com.whitestein.lsps.vaadin.forms.datasource

Interface ValueProvider

All Superinterfaces:

Serializable

All Known Implementing Classes:

LspsValueProvider, ValueProvider.AbstractValueProvider, ValueProvider.DelegatingValueProvider, ValueProvider.LocalizingValueProvider, ValueProvider.MemoizingValueProvider, ValueProvider.ToStringValueProvider, ValueProvider.ValueKeepingValueProvider

public interface ValueProvider
extends Serializable

Extracts a particular value from a row object, e.g. returns a value of a particular Record property. If the implementation should also handle attempts to change values, add it also ValueWriter interface.

Author:

mvy

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ValueProvider.AbstractValueProvider Extend this to get basic value provider functionality out of the box - return class, comparator and memoization.
static class	ValueProvider.DelegatingValueProvider Decorator pattern - delegates all calls to delegate.
static class	ValueProvider.LocalizingValueProvider Localizes values provided by the underlying value provider.
static class	ValueProvider.MemoizingValueProvider A provider which caches (memoizes) pairs of input-result, as provided by the delegate, indefinitely.
static class	ValueProvider.ToStringValueProvider Simply converts row objects to string, by calling Object.toString().
static class	ValueProvider.ValueKeepingValueProvider Hold and keeps value independently of row object.

Method Summary

Modifier and Type	Method and Description
Object	call(Object input) Provides value for given row data object.
com.google.common.collect.Ordering<Object>	getComparator() Returns comparator which compares input objects based on values provided by this value provider.
RecordHolder	getDefinition() Gets the LSPS object counterpart of this value provider.
Class<?>	getReturnJavaClass(Namespace namespace) Java class of objects provided by call(Object).
Type	getValueType(Namespace namespace) Returns the value type provided by this provider (by calls to call(Object).
ValueProvider	memoize() Returns a value provider which caches (memoizes) pairs of input-result of call(Object) indefinitely.

Method Detail

getDefinition

RecordHolder getDefinition()

Gets the LSPS object counterpart of this value provider.

Returns:

definition object, may be null if there is no counterpart.

getReturnJavaClass

Class<?> getReturnJavaClass(Namespace namespace)

Java class of objects provided by call(Object). If in doubt, return Object.class.

Parameters:

namespace - calling namespace, not null.

Returns:

the java class of returned objects, not null.

getValueType

Type getValueType(Namespace namespace)

Returns the value type provided by this provider (by calls to call(Object). When in doubt, return SimpleType.OBJECT.

Parameters:

namespace - calling namespace, not null.

Returns:

the type, not null.

call

Object call(Object input)

Provides value for given row data object.

Parameters:

input - the input object, mostly RecordHolder, may be null.

Returns:

cell value, mostly String, may be null.

getComparator

com.google.common.collect.Ordering<Object> getComparator()

Returns comparator which compares input objects based on values provided by this value provider. The values provided by call(Object) must be Comparable!

Returns:

null-first ordering which calls call(Object) on every input object and sorts the objects by comparing output values. Never null.

memoize

ValueProvider memoize()

Returns a value provider which caches (memoizes) pairs of input-result of call(Object) indefinitely.

Returns:

a memoizing value provider, not null.