Improved select case parsing

src/main/java/com/scriptbasic/context/ContextBuilder.java

@@ -98,7 +98,8 @@ private static void createReaderDependentComponents(final SourceReader reader, f
         ctx.lexicalAnalyzer = new ScriptBasicLexicalAnalyzer(reader);
         ctx.nestedStructureHouseKeeper = new GenericNestedStructureHouseKeeper(ctx.lexicalAnalyzer);
         final var commandFactory = new BasicCommandFactory(ctx);
-        ctx.syntaxAnalyzer = new BasicSyntaxAnalyzer(ctx.lexicalAnalyzer, commandFactory);
+        ctx.syntaxAnalyzer = new BasicSyntaxAnalyzer(ctx.lexicalAnalyzer, commandFactory,
+                                                     ctx.nestedStructureHouseKeeper);
     }
 
     private static void createReusableComponents(final Context ctx) {

src/main/java/com/scriptbasic/interfaces/NestedStructureHouseKeeper.java

@@ -51,4 +51,14 @@ public interface NestedStructureHouseKeeper {
      */
     <T extends NestedStructure> T pop(Class<T> expectedClass)
             throws AnalysisException;
+
+    /**
+     * Check final state of nested structures.
+     * 
+     * Check if there are no opened nested structures
+     * or any other pending blocks.
+     * 
+     * @throws AnalysisException when there are some elements on the stack
+     */
+    void checkFinalState() throws AnalysisException;
 }

src/main/java/com/scriptbasic/syntax/AbstractNestedStructureHouseKeeper.java

@@ -83,4 +83,11 @@ public <T> boolean match(final Class<T> expectedClass) {
             return expectedClass.isAssignableFrom(getElementType());
         }
     }
+
+    @Override
+    public void checkFinalState() throws AnalysisException {
+        if (stack.size() > 0) {
+            throw new BasicSyntaxException("There is at least one opened block on the stack. Block is not properly closed.");
+        }
+    }
 }

src/main/java/com/scriptbasic/syntax/BasicSyntaxAnalyzer.java

@@ -5,14 +5,17 @@
 public final class BasicSyntaxAnalyzer implements SyntaxAnalyzer {
     private final LexicalAnalyzer lexicalAnalyzer;
     private final CommandFactory commandFactory;
-    private LexicalElement lexicalElement;
+    private final NestedStructureHouseKeeper nestedStructureHouseKeeper;
+    private LexicalElement lexicalElement;    
 
-    public BasicSyntaxAnalyzer(final LexicalAnalyzer lexicalAnalyzer, final CommandFactory commandFactory) {
+    public BasicSyntaxAnalyzer(final LexicalAnalyzer lexicalAnalyzer, final CommandFactory commandFactory, 
+                               final NestedStructureHouseKeeper nestedStructureHouseKeeper) {
         this.lexicalAnalyzer = lexicalAnalyzer;
         this.commandFactory = commandFactory;
+        this.nestedStructureHouseKeeper = nestedStructureHouseKeeper;
     }
 
-    private static boolean lineToIgnore(final String lexString) {
+    public static boolean lineToIgnore(final String lexString) {
         return lexString.equals("\n") || lexString.equals("'")
                 || lexString.equalsIgnoreCase(ScriptBasicKeyWords.KEYWORD_REM);
     }
@@ -49,11 +52,12 @@ public BuildableProgram analyze() throws AnalysisException {
             }
             this.lexicalElement = lexicalAnalyzer.peek();
         }
+        nestedStructureHouseKeeper.checkFinalState();
         buildableProgram.postprocess();
         return buildableProgram;
     }
 
-    private void consumeIgnoredLine(final LexicalAnalyzer lexicalAnalyzer, String lexString) throws AnalysisException {
+    public static void consumeIgnoredLine(final LexicalAnalyzer lexicalAnalyzer, String lexString) throws AnalysisException {
         while (!lexString.equals("\n")) {
             final var le = lexicalAnalyzer.get();
             if (le == null) {

src/main/java/com/scriptbasic/syntax/commands/CommandAnalyzerSelect.java

@@ -3,33 +3,48 @@
 import com.scriptbasic.context.Context;
 import com.scriptbasic.executors.commands.CommandSelect;
 import com.scriptbasic.interfaces.AnalysisException;
+import com.scriptbasic.interfaces.BasicSyntaxException;
 import com.scriptbasic.interfaces.ScriptBasicKeyWords;
 import com.scriptbasic.spi.Command;
+import com.scriptbasic.syntax.BasicSyntaxAnalyzer;
 
