com.ibm.icu.number.ScientificNotation Maven / Gradle / Ivy
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// © 2017 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
package com.ibm.icu.number;
import com.ibm.icu.impl.number.DecimalQuantity;
import com.ibm.icu.impl.number.MicroProps;
import com.ibm.icu.impl.number.MicroPropsGenerator;
import com.ibm.icu.impl.number.Modifier;
import com.ibm.icu.impl.number.MultiplierProducer;
import com.ibm.icu.impl.number.NumberStringBuilder;
import com.ibm.icu.impl.number.RoundingUtils;
import com.ibm.icu.number.NumberFormatter.SignDisplay;
import com.ibm.icu.number.Rounder.SignificantRounderImpl;
import com.ibm.icu.text.DecimalFormatSymbols;
import com.ibm.icu.text.NumberFormat;
/**
* A class that defines the scientific notation style to be used when formatting numbers in
* NumberFormatter.
*
*
* To create a ScientificNotation, use one of the factory methods in {@link Notation}.
*
* @draft ICU 60
* @provisional This API might change or be removed in a future release.
* @see NumberFormatter
*/
public class ScientificNotation extends Notation implements Cloneable {
int engineeringInterval;
boolean requireMinInt;
int minExponentDigits;
SignDisplay exponentSignDisplay;
/* package-private */ ScientificNotation(
int engineeringInterval,
boolean requireMinInt,
int minExponentDigits,
SignDisplay exponentSignDisplay) {
this.engineeringInterval = engineeringInterval;
this.requireMinInt = requireMinInt;
this.minExponentDigits = minExponentDigits;
this.exponentSignDisplay = exponentSignDisplay;
}
/**
* Sets the minimum number of digits to show in the exponent of scientific notation, padding with
* zeros if necessary. Useful for fixed-width display.
*
*
* For example, with minExponentDigits=2, the number 123 will be printed as "1.23E02" in
* en-US instead of the default "1.23E2".
*
* @param minExponentDigits
* The minimum number of digits to show in the exponent.
* @return A ScientificNotation, for chaining.
* @draft ICU 60
* @provisional This API might change or be removed in a future release.
* @see NumberFormatter
*/
public ScientificNotation withMinExponentDigits(int minExponentDigits) {
if (minExponentDigits >= 1 && minExponentDigits <= RoundingUtils.MAX_INT_FRAC_SIG) {
ScientificNotation other = (ScientificNotation) this.clone();
other.minExponentDigits = minExponentDigits;
return other;
} else {
throw new IllegalArgumentException("Integer digits must be between 1 and "
+ RoundingUtils.MAX_INT_FRAC_SIG
+ " (inclusive)");
}
}
/**
* Sets whether to show the sign on positive and negative exponents in scientific notation. The
* default is AUTO, showing the minus sign but not the plus sign.
*
*
* For example, with exponentSignDisplay=ALWAYS, the number 123 will be printed as "1.23E+2" in
* en-US instead of the default "1.23E2".
*
* @param exponentSignDisplay
* The strategy for displaying the sign in the exponent.
* @return A ScientificNotation, for chaining.
* @draft ICU 60
* @provisional This API might change or be removed in a future release.
* @see NumberFormatter
*/
public ScientificNotation withExponentSignDisplay(SignDisplay exponentSignDisplay) {
ScientificNotation other = (ScientificNotation) this.clone();
other.exponentSignDisplay = exponentSignDisplay;
return other;
}
/**
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
@Override
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
// Should not happen since parent is Object
throw new AssertionError(e);
}
}
/* package-private */ MicroPropsGenerator withLocaleData(
DecimalFormatSymbols symbols,
boolean build,
MicroPropsGenerator parent) {
return new ScientificHandler(this, symbols, build, parent);
}
// NOTE: The object lifecycle of ScientificModifier and ScientificHandler differ greatly in Java and
// C++.
//
// During formatting, we need to provide an object with state (the exponent) as the inner modifier.
//
// In Java, where the priority is put on reducing object creations, the unsafe code path re-uses the
// ScientificHandler as a ScientificModifier, and the safe code path pre-computes 25
// ScientificModifier
// instances. This scheme reduces the number of object creations by 1 in both safe and unsafe.
