/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.dev.jjs.impl;
import com.google.gwt.dev.jjs.InternalCompilerException;
import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.jjs.ast.AccessModifier;
import com.google.gwt.dev.jjs.SourceOrigin;
import com.google.gwt.dev.jjs.ast.Context;
import com.google.gwt.dev.jjs.ast.JBlock;
import com.google.gwt.dev.jjs.ast.JCaseStatement;
import com.google.gwt.dev.jjs.ast.JClassType;
import com.google.gwt.dev.jjs.ast.JExpression;
import com.google.gwt.dev.jjs.ast.JGwtCreate;
import com.google.gwt.dev.jjs.ast.JMethod;
import com.google.gwt.dev.jjs.ast.JMethodBody;
import com.google.gwt.dev.jjs.ast.JMethodCall;
import com.google.gwt.dev.jjs.ast.JModVisitor;
import com.google.gwt.dev.jjs.ast.JProgram;
import com.google.gwt.dev.jjs.ast.JReboundEntryPoint;
import com.google.gwt.dev.jjs.ast.JReturnStatement;
import com.google.gwt.dev.jjs.ast.JSwitchStatement;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
/**
* Replaces any "GWT.create()" calls with a new expression for the actual result
* of the deferred binding decision.
*/
public class ResolveRebinds {
private class RebindVisitor extends JModVisitor {
@Override
public void endVisit(JGwtCreate x, Context ctx) {
if (isSoftRebind(x.getSourceType())) {
JMethod method =
rebindMethod(x.getSourceInfo(), x.getSourceType(), x.getResultTypes(), x
.getInstantiationExpressions());
JMethodCall call = new JMethodCall(x.getSourceInfo(), null, method);
ctx.replaceMe(call);
return;
}
String rebindResult = rebind(x.getSourceType());
List<String> rebindResults = x.getResultTypes();
for (int i = 0; i < rebindResults.size(); ++i) {
// Find the matching rebound type.
if (rebindResult.equals(rebindResults.get(i))) {
// Replace with the associated instantiation expression.
ctx.replaceMe(x.getInstantiationExpressions().get(i));
return;
}
}
throw new InternalCompilerException("No matching rebind result in all rebind results!");
}
@Override
public void endVisit(JReboundEntryPoint x, Context ctx) {
if (isSoftRebind(x.getSourceType())) {
JMethod method =
rebindMethod(x.getSourceInfo(), x.getSourceType(), x.getResultTypes(), x
.getEntryCalls());
JMethodCall call = new JMethodCall(x.getSourceInfo(), null, method);
ctx.replaceMe(call.makeStatement());
return;
}
String rebindResult = rebind(x.getSourceType());
List<String> rebindResults = x.getResultTypes();
for (int i = 0; i < rebindResults.size(); ++i) {
// Find the matching rebound type.
if (rebindResult.equals(rebindResults.get(i))) {
// Replace with the associated instantiation expression.
ctx.replaceMe(x.getEntryCalls().get(i).makeStatement());
return;
}
}
throw new InternalCompilerException("No matching rebind result in all rebind results!");
}
}
public static boolean exec(JProgram program, Map<String, String>[] orderedRebindAnswers) {
return new ResolveRebinds(program, orderedRebindAnswers).execImpl();
}
/**
* Returns the rebind answers that do not vary across various maps of rebind
* answers.
*/
public static Map<String, String> getHardRebindAnswers(Map<String, String>[] rebindAnswers) {
Iterator<Map<String, String>> it = Arrays.asList(rebindAnswers).iterator();
// Start with an arbitrary copy of a rebind answer map
Map<String, String> toReturn = new HashMap<String, String>(it.next());
while (it.hasNext()) {
Map<String, String> next = it.next();
// Only keep key/value pairs present in the other rebind map
toReturn.entrySet().retainAll(next.entrySet());
}
return toReturn;
}
private final Map<String, String> hardRebindAnswers;
private final JClassType holderType;
private final Map<String, String>[] orderedRebindAnswers;
private final JMethod permutationIdMethod;
private final JProgram program;
private final Map<String, JMethod> rebindMethods = new HashMap<String, JMethod>();
private ResolveRebinds(JProgram program, Map<String, String>[] orderedRebindAnswers) {
this.program = program;
this.orderedRebindAnswers = orderedRebindAnswers;
this.hardRebindAnswers = getHardRebindAnswers(orderedRebindAnswers);
this.holderType = (JClassType) program.getIndexedType("CollapsedPropertyHolder");
this.permutationIdMethod = program.getIndexedMethod("CollapsedPropertyHolder.getPermutationId");
}
public String rebind(String reqType) {
// Rebinds are always on a source type name.
