EventProxy.java
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/*
* This file is part of LiteLoader.
* Copyright (C) 2012-16 Adam Mummery-Smith
* All Rights Reserved.
*/
package com.mumfrey.liteloader.core.event;
import java.util.concurrent.Callable;
import javax.management.RuntimeErrorException;
import org.spongepowered.asm.lib.Type;
import org.spongepowered.asm.util.SignaturePrinter;
import com.mumfrey.liteloader.transformers.event.EventInfo;
import net.minecraft.crash.CrashReport;
import net.minecraft.crash.CrashReportCategory;
/**
* EventProxy is a special class used by the EventInjectionTransformer, it is a
* stub class into which all of the injected event callback methods are
* injected. Each event handler method contains a try/catch block which invokes
* one of the error reporting methods contained below when an error occurs, in
* order to provide more meaningful information to the user and to mod makers.
*
* @author Adam Mummery-Smith
*/
public final class EventProxy
{
static String error;
static StringBuilder errorDetails;
static
{
new Exception().printStackTrace();
if (true) throw new InstantiationError("EventProxy was loaded before transformation, this is bad!");
}
/**
* Private because we never instance this class!
*/
private EventProxy() {}
// The event injection subsystem creates event stubs in this class which (if written in java) would
// look something like the following:
//
// public static void $event00000(EventInfo<?> e)
// {
// try
// {
// // Handlers sorted by priority
// com.example.mod.EventHandler.onWhateverEvent(e);
// com.example.anothermod.FooClass.onBarEvent(e);
// }
// catch (NoClassDefFoundError err)
// {
// onMissingClass(err, e);
// }
// catch (NoSuchMethodError err)
// {
// onMissingHandler(err, e);
// }
// }
protected static void onMissingClass(Error err, EventInfo<?> e)
{
EventProxy.error = "Missing Event Handler Class!";
EventProxy.errorDetails = new StringBuilder();
EventProxy.addCrashDetailLine("\n");
EventProxy.addCrashDetailLine("You are seeing this message because an event callback was injected by the Event");
EventProxy.addCrashDetailLine("Injection Subsystem but the specified callback class was not defined! The");
EventProxy.addCrashDetailLine("details of the missing callback are as follows:");
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine(" Event Name: " + e.getName());
EventProxy.addCrashDetailLine(" Cancellable: " + e.isCancellable());
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine(" Callback class: " + err.getMessage().replace('/', '.'));
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine("If you are the mod author then in order to fix the error you must provide an");
EventProxy.addCrashDetailLine("implementation for the specified class, or check that the class name and package");
EventProxy.addCrashDetailLine("are correct.");
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine("This is an unrecoverable error, please report it to the mod author and remove");
EventProxy.addCrashDetailLine("the offending mod.");
EventProxy.addStackTrace(err);
throw new RuntimeErrorException(err, "Missing event handler class for event " + e.getName() + ", see crash report for details");
}
protected static void onMissingHandler(Error err, EventInfo<?> e)
{
String descriptor = err.getMessage();
int dotPos = descriptor.lastIndexOf('.');
int bracketPos = descriptor.indexOf('(');
String signature = descriptor.substring(bracketPos);
String sourceClass = e.getSource() != null ? e.getSource().getClass().getSimpleName() : "?";
EventProxy.error = "Missing Event Handler Method!";
EventProxy.errorDetails = new StringBuilder();
EventProxy.addCrashDetailLine("\n");
EventProxy.addCrashDetailLine("You are seeing this message because an event callback was injected by the Event");
EventProxy.addCrashDetailLine("Injection Subsystem but the specified callback method was not defined. The");
EventProxy.addCrashDetailLine("details of the missing callback are as follows:");
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine(" Event Name: " + e.getName());
EventProxy.addCrashDetailLine(" Cancellable: " + e.isCancellable());
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine(" Callback class: " + descriptor.substring(0, dotPos));
EventProxy.addCrashDetailLine(" Callback method: " + descriptor.substring(dotPos + 1, bracketPos));
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine("If you are the mod author then in order to fix the error you must add a suitable");
EventProxy.addCrashDetailLine("callback method in the above class. The method signature should be as follows:");
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine(EventProxy.generateHandlerTemplate(descriptor.substring(dotPos + 1, bracketPos), signature, sourceClass));
EventProxy.addDetailLineBreak();
EventProxy.addCrashDetailLine("This is an unrecoverable error, please report it to the mod author and remove");
EventProxy.addCrashDetailLine("the offending mod.");
EventProxy.addStackTrace(err);
throw new RuntimeErrorException(err, "Missing event handler method for event " + e.getName() + ", see crash report for details");
}
private static void addStackTrace(Error err)
{
EventProxy.addDetailLineBreak();
EventProxy.errorDetails.append("Stacktrace:").append('\n');
EventProxy.addDetailLineBreak();
StackTraceElement[] stackTrace = err.getStackTrace();
for (int i = 0; i < stackTrace.length; i++)
{
EventProxy.addCrashDetailLine(String.format(" %3d) %s", i + 1, stackTrace[i]));
}
}
protected static String generateHandlerTemplate(String methodName, String signature, String sourceClass)
{
Type[] argTypes = Type.getArgumentTypes(signature);
StringBuilder tpl = new StringBuilder();
tpl.append(" public static void ").append(methodName).append('(');
for (int var = 0; var < argTypes.length; var++)
{
if (EventProxy.appendTypeName(tpl, argTypes[var], sourceClass)) tpl.append("[]");
if (var == 0) tpl.append(" e");
if (var > 0) tpl.append(" arg").append(String.valueOf(var));
if (var < argTypes.length - 1) tpl.append(", ");
}
tpl.append(")\n\t {\n\t // handler code here\n\t }");
String template = tpl.toString();
if (template.contains(", ReturnType>"))
{
template = template.replace("static void", "static <ReturnType> void");
}
return template;
}
private static boolean appendTypeName(StringBuilder tpl, Type type, String sourceClass)
{
switch (type.getSort())
{
case Type.ARRAY:
EventProxy.appendTypeName(tpl, type.getElementType(), sourceClass);
return true;
case Type.OBJECT:
String typeName = type.getClassName();
typeName = typeName.substring(typeName.lastIndexOf('.') + 1);
tpl.append(typeName);
if (typeName.endsWith("ReturnEventInfo"))
{
tpl.append('<').append(sourceClass).append(", ReturnType>");
}
else if (typeName.endsWith("EventInfo"))
{
tpl.append('<').append(sourceClass).append('>');
}
return false;
default:
tpl.append(SignaturePrinter.getTypeName(type, false));
return false;
}
}
private static void addDetailLineBreak()
{
System.err.println();
EventProxy.errorDetails.append('\n');
}
private static void addCrashDetailLine(String string)
{
System.err.println(string);
EventProxy.errorDetails.append('\t').append(string).append('\n');
}
public static void populateCrashReport(CrashReport crashReport)
{
if (EventProxy.error != null)
{
CrashReportCategory category = crashReport.makeCategoryDepth("Event Handler Error", 1);
category.addCrashSection(EventProxy.error, new Callable<String>()
{
@Override
public String call() throws Exception
{
return EventProxy.errorDetails.toString();
}
});
}
}
}