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#include "rules.ih"
void Rules::determineFirst()
{
size_t lastCount = 0; // counts the number of first-elements.
while (true)
{
// Process all non-terminals (N). Handle all the production rules of
// these non-terminals. For an empty production, the N gets <empty>.
// For non-empty productions: add those element's first symbols, and
// stop if an element has no empty production. If, at the end, the
// final element has an empty production, add <empty> as well
NonTerminal::resetCounter();
for_each(d_nonTerminal.begin(), d_nonTerminal.end(),
&NonTerminal::setFirst);
if (lastCount == NonTerminal::counter())
break;
lastCount = NonTerminal::counter();
}
}
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