MySQL 之动态字符串处理

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>typedef struct st_dynamic_string<br /> </li><li>{<br /></li><li>char *str;<br /></li><li>size_t length,max_length,alloc_increment;<br /></li><li>} DYNAMIC_STRING; </li></ol>

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>my_bool init_dynamic_string(DYNAMIC_STRING *str, const char *init_str,size_t init_alloc, size_t alloc_increment)<br /> </li><li>{<br /></li><li>size_t length;<br /></li><li>DBUG_ENTER("init_dynamic_string");<br /></li><li><br /></li><li>if (!alloc_increment) <br /></li><li>alloc_increment=128;<br /></li><li>length=1;<br /></li><li>if (init_str && (length= strlen(init_str)+1) < init_alloc) <br /></li><li>init_alloc=((length+alloc_increment-1)/alloc_increment)*alloc_increment; <br /></li><li>if (!init_alloc)<br /></li><li>init_alloc=alloc_increment;<br /></li><li><br /></li><li>if (!(str->str=(char*) my_malloc(init_alloc,MYF(MY_WME))))<br /></li><li>DBUG_RETURN(TRUE);<br /></li><li>str->length=length-1;<br /></li><li>if (init_str)<br /></li><li>memcpy(str->str,init_str,length);<br /></li><li>str->max_length=init_alloc;<br /></li><li>str->alloc_increment=alloc_increment;<br /></li><li>DBUG_RETURN(FALSE);<br /></li><li>} </li></ol>

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>my_bool dynstr_append_mem(DYNAMIC_STRING *str, const char *append,<br /> </li><li>size_t length)<br /></li><li>{<br /></li><li>char *new_ptr;<br /></li><li>if (str->length+length >= str->max_length) //如果新增字符串后，总长度超过缓冲区大小<br /></li><li>{<br /></li><li>//需要分配多少个alloc_increment 大小的内存，才能存下新增后的字符串<br /></li><li>size_t new_length=(str->length+length+str->alloc_increment)/<br /></li><li>str->alloc_increment; <br /></li><li>new_length*=str->alloc_increment;<br /></li><li><br /></li><li>if (!(new_ptr=(char*) my_realloc(str->str,new_length,MYF(MY_WME))))<br /></li><li>return TRUE;<br /></li><li>str->str=new_ptr;<br /></li><li>str->max_length=new_length;<br /></li><li>}<br /></li><li>//将新分配的内容，append到str之后<br /></li><li>memcpy(str->str + str->length,append,length);<br /></li><li>str->length+=length; //扩容之后str新的长度<br /></li><li>str->str[str->length]=0; /* Safety for C programs */ //字符串最后一个字符为’'<br /></li><li>return FALSE;<br /></li><li>} </li></ol>

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>my_bool dynstr_trunc(DYNAMIC_STRING *str, size_t n)<br /> </li><li>{<br /></li><li>str->length-=n;<br /></li><li>str->str[str->length]= '';<br /></li><li>return FALSE;<br /></li><li>} </li></ol>

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>char *strcend(register const char *s, register pchar c)<br /> </li><li>{<br /></li><li>for (;;)<br /></li><li>{<br /></li><li>if (*s == (char) c) return (char*) s;<br /></li><li>if (!*s++) return (char*) s-1;<br /></li><li>}<br /></li><li>} </li></ol>

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>my_bool dynstr_realloc(DYNAMIC_STRING *str, size_t additional_size)<br /> </li><li>{<br /></li><li>DBUG_ENTER("dynstr_realloc");<br /></li><li><br /></li><li>if (!additional_size) DBUG_RETURN(FALSE);<br /></li><li>if (str->length + additional_size > str->max_length) //如果新的字符串内容超过缓冲区的最大长度<br /></li><li>{<br /></li><li>str->max_length=((str->length + additional_size+str->alloc_increment-1)/<br /></li><li>str->alloc_increment)*str->alloc_increment;<br /></li><li>if (!(str->str=(char*) my_realloc(str->str,str->max_length,MYF(MY_WME))))<br /></li><li>DBUG_RETURN(TRUE);<br /></li><li>}<br /></li><li>DBUG_RETURN(FALSE);<br /></li><li>} </li></ol>

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>/*<br /> </li><li>Concatenates any number of strings, escapes any OS quote in the result then<br /></li><li>surround the whole affair in another set of quotes which is finally appended<br /></li><li>to specified DYNAMIC_STRING. This function is especially useful when<br /></li><li>building strings to be executed with the system() function.<br /></li><li><br /></li><li>@param str Dynamic String which will have addtional strings appended.<br /></li><li>@param append String to be appended.<br /></li><li>@param ... Optional. Additional string(s) to be appended.<br /></li><li><br /></li><li>@note The final argument in the list must be NullS even if no additional<br /></li><li>options are passed.<br /></li><li><br /></li><li>@return True = Success.<br /></li><li>*/<br /></li><li><br /></li><li>my_bool dynstr_append_os_quoted(DYNAMIC_STRING *str, const char *append, ...)<br /></li><li>{<br /></li><li><br /></li><li>const char *quote_str= "'";<br /></li><li>const uint quote_len= 1;<br /></li><li>my_bool ret= TRUE;<br /></li><li>va_list dirty_text;<br /></li><li><br /></li><li>ret&= dynstr_append_mem(str, quote_str, quote_len); /* Leading quote */<br /></li><li>va_start(dirty_text, append);<br /></li><li>while (append != NullS)<br /></li><li>{<br /></li><li>const char *cur_pos= append;<br /></li><li>const char *next_pos= cur_pos;<br /></li><li><br /></li><li>/* Search for quote in each string and replace with escaped quote */<br /></li><li>while(*(next_pos= strcend(cur_pos, quote_str[0])) != '')<br /></li><li>{<br /></li><li>ret&= dynstr_append_mem(str, cur_pos, (uint) (next_pos - cur_pos));<br /></li><li>ret&= dynstr_append_mem(str ,"\", 1);<br /></li><li>ret&= dynstr_append_mem(str, quote_str, quote_len);<br /></li><li>cur_pos= next_pos + 1;<br /></li><li>}<br /></li><li>ret&= dynstr_append_mem(str, cur_pos, (uint) (next_pos - cur_pos));<br /></li><li>append= va_arg(dirty_text, char *);<br /></li><li>}<br /></li><li>va_end(dirty_text);<br /></li><li>ret&= dynstr_append_mem(str, quote_str, quote_len); /* Trailing quote */<br /></li><li><br /></li><li>return ret;<br /></li><li>} </li></ol>