Eliminate Java 9 language components to be JRE8 compatible

Author: Sebastian Höfer

src/main/java/org/jqassistant/contrib/plugin/javascript/scanner/listener/JavaScriptListener.java

@@ -6,6 +6,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
+import java.util.NoSuchElementException;
 import java.util.Optional;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -47,6 +48,7 @@
 import org.jqassistant.contrib.plugin.javascript.scanner.visitor.helpers.ObjectStoreHelper;
 import org.jqassistant.contrib.plugin.javascript.scanner.visitor.helpers.ParameterStoreHelper;
 import org.jqassistant.contrib.plugin.javascript.scanner.visitor.helpers.PrimitiveStoreHelper;
+import org.jqassistant.contrib.plugin.javascript.scanner.visitor.helpers.StreamHelper;
 import org.jqassistant.contrib.plugin.javascript.scanner.visitor.helpers.VariableStoreHelper;
 
 import com.buschmais.jqassistant.core.store.api.Store;
@@ -172,38 +174,37 @@ public void exitMethodDefinition(MethodDefinitionContext ctx) {
 		artifactStack.pop();
 	}
 
-	private FunctionDescriptor getLastDefinedFunction() {
+	@Override
+	public void enterFormalParameterArg(FormalParameterArgContext ctx) {
+		int countParamtersBefore = countLastParameters().intValue();
+		FunctionDescriptor function = getLastDefinedFunction();
+		FunctionParameterDescriptor ecmaParam = new ParameterStoreHelper(countParamtersBefore).createNodeIn(store, ctx);
+		setQualifiedName(function, ecmaParam, ecmaParam.getName());
+		amendStack(ecmaParam);
+		function.getParameters().add(ecmaParam);
+	}
+	
+	private Long countLastParameters() {
 		// https://stackoverflow.com/questions/24010109/java-8-stream-reverse-order
 		ListIterator<JavaScriptDescriptor> listIterator = artifacts.listIterator(artifacts.size());
-		return Stream.generate(listIterator::previous)
-			      .limit(artifacts.size())
-			      .filter((e) -> e instanceof FunctionDescriptor)
-			      .map((e) -> (FunctionDescriptor)e)
-			      .findFirst()
-			      .orElseThrow();
+		Stream<JavaScriptDescriptor> reverseParamterStream = Stream.generate(listIterator::previous).limit(artifacts.size());
+		return StreamHelper.takeWhile(reverseParamterStream, (desc) -> desc instanceof FunctionParameterDescriptor)
+						   .collect(Collectors.counting());
+		
 
-			      
 	}
 
-	private Long countLastParameters() {
+	private FunctionDescriptor getLastDefinedFunction() {
 		// https://stackoverflow.com/questions/24010109/java-8-stream-reverse-order
 		ListIterator<JavaScriptDescriptor> listIterator = artifacts.listIterator(artifacts.size());
 		return Stream.generate(listIterator::previous)
-			      .limit(artifacts.size())
-			      .takeWhile((desc) -> desc instanceof FunctionParameterDescriptor) // JAVA 9
-			      .collect(Collectors.counting());
+				.limit(artifacts.size())
+				.filter((e) -> e instanceof FunctionDescriptor)
+				.map((e) -> (FunctionDescriptor)e)
+				.findFirst()
+				.orElseThrow(() -> new NoSuchElementException("the last function wasn't found")); // Function not found shoudn't be happening
+		
 
-			      
-	}
-	
-	@Override
-	public void enterFormalParameterArg(FormalParameterArgContext ctx) {
-		int countParamtersBefore = countLastParameters().intValue();
-		FunctionDescriptor function = getLastDefinedFunction();
-		FunctionParameterDescriptor ecmaParam = new ParameterStoreHelper(countParamtersBefore).createNodeIn(store, ctx);
-		setQualifiedName(function, ecmaParam, ecmaParam.getName());
-		amendStack(ecmaParam);
-		function.getParameters().add(ecmaParam);
 	}
 
 	@Override

src/main/java/org/jqassistant/contrib/plugin/javascript/scanner/visitor/helpers/StreamHelper.java

@@ -0,0 +1,37 @@
+package org.jqassistant.contrib.plugin.javascript.scanner.visitor.helpers;
+
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+public class StreamHelper {
+
+	// https://stackoverflow.com/questions/20746429/limit-a-stream-by-a-predicate
+	public static <T> Stream<T> takeWhile(Stream<T> stream, Predicate<? super T> predicate) {
+		return StreamSupport.stream(takeWhile(stream.spliterator(), predicate), false);
+	}
+
+	private static <T> Spliterator<T> takeWhile(Spliterator<T> splitr, Predicate<? super T> predicate) {
+		return new Spliterators.AbstractSpliterator<T>(splitr.estimateSize(), 0) {
+			boolean stillGoing = true;
+			
+			@Override
+			public boolean tryAdvance(Consumer<? super T> consumer) {
+				if (stillGoing) {
+					boolean hadNext = splitr.tryAdvance(elem -> {
+						if (predicate.test(elem)) {
+							consumer.accept(elem);
+						} else {
+							stillGoing = false;
+						}
+					});
+					return hadNext && stillGoing;
+				}
+				return false;
+			}
+		};
+	}
+}