CFG as tuple of labels

.gitignore

@@ -0,0 +1,244 @@
+project/target
+project/.bloop/
+project/metals.sbt
+project/project/*
+target
+.env
+.jvmopts
+.sbtopts
+.metals/
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+*/.bloop/
+.bloop/
+
+# Created by https://www.gitignore.io/api/java,linux,macos,scala,eclipse,intellij+all
+# Edit at https://www.gitignore.io/?templates=java,linux,macos,scala,eclipse,intellij+all
+
+### Eclipse ###
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+bin/
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build.sbt

@@ -6,5 +6,3 @@ scalaVersion := "2.13.6"
 
 libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.0" % "test"
 libraryDependencies += "org.scalatest" %% "scalatest-featurespec" % "3.2.0" % "test"
-
-libraryDependencies += "org.scala-graph" %% "graph-core" % "1.13.2"

project/build.properties

@@ -0,0 +1 @@
+sbt.version=1.5.4

src/main/scala/br/unb/cic/wlang/AvailableExpression.scala

@@ -0,0 +1,82 @@
+package br.unb.cic.wlang
+
+import br.unb.cic.wlang.CFGBuilder._
+import br.unb.cic.wlang.WhileProgram._
+
+object AvailableExpression {
+  def process(program: WhileProgram): Abstraction = {
+    val bottom = nonTrivialExpressions(program)
+    val initialExit =
+      labels(program).foldLeft(Map[Int, Set[AExp]]()) { (m, label) => m + (label -> bottom) }
+
+    val abstraction = Abstraction(Map.empty, initialExit)
+    process(program, abstraction)
+  }
+
+  private def process(program: WhileProgram, abstraction: Abstraction): Abstraction = {
+    val (newAbstraction, continue) = iterate(labels(program), program, abstraction)
+    if (continue) {
+      process(program, newAbstraction)
+    } else {
+      newAbstraction
+    }
+  }
+
+  private def iterate(labels: Set[Int], program: WhileProgram, abstraction: Abstraction): (Abstraction, Boolean) = {
+    val newAbstraction = labels.foldLeft(abstraction) { (abstraction, label) => {
+        val newAbstractionForLabel = generateNewAbstractionForLabel(label, program,abstraction)
+        val newEntry = newAbstractionForLabel._1
+        val newExit = newAbstractionForLabel._2
+        Abstraction(abstraction.entry + newEntry, abstraction.exit + newExit)
+      }
+    }
+    (newAbstraction, abstraction != newAbstraction)
+  }
+  private def generateNewAbstractionForLabel(label: Int, program: WhileProgram, abstraction: Abstraction): ((Int, Set[AExp]), (Int, Set[AExp])) = {
+    val entry = generateEntry(label, program, abstraction)
+    val exit = generateExit(label, program, Map(label -> entry))
+    (label -> entry, label -> exit)
+  }
+
+  private def kill(block: Block, nonTrivialExpressions: Set[AExp]): Set[AExp] = block match {
+    case Assignment(name, _, _) => nonTrivialExpressions.filter(exp => expHasVariable(name, exp))
+    case Skip(_) => Set.empty
+    case Condition(_, _) => Set.empty
+  }
+
+  private def gen(block: Block): Set[AExp] = block match {
+    case Assignment(name, exp, _) => nonTrivialExpressions(exp).filterNot(exp => expHasVariable(name, exp))
+    case Skip(_) => Set.empty
+    case Condition(exp, _) => nonTrivialExpressions(exp)
+  }
+
+  private def expHasVariable(name: String, exp: AExp): Boolean = exp match {
+    case Var(n) => n == name
+    case Const(_) => false
+    case OpArith(_, a1, a2) => expHasVariable(name, a1) || expHasVariable(name, a2)
+  }
+
+  private def generateExit(label: Int, program: WhileProgram, entry: Map[Int, Set[AExp]]) = {
+    val calculatedBlock = block(label, program.stmt).get
+    val nonTrivialExpressions = WhileProgram.nonTrivialExpressions(program)
+    val exit =
+      (entry(label) diff kill(calculatedBlock, nonTrivialExpressions)) union gen(calculatedBlock)
+    exit
+  }
+
+  private def generateEntry(label: Int, program: WhileProgram, abstraction: Abstraction): Set[AExp] = {
+
+    if (label == initLabel(program.stmt)) {
+      Set.empty
+    } else {
+      val sets = (for {
+        (from, to) <- flow(program.stmt)
+        if to == label
+      } yield abstraction.exit(from)).toList
+      sets.foldLeft[Set[AExp]](nonTrivialExpressions(program))((s1,s2) => s1 intersect s2)
+    }
+
+  }
+
+  case class Abstraction(entry: Map[Int, Set[AExp]], exit: Map[Int, Set[AExp]])
+}