com.google.errorprone.bugpatterns.DateFormatConstant.java Source code

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Here is the source code for com.google.errorprone.bugpatterns.DateFormatConstant.java

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/*
 * Copyright 2017 The Error Prone 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.errorprone.bugpatterns;

import static com.google.errorprone.BugPattern.Category.JDK;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.fixes.SuggestedFixes.renameVariable;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.isSubtype;

import com.google.common.base.Ascii;
import com.google.common.base.CaseFormat;
import com.google.errorprone.BugPattern;
import com.google.errorprone.BugPattern.ProvidesFix;
import com.google.errorprone.BugPattern.StandardTags;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.VariableTree;
import com.sun.source.util.TreeScanner;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import java.util.Objects;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.Modifier;

/** @author cushon@google.com (Liam Miller-Cushon) */
@BugPattern(name = "DateFormatConstant", category = JDK, summary = "DateFormat is not thread-safe, and should not be used as a constant field.", severity = WARNING, tags = StandardTags.FRAGILE_CODE, providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
public class DateFormatConstant extends BugChecker implements VariableTreeMatcher {

    @Override
    public Description matchVariable(VariableTree tree, VisitorState state) {
        if (tree.getInitializer() == null) {
            return NO_MATCH;
        }
        VarSymbol sym = ASTHelpers.getSymbol(tree);
        if (sym == null || sym.getKind() != ElementKind.FIELD) {
            return NO_MATCH;
        }
        String name = sym.getSimpleName().toString();
        if (!(sym.isStatic() && sym.getModifiers().contains(Modifier.FINAL))) {
            return NO_MATCH;
        }
        if (!name.equals(Ascii.toUpperCase(name))) {
            return NO_MATCH;
        }
        if (!isSubtype(getType(tree), state.getTypeFromString("java.text.DateFormat"), state)) {
            return NO_MATCH;
        }
        SuggestedFix rename = renameVariable(tree,
                CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, tree.getName().toString()), state);
        return buildDescription(tree).addFix(threadLocalFix(tree, state, sym, rename)).addFix(rename).build();
    }

    private static Fix threadLocalFix(VariableTree tree, VisitorState state, final VarSymbol sym,
            SuggestedFix rename) {
        SuggestedFix.Builder fix = SuggestedFix.builder().merge(rename)
                .replace(tree.getType(), String.format("ThreadLocal<%s>", state.getSourceForNode(tree.getType())))
                .prefixWith(tree.getInitializer(), "ThreadLocal.withInitial(() -> ")
                .postfixWith(tree.getInitializer(), ")");
        CompilationUnitTree unit = state.getPath().getCompilationUnit();
        unit.accept(new TreeScanner<Void, Void>() {
            @Override
            public Void visitIdentifier(IdentifierTree tree, Void unused) {
                if (Objects.equals(ASTHelpers.getSymbol(tree), sym)) {
                    fix.postfixWith(tree, ".get()");
                }
                return null;
            }
        }, null);
        return fix.build();
    }
}