Package com.inductiveautomation.ignition.common.expressions

Class MapElementExtractor

java.lang.Object

com.inductiveautomation.ignition.common.expressions.MapElementExtractor

All Implemented Interfaces:

ElementExtractor<Object>

public class MapElementExtractor
extends Object
implements ElementExtractor<Object>

An ElementExtractor over plain Java objects: Maps are the map elements, Java arrays (accessed reflectively) are the array elements, and everything else is a primitive returned as-is by toJava(java.lang.Object).

Nested Class Summary

Nested classes/interfaces inherited from interface com.inductiveautomation.ignition.common.expressions.ElementExtractor

ElementExtractor.ElementNotFoundException

Field Summary

Fields

Modifier and Type	Field	Description
static final MapElementExtractor	INSTANCE	The stateless, shared instance.

Method Summary

Modifier and Type	Method	Description
String	arrayName()
int	arraySize(Object element)
@Nullable Object	extractIndex(Object element, int index)
@Nullable Object	extractKey(Object element, String key)
boolean	isArray(@Nullable Object element)
boolean	isMap(@Nullable Object element)
boolean	isNull(@Nullable Object element)
boolean	isPrimitive(@Nullable Object element)
String	mapName()
Object	toJava(Object element)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

INSTANCE

public static final MapElementExtractor INSTANCE

The stateless, shared instance.

Method Details

isMap

public boolean isMap(@Nullable Object element)

Specified by:

isMap in interface ElementExtractor<Object>

Returns:

true if element is a map: a container ElementExtractor.extractKey(T, java.lang.String) can step into; false for null.

extractKey

public @Nullable Object extractKey(Object element,
 String key)

Specified by:

extractKey in interface ElementExtractor<Object>

Returns:

the value at key; null if the key is present with a null value.

mapName

public String mapName()

Specified by:

mapName in interface ElementExtractor<Object>

Returns:

the representation's name for its map type (e.g. "JsonObject"), used in type-mismatch error messages.

isArray

public boolean isArray(@Nullable Object element)

Specified by:

isArray in interface ElementExtractor<Object>

Returns:

true if element is an array: a container ElementExtractor.extractIndex(T, int) can step into; false for null.

extractIndex

public @Nullable Object extractIndex(Object element,
 int index)

Specified by:

extractIndex in interface ElementExtractor<Object>

Returns:

the value at index; null if the slot holds a null value.

arraySize

public int arraySize(Object element)

Specified by:

arraySize in interface ElementExtractor<Object>

Returns:

the number of elements in element, for which ElementExtractor.isArray(T) is true.

arrayName

public String arrayName()

Specified by:

arrayName in interface ElementExtractor<Object>

Returns:

the representation's name for its array type (e.g. "JsonArray"), used in type-mismatch and out-of-bounds error messages.

isNull

public boolean isNull(@Nullable Object element)

Specified by:

isNull in interface ElementExtractor<Object>

Returns:

true if element is a Java null or the representation's own null element (e.g. JsonNull).

isPrimitive

public boolean isPrimitive(@Nullable Object element)

Specified by:

isPrimitive in interface ElementExtractor<Object>

Returns:

true if element is a leaf value — null or a primitive — that ElementExtractor.toJava(T) converts to a plain Java value; false if it is a map or array, which the evaluator returns in its native representation.

toJava

public Object toJava(Object element)

Specified by:

toJava in interface ElementExtractor<Object>

Returns:

the plain Java equivalent (e.g. String, Long, Double, Boolean) of an element for which ElementExtractor.isPrimitive(T) is true; null for the representation's null element.