trim abstract semantics

lisa/lisa-analyses/src/main/java/it/unive/lisa/analysis/string/tarsis/RegexAutomaton.java

@@ -466,4 +466,8 @@ public RegexAutomaton repeat(long n) {
 			return emptyString();		
 		return toRegex().simplify().repeat(n).toAutomaton(this).minimize();
 	}
+
+	public RegexAutomaton trim() {
+		return toRegex().trim().toAutomaton(this);			
+	}
 }

lisa/lisa-analyses/src/main/java/it/unive/lisa/analysis/string/tarsis/Tarsis.java

@@ -424,4 +424,8 @@ else if (intv.interval.isFinite()) {
 		} else
 			return new Tarsis(a.repeat(intv.interval.getLow().toLong()).concat(a.star()));
 	}
+
+	public Tarsis trim() {
+		return new Tarsis(this.a.trim());
+	}
 }

lisa/lisa-analyses/src/test/java/it/unive/lisa/analysis/string/tarsis/TrimTest.java

@@ -0,0 +1,31 @@
+package it.unive.lisa.analysis.string.tarsis;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import it.unive.lisa.util.numeric.MathNumberConversionException;
+
+public class TrimTest {
+
+	@Test
+	public void repeatSingleString() throws MathNumberConversionException {
+		RegexAutomaton abc = RegexAutomaton.string("abc");
+		RegexAutomaton ws = RegexAutomaton.string("   ");
+		RegexAutomaton epsilon = RegexAutomaton.string("");
+		RegexAutomaton abc_with_ws = RegexAutomaton.string("   a b c   ");
+
+		Tarsis a = new Tarsis(abc);
+		Tarsis b = new Tarsis(ws);
+		Tarsis c = new Tarsis(abc_with_ws);
+
+		// "abc".trim() = "abc"
+		assertTrue(a.trim().getAutomaton().isEqualTo(abc));
+
+		// "   ".trim() = ""
+		assertTrue(b.trim().getAutomaton().isEqualTo(epsilon));
+
+		// "   a b c   ".trim() = "a b c"
+		assertTrue(c.trim().getAutomaton().isEqualTo(RegexAutomaton.string("a b c")));
+	}
+}

lisa/lisa-sdk/src/main/java/it/unive/lisa/util/datastructures/regex/Atom.java

@@ -194,4 +194,9 @@ public RegularExpression repeat(long n) {
 		r.simplify();
 		return r;
 	}
+
+	@Override
+	public RegularExpression trim() {
+		return new Atom(this.string.trim());
+	}
 }

lisa/lisa-sdk/src/main/java/it/unive/lisa/util/datastructures/regex/Comp.java

@@ -300,4 +300,14 @@ public RegularExpression repeat(long n) {
 			r = new Comp(r, this);
 		return r.simplify();
 	}
+
+	@Override
+	public RegularExpression trim() {
+
+		RegularExpression trimFirst = first.trim().simplify();
+		if (trimFirst.isEmpty())
+			return second.trim();
+		else
+			return new Comp(trimFirst, second).simplify();
+	}
 }

lisa/lisa-sdk/src/main/java/it/unive/lisa/util/datastructures/regex/EmptySet.java

@@ -137,4 +137,9 @@ protected int compareToAux(RegularExpression other) {
 	public RegularExpression repeat(long n) {
 		return this;
 	}
+
+	@Override
+	public RegularExpression trim() {
+		return this;
+	}
 }

lisa/lisa-sdk/src/main/java/it/unive/lisa/util/datastructures/regex/Or.java

@@ -283,4 +283,9 @@ protected int compareToAux(RegularExpression other) {
 	public RegularExpression repeat(long n) {
 		return new Or(first.repeat(n), second.repeat(n)).simplify();
 	}
+
+	@Override
+	public RegularExpression trim() {
+		return new Or(first.trim(), second.trim());
+	}
 }

lisa/lisa-sdk/src/main/java/it/unive/lisa/util/datastructures/regex/RegularExpression.java

@@ -313,6 +313,7 @@ public String toString() {
 
 	public abstract RegularExpression repeat(long n);
 
+	public abstract RegularExpression trim();
 	/**
 	 * Yields {@code true} if and only if this regular expression corresponds to
 	 * the empty string or to no strings at all.

lisa/lisa-sdk/src/main/java/it/unive/lisa/util/datastructures/regex/Star.java

@@ -240,4 +240,9 @@ protected int compareToAux(RegularExpression other) {
 	public RegularExpression repeat(long n) {
 		return this;
 	}
+
+	@Override
+	public RegularExpression trim() {
+		return new Star(op.trim());
+	}
 }