redis源码分析（二）、redis源码分析之sds字符串
sds字符串
Redis 只会使用 C 字符串作为字面量， 在大多数情况下， Redis 使用 SDS （Simple Dynamic String，简单动态字符串）作为字符串表示。
比起 C 字符串， SDS 具有以下优点：
- 常数复杂度获取字符串长度。
- 杜绝缓冲区溢出。
- 减少修改字符串长度时所需的内存重分配次数。
- 二进制安全。
- 兼容部分 C 字符串函数。
根据传统， C 语言使用长度为N+1的字符数组来表示长度为 N 的字符串，并且字符数组的最后一个元素总是空字符 ‘\0’ 。
C 语言使用的这种简单的字符串表示方式， 并不能满足 Redis 对字符串在安全性、效率、以及功能方面的要求， 本节接下来的内容将详细对比 C 字符串和 SDS 之间的区别， 并说明 SDS 比 C 字符串更适用于 Redis 的原因。
SDS又叫简单动态字符串，在Redis中默认使用SDS来表示字符串。比如在Redis中的键值对中的键一般都是使用SDS来实现。首先需要说明的是在Redis中，字符串不是用传统的字符串来实现，而是Redis自己构建了一个结构来表示字符串。优点如下：
1、O(1)时间内获取字符串长度。常数复杂度获取字符串长度(依据其结构特性，只需要访问其结构体成员len既可获得字符串长度)
2、杜绝缓冲区溢出，另外SDS还提供的一些API操作，是二进制安全的(也就是不会因为空格等特殊字符而中断字符串)、不会溢出(API操作会检查其长度)
3、减少了修改字符串时带来的内存重分配次数。
- 对于增长字符串其采用的策略是检查修改之后的长度大小，如果小于1024*1024，则分配2倍的修改后的长度+1
- 对于减少的字符串其并不立即释放空间，而是回归到alloc中去。（自动查阅redis内存分配与释放策略）
typedef char *sds;//底层用于存储字符串的数据结构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. */
struct __attribute__ ((__packed__)) sdshdr5 {
//低三位保存type，高5位保存长度
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[];
};从代码中可以看出，SDS表示的字符串是有SDS header和char*指针组成，而SDS的头部主要由四部分组成：
len：SDS字符串已使用的空间。 alloc：申请的空间，减去len就是未使用的空间，初始时和len一致。
flag：只使用了低三位表示类型，细化了SDS的分类，根据字符串的长度的不同选择不同的sds结构体，而结构体的主要区别是len和alloc的类型，这样做可以节省一部分空间大小，毕竟在redis字符串非常多，进一步的可以节省空间。
buf: 用了C的特性表示不定长字符串。
除了sdshdr5之外，其他结构都是相似的。我们先看看sdshdr，它只有flags和buf成员，其中flag空间被C充分利用，其第三位保存了SDS字符串的类型.
#define SDS_TYPE_MASK 7 // 类型掩码
#define SDS_TYPE_BITS 3
#define SDS_HDR_VAR(T,s) struct sdshdr##T *sh = (void*)((s)-(sizeof(struct sdshdr##T))); // 获取header头指针
#define SDS_HDR(T,s) ((struct sdshdr##T *)((s)-(sizeof(struct sdshdr##T)))) // 获取header头指针
#define SDS_TYPE_5_LEN(f) ((f)>>SDS_TYPE_BITS) // 获取sdshdr5的长度,低三位保存了type/*sds结构一共有五种Header定义，其目的是为了满足不同长度的字符串可以使用不同大小的Header，从而节省内存。
Header部分主要包含以下几个部分：len、alloc、flags其中
len：表示字符串真正的长度，不包含空终止字和alloc以及flag
alloc：表示字符串的最大容量，不包含Header和最后的空终止字符和flag
flag：只用了3位表示sds的type 就是表示header的类型*/
// 五种header类型，flags取值为0~4
#define SDS_TYPE_5 0
#define SDS_TYPE_8 1
#define SDS_TYPE_16 2
#define SDS_TYPE_32 3
#define SDS_TYPE_64 4sdsnewlen函数 sds创建函数
/* 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 sdsnewlen(const void *init, size_t initlen) {
void *sh;
sds s;
// 根据initlen 求sds使用的结构体类型
char type = sdsReqType(initlen);
//下面是我在测试的时候添加的打印字符串类型代码，源码中没有
int type_t = type;
printf("sds.c------->sdsnewlen: the sds type is: [ %d ]\n", type_t);
/* Empty strings are usually created in order to append. Use type 8
* since type 5 is not good at this. */
//type5 不再使用 而是直接使用type8
if (type == SDS_TYPE_5 && initlen == 0) type = SDS_TYPE_8;
//sds使用的结构体的大小
int hdrlen = sdsHdrSize(type);
unsigned char *fp; /* flags pointer. */ //flag的第三位表示sds使用的结构体
//分配内层 大小是sds结构体的大小: hdrlen + buf的大小initlen + '\0'
sh = s_malloc(hdrlen+initlen+1);
//init为null的时候 直接初始化sh内容
if (!init)
memset(sh, 0, hdrlen+initlen+1);
//sh 分配失败的情况直接返回null
if (sh == NULL) return NULL;
