gecko/build/annotationProcessors/CodeGenerator.java

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.gecko.annotationProcessors;
import org.mozilla.gecko.annotationProcessors.utils.Utils;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.HashSet;
public class CodeGenerator {
// Buffers holding the strings to ultimately be written to the output files.
private final StringBuilder wrapperStartupCode = new StringBuilder();
private final StringBuilder wrapperMethodBodies = new StringBuilder();
private final StringBuilder headerFields = new StringBuilder();
private final StringBuilder headerMethods = new StringBuilder();
private final HashSet<String> seenClasses = new HashSet<String>();
private final String GENERATED_COMMENT = "// GENERATED CODE\n" +
"// Generated by the Java program at /build/annotationProcessors at compile time from\n" +
"// annotations on Java methods. To update, change the annotations on the corresponding Java\n" +
"// methods and rerun the build. Manually updating this file will cause your build to fail.\n\n";
public CodeGenerator() {
// Write the file header things. Includes and so forth.
// GeneratedJNIWrappers.cpp is generated as the concatenation of wrapperStartupCode with
// wrapperMethodBodies. Similarly, GeneratedJNIWrappers.h is the concatenation of headerFields
// with headerMethods.
wrapperStartupCode.append(GENERATED_COMMENT);
wrapperStartupCode.append(
"#include \"nsXPCOMStrings.h\"\n" +
"#include \"AndroidBridge.h\"\n" +
"#include \"AndroidBridgeUtilities.h\"\n" +
"\n" +
"#ifdef DEBUG\n" +
"#define ALOG_BRIDGE(args...) ALOG(args)\n" +
"#else\n" +
"#define ALOG_BRIDGE(args...) ((void)0)\n" +
"#endif\n" +
"\n" +
"using namespace mozilla;\n" +
"void AndroidBridge::InitStubs(JNIEnv *jEnv) {\n" +
" initInit();\n");
// Now we write the various GetStaticMethodID calls here...
headerFields.append("protected:\n\n");
headerMethods.append(GENERATED_COMMENT);
headerMethods.append("public:\n\n");
}
/**
* Append the appropriate generated code to the buffers for the method provided.
*
* @param aMethodTuple The Java method, plus the name for the generated method.
* @param aClass The class to which the Java method belongs.
*/
public void generateMethod(MethodWithAnnotationInfo aMethodTuple, Class<?> aClass) {
// Unpack the tuple and extract some useful fields from the Method..
Method aMethod = aMethodTuple.method;
String CMethodName = aMethodTuple.wrapperName;
String javaMethodName = aMethod.getName();
ensureClassHeaderAndStartup(aClass);
writeHeaderField(CMethodName);
writeStartupCode(CMethodName, javaMethodName, aMethod, aClass);
// Get the C++ method signature for this method.
String implementationSignature = Utils.getCImplementationMethodSignature(aMethod, CMethodName);
String headerSignature = Utils.getCHeaderMethodSignature(aMethod, CMethodName, aMethodTuple.isStatic);
// Add the header signature to the header file.
headerMethods.append(headerSignature);
headerMethods.append(";\n");
// Use the implementation signature to generate the method body...
writeMethodBody(implementationSignature, CMethodName, aMethod, aClass, aMethodTuple.isStatic, aMethodTuple.isMultithreaded);
}
/**
* Writes the appropriate header and startup code to ensure the existence of a reference to the
* class specified. If this is already done, does nothing.
*
* @param aClass The target class.
*/
private void ensureClassHeaderAndStartup(Class<?> aClass) {
String className = aClass.getCanonicalName();
if (seenClasses.contains(className)) {
return;
}
// Add a field to hold the reference...
headerFields.append("\njclass ");
headerFields.append(Utils.getClassReferenceName(aClass));
headerFields.append(";\n");
// Add startup code to populate it..
wrapperStartupCode.append('\n');
wrapperStartupCode.append(Utils.getStartupLineForClass(aClass));
seenClasses.add(className);
}
/**
* Generates the method body of the C++ wrapper function for the Java method indicated.
*
* @param methodSignature The previously-generated C++ method signature for the method to be
* generated.
* @param aCMethodName The C++ method name for the method to be generated.
* @param aMethod The Java method to be wrapped by the C++ method being generated.
* @param aClass The Java class to which the method belongs.
