--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/Fahad/Eclipse/ScalaProjects/src/CodeSamples/PatternMatching.sc Sat Nov 01 20:25:21 2014 +0000
@@ -0,0 +1,46 @@
+package CodeSamples
+
+object PatternMatching {
+ def matchTest(x: Any): Any = x match {
+ case 1 => "one"
+ case "two" => 2
+ case y: Int => "scala.Int"
+ case _ => "many"
+ } //> matchTest: (x: Any)Any
+
+ matchTest("Two") //> res0: Any = many
+ matchTest("Test") //> res1: Any = many
+ matchTest(1) //> res2: Any = one
+ matchTest(2) //> res3: Any = scala.Int
+
+ def matchTest2(x: Any) {
+ x match {
+ case 1 => "one"
+ case "two" => 2
+ case y: Int => "scala.Int"
+ case _ => "many"
+ }
+ } //> matchTest2: (x: Any)Unit
+
+ //Matching Using case Classes
+ case class Person(name: String, age: Int)
+
+ def caseClassTest(): Unit = {
+ val alice = new Person("Alice", 25)
+ val bob = new Person("Bob", 32)
+ val charlie = new Person("Charlie", 32)
+
+ for (person <- List(alice, bob, charlie)) {
+ person match {
+ case Person("Alice", 25) => println("Hi Alice!")
+ case Person("Bob", 32) => println("Hi Bob!")
+ case Person(name, age) =>
+ println("Age: " + age + " year, name: " + name + "?")
+ }
+ }
+ } //> caseClassTest: ()Unit
+
+ caseClassTest() //> Hi Alice!
+ //| Hi Bob!
+ //| Age: 32 year, name: Charlie?
+}
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/Fahad/Eclipse/ScalaProjects/src/Handouts/Handout2.sc Sat Nov 01 20:25:21 2014 +0000
@@ -0,0 +1,118 @@
+package Handouts
+
+import io.Source
+import scala.util.matching.Regex
+import scala.util._
+
+object Handout2 {
+ abstract class Rexp
+ case object NULL extends Rexp
+ case object EMPTY extends Rexp
+ case class CHAR(c: Char) extends Rexp
+ case class ALT(r1: Rexp, r2: Rexp) extends Rexp
+ case class SEQ(r1: Rexp, r2: Rexp) extends Rexp
+ case class STAR(r: Rexp) extends Rexp
+ case class NTIMES(r: Rexp, n: Int) extends Rexp
+
+ def OPT(r: Rexp) = ALT(r, EMPTY) //> OPT: (r: Handouts.Handout2.Rexp)Handouts.Handout2.ALT
+
+ /*
+ def NTIMES(r: Rexp, n: Int): Rexp = n match {
+ case 0 => EMPTY
+ case 1 => r
+ case n => SEQ(r, NTIMES(r, n - 1))
+ }
+ */
+
+ def nullable(r: Rexp): Boolean = r match {
+ case NULL => false
+ case EMPTY => true
+ case CHAR(_) => false
+ case ALT(r1, r2) => nullable(r1) || nullable(r2)
+ case SEQ(r1, r2) => nullable(r1) && nullable(r2)
+ case STAR(_) => true
+ case NTIMES(r, i) => if (i == 0) true else nullable(r)
+ } //> nullable: (r: Handouts.Handout2.Rexp)Boolean
+
+ def der(c: Char, r: Rexp): Rexp = r match {
+ case NULL => NULL
+ case EMPTY => NULL
+ case CHAR(d) => if (c == d) EMPTY else NULL
+ case ALT(r1, r2) => ALT(der(c, r1), der(c, r2))
+ case SEQ(r1, r2) =>
+ if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2))
+ else SEQ(der(c, r1), r2)