// s为数据部分的起始指针 指向buf地址指针
s = (char*)sh+hdrlen;
//fp指向flag flag的低三位表示sds使用的结构体类型
fp = ((unsigned char*)s)-1;
//根据sds使用的结构体类型 给结构体中的成员赋值
switch(type) {
case SDS_TYPE_5: {
// initlen << SDS_TYPE_BITS 把initlen的值保存到flag的高5位中去 低三位保存type的值
*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;
}
}
if (initlen && init)
//拷贝数据部分
memcpy(s, init, initlen);
// 与C字符串兼容
s[initlen] = '\0';
// 返回创建的sds字符串指针
return s;
}sdsMakeRoomFor函数
函数原型：sds sdsMakeRoomFor(sds s, size_t addlen)
说明：实现扩充已有sds的可用空间为指定的大小，扩充规则是：当addlen的长度小于10241024时，则申请的空间是2(addlen+len)，否则扩充为1024*1024大小。
返回值:扩充后的sds对象
/* 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. */
sds sdsMakeRoomFor(sds s, size_t addlen) {
void *sh, *newsh;
size_t avail = sdsavail(s); //返回剩余可用的空间。
size_t len, newlen;
char type, oldtype = s[-1] & SDS_TYPE_MASK; //获取type
int hdrlen;
/* Return ASAP if there is enough space left. */
if (avail >= addlen) return s; //如果可用空间大于addlen直接返回旧的字符串
len = sdslen(s); //求sds的长度
sh = (char*)s-sdsHdrSize(oldtype);
newlen = (len+addlen);
if (newlen < SDS_MAX_PREALLOC)
newlen *= 2;
else
newlen += SDS_MAX_PREALLOC;
//根据newlen调整sds的type
type = sdsReqType(newlen);
/* 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;
//根据type获取sds使用的结构体的长度
hdrlen = sdsHdrSize(type);
//若类型和原有类型一样，则采用realloc分配空间，否则重新分配采用malloc函数分配空间
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); //把s中的字符串拷贝到newsh指向的buf中去
s_free(sh);//释放旧的sh空间
s = (char*)newsh+hdrlen; //s指向重新分配的字符串
s[-1] = type; //指定newsds的type
sdssetlen(s, len); //设置新的字符串的长度
}
sdssetalloc(s, newlen); //设置新的newsh的分配的空间长度
return s;
}sdscatlen :sds提供了字符串的连接函数，用来连接两个字符串
//sds字符串连接
sds sdscatlen(sds s, const void *t, size_t len) {
size_t curlen = sdslen(s);
//扩展s的空间
s = sdsMakeRoomFor(s,len);
if (s == NULL) return NULL;
// 连接新字符串
memcpy(s+curlen, t, len);
// 设定连接后字符串长度
sdssetlen(s, curlen+len);
s[curlen+len] = '\0';
return s;
}sds sdsempty(void); // 清空sds
sds sdsdup(const sds s); // 复制字符串
sds sdsgrowzero(sds s, size_t len); // 扩展字符串到指定长度
sds sdscpylen(sds s, const char *t, size_t len); // 字符串的复制
sds sdscpy(sds s, const char *t); // 字符串的复制
sds sdscatfmt(sds s, char const *fmt, ...); //字符串格式化输出
sds sdstrim(sds s, const char *cset); //字符串缩减
void sdsrange(sds s, int start, int end); //字符串截取函数
void sdsupdatelen(sds s); //更新字符串最新的长度
void sdsclear(sds s); //字符串清空操作
void sdstolower(sds s); //sds字符转小写表示
void sdstoupper(sds s); //sds字符统一转大写
sds sdsjoin(char **argv, int argc, char *sep); //以分隔符连接字符串子数组构成新的字符串sdsull2str 把一个long long的类型的数转成字符串
#include 整个sds.c文件
/* SDSLib 2.0 -- A C dynamic strings library
*
* Copyright (c) 2006-2015, Salvatore Sanfilippo
* Copyright (c) 2015, Oran Agra
* Copyright (c) 2015, Redis Labs, Inc
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include . */
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".
*
* 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