*/
private void writeMethodBody(String methodSignature, String aCMethodName, Method aMethod, Class<?> aClass, boolean aIsStaticBridgeMethod, boolean aIsMultithreaded) {
Class<?>[] argumentTypes = aMethod.getParameterTypes();
Class<?> returnType = aMethod.getReturnType();
// The start-of-function boilerplate. Does the bridge exist? Does the env exist? etc.
wrapperMethodBodies.append('\n');
wrapperMethodBodies.append(methodSignature);
wrapperMethodBodies.append(" {\n");
// Static stubs check the bridge instance has been created before trying to run.
if (aIsStaticBridgeMethod) {
wrapperMethodBodies.append(" if (!sBridge) {\n" +
" ALOG_BRIDGE(\"Aborted: No sBridge - %s\", __PRETTY_FUNCTION__);\n" +
" return").append(Utils.getFailureReturnForType(returnType)).append(";\n" +
" }\n\n");
}
wrapperMethodBodies.append(" JNIEnv *env = ");
if (!aIsMultithreaded) {
wrapperMethodBodies.append("GetJNIEnv();\n");
} else {
wrapperMethodBodies.append("GetJNIForThread();\n");
}
wrapperMethodBodies.append(" if (!env) {\n" +
" ALOG_BRIDGE(\"Aborted: No env - %s\", __PRETTY_FUNCTION__);\n" +
" return").append(Utils.getFailureReturnForType(returnType)).append(";\n" +
" }\n\n");
boolean isObjectReturningMethod = !returnType.getCanonicalName().equals("void") && Utils.doesReturnObjectType(aMethod);
// Determine the number of local refs required for our local frame..
// AutoLocalJNIFrame is not applicable here due to it's inability to handle return values.
int localReferencesNeeded = Utils.enumerateReferenceArguments(aMethod);
if (isObjectReturningMethod) {
localReferencesNeeded++;
}
wrapperMethodBodies.append(" if (env->PushLocalFrame(").append(localReferencesNeeded).append(") != 0) {\n" +
" ALOG_BRIDGE(\"Exceptional exit of: %s\", __PRETTY_FUNCTION__);\n" +
" env->ExceptionDescribe();\n"+
" env->ExceptionClear();\n" +
" return").append(Utils.getFailureReturnForType(returnType)).append(";\n" +
" }\n\n");
// Marshall arguments, if we have any.
boolean hasArguments = argumentTypes.length != 0;
// We buffer the arguments to the call separately to avoid needing to repeatedly iterate the
// argument list while building this line. In the coming code block, we simultaneously
// construct any argument marshalling code (Creation of jstrings, placement of arguments
// into an argument array, etc. and the actual argument list passed to the function (in
// argumentContent).
StringBuilder argumentContent = new StringBuilder();
if (hasArguments) {
argumentContent.append(", ");
// If we have >2 arguments, use the jvalue[] calling approach.
if (argumentTypes.length > 2) {
wrapperMethodBodies.append(" jvalue args[").append(argumentTypes.length).append("];\n");
for (int aT = 0; aT < argumentTypes.length; aT++) {
wrapperMethodBodies.append(" args[").append(aT).append("].");
wrapperMethodBodies.append(Utils.getArrayArgumentMashallingLine(argumentTypes[aT], "a" + aT));
}
// The only argument is the array of arguments.
argumentContent.append("args");
wrapperMethodBodies.append('\n');
} else {
// Otherwise, use the vanilla calling approach.
boolean needsNewline = false;
for (int aT = 0; aT < argumentTypes.length; aT++) {
// If the argument is a string-esque type, create a jstring from it, otherwise
// it can be passed directly.
if (Utils.isCharSequence(argumentTypes[aT])) {
wrapperMethodBodies.append(" jstring j").append(aT).append(" = NewJavaString(env, a").append(aT).append(");\n");
needsNewline = true;
// Ensure we refer to the newly constructed Java string - not to the original
// parameter to the wrapper function.
argumentContent.append('j').append(aT);
} else {
argumentContent.append('a').append(aT);
}
if (aT != argumentTypes.length - 1) {
argumentContent.append(", ");
}
}
if (needsNewline) {
wrapperMethodBodies.append('\n');
}
}
}
wrapperMethodBodies.append(" ");
if (!returnType.getCanonicalName().equals("void")) {
if (isObjectReturningMethod) {
wrapperMethodBodies.append("jobject");
} else {
wrapperMethodBodies.append(Utils.getCReturnType(returnType));
}
wrapperMethodBodies.append(" temp = ");
}
boolean isStaticJavaMethod = Utils.isMethodStatic(aMethod);
// The call into Java
wrapperMethodBodies.append("env->");
wrapperMethodBodies.append(Utils.getCallPrefix(returnType, isStaticJavaMethod));
if (argumentTypes.length > 2) {
wrapperMethodBodies.append('A');
}
wrapperMethodBodies.append('(');
// If the underlying Java method is nonstatic, we provide the target object to the JNI.
