cache: add string append instruction

cache/src/main/java/net/runelite/cache/script/Instructions.java

@@ -55,7 +55,7 @@ public class Instructions
 		add(Opcodes.ISTORE, "istore", 1, 0);
 		add(Opcodes.SLOAD, "sload", 0, 0, 0, 1);
 		add(Opcodes.SSTORE, "sstore", 0, 0, 1, 0);
-		// 37 - pops strings eq to int operand, pushes 1 string
+		add(Opcodes.STRING_APPEND, 0, 0, -1, 1);
 		add(Opcodes.POP_INT, "pop_int", 1, 0);
 		add(Opcodes.POP_STRING, "pop_string", 0, 0, 1, 0);
 		add(Opcodes.INVOKE, "invoke", -1, -1, -1, -1);

cache/src/main/java/net/runelite/cache/script/Opcodes.java

@@ -42,6 +42,7 @@ public class Opcodes
 	public static final int ISTORE = 34;
 	public static final int SLOAD = 35;
 	public static final int SSTORE = 36;
+	public static final int STRING_APPEND = 37;
 	public static final int POP_INT = 38;
 	public static final int POP_STRING = 39;
 	public static final int INVOKE = 40;

cache/src/main/java/net/runelite/cache/script/interpreter/InstructionHandlers.java

@@ -37,6 +37,7 @@ import net.runelite.cache.script.interpreter.instructions.Invoke;
 import net.runelite.cache.script.interpreter.instructions.Jump;
 import net.runelite.cache.script.interpreter.instructions.LoadInt;
 import net.runelite.cache.script.interpreter.instructions.Return;
+import net.runelite.cache.script.interpreter.instructions.StringAppend;
 import net.runelite.cache.script.interpreter.instructions.Switch;
 
 public class InstructionHandlers
@@ -61,6 +62,7 @@ public class InstructionHandlers
 		add(Opcodes.INVOKE, new Invoke());
 		add(Opcodes.RETURN, new Return());
 		add(Opcodes.SWITCH, new Switch());
+		add(Opcodes.STRING_APPEND, new StringAppend());
 	}
 
 	private static void add(int opcode, InstructionHandler handler)

cache/src/main/java/net/runelite/cache/script/interpreter/instructions/StringAppend.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2017, Adam <Adam@sigterm.info>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.runelite.cache.script.interpreter.instructions;
+
+import net.runelite.cache.script.interpreter.Frame;
+import net.runelite.cache.script.interpreter.InstructionContext;
+import net.runelite.cache.script.interpreter.InstructionHandler;
+import net.runelite.cache.script.interpreter.ScriptInstruction;
+import net.runelite.cache.script.interpreter.Stack;
+import net.runelite.cache.script.interpreter.StackContext;
+
+public class StringAppend extends InstructionHandler
+{
+	@Override
+	public void execute(Frame frame, InstructionContext ctx)
+	{
+		Stack stringStack = frame.getStringStack();
+		ScriptInstruction scriptInstruction = ctx.getScriptInstruction();
+		int number = scriptInstruction.getIop();
+
+		for (int i = 0; i < number; ++i)
+		{
+			StackContext sctx = stringStack.pop();
+			ctx.popsString(sctx);
+			sctx.poppedBy(ctx);
+		}
+
+		// push appended string
+		StackContext sctx = new StackContext(ctx, null);
+		stringStack.push(sctx);
+		ctx.pushesString(sctx);
+	}
+
+}