Execute a Markov algorithm: Difference between revisions
added C++
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"I bought a bag of apples with my money from T shop."
=={{header|C++}}==
<lang cpp>
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
struct rule
{
std::string pattern;
std::string replacement;
bool terminal;
rule(std::string pat, std::string rep, bool term):
pattern(pat),
replacement(rep),
terminal(term)
{
}
};
std::string const whitespace = " \t";
std::string::size_type const npos = std::string::npos;
bool is_whitespace(char c)
{
return whitespace.find(c) != npos;
}
int main(int argc, char* argv[])
{
if (argc != 3)
{
std::cout << "usage:\n " << argv[0] << " rulefile text\n";
return EXIT_FAILURE;
}
std::ifstream rulefile(argv[1]);
std::vector<rule> rules;
std::string line;
while (std::getline(rulefile, line))
{
std::string::size_type pos;
// remove comments
pos = line.find('#');
if (pos != npos)
line.resize(pos);
// ignore lines consisting only of whitespace
if (line.find_first_not_of(whitespace) == npos)
continue;
// find "->" surrounded by whitespace
pos = line.find("->");
while (pos != npos && (pos == 0 || !is_whitespace(line[pos-1])))
pos = line.find("->", pos+1);
if (pos == npos || line.length() < pos+3 || !is_whitespace(line[pos+2]))
{
std::cerr << "invalid rule: " << line << "\n";
return EXIT_FAILURE;
}
std::string pattern = line.substr(0, pos-1);
std::string replacement = line.substr(pos+3);
// remove additional separating whitespace
pattern.erase(pattern.find_last_not_of(whitespace)+1);
replacement.erase(0, replacement.find_first_not_of(whitespace));
// test for terminal rule
bool terminal = !replacement.empty() && replacement[0] == '.';
if (terminal)
replacement.erase(0,1);
rules.push_back(rule(pattern, replacement, terminal));
}
std::string text = argv[2];
std::vector<rule>::iterator iter = rules.begin();
while (iter != rules.end())
{
std::string::size_type pos = text.find(iter->pattern);
if (pos != npos)
{
text.replace(pos, iter->pattern.length(), iter->replacement);
if (iter->terminal)
break;
iter = rules.begin();
}
++iter;
}
std::cout << text << "\n";
}
</lang>
=={{header|J}}==
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