Unreachable Code

src/main/java/ch/njol/skript/ScriptLoader.java

@@ -949,9 +949,10 @@ public static ArrayList<TriggerItem> loadItems(SectionNode node) {
 
 		if (Skript.debug())
 			parser.setIndentation(parser.getIndentation() + "    ");
-		
+
 		ArrayList<TriggerItem> items = new ArrayList<>();
 
+		boolean executionStops = false;
 		for (Node subNode : node) {
 			parser.setNode(subNode);
 
@@ -962,10 +963,11 @@ public static ArrayList<TriggerItem> loadItems(SectionNode node) {
 			if (!SkriptParser.validateLine(expr))
 				continue;
 
+			TriggerItem item;
 			if (subNode instanceof SimpleNode) {
 				long start = System.currentTimeMillis();
-				Statement stmt = Statement.parse(expr, items, "Can't understand this condition/effect: " + expr);
-				if (stmt == null)
+				item = Statement.parse(expr, items, "Can't understand this condition/effect: " + expr);
+				if (item == null)
 					continue;
 				long requiredTime = SkriptConfig.longParseTimeWarningThreshold.value().getMilliSeconds();
 				if (requiredTime > 0) {
@@ -978,34 +980,40 @@ public static ArrayList<TriggerItem> loadItems(SectionNode node) {
 				}
 
 				if (Skript.debug() || subNode.debug())
-					Skript.debug(SkriptColor.replaceColorChar(parser.getIndentation() + stmt.toString(null, true)));
+					Skript.debug(SkriptColor.replaceColorChar(parser.getIndentation() + item.toString(null, true)));
 
-				items.add(stmt);
+				items.add(item);
 			} else if (subNode instanceof SectionNode) {
 				TypeHints.enterScope(); // Begin conditional type hints
 
-				Section section = Section.parse(expr, "Can't understand this section: " + expr, (SectionNode) subNode, items);
-				if (section == null)
+				item = Section.parse(expr, "Can't understand this section: " + expr, (SectionNode) subNode, items);
+				if (item == null)
 					continue;
 
 				if (Skript.debug() || subNode.debug())
-					Skript.debug(SkriptColor.replaceColorChar(parser.getIndentation() + section.toString(null, true)));
+					Skript.debug(SkriptColor.replaceColorChar(parser.getIndentation() + item.toString(null, true)));
 
-				items.add(section);
+				items.add(item);
 
 				// Destroy these conditional type hints
 				TypeHints.exitScope();
+			} else {
+				continue;
 			}
+
+			if (executionStops)
+				Skript.warning("Unreachable code. The previous statement stops further execution.");
+			executionStops = item.executionIntent() != null;
 		}
-		
+
 		for (int i = 0; i < items.size() - 1; i++)
 			items.get(i).setNext(items.get(i + 1));
 
 		parser.setNode(node);
-		
+
 		if (Skript.debug())
 			parser.setIndentation(parser.getIndentation().substring(0, parser.getIndentation().length() - 4));
-		
+
 		return items;
 	}
 

src/main/java/ch/njol/skript/effects/EffExit.java

@@ -23,13 +23,8 @@
 import ch.njol.skript.doc.Examples;
 import ch.njol.skript.doc.Name;
 import ch.njol.skript.doc.Since;
-import ch.njol.skript.lang.Effect;
-import ch.njol.skript.lang.Expression;
-import ch.njol.skript.lang.SectionExitHandler;
-import ch.njol.skript.lang.LoopSection;
+import ch.njol.skript.lang.*;
 import ch.njol.skript.lang.SkriptParser.ParseResult;
-import ch.njol.skript.lang.TriggerItem;
-import ch.njol.skript.lang.TriggerSection;
 import ch.njol.skript.lang.parser.ParserInstance;
 import ch.njol.skript.log.ErrorQuality;
 import ch.njol.skript.sections.SecConditional;
@@ -51,7 +46,7 @@
 		"\tset loop-block to water"
 })
 @Since("<i>unknown</i> (before 2.1)")
-public class EffExit extends Effect { // TODO [code style] warn user about code after a stop effect
+public class EffExit extends Effect {
 
