Rewrite Assembly Transformers

asm-api/build.gradle

@@ -0,0 +1,13 @@
+dependencies {
+    /* OW2 ASM v5.0.3 */
+    compileOnly('org.ow2.asm:asm-debug-all:5.0.3')
+
+    /* Google Guava v17.0 */
+    compileOnly('com.google.guava:guava:17.0')
+
+    /* Apache Commons Lang v3 */
+    compileOnly('org.apache.commons:commons-lang3:3.3.2')
+
+    /* Apache Log4J v2.0-beta9 */
+    compileOnly('org.apache.logging.log4j:log4j-api:2.0-beta9')
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/Hook.java

@@ -0,0 +1,9 @@
+package codes.biscuit.skyblockaddons.asm.api;
+
+/**
+ * Listener to triggered actions by triggers that were injected using {@link Transformer}
+ *
+ * @author iHDeveloper
+ */
+public interface Hook {
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/Transformer.java

@@ -0,0 +1,48 @@
+package codes.biscuit.skyblockaddons.asm.api;
+
+import codes.biscuit.skyblockaddons.asm.api.helper.TransformClassHelper;
+import org.objectweb.asm.tree.ClassNode;
+
+/**
+ * Transforming the targeted classes in order to change how the class behave.
+ * Or, injecting hooks triggers.
+ *
+ * @author iHDeveloper
+ */
+public abstract class Transformer {
+
+    /**
+     * Puts a single class helper into an array
+     *
+     * @param classHelper The class helper to put into an array
+     * @return An array containing single class helper
+     */
+    protected TransformClassHelper[] single(TransformClassHelper classHelper) {
+        return new TransformClassHelper[] { classHelper };
+    }
+
+    /**
+     * Puts multiple class helpers into an array
+     * @param classHelpers The class helpers to put into an array
+     * @return An array containing multiple class helpers
+     */
+    protected TransformClassHelper[] multiple(TransformClassHelper... classHelpers) {
+        return classHelpers;
+    }
+
+    /**
+     * Get the targeted class helpers
+     *
+     * @return An array of class helpers
+     */
+    public abstract TransformClassHelper[] targets();
+
+    /**
+     * Transform a class node with its helper
+     *
+     * @param engine The engine which is performing the transformation process
+     * @param targetClassHelper The class helper of the target to transform
+     * @param node The class node of the target
+     */
+    public abstract void transform(TransformerEngine engine, TransformClassHelper targetClassHelper, ClassNode node);
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/TransformerEngine.java

@@ -0,0 +1,97 @@
+package codes.biscuit.skyblockaddons.asm.api;
+
+import codes.biscuit.skyblockaddons.asm.api.helper.TransformClassHelper;
+import codes.biscuit.skyblockaddons.asm.api.helper.normal.NormalTransformClassHelper;
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.Multimap;
+import org.apache.commons.lang3.mutable.MutableInt;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.tree.ClassNode;
+
+/**
+ * Manage the transformers and transform any class node.
+ *
+ * @author iHDeveloper
+ */
+public abstract class TransformerEngine {
+
+    private Logger logger = LogManager.getLogger("SBA: ASM Transformers");
+    private Multimap<String, Transformer> transformers = ArrayListMultimap.create();
+    private MutableInt writeFlags = new MutableInt();
+
+    /**
+     * Create an engine with transformers built-in
+     *
+     * @param transformers The transformers to register into the engine
+     */
+    public TransformerEngine(Transformer[] transformers) {
+        for (Transformer transformer : transformers) {
+            register(transformer);
+        }
+    }
+
+    /**
+     * Check if the class name is a target for transformation
+     *
+     * @param name The class name
+     */
+    public boolean exists(String name) {
+        return transformers.containsKey(name);
+    }
+
+    /**
+     * Transform the class node through the transformers
+     *
+     * @param node The class to transform
+     */
+    public void transform(String name, ClassNode node) {
+        TransformClassHelper classHelper = new NormalTransformClassHelper(name);
+
+        writeFlags.setValue(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
+
+        for (Transformer transformer : transformers.get(name)) {
+            transformer.transform(this, classHelper, node);
+        }
+    }
+
+    /**
+     * Get the engine logger
+     *
+     * @return The logger of the engine
+     */
+    public Logger getLogger() {
+        return logger;
+    }
+
+    /**
+     * Set the write flags of the current class for the writer
+     *
+     * @param flags The flags for the class writer see {@link ClassWriter}
+     */
+    public void setWriteFlags(int flags) {
+        writeFlags.setValue(flags);
+    }
+
+    /**
+     * Get the current write flags
+     *
+     * @return The write flags as integer
+     */
+    public int getWriteFlags() {
+        return writeFlags.getValue();
+    }
+
+    /**
+     * Register a transformer with its targets
+     *
+     * @param transformer The transformer to register
+     */
+    protected void register(Transformer transformer) {
+        for (TransformClassHelper targetClassHelper : transformer.targets()) {
+            transformers.put(targetClassHelper.getTransformerName(), transformer);
+        }
+    }
+
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/helper/HookResult.java

