/*
* Copyright 2017 Google Inc. All Rights Reserved.
*
* 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.matchers.Description.NO_MATCH;
import static com.google.errorprone.util.ASTHelpers.constValue;
import com.google.common.base.CharMatcher;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.LiteralTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.LiteralTree;
import com.sun.tools.javac.code.Type;
import java.math.BigDecimal;
/** @author cushon@google.com (Liam Miller-Cushon) */
@BugPattern(
name = "FloatingPointLiteralPrecision",
category = JDK,
summary = "Floating point literal loses precision",
severity = WARNING
)
public class FloatingPointLiteralPrecision extends BugChecker implements LiteralTreeMatcher {
@Override
public Description matchLiteral(LiteralTree tree, VisitorState state) {
Type type = ASTHelpers.getType(tree);
if (type == null) {
return NO_MATCH;
}
String suffix;
BigDecimal value;
switch (type.getKind()) {
case DOUBLE:
value = new BigDecimal(Double.toString(constValue(tree, Double.class)));
suffix = "";
break;
case FLOAT:
value = new BigDecimal(Float.toString(constValue(tree, Float.class)));
suffix = "f";
break;
default:
return NO_MATCH;
}
String source = state.getSourceForNode(tree);
switch (source.charAt(source.length() - 1)) {
case 'f':
case 'F':
case 'd':
case 'D':
source = source.substring(0, source.length() - 1);
break;
default: // fall out
}
source = CharMatcher.is('_').removeFrom(source);
BigDecimal exact;
try {
exact = new BigDecimal(source);
} catch (NumberFormatException e) {
// BigDecimal doesn't support e.g. hex floats
return NO_MATCH;
}
// Compare the actual and exact value, ignoring scale.
// BigDecimal#equals returns false for e.g. `1.0` and `1.00`.
if (exact.compareTo(value) == 0) {
return NO_MATCH;
}
return describeMatch(tree, SuggestedFix.replace(tree, value + suffix));
}
}