/*
* Copyright 2011 The Closure Compiler Authors.
*
* 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.javascript.jscomp;
import com.google.common.base.Preconditions;
import com.google.javascript.rhino.InputId;
import com.google.javascript.rhino.Node;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
/**
* An implementation for {@code ReferenceMap} that is specific to global scope
* and can be used in different passes. In other words instead of relying on
* Var object it relies on the name of the variable. It also supports hot-swap
* update of reference map for a specific script.
*
* @see ReferenceCollectingCallback#exitScope(NodeTraversal)
*
* @author bashir@google.com (Bashir Sadjad)
*/
class GlobalVarReferenceMap implements ReferenceMap {
private Map<String, ReferenceCollection> refMap = null;
private final Map<InputId, Integer> inputOrder;
/**
* @param inputs The ordered list of all inputs for the compiler.
*/
GlobalVarReferenceMap(List<CompilerInput> inputs, List<CompilerInput> externs) {
inputOrder = new HashMap<>();
int ind = 0;
for (CompilerInput extern : externs) {
inputOrder.put(extern.getInputId(), ind);
ind++;
}
for (CompilerInput input : inputs) {
inputOrder.put(input.getInputId(), ind);
ind++;
}
}
@Override
public ReferenceCollection getReferences(Var var) {
if (!var.isGlobal()) {
return null;
}
return refMap.get(var.getName());
}
/**
* Resets global var reference map with the new provide map.
*
* @param globalRefMap The reference map result of a
* {@link ReferenceCollectingCallback} pass collected from the whole AST.
*/
private void resetGlobalVarReferences(
Map<Var, ReferenceCollection> globalRefMap) {
refMap = new LinkedHashMap<>();
for (Entry<Var, ReferenceCollection> entry : globalRefMap.entrySet()) {
Var var = entry.getKey();
if (var.isGlobal()) {
refMap.put(var.getName(), entry.getValue());
}
}
}
/**
* Updates the internal reference map based on the provided parameters. If
* {@code scriptRoot} is not SCRIPT, it basically replaces the internal map
* with the new one, otherwise it replaces all the information associated to
* the given script.
*
* @param refMapPatch The reference map result of a
* {@link ReferenceCollectingCallback} pass which might be collected from
* the whole AST or just a sub-tree associated to a SCRIPT node.
* @param root AST sub-tree root on which reference collection was done.
*/
void updateGlobalVarReferences(Map<Var, ReferenceCollection>
refMapPatch, Node root) {
if (refMap == null || !root.isScript()) {
resetGlobalVarReferences(refMapPatch);
return;
}
InputId inputId = root.getInputId();
Preconditions.checkNotNull(inputId);
// Note there are two assumptions here (i) the order of compiler inputs
// has not changed and (ii) all references are in the order they appear
// in AST (this is enforced in ReferenceCollectionCallback).
removeScriptReferences(inputId);
for (Entry<Var, ReferenceCollection> entry : refMapPatch.entrySet()) {
Var var = entry.getKey();
if (var.isGlobal()) {
replaceReferences(var.getName(), inputId, entry.getValue());
}
}
}
private void removeScriptReferences(InputId inputId) {
Preconditions.checkNotNull(inputId);
if (!inputOrder.containsKey(inputId)) {
return; // Input did not exist when last computed, so skip
}
// TODO(bashir): If this is too slow it is not too difficult to make it
// faster with keeping an index for variables accessed in sourceName.
for (ReferenceCollection collection : refMap.values()) {
if (collection == null) {
continue;
}
List<Reference> oldRefs = collection.references;
SourceRefRange range = findSourceRefRange(oldRefs, inputId);
List<Reference> newRefs = new ArrayList<>(range.refsBefore());
newRefs.addAll(range.refsAfter());
collection.references = newRefs;
}
}
private void replaceReferences(String varName, InputId inputId,
ReferenceCollection newSourceCollection) {
ReferenceCollection combined = new ReferenceCollection();
List<Reference> combinedRefs = combined.references;
ReferenceCollection oldCollection = refMap.get(varName);
refMap.put(varName, combined);
if (oldCollection == null) {
combinedRefs.addAll(newSourceCollection.references);
return;
}
// otherwise replace previous references that are from sourceName
SourceRefRange range = findSourceRefRange(oldCollection.references,
inputId);
combinedRefs.addAll(range.refsBefore());
combinedRefs.addAll(newSourceCollection.references);
combinedRefs.addAll(range.refsAfter());
}
/**
* Finds the range of references associated to {@code sourceName}. Note that
* even if there is no sourceName references the returned information can be
* used to decide where to insert new sourceName refs.
*/
private SourceRefRange findSourceRefRange(List<Reference> refList,
InputId inputId) {
Preconditions.checkNotNull(inputId);
// TODO(bashir): We can do binary search here, but since this is fast enough
// right now, we just do a linear search for simplicity.
int lastBefore = -1;
int firstAfter = refList.size();
int index = 0;
Preconditions.checkState(inputOrder.containsKey(inputId), inputId.getIdName());
int sourceInputOrder = inputOrder.get(inputId);
for (Reference ref : refList) {
Preconditions.checkNotNull(ref.getInputId());
int order = inputOrder.get(ref.getInputId());
if (order < sourceInputOrder) {
lastBefore = index;
} else if (order > sourceInputOrder) {
firstAfter = index;
break;
}
index++;
}
return new SourceRefRange(refList, lastBefore, firstAfter);
}
private static class SourceRefRange {
private final int lastBefore;
private final int firstAfter;
private final List<Reference> refList;
SourceRefRange(List<Reference> refList, int lastBefore,
int firstAfter) {
this.lastBefore = Math.max(lastBefore, -1);
this.firstAfter = Math.min(firstAfter, refList.size());
this.refList = refList;
}
/** Note that the returned list is backed by {@code refList}! */
List<Reference> refsBefore() {
return refList.subList(0, lastBefore + 1);
}
/** Note that the returned list is backed by {@code refList}! */
List<Reference> refsAfter() {
return refList.subList(firstAfter, refList.size());
}
}
/**
* @param globalScope a new Global Scope to replace the scope of references
* with.
*/
public void updateReferencesWithGlobalScope(Scope globalScope) {
for (ReferenceCollection collection : refMap.values()) {
List<Reference> newRefs = new ArrayList<>(collection.references.size());
for (Reference ref : collection) {
if (ref.getScope() != globalScope) {
newRefs.add(ref.cloneWithNewScope(globalScope));
} else {
newRefs.add(ref);
}
}
collection.references = newRefs;
}
}
/**
* A CleanupPass implementation that will replace references to old Syntactic
* Global Scopes generated in previous compile runs with references to the
* Global Typed Scope.
*
* @author tylerg@google.com (Tyler Goodwin)
*/
static class GlobalVarRefCleanupPass implements HotSwapCompilerPass {
private final AbstractCompiler compiler;
public GlobalVarRefCleanupPass(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override
public void hotSwapScript(Node scriptRoot, Node originalRoot) {
GlobalVarReferenceMap refMap = compiler.getGlobalVarReferences();
if (refMap != null) {
refMap.updateReferencesWithGlobalScope(compiler.getTopScope());
}
}
@Override
public void process(Node externs, Node root) {
// GlobalVarRefCleanupPass should not do work during process.
}
}
}