package com.slmn.buildin.money;
import java.math.BigDecimal;
import java.math.BigInteger;
/**
* Converter from String/double/float/integer types into Money instances.
* Requies the precision to be specified for double->Money conversion. Precision is usually based
* on the smallest tick in your exchange data.
*/
public class MoneyFactory {
static final int MAX_LONG_LENGTH = Long.toString( Long.MAX_VALUE ).length();
public static final int MAX_ALLOWED_PRECISION = 15;
//needed for overflow checking during conversion
private static final long MAX_LONG_DIVIDED_BY_10 = Long.MAX_VALUE / 10;
/** Non-negative powers of 10 */
static final long[] MULTIPLIERS = new long[ MoneyFactory.MAX_ALLOWED_PRECISION + 1 ];
/** Non-positive powers of 10 */
static final double[] MULTIPLIERS_NEG = new double[ MoneyFactory.MAX_ALLOWED_PRECISION + 1 ];
static
{
long val = 1;
for ( int i = 0; i <= MoneyFactory.MAX_ALLOWED_PRECISION; ++i )
{
MULTIPLIERS[ i ] = val;
MULTIPLIERS_NEG[ i ] = 1.0 / val;
val *= 10;
}
}
static void checkPrecision(int precision) {
if ( precision < 0 || precision > MAX_ALLOWED_PRECISION )
throw new IllegalArgumentException( "Precision must be between 0 and " + MAX_ALLOWED_PRECISION );
}
/**
* Convert from currency units and their precision into Money object.
* @param units Currency units (cents, for example)
* @param precision Number of digits after decimal point in your smallest possible currency unit. Should be between
* 0 and <code>MAX_ALLOWED_PRECISION</code> (inclusive).
* @return Money object
* @throws java.lang.IllegalArgumentException In case of invalid precision
*/
public static Money fromUnits( final long units, final int precision )
{
checkPrecision( precision );
return new MoneyLong( units, precision );
}
/**
* Same as <code>fromString</code>, but characters are extracted from the given part of char array
* @param chars Char array
* @param offset Start position
* @param length number of characters to process
* @return Money object
*/
public static Money fromCharArray( final char[] chars, final int offset, final int length )
{
return fromCharSequence( new CharArraySeq( chars, offset, length ) );
}
private static class CharArraySeq implements CharSequence
{
private final char[] chars;
private final int offset;
private final int length;
private CharArraySeq(char[] chars, int offset, int length) {
this.chars = chars;
this.offset = offset;
this.length = length;
}
public int length() {
return length;
}
public char charAt( final int index ) {
return chars[ offset + index ];
}
public CharSequence subSequence(int start, int end) {
//not needed for this implemenration
return null;
}
}
/**
* Same as <code>fromString</code>, but characters are extracted from the given part of byte array.
* We expect the data to be ASCII-encoded in the given part of the array.
* @param bytes Byte array
* @param offset Start position
* @param length number of characters to process
* @return Money object
*/
public static Money fromByteArray( final byte[] bytes, final int offset, final int length )
{
return fromCharSequence( new ByteArraySeq( bytes, offset, length));
}
private static class ByteArraySeq implements CharSequence
{
private final byte[] bytes;
private final int offset;
private final int length;
private ByteArraySeq(byte[] bytes, int offset, int length) {
this.bytes = bytes;
this.offset = offset;
this.length = length;
}
public int length() {
return length;
}
public char charAt(int index) {
return (char) bytes[offset + index];
}
public CharSequence subSequence(int start, int end) {
return null; //not needed for this implementation
}
}
/**
* Same as <code>fromString</code>, but characters are extracted from the <code>CharSequence</code>
* @param seq <code>CharSequence</code> object, may be more convenient in some situations.
* @return Money object
*/
public static Money fromCharSequence( final CharSequence seq )
{
final Money fast = parseFast( seq );
if ( fast != null )
return fast;
return fromString0( seq.toString() ); //slow path, convert to String
}
/**
* Convert a String monetary value into a Money object. We support a single format - dot-separated decimal part without
* the scientific notation support ( valid example - 355.56 ).
