static void expandOn(const map<string, Definition>& grammar, int aNonTerminalPos, vector<string>& aResult)
{
if(aNonTerminalPos == -1)
{
// Base case //
return;
}
else
{
// Recursive case //
auto iterator = grammar.find(aResult[aNonTerminalPos]);
// If non-terminal is not defined then display error msg and exit.
if(iterator == grammar.end()) {
cout << "Could not find \"" << aResult[aNonTerminalPos] << "\" in the grammar file." << endl;
exit (EXIT_FAILURE);
}
Definition myDefinition = iterator->second;
Production myRandProduction = myDefinition.getRandomProduction();
// Get iterator 1 passed pos to insert.
auto resultIterator = aResult.begin()+aNonTerminalPos+1;
aResult.insert(resultIterator, myRandProduction.begin(), myRandProduction.end());
// Get new valid iterator and delete expanded non-terminal.
resultIterator = aResult.begin()+aNonTerminalPos;
aResult.erase(resultIterator);
// Iterate through result vector to expand on non-terminals.
// Start from previously expanded position.
int newNonTerminalPos = -1;
int pos = aNonTerminalPos;
for(auto start = aResult.begin()+aNonTerminalPos; start != aResult.end(); start++)
{
// Check if non-terminal.
if( (*start)[0] == '<')
{
newNonTerminalPos = pos;
break;
}
pos++;
}
// Recurse.
expandOn(grammar, newNonTerminalPos, aResult);
}
}
static void expendProduction(Production& production, const map<string, Definition>& grammar) {
for (auto iter = production.begin(); iter < production.end(); ++iter) {
string str = *iter;
if (str.find('<') == std::string::npos) {
cout << str << " ";
} else {
Definition def = grammar.at(str);
Production prod = def.getRandomProduction();
expendProduction(prod, grammar);
}
}
}
static void generateRandomSentences(const map<string, Definition>& grammar,
int numSentencesNeeded)
{
for (int i = 0; i < numSentencesNeeded; i++) {
map<string,Definition>::const_iterator it;
it = grammar.find("<start>");
const Production startProduction = it->second.getRandomProduction();
vector<string> sentence;
// Copy startProduction into a vector
for (auto pi = startProduction.begin(); pi != startProduction.end(); ++pi) {
string word = *pi;
sentence.push_back(word);
}
printProduction (grammar, sentence);
}
cout << endl;
}
static void printProduction( const map<string, Definition>& grammar, vector<string> sentence)
{
bool nonterminalExpanded = false;
vector<string> nextSentence;
// Generate next sentence, expanding at most 1 nonterminal
for (auto vi = sentence.begin(); vi != sentence.end(); ++vi) {
string word = *vi;
if (word.front() == '<' && !nonterminalExpanded) { //if 1st nonterminal
map<string,Definition>::const_iterator it;
it = grammar.find(word);
// if expansion is in grammar
if (it != grammar.end()) {
const Production nextProduction = it->second.getRandomProduction();
for (auto pi = nextProduction.begin(); pi != nextProduction.end(); ++pi) {
nextSentence.push_back(*pi);
}
nonterminalExpanded = true;
}
// else expansion references an undefined non-terminal, exit program
else {
cerr << "Could not find \"" << word << "\" in the grammar file." << endl;
exit(0);
}
}
else if (nonterminalExpanded) {
nextSentence.push_back(word);
}
else {
nextSentence.push_back(word);
}
}
// If nonterminals were expanded we print next Sentence
if (nonterminalExpanded == true) {
printProduction(grammar, nextSentence);
}
else {
for (auto vi = nextSentence.begin(); vi != nextSentence.end(); ++vi) {
vi++;
if (vi != nextSentence.end()) {
string nextWord = *vi;
vi--;
if (nextWord.compare(",") == 0 || nextWord.compare(".") == 0 ||
nextWord.compare("?") == 0 || nextWord.compare("!") == 0 ||
nextWord.compare(":") == 0) {
cout << *vi;
}
else {
cout << *vi << " ";
}
}
else {
vi--;
cout << *vi << " ";
}
}
}
}