/*
* Copyright 2015 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.deps;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.Multimap;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* A sorted list of inputs following the ES6 module ordering spec.
* <p>
* Orders such that each input always comes after its dependencies.
* Circular references are allowed by emitting the current input in the moment
* before a loop would complete.
* <p>
* The resulting order is not the same as the user-provided order but is
* influenced by it since it may take more than one graph traversal to account
* for all provided inputs and the graph traversals start with the first user
* provided input and continue from there.
* <p>
* Also exposes other information about the inputs, like which inputs
* do not provide symbols.
*
* @author stalcup@google.com (John Stalcup)
*/
public final class Es6SortedDependencies<INPUT extends DependencyInfo>
implements SortedDependencies<INPUT> {
private final List<INPUT> userOrderedInputs = new ArrayList<>();
private final List<INPUT> importOrderedInputs = new ArrayList<>();
private final Set<INPUT> completedInputs = new HashSet<>();
private final Map<String, INPUT> nonExportingInputs = new LinkedHashMap<>();
private final Map<String, INPUT> exportingInputBySymbolName = new HashMap<>();
// Maps an input A to the inputs it depends on, ie, inputs that provide stuff that A requires.
private final Multimap<INPUT, INPUT> importedInputByImportingInput = LinkedHashMultimap.create();
public Es6SortedDependencies(List<INPUT> userOrderedInputs) {
this.userOrderedInputs.addAll(userOrderedInputs);
processInputs();
}
@Override
public List<INPUT> getDependenciesOf(List<INPUT> rootInputs, boolean sorted) {
Preconditions.checkArgument(userOrderedInputs.containsAll(rootInputs));
Set<INPUT> includedInputs = new HashSet<>();
Deque<INPUT> worklist = new ArrayDeque<>(rootInputs);
while (!worklist.isEmpty()) {
INPUT input = worklist.pop();
if (includedInputs.add(input)) {
for (String symbolName : input.getRequires()) {
INPUT importedSymbolName = exportingInputBySymbolName.get(symbolName);
if (importedSymbolName != null) {
worklist.add(importedSymbolName);
}
}
}
}
ImmutableList.Builder<INPUT> builder = ImmutableList.builder();
for (INPUT input : (sorted ? importOrderedInputs : userOrderedInputs)) {
if (includedInputs.contains(input)) {
builder.add(input);
}
}
return builder.build();
}
@Override
public INPUT getInputProviding(String symbolName) throws MissingProvideException {
INPUT input = maybeGetInputProviding(symbolName);
if (input != null) {
return input;
}
throw new MissingProvideException(symbolName);
}
@Override
public List<INPUT> getInputsWithoutProvides() {
return ImmutableList.copyOf(nonExportingInputs.values());
}
@Override
public List<INPUT> getSortedDependenciesOf(List<INPUT> roots) {
return getDependenciesOf(roots, true);
}
@Override
public List<INPUT> getSortedList() {
return Collections.unmodifiableList(importOrderedInputs);
}
@Override
public INPUT maybeGetInputProviding(String symbol) {
if (exportingInputBySymbolName.containsKey(symbol)) {
return exportingInputBySymbolName.get(symbol);
}
return nonExportingInputs.get(ModuleNames.fileToModuleName(symbol));
}
private void orderInput(INPUT input) {
if (completedInputs.contains(input)) {
return;
}
completedInputs.add(input);
for (INPUT importedInput : importedInputByImportingInput.get(input)) {
orderInput(importedInput);
}
// Emit an input after its imports have been emitted.
importOrderedInputs.add(input);
}
private void processInputs() {
// Index.
for (INPUT userOrderedInput : userOrderedInputs) {
Collection<String> provides = userOrderedInput.getProvides();
String firstProvide = Iterables.getFirst(provides, null);
if (firstProvide == null
// TODO(sdh): It would be better to have a more robust way to distinguish
// between actual provided symbols and synthetic symbols generated for
// ES6 (or other) modules. We can't read loadFlags here (to see if
// the module type is 'es6') either, since that requires a full parse.
// So for now we rely on the heuristic that all generated provides start
// with "module$".
|| (provides.size() == 1 && firstProvide.startsWith("module$"))) {
nonExportingInputs.put(
ModuleNames.fileToModuleName(userOrderedInput.getName()), userOrderedInput);
}
for (String providedSymbolName : userOrderedInput.getProvides()) {
exportingInputBySymbolName.put(providedSymbolName, userOrderedInput);
}
}
for (INPUT userOrderedInput : userOrderedInputs) {
for (String symbolName : userOrderedInput.getRequires()) {
INPUT importedInput = exportingInputBySymbolName.get(symbolName);
if (importedInput != null) {
importedInputByImportingInput.put(userOrderedInput, importedInput);
}
}
}
// Order.
// For each input, traverse in user-provided order.
for (INPUT userOrderedInput : userOrderedInputs) {
// Traverse the graph starting from this input and record any
// newly-reached inputs.
orderInput(userOrderedInput);
}
// Free temporary indexes.
completedInputs.clear();
importedInputByImportingInput.clear();
}
}