org.truffleruby.parser.SafeDecimalParser Maven / Gradle / Ivy
Show all versions of ruby-language Show documentation
/*
***** BEGIN LICENSE BLOCK *****
* Version: EPL 2.0/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Eclipse Public
* 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.eclipse.org/legal/epl-v20.html
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the EPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the EPL, the GPL or the LGPL.
***** END LICENSE BLOCK *****/
package org.truffleruby.parser;
import java.math.BigDecimal;
class SafeDecimalParser {
/** Constant 2 */
protected static final BigDecimal TWO = new BigDecimal(2);
/** Lower allowed value */
protected static final BigDecimal LOWER = new BigDecimal("2.22507385850720113605e-308");
/** Upper allowed value */
protected static final BigDecimal UPPER = new BigDecimal("2.22507385850720125958e-308");
/** The middle of the bad interval - used for rounding bad values */
protected static final BigDecimal MIDDLE = LOWER.add(UPPER).divide(TWO);
/** Upper allowed value as Double */
private static final Double UPPER_DOUBLE = Double.valueOf(UPPER.doubleValue());
/** Lower allowed value as Double */
private static final Double LOWER_DOUBLE = Double.valueOf(LOWER.doubleValue());
/** Digit sequence to trigger the slow path */
private static final String SUSPICIOUS_DIGITS = "22250738585072";
/** Heuristic test if we should look closer at the value
*
* @param s The non-null input String
* @return true if the value is suspicious, false otherwise */
protected static final boolean isSuspicious(String s) {
return digits(s).contains(SUSPICIOUS_DIGITS);
}
/** Safe parsing of a String into a Double
*
* @param s The input String, can be null
* @return The Double value */
protected static final Double decimalValueOf(String s) {
Double result = null;
if (s != null) {
if (isSuspicious(s)) {
// take the slow path
result = parseSafely(s);
} else {
result = Double.valueOf(s);
}
}
return result;
}
/** Safe way of getting the double value
* prevents BigDecimal from calling Double.parseDouble()
*
* @param number
* @return the double value */
protected static final double decimalValue(Number number) {
double result = 0;
if (number != null) {
if (number instanceof BigDecimal) {
result = decimalValue((BigDecimal) number);
} else {
result = number.doubleValue();
}
}
return result;
}
/** Safe way of getting the double value
* Prevents BigDecimal from calling Double.parseDouble()
*
* @param bigDecimal
* @return the double value */
protected static final double decimalValue(BigDecimal bigDecimal) {
double result = 0.0;
if (bigDecimal != null) {
if (isDangerous(bigDecimal)) {
result = decimalValueOf(bigDecimal.toString()).doubleValue();
} else {
result = bigDecimal.doubleValue();
}
}
return result;
}
/** Slow parsing of a suspicious value
*
* Rounding takes place if the value is inside the bad interval
*
* @param s The non-null input String
* @return the double value */
private static final Double parseSafely(String s) {
Double result;
BigDecimal bd = new BigDecimal(s);
if (isDangerous(bd)) {
if (bd.compareTo(MIDDLE) >= 0) {
result = UPPER_DOUBLE;
} else {
result = LOWER_DOUBLE;
}
} else {
result = Double.valueOf(s);
}
return result;
}
/** Extract the digits from a numeric string
*
* @param s The non-null String value
* @return A String containing only the digits */
private static final String digits(String s) {
char[] ca = s.toCharArray();
int len = ca.length;
StringBuilder b = new StringBuilder(len);
for (int i = 0; i < len; i++) {
char c = ca[i];
if (c >= '0' && c <= '9') {
b.append(c);
}
}
return b.toString();
}
/** Tests if the value is in the dangerous interval
*
* @param bd The big decimal value
* @return true if the value is dangerous, false otherwise */
private static final boolean isDangerous(BigDecimal bd) {
return bd.compareTo(UPPER) < 0 && bd.compareTo(LOWER) > 0;
}
}