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+package codes.biscuit.skyblockaddons.asm.api.helper;
+
+/**
+ * A helper for getting result from hook to include in return or another function.
+ *
+ * @param <V> The type of the result we are getting from the hook
+ *
+ * @author iHDeveloper
+ */
+public class HookResult<V> {
+
+    private boolean empty = false;
+    private V value = null;
+
+    /**
+     * Check if the result is empty or not. Or, have the result been set before or not.
+     *
+     * @return Is the result empty or not
+     */
+    public boolean is() {
+        return empty;
+    }
+
+    /**
+     * Set the result to be nothing but it's not empty!
+     */
+    public void set() {
+        set(null);
+    }
+
+    /**
+     * Set the result to certain value. And, it's not empty anymore.
+     *
+     * @param value The value to include in the result
+     */
+    public void set(V value) {
+        this.value = value;
+        this.empty = true;
+    }
+
+    /**
+     * Get the value from the result
+     *
+     * @return The value that's has been set by the hook
+     */
+    public V get() {
+        return value;
+    }
+
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/helper/TransformClassHelper.java

@@ -0,0 +1,35 @@
+package codes.biscuit.skyblockaddons.asm.api.helper;
+
+import lombok.Getter;
+
+/**
+ * An identifier for a class to transform
+ *
+ * @author iHDeveloper
+ */
+public abstract class TransformClassHelper {
+
+    /**
+     * @return The name used for the owner of a field or method, or a field type.
+     */
+    public final String getNameAsOwner() {
+        return "L" + getName() + ";";
+    }
+
+    /**
+     * @return The name used to identify this class
+     */
+    public String getTransformerName() {
+        // The regex matches single slash or multiple and replace them with one dot
+        return getName().replaceAll("(\\/)+", ".");
+    }
+
+    public boolean equals(TransformClassHelper classHelper) {
+        return getTransformerName().equals(classHelper.getTransformerName());
+    }
+
+    /**
+     * @return The raw name of the class
+     */
+    public abstract String getName();
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/helper/TransformFieldHelper.java

@@ -0,0 +1,77 @@
+package codes.biscuit.skyblockaddons.asm.api.helper;
+
+import lombok.Getter;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.FieldInsnNode;
+
+/**
+ * An identifier for a field to transform
+ *
+ * @author iHDeveloper
+ */
+@Getter
+public class TransformFieldHelper {
+
+    private final TransformClassHelper owner;
+    private final String name;
+    private String type;
+
+    /**
+     * Create a field helper to help the transformation process
+     *
+     * @param owner The owner of the field
+     * @param name The name of the field
+     * @param type A non-class field type {@link TransformFieldTypes}
+     */
+    public TransformFieldHelper(TransformClassHelper owner, String name, char type) {
+        this(owner, name, "");
+        this.type = "" + type;
+    }
+
+    /**
+     * Create a field helper to help the transformation process
+     *
+     * @param owner The owner of the field
+     * @param name The name of the field
+     * @param type A class helper if the field type is class
+     */
+    public TransformFieldHelper(TransformClassHelper owner, String name, TransformClassHelper type) {
+        this(owner, name, type.getNameAsOwner());
+    }
+
+    /**
+     * Create a field helper to help the transformation process
+     *
+     * @param owner The owner of the field
+     * @param name The name of the field
+     * @param type The raw name of the class
+     */
+    public TransformFieldHelper(TransformClassHelper owner, String name, String type) {
+        this.owner = owner;
+        this.name = name;
+        this.type = "L" + type + ";";
+    }
+
+    /**
+     * Generate the get field instruction of the field
+     *
+     * @return An instruction node of the get field instruction
+     */
+    public FieldInsnNode createGetInstruction() {
+        return new FieldInsnNode(Opcodes.GETFIELD, owner.getNameAsOwner(), name, type);
+    }
+
+    /**
+     * Generate the put instruction of the field
+     *
+     * @return An instruction node of the put field instruction
+     */
+    public FieldInsnNode createPutInstruction() {
+        return new FieldInsnNode(Opcodes.PUTFIELD, owner.getNameAsOwner(), name, type);
+    }
+
+    public boolean equals(FieldInsnNode insnNode) {
+        return name.equals(insnNode.name) && type.equals(insnNode.desc);
+    }
+
+}

asm-api/src/main/java/codes/biscuit/skyblockaddons/asm/api/helper/TransformFieldTypes.java

@@ -0,0 +1,12 @@
+package codes.biscuit.skyblockaddons.asm.api.helper;
+
+public final class TransformFieldTypes {
+    public static final char BYTE = 'B';
+    public static final char CHAR = 'C';
+    public static final char DOUBLE = 'D';
+    public static final char FLOAT = 'F';
+    public static final char INT = 'I';
+    public static final char LONG = 'j';
+    public static final char SHORT = 'S';
+    public static final char BOOLEAN = 'Z';
+}