+ case STAR(r) => SEQ(der(c, r), STAR(r))
+ case NTIMES(r, i) =>
+ if (i == 0) NULL else SEQ(der(c, r), NTIMES(r, i - 1))
+ } //> der: (c: Char, r: Handouts.Handout2.Rexp)Handouts.Handout2.Rexp
+
+ def _ders(s: List[Char], r: Rexp): Rexp = s match {
+ case Nil => r
+ case c :: s => ders(s, der(c, r))
+ } //> _ders: (s: List[Char], r: Handouts.Handout2.Rexp)Handouts.Handout2.Rexp
+
+ def ders(s: List[Char], r: Rexp): Rexp = s match {
+ case Nil => r
+ case c :: s => ders(s, simp(der(c, r)))
+ } //> ders: (s: List[Char], r: Handouts.Handout2.Rexp)Handouts.Handout2.Rexp
+
+ def matches(r: Rexp, s: String): Boolean =
+ nullable(ders(s.toList, r)) //> matches: (r: Handouts.Handout2.Rexp, s: String)Boolean
+
+ def simp(r: Rexp): Rexp = r match {
+ case ALT(r1, r2) => {
+ val r1s = simp(r1)
+ val r2s = simp(r2)
+ (r1s, r2s) match {
+ case (NULL, _) => r2s
+ case (_, NULL) => r1s
+ case _ => if (r1s == r2s) r1s else ALT(r1s, r2s)
+ }
+ }
+ case SEQ(r1, r2) => {
+ val r1s = simp(r1)
+ val r2s = simp(r2)
+ (r1s, r2s) match {
+ case (NULL, _) => NULL
+ case (_, NULL) => NULL
+ case (EMPTY, _) => r2s
+ case (_, EMPTY) => r1s
+ case _ => SEQ(r1s, r2s)
+ }
+ }
+ case NTIMES(r, n) => NTIMES(simp(r), n)
+ case r => r
+ } //> simp: (r: Handouts.Handout2.Rexp)Handouts.Handout2.Rexp
+
+ /************************************************************************************************************************************/
+ // der test
+ // r = {(a.b) + b}*
+ val r = STAR(ALT(SEQ(CHAR('a'), CHAR('b')), CHAR('b')))
+ //> r : Handouts.Handout2.STAR = STAR(ALT(SEQ(CHAR(a),CHAR(b)),CHAR(b)))
+
+ // => [{(_.b) + null} . {(a.b)+b}*]
+ der('a', r) //> res0: Handouts.Handout2.Rexp = SEQ(ALT(SEQ(EMPTY,CHAR(b)),NULL),STAR(ALT(SE
+ //| Q(CHAR(a),CHAR(b)),CHAR(b))))
+ // => [{(null.b) + _} . {(a.b)+b}*]
+ der('b', r) //> res1: Handouts.Handout2.Rexp = SEQ(ALT(SEQ(NULL,CHAR(b)),EMPTY),STAR(ALT(SE
+ //| Q(CHAR(a),CHAR(b)),CHAR(b))))
+ // => [{(null.b) + _} . {(a.b)+b}*]
+ der('c', r) //> res2: Handouts.Handout2.Rexp = SEQ(ALT(SEQ(NULL,CHAR(b)),NULL),STAR(ALT(SEQ
+ //| (CHAR(a),CHAR(b)),CHAR(b))))
+
+ val r2 = ALT(SEQ(CHAR('a'), CHAR('b')), CHAR('b'))
+ //> r2 : Handouts.Handout2.ALT = ALT(SEQ(CHAR(a),CHAR(b)),CHAR(b))
+ der('a', r2) //> res3: Handouts.Handout2.Rexp = ALT(SEQ(EMPTY,CHAR(b)),NULL)
+
+ val r3 = SEQ(CHAR('a'), CHAR('b')) //> r3 : Handouts.Handout2.SEQ = SEQ(CHAR(a),CHAR(b))
+ der('a', r3) //> res4: Handouts.Handout2.Rexp = SEQ(EMPTY,CHAR(b))
+
+ val r4 = CHAR('a') //> r4 : Handouts.Handout2.CHAR = CHAR(a)
+ der('a', r4) //> res5: Handouts.Handout2.Rexp = EMPTY
+
+ nullable(r) //> res6: Boolean = true
+ nullable(r2) //> res7: Boolean = false
+ nullable(r3) //> res8: Boolean = false
+ nullable(r4) //> res9: Boolean = false
+}
\ No newline at end of file