//
// In C++, MicroProps provides a pre-allocated ScientificModifier, and ScientificHandler simply
// populates
// the state (the exponent) into that ScientificModifier. There is no difference between safe and
// unsafe.
private static class ScientificHandler implements MicroPropsGenerator, MultiplierProducer, Modifier {
final ScientificNotation notation;
final DecimalFormatSymbols symbols;
final ScientificModifier[] precomputedMods;
final MicroPropsGenerator parent;
/* unsafe */ int exponent;
private ScientificHandler(
ScientificNotation notation,
DecimalFormatSymbols symbols,
boolean safe,
MicroPropsGenerator parent) {
this.notation = notation;
this.symbols = symbols;
this.parent = parent;
if (safe) {
// Pre-build the modifiers for exponents -12 through 12
precomputedMods = new ScientificModifier[25];
for (int i = -12; i <= 12; i++) {
precomputedMods[i + 12] = new ScientificModifier(i, this);
}
} else {
precomputedMods = null;
}
}
@Override
public MicroProps processQuantity(DecimalQuantity quantity) {
MicroProps micros = parent.processQuantity(quantity);
assert micros.rounding != null;
// Treat zero as if it had magnitude 0
int exponent;
if (quantity.isZero()) {
if (notation.requireMinInt && micros.rounding instanceof SignificantRounderImpl) {
// Show "00.000E0" on pattern "00.000E0"
((SignificantRounderImpl) micros.rounding).apply(quantity,
notation.engineeringInterval);
exponent = 0;
} else {
micros.rounding.apply(quantity);
exponent = 0;
}
} else {
exponent = -micros.rounding.chooseMultiplierAndApply(quantity, this);
}
// Add the Modifier for the scientific format.
if (precomputedMods != null && exponent >= -12 && exponent <= 12) {
// Safe code path A
micros.modInner = precomputedMods[exponent + 12];
} else if (precomputedMods != null) {
// Safe code path B
micros.modInner = new ScientificModifier(exponent, this);
} else {
// Unsafe code path: mutates the object and re-uses it as a Modifier!
this.exponent = exponent;
micros.modInner = this;
}
// We already performed rounding. Do not perform it again.
micros.rounding = Rounder.constructPassThrough();
return micros;
}
@Override
public int getMultiplier(int magnitude) {
int interval = notation.engineeringInterval;
int digitsShown;
if (notation.requireMinInt) {
// For patterns like "000.00E0" and ".00E0"
digitsShown = interval;
} else if (interval <= 1) {
// For patterns like "0.00E0" and "@@@E0"
digitsShown = 1;
} else {
// For patterns like "##0.00"
digitsShown = ((magnitude % interval + interval) % interval) + 1;
}
return digitsShown - magnitude - 1;
}
@Override
public int getPrefixLength() {
// TODO: Localized exponent separator location.
return 0;
}
@Override
public int getCodePointCount() {
// This method is not used for strong modifiers.
throw new AssertionError();
}
@Override
public boolean isStrong() {
// Scientific is always strong
return true;
}
@Override
public int apply(NumberStringBuilder output, int leftIndex, int rightIndex) {
return doApply(exponent, output, rightIndex);
}
private int doApply(int exponent, NumberStringBuilder output, int rightIndex) {
// FIXME: Localized exponent separator location.
int i = rightIndex;
// Append the exponent separator and sign
i += output.insert(i, symbols.getExponentSeparator(), NumberFormat.Field.EXPONENT_SYMBOL);
if (exponent < 0 && notation.exponentSignDisplay != SignDisplay.NEVER) {
i += output.insert(i, symbols.getMinusSignString(), NumberFormat.Field.EXPONENT_SIGN);
} else if (exponent >= 0 && notation.exponentSignDisplay == SignDisplay.ALWAYS) {
i += output.insert(i, symbols.getPlusSignString(), NumberFormat.Field.EXPONENT_SIGN);
}
// Append the exponent digits (using a simple inline algorithm)
int disp = Math.abs(exponent);
for (int j = 0; j < notation.minExponentDigits || disp > 0; j++, disp /= 10) {
int d = disp % 10;
String digitString = symbols.getDigitStringsLocal()[d];
i += output.insert(i - j, digitString, NumberFormat.Field.EXPONENT);
}
return i - rightIndex;
}
}
private static class ScientificModifier implements Modifier {
final int exponent;
final ScientificHandler handler;
ScientificModifier(int exponent, ScientificHandler handler) {
this.exponent = exponent;
this.handler = handler;
}
@Override
public int apply(NumberStringBuilder output, int leftIndex, int rightIndex) {
return handler.doApply(exponent, output, rightIndex);
}
@Override
public int getPrefixLength() {
// TODO: Localized exponent separator location.
return 0;
}
@Override
public int getCodePointCount() {
// This method is not used for strong modifiers.
throw new AssertionError();
}
@Override
public boolean isStrong() {
// Scientific is always strong
return true;
}
}
}