {        start = len+start;        if (start < 0) start = 0;    }    if (end < 0) {        end = len+end;        if (end < 0) end = 0;    }    newlen = (start > end) ? 0 : (end-start)+1;    if (newlen != 0) {        if (start >= (signed)len) {            newlen = 0;        } else if (end >= (signed)len) {            end = len-1;            newlen = (start > end) ? 0 : (end-start)+1;        }    } else {        start = 0;    }    if (start && newlen) memmove(s, s+start, newlen);    s[newlen] = 0;    sdssetlen(s,newlen);}/* Apply tolower() to every character of the sds string ‘s‘. */void sdstolower(sds s) {    int len = sdslen(s), j;    for (j = 0; j < len; j++) s[j] = tolower(s[j]);}/* Apply toupper() to every character of the sds string ‘s‘. */void sdstoupper(sds s) {    int len = sdslen(s), j;    for (j = 0; j < len; j++) s[j] = toupper(s[j]);}/* Compare two sds strings s1 and s2 with memcmp(). * * Return value: * *     positive if s1 > s2. *     negative if s1 < s2. *     0 if s1 and s2 are exactly the same binary string. * * If two strings share exactly the same prefix, but one of the two has * additional characters, the longer string is considered to be greater than * the smaller one. */int sdscmp(const sds s1, const sds s2) {    size_t l1, l2, minlen;    int cmp;    l1 = sdslen(s1);    l2 = sdslen(s2);    minlen = (l1 < l2) ? l1 : l2;    cmp = memcmp(s1,s2,minlen);    if (cmp == 0) return l1-l2;    return cmp;}/* Split ‘s‘ with separator in ‘sep‘. An array * of sds strings is returned. *count will be set * by reference to the number of tokens returned. * * On out of memory, zero length string, zero length * separator, NULL is returned. * * Note that ‘sep‘ is able to split a string using * a multi-character separator. For example * sdssplit("foo_-_bar","_-_"); will return two * elements "foo" and "bar". * * This version of the function is binary-safe but * requires length arguments. sdssplit() is just the * same function but for zero-terminated strings. */sds *sdssplitlen(const char *s, int len, const char *sep, int seplen, int *count) {    int elements = 0, slots = 5, start = 0, j;    sds *tokens;    if (seplen < 1 || len < 0) return NULL;    tokens = s_malloc(sizeof(sds)*slots);    if (tokens == NULL) return NULL;    if (len == 0) {        *count = 0;        return tokens;    }    for (j = 0; j < (len-(seplen-1)); j++) {        /* make sure there is room for the next element and the final one */        if (slots < elements+2) {            sds *newtokens;            slots *= 2;            newtokens = s_realloc(tokens,sizeof(sds)*slots);            if (newtokens == NULL) goto cleanup;            tokens = newtokens;        }        /* search the separator */        if ((seplen == 1 && *(s+j) == sep[0]) || (memcmp(s+j,sep,seplen) == 0)) {            tokens[elements] = sdsnewlen(s+start,j-start);            if (tokens[elements] == NULL) goto cleanup;            elements++;            start = j+seplen;            j = j+seplen-1; /* skip the separator */        }    }    /* Add the final element. We are sure there is room in the tokens array. */    tokens[elements] = sdsnewlen(s+start,len-start);    if (tokens[elements] == NULL) goto cleanup;    elements++;    *count = elements;    return tokens;cleanup:    {        int i;        for (i = 0; i < elements; i++) sdsfree(tokens[i]);        s_free(tokens);        *count = 0;        return NULL;    }}/* Free the result returned by sdssplitlen(), or do nothing if ‘tokens‘ is NULL. */void sdsfreesplitres(sds *tokens, int count) {    if (!tokens) return;    while(count--)        sdsfree(tokens[count]);    s_free(tokens);}/* Append to the sds string "s" an escaped string representation where * all the non-printable characters (tested with isprint()) are turned into * escapes in the form "\n\r\a...." or "\x<hex-number>". * * After the call, the modified sds string is no longer valid and all the * references must be substituted with the new pointer returned by the call. */sds sdscatrepr(sds s, const char *p, size_t len) {    s = sdscatlen(s,"\"",1);    while(len--) {        switch(*p) {        case ‘\\‘:        case ‘"‘:            s = sdscatprintf(s,"\\%c",*p);            break;        case ‘\n‘: s = sdscatlen(s,"\\n",2); break;        case ‘\r‘: