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/**
* @since 2020-08-26
*/
package sevenUnitsGUI;
import java.util.List;
import java.util.function.Predicate;
import sevenUnits.unit.Metric;
import sevenUnits.unit.UnitPrefix;
/**
* A rule that specifies whether prefix repetition is allowed
*
* @since 2020-08-26
*/
public enum DefaultPrefixRepetitionRule implements Predicate<List<UnitPrefix>> {
NO_REPETITION {
@Override
public boolean test(List<UnitPrefix> prefixes) {
return prefixes.size() <= 1;
}
},
NO_RESTRICTION {
@Override
public boolean test(List<UnitPrefix> prefixes) {
return true;
}
},
/**
* You are allowed to have any number of Yotta/Yocto followed by possibly one
* Kilo-Zetta/Milli-Zepto followed by possibly one Deca/Hecto. Same for
* reducing prefixes, don't mix magnifying and reducing. Non-metric
* (including binary) prefixes can't be repeated.
*/
COMPLEX_REPETITION {
@Override
public boolean test(List<UnitPrefix> prefixes) {
// determine whether we are magnifying or reducing
final boolean magnifying;
if (prefixes.isEmpty())
return true;
else if (prefixes.get(0).getMultiplier() > 1) {
magnifying = true;
} else {
magnifying = false;
}
// if the first prefix is non-metric (including binary prefixes),
// assume we are using non-metric prefixes
// non-metric prefixes are allowed, but can't be repeated.
if (!Metric.DECIMAL_PREFIXES.contains(prefixes.get(0)))
return NO_REPETITION.test(prefixes);
int part = 0; // 0=yotta/yoctos, 1=kilo-zetta/milli-zepto,
// 2=deka,hecto,deci,centi
for (final UnitPrefix prefix : prefixes) {
// check that the current prefix is metric and appropriately
// magnifying/reducing
if (!Metric.DECIMAL_PREFIXES.contains(prefix))
return false;
if (magnifying != prefix.getMultiplier() > 1)
return false;
// check if the current prefix is correct
// since part is set *after* this check, part designates the state
// of the *previous* prefix
switch (part) {
case 0:
// do nothing, any prefix is valid after a yotta
break;
case 1:
// after a kilo-zetta, only deka/hecto are valid
if (Metric.THOUSAND_PREFIXES.contains(prefix))
return false;
break;
case 2:
// deka/hecto must be the last prefix, so this is always invalid
return false;
}
// set part
if (Metric.YOTTA.equals(prefix) || Metric.YOCTO.equals(prefix)) {
part = 0;
} else if (Metric.THOUSAND_PREFIXES.contains(prefix)) {
part = 1;
} else {
part = 2;
}
}
return true;
}
};
}
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