* @param value Value to parse
* @return Money
* @throws java.lang.IllegalArgumentException In case of any conversion errors
*/
public static Money fromString( final String value )
{
//fast single pass parser first
final Money fast = parseFast( value );
if ( fast != null )
return fast;
return fromString0(value);
}
private static Money fromString0( final String value )
{
final int dotPos = value.indexOf('.');
final int precision = dotPos == -1 ? 0 : value.length() - dotPos - 1;
if ( precision > MAX_ALLOWED_PRECISION ) //too high precision
return new MoneyBigDecimal( value );
if ( dotPos != -1 && value.indexOf( '.', dotPos + 1 ) != -1 )
throw new IllegalArgumentException( "Unparseable String value has more than 1 decimal point: " + value );
try
{
final long units = Long.parseLong( value.replace(".", "") );
return new MoneyLong( units, precision ); //actual precision, not the maximal one
}
catch ( NumberFormatException ex )
{
try
{
return new MoneyBigDecimal( value );
}
catch ( NumberFormatException ex2 )
{
throw new IllegalArgumentException( "Unparseable value provided: " + value, ex2 );
}
}
}
/**
* Fast single pass parser, should correctly process most of positive/negative values fitting into <code>long</code>
* @param str Floating point number to parse
* @return Money object or null (if can't parse)
* @throws java.lang.IllegalArgumentException If a value has more than one decimal digit
*/
private static Money parseFast( final CharSequence str )
{
if ( str.length() >= MAX_LONG_LENGTH )
return null;
long res = 0;
int start = 0;
long sign = 1;
int precision = 0;
if ( str.charAt( 0 ) == '-' )
{
sign = -1;
start = 1;
}
else if ( str.charAt( 0 ) == '+' )
{
sign = 1;
start = 1;
}
for ( int i = start; i < str.length(); ++i )
{
final char c = str.charAt( i );
if ( c == '.' )
{
if ( precision > 0 )
throw new IllegalArgumentException( "Unparseable String value has more than 1 decimal point: " + str );
precision = str.length() - i - 1;
}
else if ( c >= '0' && c <= '9' )
res = res * 10 + ( c - '0' );
else //unsupported char, handle in the caller
return null;
}
return new MoneyLong( res * sign, precision ).normalize();
}
/**
* <p>
* Convert a double monetary value into a Money object. You will end up with the most efficient Money type
* if you have no more than <code>MAX_ALLOWED_PRECISION</code> decimal digits in your value.
* </p>
* <p>
* This method will attempt to look by ulp in both directions during conversions to cater for already slightly
* incorrect values - results of <code>double</code> operations outside this library.
* </p>
* @param value Double monetary value
* @return Money object
*/
public static Money fromDouble( final double value )
{
return fromDouble( value, MAX_ALLOWED_PRECISION );
}
/**
* <p>
* Convert a double monetary value into a Money object. You will end up with the most efficient Money type
* if you have no more than <code>precision</code> decimal digits in your value.
* </p>
* <p>
* This method will attempt to look by ulp in both directions during conversions to cater for already slightly
* incorrect values - results of <code>double</code> operations outside this library.
* </p>
* <p>
* Do not try to set too high precision for this method - it may prevent you from correcting a slightly
* incorrect value (off by ulp) into a correct one. As a result, you will end up with BigDecimal-based
* implementation, which requires more memory and which is much slower to calculate.
* </p>
* @param value Double monetary value
* @param precision Number of digits after decimal point in your smallest possible currency unit.
* Should be between 0 and <code>MAX_ALLOWED_PRECISION</code> (inclusive).
* @return Money object
*/
public static Money fromDouble( final double value, final int precision )
{
checkPrecision( precision );
//attempt direct
final Money direct = fromDoubleNoFallback( value, precision );
if ( direct != null )
return direct;
return new MoneyBigDecimal( value );
}
static MoneyLong fromDoubleNoFallback( final double value, final int precision )
{
//attempt direct
final MoneyLong direct = fromDouble0( value, precision );
if ( direct != null )
return direct;
//ulp down
final MoneyLong down = fromDouble0( Math.nextAfter( value, -Double.MAX_VALUE ), precision );
if ( down != null )
return down;
//ulp up
final MoneyLong up = fromDouble0( Math.nextAfter( value, Double.MAX_VALUE ), precision );
if ( up != null )
return up;
return null;
}
private static MoneyLong fromDouble0( final double value, final int precision )
{
final double multiplied = value * MULTIPLIERS[ precision ];
final long converted = (long) multiplied;
if ( multiplied == converted ) //here is an implicit conversion from long to double
return new MoneyLong( converted, precision ).normalize();
return null;
}
/**
* <p>
* Convert a given BigDecimal value into money. Conversion is similar to <code>toDouble</code>,
* though this method does not attempt to make any corrections: it assumes that BigDecimal is a result
* of exact calcualtions.
* </p>
* <p>
* This method will try to use the most efficient representation if possible.
* </p>
* @param value BigDecimal value to convert
* @return Money object
*/
public static Money fromBigDecimal( final BigDecimal value )
{
final BigDecimal cleaned = value.stripTrailingZeros();
//try to convert to double using a fixed precision = 3, which will cover most of currencies
//it is required to get rid of rounding issues
final double dbl = value.doubleValue();
final Money res = fromDoubleNoFallback( dbl, 3 );
if ( res != null )
return res;
final int scale = cleaned.scale();
if ( scale > MAX_ALLOWED_PRECISION || scale < -MAX_ALLOWED_PRECISION )
return new MoneyBigDecimal( cleaned );
//we may not fit into the Long, but we should try
//this value may be truncated!
final BigInteger unscaledBigInt = cleaned.unscaledValue();
final long unscaledUnits = unscaledBigInt.longValue();
//check that it was not
if ( !BigInteger.valueOf(unscaledUnits).equals( unscaledBigInt ) )
return new MoneyBigDecimal( cleaned );
//scale could be negative here - we must multiply in that case
if ( scale >= 0 )
return new MoneyLong( unscaledUnits, scale );
//multiply by 10 and each time check that sign did not change
//scale is negative
long units = unscaledUnits;
for ( int i = 0; i < -scale; ++i )
{
units *= 10;
if ( units >= MAX_LONG_DIVIDED_BY_10 )
return new MoneyBigDecimal( value );
}
return new MoneyLong( units, 0 );
}
}