s = sdscatlen(s,"\\r",2); break;        case ‘\t‘: s = sdscatlen(s,"\\t",2); break;        case ‘\a‘: s = sdscatlen(s,"\\a",2); break;        case ‘\b‘: s = sdscatlen(s,"\\b",2); break;        default:            if (isprint(*p))                s = sdscatprintf(s,"%c",*p);            else                s = sdscatprintf(s,"\\x%02x",(unsigned char)*p);            break;        }        p++;    }    return sdscatlen(s,"\"",1);}/* Helper function for sdssplitargs() that returns non zero if ‘c‘ * is a valid hex digit. */int is_hex_digit(char c) {    return (c >= ‘0‘ && c <= ‘9‘) || (c >= ‘a‘ && c <= ‘f‘) ||           (c >= ‘A‘ && c <= ‘F‘);}/* Helper function for sdssplitargs() that converts a hex digit into an * integer from 0 to 15 */int hex_digit_to_int(char c) {    switch(c) {    case ‘0‘: return 0;    case ‘1‘: return 1;    case ‘2‘: return 2;    case ‘3‘: return 3;    case ‘4‘: return 4;    case ‘5‘: return 5;    case ‘6‘: return 6;    case ‘7‘: return 7;    case ‘8‘: return 8;    case ‘9‘: return 9;    case ‘a‘: case ‘A‘: return 10;    case ‘b‘: case ‘B‘: return 11;    case ‘c‘: case ‘C‘: return 12;    case ‘d‘: case ‘D‘: return 13;    case ‘e‘: case ‘E‘: return 14;    case ‘f‘: case ‘F‘: return 15;    default: return 0;    }}/* Split a line into arguments, where every argument can be in the * following programming-language REPL-alike form: * * foo bar "newline are supported\n" and "\xff\x00otherstuff" * * The number of arguments is stored into *argc, and an array * of sds is returned. * * The caller should free the resulting array of sds strings with * sdsfreesplitres(). * * Note that sdscatrepr() is able to convert back a string into * a quoted string in the same format sdssplitargs() is able to parse. * * The function returns the allocated tokens on success, even when the * input string is empty, or NULL if the input contains unbalanced * quotes or closed quotes followed by non space characters * as in: "foo"bar or "foo‘ */sds *sdssplitargs(const char *line, int *argc) {    const char *p = line;    char *current = NULL;    char **vector = NULL;    *argc = 0;    while(1) {        /* skip blanks */        while(*p && isspace(*p)) p++;        if (*p) {            /* get a token */            int inq=0;  /* set to 1 if we are in "quotes" */            int insq=0; /* set to 1 if we are in ‘single quotes‘ */            int done=0;            if (current == NULL) current = sdsempty();            while(!done) {                if (inq) {                    if (*p == ‘\\‘ && *(p+1) == ‘x‘ &&                                             is_hex_digit(*(p+2)) &&                                             is_hex_digit(*(p+3)))                    {                        unsigned char byte;                        byte = (hex_digit_to_int(*(p+2))*16)+                                hex_digit_to_int(*(p+3));                        current = sdscatlen(current,(char*)&byte,1);                        p += 3;                    } else if (*p == ‘\\‘ && *(p+1)) {                        char c;                        p++;                        switch(*p) {                        case ‘n‘: c = ‘\n‘; break;                        case ‘r‘: c = ‘\r‘; break;                        case ‘t‘: c = ‘\t‘; break;                        case ‘b‘: c = ‘\b‘; break;                        case ‘a‘: c = ‘\a‘; break;                        default: c = *p; break;                        }                        current = sdscatlen(current,&c,1);                    } else if (*p == ‘"‘) {                        /* closing quote must be followed by a space or                         * nothing at all. */                        if (*(p+1) && !isspace(*(p+1))) goto err;                        done=1;                    } else if (!*p) {                        /* unterminated quotes */                        goto err;                    } else {                        current = sdscatlen(current,p,1);                    }                } else if (insq) {                    if (*p == ‘\\‘ && *(p+1) == ‘\‘‘) {                        p++;                        current = sdscatlen(current,"‘",1);                    } else if (*p == ‘\‘‘) {                        /* closing quote must be followed by a space or                         * nothing at all. */                        if (*(p+1) && !isspace(*(p+1))) goto err;                        done=1;                    } else if (!