org.jruby.util.SafeDecimalParser Maven / Gradle / Ivy
package org.jruby.util;
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
*/
final protected static boolean isSuspicious(String s) {
return digits(s).indexOf(SUSPICIOUS_DIGITS) >= 0;
}
/**
* Safe parsing of a String into a Double
*
* @param s
* The input String, can be null
* @return The Double value
*/
final protected static 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
*/
final protected static 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
*/
final protected static 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
*/
final private static 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
*/
final private static 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
*/
final private static boolean isDangerous(BigDecimal bd) {
return bd.compareTo(UPPER) < 0 && bd.compareTo(LOWER) > 0;
}
}