 	static {
 		Skript.registerEffect(EffExit.class,
@@ -60,15 +55,15 @@ public class EffExit extends Effect { // TODO [code style] warn user about code
 				"(exit|stop) <\\d+> (section|1:loop|2:conditional)s",
 				"(exit|stop) all (section|1:loop|2:conditional)s");
 	}
-	
+
 	private int breakLevels;
-	
+
 	private static final int EVERYTHING = 0;
 	private static final int LOOPS = 1;
 	private static final int CONDITIONALS = 2;
 	private static final String[] names = {"sections", "loops", "conditionals"};
 	private int type;
-	
+
 	@Override
 	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, ParseResult parser) {
 		switch (matchedPattern) {
@@ -99,7 +94,7 @@ public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelaye
 		}
 		return true;
 	}
-	
+
 	private static int numLevels(int type) {
 		List<TriggerSection> currentSections = ParserInstance.get().getCurrentSections();
 		if (type == EVERYTHING)
@@ -111,7 +106,7 @@ private static int numLevels(int type) {
 		}
 		return level;
 	}
-	
+
 	@Override
 	@Nullable
 	protected TriggerItem walk(Event event) {
@@ -131,15 +126,20 @@ protected TriggerItem walk(Event event) {
 		}
 		return node instanceof LoopSection ? ((LoopSection) node).getActualNext() : node.getNext();
 	}
-	
+
 	@Override
 	protected void execute(Event event) {
 		assert false;
 	}
-
+
+	@Override
+	public @Nullable ExecutionIntent executionIntent() {
+		return ExecutionIntent.stopSections(breakLevels);
+	}
+
 	@Override
 	public String toString(@Nullable Event event, boolean debug) {
 		return "stop " + breakLevels + " " + names[type];
 	}
-	
+
 }

src/main/java/ch/njol/skript/effects/EffReturn.java

@@ -23,14 +23,9 @@
 import ch.njol.skript.doc.Examples;
 import ch.njol.skript.doc.Name;
 import ch.njol.skript.doc.Since;
-import ch.njol.skript.lang.Effect;
-import ch.njol.skript.lang.Expression;
-import ch.njol.skript.lang.ReturnHandler;
+import ch.njol.skript.lang.*;
 import ch.njol.skript.lang.ReturnHandler.ReturnHandlerStack;
-import ch.njol.skript.lang.SectionExitHandler;
 import ch.njol.skript.lang.SkriptParser.ParseResult;
-import ch.njol.skript.lang.TriggerItem;
-import ch.njol.skript.lang.TriggerSection;
 import ch.njol.skript.lang.parser.ParserInstance;
 import ch.njol.skript.log.RetainingLogHandler;
 import ch.njol.skript.log.SkriptLogger;
@@ -130,6 +125,11 @@ protected void execute(Event event) {
 		assert false;
 	}
 
+	@Override
+	public ExecutionIntent executionIntent() {
+		return ExecutionIntent.stopTrigger();
+	}
+
 	@Override
 	public String toString(@Nullable Event event, boolean debug) {
 		return "return " + value.toString(event, debug);

