//===============replaceString.c===============
#include "replaceString.h"
//Normally I'd make a replaceStringMalloc to return a malloced string or a replaceStringMut to change the original string, but I'm not satisfied with those function names so it's best just to do to = (char*)malloc(replaceStringLength(from, replace, replacement)); replaceString(to, from, replace, replacement);
//If this was c++, I'd have no problem just overloading replaceString
//Returns the length of the resulting string (minus the null char)
size_t replaceStringLength(const char* from, const char* replace, const char* replacement){
size_t fromLength = strlen(from);
size_t replaceLength = strlen(replace);
size_t replacementLength = strlen(replacement);
size_t fromEndIt = 0;
size_t toLength = 0;
while(fromEndIt < fromLength){
int replaceIt = 0;
while(replaceIt < replaceLength && (fromEndIt+replaceIt) < fromLength && from[fromEndIt + replaceIt] == replace[replaceIt]){
++replaceIt;
}
if(replaceIt == replaceLength){
//Update from buffer iterator positions
toLength += (fromEndIt + replacementLength);
from += (fromEndIt + replaceLength);
fromEndIt = 0;
continue;
}
++fromEndIt;
}
toLength += fromEndIt;
return toLength;
}
//Baller replaceString by Leif Messinger
//Needs null terminated from, replace, and replacement strings as well as a large block of memory to store the result.
void replaceString(char* to, const char* from, const char* replace, const char* replacement){
size_t fromLength = strlen(from);
size_t replaceLength = strlen(replace);
size_t replacementLength = strlen(replacement);
size_t fromEndIt = 0;
while(fromEndIt < fromLength){
int replaceIt = 0;
while(replaceIt < replaceLength && (fromEndIt+replaceIt) < fromLength && from[fromEndIt + replaceIt] == replace[replaceIt]){
++replaceIt;
}
if(replaceIt == replaceLength){
//Copy the string before the matched bit
memcpyToAndShiftPointers(to, from, fromEndIt);
//Copy the replacement too
memcpyToAndShiftPointer(to, replacement, replacementLength);
//Update from buffer iterator positions
from += replaceLength;
fromEndIt = 0;
continue; //I don't want this thing to get incremented again
}
++fromEndIt;
}
//Copy the rest of the unmatched string
memcpyToAndShiftPointer(to, from, fromEndIt);
to[0] = '\0'; //Should work
}
//===============replaceString.h===============
#ifndef REPLACE_STRING_H
#define REPLACE_STRING_H
#include <string.h>
#define memcpyToAndShiftPointer(to,from,n); memcpy((to),(from),(n)); (to) += (n);
#define memcpyToAndShiftPointers(to,from,n); memcpy((to),(from),(n)); (to) += (n); (from) += n;
//Normally I'd make a replaceStringMalloc to return a malloced string or a replaceStringMut to change the original string, but I'm not satisfied with those function names so it's best just to do to = (char*)malloc(replaceStringLength(from, replace, replacement)); replaceString(to, from, replace, replacement);
//If this was c++, I'd have no problem just overloading replaceString
//Returns the length of the resulting string (minus the null char)
size_t replaceStringLength(const char* from, const char* replace, const char* replacement);
//Baller replaceString by Leif Messinger
//Needs null terminated from, replace, and replacement strings as well as a large block of memory to store the result.
void replaceString(char* to, const char* from, const char* replace, const char* replacement);
#endif
//===============replaceStringMain.c===============
#include <stdio.h>
#include <stdlib.h>
#include "replaceString.h"
#define BUFFER_SIZE (1<<21) //About a mebibyte
//There could be matches between buffers, so make sure the buffer size you set it to is good enough for your application. Basically as big as your input.
//Replaces strings from sdtin, then outputs it to stdout
//./a.out [[replace], [replacement]]...
int main(int argc, char** argv){
char* buffer1 = (char*) malloc(BUFFER_SIZE);
char* buffer2 = (char*) malloc(BUFFER_SIZE);
if(buffer1 == NULL || buffer2 == NULL){
perror("You need a couple MBs of ram my boy");
return 1;
}
while(!feof(stdin)){
fread(buffer1, BUFFER_SIZE, 1, stdin);
char* activeBuffer = buffer1;
char* inactiveBuffer = buffer2;
char* tmp;
for(size_t i = 1; (i + 1) < argc; i += 2){
//puts(activeBuffer);
replaceString(inactiveBuffer, activeBuffer, argv[i], argv[i+1]);
//Swap buffers
tmp = activeBuffer;
activeBuffer = inactiveBuffer;
inactiveBuffer = tmp;
}
fputs(activeBuffer, stdout);
}
free(buffer1);
free(buffer2);
return 0;
}