/*
* Copyright 2011-2014 Gregory Shrago
*
* 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 org.intellij.grammar.inspection;
import com.intellij.codeInspection.*;
import com.intellij.lang.ASTNode;
import com.intellij.openapi.util.TextRange;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiFile;
import com.intellij.psi.PsiRecursiveElementWalkingVisitor;
import com.intellij.psi.impl.source.tree.TreeUtil;
import gnu.trove.THashSet;
import org.intellij.grammar.analysis.BnfFirstNextAnalyzer;
import org.intellij.grammar.psi.BnfChoice;
import org.intellij.grammar.psi.BnfExpression;
import org.intellij.grammar.psi.BnfTypes;
import org.jetbrains.annotations.Nls;
import org.jetbrains.annotations.NotNull;
import java.util.List;
import java.util.Set;
/**
* @author gregsh
*/
public class BnfUnreachableChoiceBranchInspection extends LocalInspectionTool {
@Nls
@NotNull
@Override
public String getGroupDisplayName() {
return "Grammar/BNF";
}
@Nls
@NotNull
@Override
public String getDisplayName() {
return "Unreachable choice branch";
}
@NotNull
@Override
public String getShortName() {
return "BnfUnreachableChoiceBranchInspection";
}
public boolean isEnabledByDefault() {
return true;
}
@Override
public ProblemDescriptor[] checkFile(@NotNull PsiFile file, @NotNull InspectionManager manager, boolean isOnTheFly) {
ProblemsHolder problemsHolder = new ProblemsHolder(manager, file, isOnTheFly);
checkFile(file, problemsHolder);
return problemsHolder.getResultsArray();
}
private static void checkFile(PsiFile file, final ProblemsHolder problemsHolder) {
file.accept(new PsiRecursiveElementWalkingVisitor() {
@Override
public void visitElement(PsiElement element) {
if (element instanceof BnfChoice) {
checkChoice((BnfChoice)element, problemsHolder);
}
super.visitElement(element);
}
});
}
private static void checkChoice(BnfChoice choice, ProblemsHolder problemsHolder) {
Set<BnfExpression> visited = new THashSet<BnfExpression>();
THashSet<BnfExpression> first = new THashSet<BnfExpression>();
BnfFirstNextAnalyzer analyzer = new BnfFirstNextAnalyzer();
List<BnfExpression> list = choice.getExpressionList();
for (int i = 0, listSize = list.size() - 1; i < listSize; i++) {
BnfExpression child = list.get(i);
Set<String> firstSet = analyzer.asStrings(analyzer.calcFirstInner(child, first, visited));
if (firstSet.contains(BnfFirstNextAnalyzer.MATCHES_NOTHING)) {
registerProblem(choice, child, "Branch is unable to match anything due to & or ! conditions", problemsHolder);
}
else if (firstSet.contains(BnfFirstNextAnalyzer.MATCHES_EOF)) {
registerProblem(choice, child, "Branch matches empty input making the rest branches unreachable", problemsHolder);
break;
}
first.clear();
visited.clear();
}
}
static void registerProblem(BnfExpression choice, BnfExpression branch, String message, ProblemsHolder problemsHolder, LocalQuickFix... fixes) {
TextRange textRange = branch.getTextRange();
if (textRange.isEmpty()) {
ASTNode nextOr = TreeUtil.findSibling(branch.getNode(), BnfTypes.BNF_OP_OR);
ASTNode prevOr = TreeUtil.findSiblingBackward(branch.getNode(), BnfTypes.BNF_OP_OR);
int shift = choice.getTextRange().getStartOffset();
int startOffset = prevOr != null ? prevOr.getStartOffset() - shift : 0;
TextRange range = new TextRange(startOffset, nextOr != null? nextOr.getStartOffset() + 1 - shift : Math.min(startOffset + 2, choice.getTextLength()));
problemsHolder.registerProblem(choice, range, message, fixes);
}
else {
problemsHolder.registerProblem(branch, message, fixes);
}
}
}