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authorPeter Wu <peter@lekensteyn.nl>2016-05-08 16:01:51 +0200
committerPeter Wu <peter@lekensteyn.nl>2016-05-08 16:01:51 +0200
commit36fb690d33b1f487a8d299470cfe9c5d900c58a3 (patch)
tree329bdf418f3ea690f9141a36d5775447b3e37b03 /src
parent4dbbdbab2dbdd265e2c06db02823c29c236e91dd (diff)
downloadRegexTest-36fb690d33b1f487a8d299470cfe9c5d900c58a3.tar.gz
Add skeleton for PicoRec
NAT and ID regexes were taken from RegexTest.java. Tests are added before the implementation (test-driven development).
Diffstat (limited to 'src')
-rw-r--r--src/PicoRec.java72
1 files changed, 72 insertions, 0 deletions
diff --git a/src/PicoRec.java b/src/PicoRec.java
new file mode 100644
index 0000000..eec2f38
--- /dev/null
+++ b/src/PicoRec.java
@@ -0,0 +1,72 @@
+/**
+ * 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");
+ }
+}