String reboundClassName = hardRebindAnswers.get(reqType);
if (reboundClassName == null) {
// The fact that we already compute every rebind permutation before
// compiling should prevent this case from ever happening in real life.
//
throw new InternalCompilerException("Unexpected failure to rebind '" + reqType + "'");
}
assert program.getFromTypeMap(reboundClassName) != null;
return reboundClassName;
}
private boolean execImpl() {
RebindVisitor rebinder = new RebindVisitor();
rebinder.accept(program);
return rebinder.didChange();
}
private boolean isSoftRebind(String requestType) {
return !hardRebindAnswers.containsKey(requestType);
}
private JMethod rebindMethod(SourceInfo info, String requestType, List<String> resultTypes,
List<JExpression> instantiationExpressions) {
assert resultTypes.size() == instantiationExpressions.size();
JMethod toReturn = rebindMethods.get(requestType);
if (toReturn != null) {
return toReturn;
}
// Maps the result types to the various virtual permutation ids
Map<String, List<Integer>> resultsToPermutations = new LinkedHashMap<String, List<Integer>>();
for (int i = 0, j = orderedRebindAnswers.length; i < j; i++) {
Map<String, String> answerMap = orderedRebindAnswers[i];
String answerType = answerMap.get(requestType);
List<Integer> list = resultsToPermutations.get(answerType);
if (list == null) {
list = new ArrayList<Integer>();
resultsToPermutations.put(answerType, list);
}
// and map it to the permutation ID for a particular set of values
list.add(i);
}
// Pick the most-used result type to emit less code
String mostUsed = null;
{
int max = 0;
for (Map.Entry<String, List<Integer>> entry : resultsToPermutations.entrySet()) {
int size = entry.getValue().size();
if (size > max) {
max = size;
mostUsed = entry.getKey();
}
}
}
assert mostUsed != null;
info = info.makeChild(SourceOrigin.UNKNOWN);
// c_g_g_d_c_i_DOMImpl
toReturn =
new JMethod(info, requestType.replace("_", "_1").replace('.', '_'), holderType, program
.getTypeJavaLangObject().getNonNull(), false, true, true, AccessModifier.PUBLIC);
toReturn.setBody(new JMethodBody(info));
holderType.addMethod(toReturn);
toReturn.freezeParamTypes();
info.addCorrelation(info.getCorrelator().by(toReturn));
rebindMethods.put(requestType, toReturn);
// Used in the return statement at the end
JExpression mostUsedExpression = null;
JBlock switchBody = new JBlock(info);
for (int i = 0, j = resultTypes.size(); i < j; i++) {
String resultType = resultTypes.get(i);
JExpression instantiation = instantiationExpressions.get(i);
List<Integer> permutations = resultsToPermutations.get(resultType);
if (permutations == null) {
// This rebind result is unused in this permutation
continue;
} else if (resultType.equals(mostUsed)) {
// Save off the fallback expression and go onto the next type
mostUsedExpression = instantiation;
continue;
}
for (int permutationId : permutations) {
// case 33:
switchBody.addStmt(new JCaseStatement(info, program.getLiteralInt(permutationId)));
}
// return new FooImpl();
JReturnStatement ret = new JReturnStatement(info, instantiation);
switchBody.addStmt(ret);
}
assert switchBody.getStatements().size() > 0 : "No case statement emitted "
+ "for supposedly soft-rebind type " + requestType;
// switch (CollapsedPropertyHolder.getPermutationId()) { ... }
JSwitchStatement sw =
new JSwitchStatement(info, new JMethodCall(info, null, permutationIdMethod), switchBody);
// return new FallbackImpl(); at the very end.
assert mostUsedExpression != null : "No most-used expression";
JReturnStatement fallbackReturn = new JReturnStatement(info, mostUsedExpression);
JMethodBody body = (JMethodBody) toReturn.getBody();
body.getBlock().addStmt(sw);
body.getBlock().addStmt(fallbackReturn);
return toReturn;
}
}