if (!isStaticJavaMethod) {
wrapperMethodBodies.append("aTarget, ");
} else {
// If the stub to be generated is static, we need to use the singleton to access the class
// reference.
if (aIsStaticBridgeMethod) {
wrapperMethodBodies.append("sBridge->");
}
// If this is a static underlyin Java method, we need to use the class reference in our
// call.
wrapperMethodBodies.append(Utils.getClassReferenceName(aClass)).append(", ");
}
// Write the method id out..
if (aIsStaticBridgeMethod) {
wrapperMethodBodies.append("sBridge->");
}
wrapperMethodBodies.append('j');
wrapperMethodBodies.append(aCMethodName);
// Tack on the arguments, if any..
wrapperMethodBodies.append(argumentContent);
wrapperMethodBodies.append(");\n\n");
// Check for exception and return the failure value..
wrapperMethodBodies.append(" if (env->ExceptionCheck()) {\n" +
" ALOG_BRIDGE(\"Exceptional exit of: %s\", __PRETTY_FUNCTION__);\n" +
" env->ExceptionDescribe();\n" +
" env->ExceptionClear();\n" +
" env->PopLocalFrame(NULL);\n" +
" return").append(Utils.getFailureReturnForType(returnType)).append(";\n" +
" }\n");
// If we're returning an object, pop the callee's stack frame extracting our ref as the return
// value.
if (isObjectReturningMethod) {
wrapperMethodBodies.append(" ");
wrapperMethodBodies.append(Utils.getCReturnType(returnType));
wrapperMethodBodies.append(" ret = static_cast<").append(Utils.getCReturnType(returnType)).append(">(env->PopLocalFrame(temp));\n" +
" return ret;\n");
} else if (!returnType.getCanonicalName().equals("void")) {
// If we're a primitive-returning function, just return the directly-obtained primative
// from the call to Java.
wrapperMethodBodies.append(" env->PopLocalFrame(NULL);\n" +
" return temp;\n");
} else {
// If we don't return anything, just pop the stack frame and move on with life.
wrapperMethodBodies.append(" env->PopLocalFrame(NULL);\n");
}
wrapperMethodBodies.append("}\n");
}
/**
* Generates the code to get the method id of the given method on startup.
*
* @param aCMethodName The C method name of the method being generated.
* @param aJavaMethodName The name of the Java method being wrapped.
* @param aMethod The Java method being wrapped.
*/
private void writeStartupCode(String aCMethodName, String aJavaMethodName, Method aMethod, Class<?> aClass) {
wrapperStartupCode.append(" j");
wrapperStartupCode.append(aCMethodName);
wrapperStartupCode.append(" = get");
if (Utils.isMethodStatic(aMethod)) {
wrapperStartupCode.append("Static");
}
wrapperStartupCode.append("Method(\"");
wrapperStartupCode.append(aJavaMethodName);
wrapperStartupCode.append("\", \"");
wrapperStartupCode.append(Utils.getTypeSignatureString(aMethod));
wrapperStartupCode.append("\");\n");
}
/**
* Create a method id field in the header file for the C method name provided.
*
* @param aMethodName C method name to generate a method id field for.
*/
private void writeHeaderField(String aMethodName) {
headerFields.append("jmethodID j");
headerFields.append(aMethodName);
headerFields.append(";\n");
}
/**
* Get the finalised bytes to go into the generated wrappers file.
*
* @return The bytes to be written to the wrappers file.
*/
public byte[] getWrapperFileContents() {
wrapperStartupCode.append("}\n");
wrapperStartupCode.append(wrapperMethodBodies);
wrapperMethodBodies.setLength(0);
return wrapperStartupCode.toString().getBytes();
}
/**
* Get the finalised bytes to go into the generated header file.
*
* @return The bytes to be written to the header file.
*/
public byte[] getHeaderFileContents() {
headerFields.append('\n');
headerFields.append(headerMethods);
headerMethods.setLength(0);
return headerFields.toString().getBytes();
}
}