C++ separate string by selected commas - c++

Question

I was reading the following question Parsing a comma-delimited std::string on how to split a string by a comma (Someone gave me the link from my previous question) and one of the answers was:
stringstream ss( "1,1,1,1, or something else ,1,1,1,0" );
vector<string> result;
while( ss.good() )
{
string substr;
getline( ss, substr, ',' );
result.push_back( substr );
}
But what if my string was like the following, and I wanted to separate values only by the bold commas and ignoring what appears inside <>?
<a,b>,<c,d>,,<d,l>,
I want to get:
<a,b>
<c,d>
"" //Empty string
<d,l>
""
Given:<a,b>,,<c,d> It should return: <a,b> and "" and <c,d>
Given:<a,b>,<c,d> It should return:<a,b> and <c,d>
Given:<a,b>, It should return:<a,b> and ""
Given:<a,b>,,,<c,d> It should return:<a,b> and "" and "" and <c,d>
In other words, my program should behave just like the given solution above separated by , (Supposing there is no other , except the bold ones)
Here are some suggested solution and their problems:
Delete all bold commas: This will result in treating the following 2 inputs the same way while they shouldn't
<a,b>,<c,d>
<a,b>,,<c,d>
Replace all bold commas with some char and use the above algorithm: I can't select some char to replace the commas with since any value could appear in the rest of my string

Answer 1

Adding to #Carlos' answer, apart from regex (take a look at my comment); you can implement the substitution like the following (Here, I actually build a new string):
#include <algorithm>
#include <iostream>
#include <string>
int main() {
std::string str;
getline(std::cin,str);
std::string str_builder;
for (auto it = str.begin(); it != str.end(); it++) {
static bool flag = false;
if (*it == '<') {
flag = true;
}
else if (*it == '>') {
flag = false;
str_builder += *it;
}
if (flag) {
str_builder += *it;
}
}
}

Answer 2

Why not replace one set of commas with some known-to-not-clash character, then split it by the other commas, then reverse the replacement?
So replace the commas that are inside the <> with something, do the string split, replace again.

Answer 3

I think what you want is something like this:
vector<string> result;
string s = "<a,b>,,<c,d>"
int in_string = 0;
int latest_comma = 0;
for (int i = 0; i < s.size(); i++) {
if(s[i] == '<'){
result.push_back(s[i]);
in_string = 1;
latest_comma = 0;
}
else if(s[i] == '>'){
result.push_back(s[i]);
in_string = 0;
}
else if(!in_string && s[i] == ','){
if(latest_comma == 1)
result.push_back('\n');
else
latest_comma = 1;
}
else
result.push_back(s[i]);
}

Answer 4

Here is a possible code that scans a string one char at a time and splits it on commas (',') unless they are masked between brackets ('<' and '>').
Algo:
assume starting outside brackets
loop for each character:
if not a comma, or if inside brackets
store the character in the current item
if a < bracket: note that we are inside brackets
if a > bracket: note that we are outside brackets
else (an unmasked comma)
store the current item as a string into the resulting vector
clear the current item
store the last item into the resulting vector
Only 10 lines and my rubber duck agreed that it should work...
C++ implementation: I will use a vector to handle the current item because it is easier to build it one character at a time
std::vector<std::string> parse(const std::string& str) {
std::vector<std::string> result;
bool masked = false;
std::vector<char> current; // stores chars of the current item
for (const char c : str) {
if (masked || (c != ',')) {
current.push_back(c);
switch (c) {
case '<': masked = true; break;
case '>': masked = false;
}
}
else { // unmasked comma: store item and prepare next
current.push_back('\0'); // a terminating null for the vector data
result.push_back(std::string(&current[0]));
current.clear();
}
}
// do not forget the last item...
current.push_back('\0');
result.push_back(std::string(&current[0]));
return result;
}
I tested it with all your example strings and it gives the expected results.

Answer 5

Seems quite straight forward to me.
vector<string> customSplit(string s)
{
vector<string> results;
int level = 0;
std::stringstream ss;
for (char c : s)
{
switch (c)
{
case ',':
if (level == 0)
{
results.push_back(ss.str());
stringstream temp;
ss.swap(temp); // Clear ss for the new string.
}
else
{
ss << c;
}
break;
case '<':
level += 2;
case '>':
level -= 1;
default:
ss << c;
}
}
results.push_back(ss.str());
return results;
}