src/main/java/ch/njol/skript/lang/ExecutionIntent.java

@@ -0,0 +1,85 @@
+package ch.njol.skript.lang;
+
+import com.google.common.base.Preconditions;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Used to describe the intention of a {@link TriggerItem}.
+ * Currently only used to tell whether the item halts the execution or not and print the appropriate warnings.
+ * 
+ * @see TriggerItem#executionIntent() 
+ */
+public abstract class ExecutionIntent implements Comparable<ExecutionIntent> {
+
+	private ExecutionIntent() {}
+
+	public static StopTrigger stopTrigger() {
+		return new StopTrigger();
+	}
+
+	public static StopSections stopSections(int levels) {
+		Preconditions.checkArgument(levels > 0, "Depth must be at least 1");
+		return new StopSections(levels);
+	}
+
+	public static StopSections stopSection() {
+		return new StopSections(1); 
+	}
+
+	public abstract @Nullable ExecutionIntent use();
+
+	public static class StopTrigger extends ExecutionIntent {
+
+		private StopTrigger() {}
+
+		@Override
+		public StopTrigger use() {
+			return new StopTrigger();
+		}
+
+		@Override
+		@SuppressWarnings("ComparatorMethodParameterNotUsed")
+		public int compareTo(@NotNull ExecutionIntent other) {
+			return other instanceof StopTrigger ? 0 : 1;
+		}
+
+		@Override
+		public String toString() {
+			return "StopTrigger";
+		}
+
+	}
+
+	public static class StopSections extends ExecutionIntent {
+
+		private final int levels;
+
+        public StopSections(int levels) {
+			this.levels = levels;
+		}
+
+		public int levels() {
+			return levels;
+		}
+
+		public @Nullable ExecutionIntent.StopSections use() {
+			return levels > 1 ? new StopSections(levels - 1) : null;
+		}
+
+		@Override
+		public int compareTo(@NotNull ExecutionIntent other) {
+			if (other instanceof StopTrigger)
+				return -1;
+			int levels = ((StopSections) other).levels;
+			return Integer.compare(this.levels, levels);
+		}
+
+		@Override
+		public String toString() {
+			return "StopSections(" + levels + ")";
+		}
+
+	}
+
+}

src/main/java/ch/njol/skript/lang/ExpressionList.java

@@ -28,13 +28,10 @@
 import ch.njol.util.coll.CollectionUtils;
 import org.bukkit.event.Event;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 
 import java.lang.reflect.Array;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.List;
-import java.util.NoSuchElementException;
+import java.util.*;
 
 /**
  * A list of expressions.
@@ -302,6 +299,23 @@ public Expression<? extends T>[] getExpressions() {
 		return expressions;
 	}
 
+	/**
+	 * Retrieves all expressions, including those nested within any {@code ExpressionList}s.
+	 *
+	 * @return A list of all expressions.
+	 */
+	public List<Expression<? extends T>> getAllExpressions() {
+		List<Expression<? extends T>> expressions = new ArrayList<>();
+		for (Expression<? extends T> expression : this.expressions) {
+			if (expression instanceof ExpressionList<?>) {
+				expressions.addAll(((ExpressionList<? extends T>) expression).getAllExpressions());
+				continue;
+			}
+			expressions.add(expression);
+		}
+		return expressions;
+	}
+
 	@Override
 	@SuppressWarnings("unchecked")
 	public Expression<T> simplify() {

src/main/java/ch/njol/skript/lang/TriggerItem.java

@@ -110,6 +110,20 @@ public static boolean walk(TriggerItem start, Event event) {
 		return false;
 	}
 
+	/**
+	 * Returns whether this item stops the execution of the current trigger or section(s).
+	 * <br>
+	 * If present, and there are statement(s) after this one, the parser will print a warning
+	 * to the user.
+	 * <p>
+	 * <b>Note: This method is used purely to print warnings and doesn't affect parsing, execution or anything else.</b>
+	 *
+	 * @return whether this item stops the execution of the current trigger or section.
+	 */
+	public @Nullable ExecutionIntent executionIntent() {
+		return null;
+	}
+
 	/**
 	 * how much to indent each level
 	 */
@@ -167,4 +181,8 @@ public TriggerItem setNext(@Nullable TriggerItem next) {
 		return next;
 	}
 
+	public @Nullable TriggerItem getActualNext() {
+		return next;
+	}
+
 }

src/main/java/ch/njol/skript/lang/TriggerSection.java

@@ -113,4 +113,16 @@ protected final boolean run(Event event) {
 		}
 	}
 
+	protected @Nullable ExecutionIntent triggerExecutionIntent() {
+		TriggerItem current = first;
+		while (current != null && current != last) {
+			ExecutionIntent executionIntent = current.executionIntent();
+			if (executionIntent != null)
+				return executionIntent.use();
+			current = current.getActualNext();
+		}
+		ExecutionIntent executionIntent = current != null ? current.executionIntent() : null;
+		return executionIntent != null ? executionIntent.use() : null;
+	}
+
 }