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/**
* Recognizer for the language described by grammar-ll1.txt.
*/
import dk.brics.automaton.RegExp;
import dk.brics.automaton.RunAutomaton;
public class PicoRec {
/** Regular expression describing the ID symbol. */
private final static String idRegex = "[a-z][a-z0-9]*";
/** Regular expression describing the NAT symbol. */
private final static String natRegex = "0|[1-9][0-9]*";
private final RunAutomaton idR, natR;
public PicoRec() {
idR = new RunAutomaton(new RegExp(idRegex).toAutomaton());
natR = new RunAutomaton(new RegExp(natRegex).toAutomaton());
}
/**
* Try to parse the input.
*
* @return true if the language is recognized, false otherwise.
*/
public boolean parse(String text) {
// TODO implement this
return false;
}
/* Convenience functions for testing. */
private void check(String input, boolean expectOk) {
boolean accepted = parse(input);
System.out.println("Testing input: " + input);
if (expectOk && !accepted || !expectOk && accepted) {
throw new RuntimeException("Unexpected result for " + input);
}
}
private void check(String[] input, boolean expectOk) {
check(String.join("\n", input), expectOk);
}
private void assertOk(String... input) {
check(input, true);
}
private void assertFail(String... input) {
check(input, false);
}
public static void main(String[] args) {
PicoRec rec = new PicoRec();
// minimal program satisfying the language, without whitespace.
rec.assertOk("begindeclare|end");
// simple expression
rec.assertOk("begin declare a | a := 1 end");
// Trivial failures
rec.assertFail("");
rec.assertFail("begin");
rec.assertFail("begin declare");
rec.assertFail("begin declare |");
rec.assertFail("begin declare | end end");
rec.assertFail("begin declare end");
rec.assertFail("begin end");
rec.assertFail("end");
}
}
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