From e3f452250e51b7271f3989c7dfd12e4422934942 Mon Sep 17 00:00:00 2001
From: Michael Smith
Date: Thu, 21 May 2015 23:30:00 +0100
Subject: Support Gradle alongside SSJB

This makes builds faster, simpler and better automated but still keeps
Cuchaz happy. :)
---
 .../enigma/bytecode/LocalVariableRenamer.java      | 123 +++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 src/cuchaz/enigma/bytecode/LocalVariableRenamer.java

(limited to 'src/cuchaz/enigma/bytecode/LocalVariableRenamer.java')

diff --git a/src/cuchaz/enigma/bytecode/LocalVariableRenamer.java b/src/cuchaz/enigma/bytecode/LocalVariableRenamer.java
new file mode 100644
index 0000000..ae0455f
--- /dev/null
+++ b/src/cuchaz/enigma/bytecode/LocalVariableRenamer.java
@@ -0,0 +1,123 @@
+/*******************************************************************************
+ * Copyright (c) 2015 Jeff Martin.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Lesser General Public
+ * License v3.0 which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/lgpl.html
+ * 
+ * Contributors:
+ *     Jeff Martin - initial API and implementation
+ ******************************************************************************/
+package cuchaz.enigma.bytecode;
+
+import javassist.CtBehavior;
+import javassist.CtClass;
+import javassist.bytecode.ByteArray;
+import javassist.bytecode.CodeAttribute;
+import javassist.bytecode.ConstPool;
+import javassist.bytecode.LocalVariableAttribute;
+import javassist.bytecode.LocalVariableTypeAttribute;
+import cuchaz.enigma.mapping.ArgumentEntry;
+import cuchaz.enigma.mapping.BehaviorEntry;
+import cuchaz.enigma.mapping.EntryFactory;
+import cuchaz.enigma.mapping.Translator;
+
+
+public class LocalVariableRenamer {
+	
+	private Translator m_translator;
+	
+	public LocalVariableRenamer(Translator translator) {
+		m_translator = translator;
+	}
+
+	public void rename(CtClass c) {
+		for (CtBehavior behavior : c.getDeclaredBehaviors()) {
+			
+			// if there's a local variable table, just rename everything to v1, v2, v3, ... for now
+			CodeAttribute codeAttribute = behavior.getMethodInfo().getCodeAttribute();
+			if (codeAttribute == null) {
+				continue;
+			}
+			
+			BehaviorEntry behaviorEntry = EntryFactory.getBehaviorEntry(behavior);
+			ConstPool constants = c.getClassFile().getConstPool();
+			
+			LocalVariableAttribute table = (LocalVariableAttribute)codeAttribute.getAttribute(LocalVariableAttribute.tag);
+			if (table != null) {
+				renameLVT(behaviorEntry, constants, table);
+			}
+			
+			LocalVariableTypeAttribute typeTable = (LocalVariableTypeAttribute)codeAttribute.getAttribute(LocalVariableAttribute.typeTag);
+			if (typeTable != null) {
+				renameLVTT(typeTable, table);
+			}
+		}
+	}
+
+	// DEBUG
+	@SuppressWarnings("unused")
+	private void dumpTable(LocalVariableAttribute table) {
+		for (int i=0; i<table.tableLength(); i++) {
+			System.out.println(String.format("\t%d (%d): %s %s",
+				i, table.index(i), table.variableName(i), table.descriptor(i)
+			));
+		}
+	}
+
+	private void renameLVT(BehaviorEntry behaviorEntry, ConstPool constants, LocalVariableAttribute table) {
+		
+		// skip empty tables
+		if (table.tableLength() <= 0) {
+			return;
+		}
+		
+		// where do we start counting variables?
+		int starti = 0;
+		if (table.variableName(0).equals("this")) {
+			// skip the "this" variable
+			starti = 1;
+		}
+		
+		// rename method arguments first
+		int numArgs = 0;
+		if (behaviorEntry.getSignature() != null) {
+			numArgs = behaviorEntry.getSignature().getArgumentTypes().size();
+			for (int i=starti; i<starti + numArgs && i<table.tableLength(); i++) {
+				int argi = i - starti;
+				String argName = m_translator.translate(new ArgumentEntry(behaviorEntry, argi, ""));
+				if (argName == null) {
+					argName = "a" + (argi + 1);
+				}
+				renameVariable(table, i, constants.addUtf8Info(argName));
+			}
+		}
+		
+		// then rename the rest of the args, if any
+		for (int i=starti + numArgs; i<table.tableLength(); i++) {
+			int firstIndex = table.index(starti + numArgs);
+			renameVariable(table, i, constants.addUtf8Info("v" + (table.index(i) - firstIndex + 1)));
+		}
+	}
+	
+	private void renameLVTT(LocalVariableTypeAttribute typeTable, LocalVariableAttribute table) {
+		// rename args to the same names as in the LVT
+		for (int i=0; i<typeTable.tableLength(); i++) {
+			renameVariable(typeTable, i, getNameIndex(table, typeTable.index(i)));
+		}
+	}
+
+	private void renameVariable(LocalVariableAttribute table, int i, int stringId) {
+		// based off of LocalVariableAttribute.nameIndex()
+		ByteArray.write16bit(stringId, table.get(), i*10 + 6);
+	}
+	
+	private int getNameIndex(LocalVariableAttribute table, int index) {
+		for (int i=0; i<table.tableLength(); i++) {
+			if (table.index(i) == index) {
+				return table.nameIndex(i);
+			}
+		}
+		return 0;
+	}
+}
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