feat: implemented field and method proxies

1 files changed, 223 insertions, 0 deletions

diff --git a/src/main/java/ftbsc/lll/proxies/MethodProxy.java b/src/main/java/ftbsc/lll/proxies/MethodProxy.java
new file mode 100644
index 0000000..1df4678
--- /dev/null
+++ b/src/main/java/ftbsc/lll/proxies/MethodProxy.java
@@ -0,0 +1,223 @@
+package ftbsc.lll.proxies;
+
+import ftbsc.lll.tools.DescriptorBuilder;
+import org.objectweb.asm.Type;
+
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A container for information about class methods to be used
+ * in ASM patching.
+ * @since 0.3.0
+ */
+public class MethodProxy extends AbstractProxy {
+
+	/**
+	 * The parameters of the method.
+	 * It holds fully qualified names for objects, and {@link Class}
+	 * objects for primitives.
+	 */
+	private final Object[] parameters;
+
+	/**
+	 * The return type of the method.
+	 * It contains if it's an object, or a {@link Class}
+	 * object for primitives.
+	 */
+	private final Object returnType;
+
+	/**
+	 * Caches the the descriptor after generating it once for
+	 * performance.
+	 */
+	private String descriptorCache;
+
+	/**
+	 * A public constructor, builds a proxy from a {@link Method}
+	 * obtained from reflection.
+	 * @param m the {@link Method} object corresponding to this.
+	 */
+	public MethodProxy(Method m) {
+		super(m.getName(), m.getModifiers(), Type.getInternalName(m.getDeclaringClass()));
+		List<Object> parameters = new ArrayList<>();
+		for(Class<?> p : m.getParameterTypes())
+			parameters.add(p.isPrimitive() ? p	: new TypeContainer(p));
+		this.parameters = parameters.toArray();
+		Class<?> returnType = m.getReturnType();
+		this.returnType = returnType.isPrimitive() ? returnType	: new TypeContainer(returnType);
+	}
+
+	/**
+	 * A protected constructor, called only from the builder.
+	 * @param srgName the SRG name of the method
+	 * @param modifiers the modifiers of the method
+	 * @param parent the FQN of the parent class of the method
+	 * @param parameters the parameters of the method
+	 * @param returnType the return type of the method
+	 */
+	protected MethodProxy(String srgName, int modifiers, String parent, Object[] parameters, Object returnType) {
+		super(srgName, modifiers, parent);
+		this.parameters = parameters;
+		this.returnType = returnType;
+		this.descriptorCache = null;
+	}
+
+	/**
+	 * Builds (or returns from cache if present)
+	 * the method's descriptor.
+	 * @return the method's descriptor
+	 */
+	@Override
+	public String getDescriptor() {
+		if(this.descriptorCache != null)
+			return this.descriptorCache;
+		DescriptorBuilder b = new DescriptorBuilder();
+		for(Object p : this.parameters)
+			addParameterToBuilder(b, p);
+		addParameterToBuilder(b, this.returnType);
+		this.descriptorCache = b.build();
+		return this.descriptorCache;
+	}
+
+	/**
+	 * A static method used internally to correctly insert a
+	 * {@link TypeContainer} into a {@link DescriptorBuilder}.
+	 * @param b the {@link DescriptorBuilder}
+	 * @param p the {@link TypeContainer}
+	 */
+	private static void addParameterToBuilder(DescriptorBuilder b, Object p) {
+		if(p instanceof TypeContainer) {
+			TypeContainer param = (TypeContainer) p;
+			b.addParameter(param.fqn, param.arrayLevel);
+		} else b.addParameter((Class<?>) p);
+	}
+
+	/**
+	 * Returns a new instance of {@link MethodProxy.Builder}.
+	 * @param srgName the SRG name of the method
+	 * @return the builder object for method proxies
+	 */
+	public static Builder builder(String srgName) {
+		return new Builder(srgName);
+	}
+
+	/**
+	 * A builder object for {@link MethodProxy}.
+	 */
+	public static class Builder extends AbstractProxy.Builder<MethodProxy> {
+		/**
+		 * The parameters of the method.
+		 */
+		private final List<Object> parameters;
+
+		/**
+		 * The return type of the method. Defaults to void.
+		 */
+		private Object returnType;
+
+		/**
+		 * The constructor of the builder, used only internally.
+		 * @param srgName the SRG name of the method
+		 */
+		Builder(String srgName) {
+			super(srgName);
+			this.parameters = new ArrayList<>();
+			this.returnType = void.class;
+		}
+
+		/**
+		 * Adds a parameter of a given type.
+		 * @param fqn the fully qualified name of the parameter type
+		 * @param arrayLevel the array level of the parameter type
+		 * @return the builder's state after the change
+		 */
+		public Builder addParameter(String fqn, int arrayLevel) {
+			this.parameters.add(new TypeContainer(fqn, arrayLevel));
+			return this;
+		}
+
+		/**
+		 * Adds a parameter of a given type.
+		 * @param paramType the {@link Class} object corresponding to
+		 *                  the parameter type.
+		 * @return the builder's state after the change
+		 */
+		public Builder addParameter(Class<?> paramType) {
+			this.parameters.add(paramType);
+			return this;
+		}
+
+		/**
+		 * Sets the return type to the given type.
+		 * @param fqn the fully qualified name of the return type
+		 * @param arrayLevel the array level of the return type
+		 * @return the builder's state after the change
+		 */
+		public Builder setReturnType(String fqn, int arrayLevel) {
+			this.returnType = new TypeContainer(fqn, arrayLevel);
+			return this;
+		}
+
+		/**
+		 * Sets the return type to the given type.
+		 * @param returnType the {@link Class} object corresponding to
+		 *                   the return type
+		 * @return the builder's state after the change
+		 */
+		public Builder setReturnType(Class<?> returnType) {
+			this.returnType = returnType;
+			return this;
+		}
+
+		/**
+		 * Builds a {@link MethodProxy} of the given kind.
+		 * @return the built {@link MethodProxy}
+		 */
+		@Override
+		public MethodProxy build() {
+			return new MethodProxy(srgName, modifiers, parent, parameters.toArray(), returnType);
+		}
+	}
+
+	/**
+	 * A container class, holding information about a given type.
+	 */
+	protected static class TypeContainer {
+		/**
+		 * The fully qualified name of the type.
+		 */
+		public final String fqn;
+
+		/**
+		 * The array level of the type.
+		 */
+		public final int arrayLevel;
+
+		/**
+		 * Public constructor for the class.
+		 * @param fqn the fully qualified name of the type
+		 * @param arrayLevel the array level of the type
+		 */
+		public TypeContainer(String fqn, int arrayLevel) {
+			this.fqn = fqn;
+			this.arrayLevel = arrayLevel;
+		}
+
+		/**
+		 * Public constructor for the class, extracting the
+		 * necessary information from a {@link Class} object.
+		 * @param clazz the class object
+		 */
+		public TypeContainer(Class<?> clazz) {
+			int arrayLevel = 0;
+			while(clazz.isArray()) {
+				arrayLevel++;
+				clazz = clazz.getComponentType();
+			}
+			this.arrayLevel = arrayLevel;
+			this.fqn = clazz.getCanonicalName();
+		}
+	}
+}