Add check for balanced brackets in WhileLoopAnalysis

Author: Zomis

src/main/groovy/net/zomis/brainf/analyze/IndexCounters.groovy

@@ -4,7 +4,7 @@ import java.util.stream.Stream
 
 class IndexCounters {
     private final Map<Integer, IndexCounter> counters = [:]
-    private final Stack<IndexCounter> recentCounters = new Stack<>()
+    private final Deque<IndexCounter> recentCounters = new LinkedList<>()
 
     Stream<Map.Entry<Integer, IndexCounter>> sorted() {
         counters.entrySet().stream().sorted(Comparator.comparingInt({it.key}))
@@ -16,7 +16,7 @@ class IndexCounters {
 
     void begin(IndexCounter counter) {
         assert counter : 'Cannot begin on null counter'
-        recentCounters.push(counter)
+        recentCounters.addLast(counter)
         counter.begin()
     }
 
@@ -25,11 +25,11 @@ class IndexCounters {
     }
 
     void finishLast() {
-        recentCounters.pop().finishLast()
+        recentCounters.removeLast().finishLast()
     }
 
     IndexCounter recent() {
-        recentCounters.peek()
+        recentCounters.peekLast()
     }
 
     IndexCounter getOrCreate(int i) {

src/main/groovy/net/zomis/brainf/analyze/analyzers/WhileLoopAnalysis.groovy

@@ -29,6 +29,8 @@ class WhileLoopAnalysis implements BrainfuckAnalyzer {
     }
 
     private final IndexCounters whileLoopCounts = new IndexCounters()
+    private int bracketsOpened
+    private int bracketsClosed
 
     IndexCounters getWhileLoopCounts() {
         return this.whileLoopCounts
@@ -39,9 +41,25 @@ class WhileLoopAnalysis implements BrainfuckAnalyzer {
         return new CellLoops()
     }
 
+    @Override
+    void beforeStart(BrainfuckRunner runner) {
+        for (int i = 0; i < runner.code.commandCount; i++) {
+            BrainfuckCommand command = runner.code.getCommandAt(i)
+            if (command == BrainFCommand.WHILE) {
+                bracketsOpened++
+            }
+            if (command == BrainFCommand.END_WHILE) {
+                bracketsClosed++
+            }
+        }
+    }
+
     @Override
     void print() {
         println 'While loops analysis'
+        if (bracketsOpened != bracketsClosed) {
+            println "ERROR: Number of starting brackets ($bracketsOpened) mismatch number of ending brackets ($bracketsClosed)"
+        }
         whileLoopCounts.sorted().forEach({entry ->
             println "$entry.key $entry.value"
         })
@@ -63,7 +81,11 @@ class WhileLoopAnalysis implements BrainfuckAnalyzer {
         }
 
         if (command == BrainFCommand.END_WHILE) {
-            whileLoopCounts.recent().increase()
+            IndexCounter recent = whileLoopCounts.recent()
+            if (recent == null) {
+                return
+            }
+            recent.increase()
             int startIndex = whileLoopCounts.recent().forIndex
             int current = runner.memory.value
             if (current == 0) {
@@ -74,4 +96,17 @@ class WhileLoopAnalysis implements BrainfuckAnalyzer {
             }
         }
     }
+
+    int getBracketsOpened() {
+        this.@bracketsOpened
+    }
+
+    int getBracketsClosed() {
+        this.@bracketsClosed
+    }
+
+    boolean isBracketsMatching() {
+        this.bracketsClosed == this.bracketsOpened
+    }
+
 }

src/test/groovy/net/zomis/brainf/BrainTest.groovy

@@ -117,6 +117,20 @@ public class BrainTest extends BrainfuckTest {
         assert brain.getOutput() == "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
     }
 
+    @Test
+    public void unbalanced1() {
+        source.addCommands("++[->+<] ]")
+        analyze(new WhileLoopAnalysis())
+        assert !analyze.get(WhileLoopAnalysis).bracketsMatching
+    }
+
+    @Test
+    public void unbalanced2() {
+        source.addCommands("++ [ [->+<]")
+        analyze(new WhileLoopAnalysis())
+        assert !analyze.get(WhileLoopAnalysis).bracketsMatching
+    }
+
     @Test
     public void fizzBuzz() {
         source.addCommands(BrainfuckRunner.classLoader.getResource('fizzbuzz.bf').text);