Class EmptyList
- All Implemented Interfaces:
ContainingType,Type,WrappingType
A special case of a list type, which is always empty. It is special, as it is co-variant with any other list, e.g. an empty list can be assigned to any other list type without upsetting type safety.
It wraps a list of type nothing, so that if you want to pretend it's a list, Type#find will do the right thing. Note that we return a list of type nothing so that if you attempt to use the member type, no equivalence or covariance is going to work for you
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Field Summary
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Method Summary
Modifier and TypeMethodDescriptionasStruct()Attempt to convert the given value in to one represented by this type.intestimateSize(Object entry) Estimate the number of bytes used to serialize the given value to an output stream.Class<?>The underlying java class used to represent this type.voidtoBytes(DataOutputStream os, Object toWrite) toString()<T,U> U visit(TypeVisitor<T, U> tv, T data) Type specific visiting logic.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitMethods inherited from interface nz.org.riskscape.engine.types.Type
checkForNull, find, findAllowNull, getUnwrappedType, isA, isNumeric, isWrapped, toString, unwrapMethods inherited from interface nz.org.riskscape.engine.types.WrappingType
isNullable
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Field Details
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INSTANCE
The one and only instance of an EmptyList type
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AS_STRUCT
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Method Details
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getContainedType
- Specified by:
getContainedTypein interfaceContainingType- Returns:
- The type that this
ContainingTypecontains.
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coerce
Description copied from interface:TypeAttempt to convert the given value in to one represented by this type.
- Specified by:
coercein interfaceType- Parameters:
value- The value to coerce- Returns:
- A value that conforms to this type
- Throws:
CoercionException- if the given object can not be converted to something represented by this type
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internalType
Description copied from interface:TypeThe underlying java class used to represent this type.
- Specified by:
internalTypein interfaceType
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asStruct
- Specified by:
asStructin interfaceType- Specified by:
asStructin interfaceWrappingType
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estimateSize
Description copied from interface:TypeEstimate the number of bytes used to serialize the given value to an output stream.
- Specified by:
estimateSizein interfaceType- Specified by:
estimateSizein interfaceWrappingType- Parameters:
entry- the value of this type to measure. Must be ofType.internalType()or aClassCastExceptionis going to happen- Returns:
- the estimated number of bytes, or zero if no estimation was possible.
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toBytes
- Specified by:
toBytesin interfaceType- Specified by:
toBytesin interfaceWrappingType- Throws:
IOException
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fromBytes
- Specified by:
fromBytesin interfaceType- Specified by:
fromBytesin interfaceWrappingType- Throws:
IOException
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toString
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visit
Description copied from interface:TypeType specific visiting logic. Types must decide whether they are atomic or compound and call the relevant method on
TypeVisitor. It's up to each compound type to decide how they want to structure their children, e.g. order, metadata, and what's considered a child or not.- Specified by:
visitin interfaceContainingType- Specified by:
visitin interfaceType- Specified by:
visitin interfaceWrappingType
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getUnderlyingType
- Specified by:
getUnderlyingTypein interfaceWrappingType- Returns:
- the type that we immediately wrap. Used by
Type.getUnwrappedType()to descend through all wrappedTypeto find the first unwrapped one.
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