 public class CommandAnalyzerSelect
-	extends AbstractCommandAnalyzer
-{
-
-	public CommandAnalyzerSelect(Context ctx)		
-	{
-		super(ctx);
-	}
-
-	@Override
-	public Command analyze() throws AnalysisException {
-		final var lexicalElement = ctx.lexicalAnalyzer.peek();
-		// consume optional case statement
-		if(lexicalElement.isSymbol(ScriptBasicKeyWords.KEYWORD_CASE)) 
-			ctx.lexicalAnalyzer.get();
-		// read expression till end of line
-		final var expression = analyzeExpression();
-		consumeEndOfLine();
-
-		final var node = new CommandSelect();
-		node.setExpression(expression);
-		pushNode(node);
-
-		return node;
-	}
+        extends AbstractCommandAnalyzer {
+
+    public CommandAnalyzerSelect(Context ctx) {
+        super(ctx);
+    }
+
+    @Override
+    public Command analyze() throws AnalysisException {
+        var lexicalElement = ctx.lexicalAnalyzer.peek();
+        // consume optional case statement
+        if (lexicalElement.isSymbol(ScriptBasicKeyWords.KEYWORD_CASE))
+            ctx.lexicalAnalyzer.get();
+        // read expression till end of line
+        final var expression = analyzeExpression();
+        consumeEndOfLine();
+
+        final var node = new CommandSelect();
+        node.setExpression(expression);
+        pushNode(node);
+
+        // next command has to be 'case'
+        // first skip any comments
+        lexicalElement = ctx.lexicalAnalyzer.peek();
+        while (lexicalElement != null && BasicSyntaxAnalyzer.lineToIgnore(lexicalElement.getLexeme())) {
+            ctx.lexicalAnalyzer.get();
+            BasicSyntaxAnalyzer.consumeIgnoredLine(ctx.lexicalAnalyzer, lexicalElement.getLexeme());
+            lexicalElement = ctx.lexicalAnalyzer.peek();
+        }
+        if (lexicalElement == null) {
+            throw new BasicSyntaxException("Preliminary end of file");
+        }
+        if (!lexicalElement.isSymbol(ScriptBasicKeyWords.KEYWORD_CASE)) {
+            throw new BasicSyntaxException("Expected case statement, but found: " + lexicalElement.getLexeme());
+        }
+
+        return node;
+    }
 
 }

src/test/java/com/scriptbasic/testprograms/TestPrograms.java

@@ -61,12 +61,13 @@ public void testPrograms() throws Exception {
         codeTest("TestEmpty.bas", "");
         codeTest("TestPrintHello.bas", "hello");
         codeTest("TestIf.bas", "111");
-        codeTest("TestSelect1.bas", "111111");
+        codeTest("TestSelect1.bas", "1111111");
         codeTest("TestSelect2.bas", "2468");
         codeTest("TestSelect3.bas", "0 1 1 2 3 5 8");
         testSyntaxFail("TestSelectBadSyntax1.bas");
         testSyntaxFail("TestSelectBadSyntax2.bas");
         testSyntaxFail("TestSelectBadSyntax3.bas");
+        testSyntaxFail("TestSelectBadSyntax4.bas");
         codeTest("TestBooleanConversions.bas", "111111");
         codeTest("TestArrays.bas", "OK");
         try {

src/test/resources/com/scriptbasic/testprograms/TestSelect1.bas

@@ -45,4 +45,15 @@ case is "1": print "1"
 case is "2": print "2"
 end select
 
+' Test comments inside select case
+select case v
+rem comment before first case
+case "0": print "0"
+rem comment between case
+case "1": print "1"
+case "2": print "2"
+rem comment before end select
+end select
+rem comment after end select
+
 print "1"

src/test/resources/com/scriptbasic/testprograms/TestSelectBadSyntax1.bas

@@ -5,3 +5,4 @@
 
 select case v
 if true then print "1"
+end select

src/test/resources/com/scriptbasic/testprograms/TestSelectBadSyntax4.bas

@@ -0,0 +1,10 @@
+'
+' This program is used to test the bad syntax of 
+' command select case ... end select
+' when the 'end select' is missing
+'
+
+select case "1"
+case "0": print "0"
+case "1": print "1"
+case "2": print "2"