*p) {                        /* unterminated quotes */                        goto err;                    } else {                        current = sdscatlen(current,p,1);                    }                } else {                    switch(*p) {                    case ‘ ‘:                    case ‘\n‘:                    case ‘\r‘:                    case ‘\t‘:                    case ‘\0‘:                        done=1;                        break;                    case ‘"‘:                        inq=1;                        break;                    case ‘\‘‘:                        insq=1;                        break;                    default:                        current = sdscatlen(current,p,1);                        break;                    }                }                if (*p) p++;            }            /* add the token to the vector */            vector = s_realloc(vector,((*argc)+1)*sizeof(char*));            vector[*argc] = current;            (*argc)++;            current = NULL;        } else {            /* Even on empty input string return something not NULL. */            if (vector == NULL) vector = s_malloc(sizeof(void*));            return vector;        }    }err:    while((*argc)--)        sdsfree(vector[*argc]);    s_free(vector);    if (current) sdsfree(current);    *argc = 0;    return NULL;}/* Modify the string substituting all the occurrences of the set of * characters specified in the ‘from‘ string to the corresponding character * in the ‘to‘ array. * * For instance: sdsmapchars(mystring, "ho", "01", 2) * will have the effect of turning the string "hello" into "0ell1". * * The function returns the sds string pointer, that is always the same * as the input pointer since no resize is needed. */sds sdsmapchars(sds s, const char *from, const char *to, size_t setlen) {    size_t j, i, l = sdslen(s);    for (j = 0; j < l; j++) {        for (i = 0; i < setlen; i++) {            if (s[j] == from[i]) {                s[j] = to[i];                break;            }        }    }    return s;}/* Join an array of C strings using the specified separator (also a C string). * Returns the result as an sds string. */sds sdsjoin(char **argv, int argc, char *sep) {    sds join = sdsempty();    int j;    for (j = 0; j < argc; j++) {        join = sdscat(join, argv[j]);        if (j != argc-1) join = sdscat(join,sep);    }    return join;}/* Like sdsjoin, but joins an array of SDS strings. */sds sdsjoinsds(sds *argv, int argc, const char *sep, size_t seplen) {    sds join = sdsempty();    int j;    for (j = 0; j < argc; j++) {        join = sdscatsds(join, argv[j]);        if (j != argc-1) join = sdscatlen(join,sep,seplen);    }    return join;}/* Wrappers to the allocators used by SDS. Note that SDS will actually * just use the macros defined into sdsalloc.h in order to avoid to pay * the overhead of function calls. Here we define these wrappers only for * the programs SDS is linked to, if they want to touch the SDS internals * even if they use a different allocator. */void *sds_malloc(size_t size) { return s_malloc(size); }void *sds_realloc(void *ptr, size_t size) { return s_realloc(ptr,size); }void sds_free(void *ptr) { s_free(ptr); }#if defined(SDS_TEST_MAIN)#include <stdio.h>#include "testhelp.h"#include "limits.h"#define UNUSED(x) (void)(x)int sdsTest(void) {    {        sds x = sdsnew("foo"), y;        test_cond("Create a string and obtain the length",            sdslen(x) == 3 && memcmp(x,"foo\0",4) == 0)        sdsfree(x);        x = sdsnewlen("foo",2);        test_cond("Create a string with specified length",            sdslen(x) == 2 && memcmp(x,"fo\0",3) == 0)        x = sdscat(x,"bar");        test_cond("Strings concatenation",            sdslen(x) == 5 && memcmp(x,"fobar\0",6) == 0);        x = sdscpy(x,"a");        test_cond("sdscpy() against an originally longer string",            sdslen(x) == 1 && memcmp(x,"a\0",2) == 0)        x = sdscpy(x,"xyzxxxxxxxxxxyyyyyyyyyykkkkkkkkkk");        test_cond("sdscpy() against an originally shorter string",            sdslen(x) == 33 &&            memcmp(x,"xyzxxxxxxxxxxyyyyyyyyyykkkkkkkkkk\0",33) == 0)        sdsfree(x);        x = sdscatprintf(sdsempty(),"%d",123);        test_cond("sdscatprintf() seems working in the base case",            sdslen(x) == 3 && memcmp(x,"123\0",4) == 0)        sdsfree(x);        x = sdsnew("--");        x = sdscatfmt(x, "Hello %s World %I,%I--", "Hi!", LLONG_MIN,LLONG_MAX);        test_cond("sdscatfmt() seems working in the base case",            sdslen(x) == 60 &&            memcmp(x,"--Hello Hi! World -9223372036854775808,"                     "9223372036854775807--",60) == 0)        printf("[%s]\n",x);        sdsfree(x);        x = sdsnew("--");        x = sdscatfmt(x, "%u,%U--", UINT_MAX, ULLONG_MAX);        test_cond("sdscatfmt() seems working with unsigned numbers",            sdslen(x) == 35 &&            memcmp(x,"--4294967295,18446744073709551615--",35) == 0)        sdsfree(x);        x = sdsnew(" x ");        sdstrim(x," x");        test_cond("sdstrim() works when all chars match",            sdslen(x) == 0)        sdsfree(x);        x = sdsnew(" x ");        sdstrim(x," ");        test_cond("sdstrim() works when a single char remains",            sdslen(x) == 1 && x[0] == ‘x‘)        sdsfree(x);        x = sdsnew("xxciaoyyy");        sdstrim(x,"xy");        test_cond("sdstrim() correctly trims characters",            sdslen(x) == 4 && memcmp(x,"ciao\0",5) == 0)        y = sdsdup(x);        sdsrange(y,1,1);        test_cond("sdsrange(...,1,1)",            sdslen(y) == 1 && memcmp(y,"i\0",2) == 0)        sdsfree(y);        y = sdsdup(x);        sdsrange(y,1,-1);        test_cond("sdsrange(...,1,-1)",            sdslen(y) == 3 && memcmp(y,"iao\0",4) == 0)        sdsfree(y);        y = sdsdup(x);        sdsrange(y,-2,-1);        test_cond("sdsrange(...,-2,-1)",            sdslen(y) == 2 && memcmp(y,"ao\0",3) == 0)        sdsfree(y);        y = sdsdup(x);        sdsrange(y,2,1);        test_cond("sdsrange(...,2,1)",            sdslen(y) == 0 && memcmp(y,"\0",1) == 0)        sdsfree(y);        y = sdsdup(x);        sdsrange(y,1,100);        test_cond("sdsrange(...,1,100)",            sdslen(y) == 3 && memcmp(y,"iao\0",4) == 0)        sdsfree(y);        y = sdsdup(x);        sdsrange(y,100,100);        test_cond("sdsrange(...,100,100)",            sdslen(y) == 0 && memcmp(y,"\0",1) == 0)        sdsfree(y);        sdsfree(x);        x = sdsnew("foo");        y = sdsnew("foa");        test_cond("sdscmp(foo,foa)", sdscmp(x,y) > 0)        sdsfree(y);        sdsfree(x);        x = sdsnew("bar");        y = sdsnew("bar");        test_cond("sdscmp(bar,bar)", sdscmp(x,y) == 0)        sdsfree(y);        sdsfree(x);        x = sdsnew("aar");        y = sdsnew("bar");        test_cond("sdscmp(bar,bar)", sdscmp(x,y) < 0)        sdsfree(y);        sdsfree(x);        x = sdsnewlen("\a\n\0foo\r",7);        y = sdscatrepr(sdsempty(),x,sdslen(x));        test_cond("sdscatrepr(...data...)",            memcmp(y,"\"\\a\\n\\x00foo\\r\"",15) == 0)        {            unsigned int oldfree;            char *p;            int step = 10, j, i;            sdsfree(x);            sdsfree(y);            x = sdsnew("0");            test_cond("sdsnew() free/len buffers", sdslen(x) == 1 && sdsavail(x) == 0);            /* Run the test a few times in order to hit the first two             * SDS header types. */            for (i = 0; i < 10; i++) {                int oldlen = sdslen(x);                x = sdsMakeRoomFor(x,step);                int type = x[-1]&SDS_TYPE_MASK;                test_cond("sdsMakeRoomFor() len", sdslen(x) == oldlen);                if (type != SDS_TYPE_5) {                    test_cond("sdsMakeRoomFor() free", sdsavail(x) >= step);                    oldfree = sdsavail(x);                }                p = x+oldlen;                for (j = 0; j < step; j++) {                    p[j] = ‘A‘+j;                }                sdsIncrLen(x,step);            }            test_cond("sdsMakeRoomFor() content",                memcmp("0ABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJ",x,101) == 0);            test_cond("sdsMakeRoomFor() final length",sdslen(x)==101);            sdsfree(x);        }    }    test_report()    return 0;}#endif#ifdef SDS_TEST_MAINint main(void) {    return sdsTest();}#endif