Package org.apache.calcite.rel.externalize

Class RelJsonWriter

java.lang.Object

org.apache.calcite.rel.externalize.RelJsonWriter

All Implemented Interfaces:

RelWriter

public class RelJsonWriter
extends Object
implements RelWriter

Callback for a relational expression to dump itself as JSON.

See Also:

• RelJsonReader

Field Summary

Fields

Modifier and Type	Field	Description
protected final JsonBuilder	jsonBuilder
protected final RelJson	relJson
protected final List<@Nullable Object>	relList

Constructor Summary

Constructors

Constructor	Description
RelJsonWriter()	Creates a RelJsonWriter with a private JsonBuilder.
RelJsonWriter(JsonBuilder jsonBuilder)	Creates a RelJsonWriter with a given JsonBuilder.
RelJsonWriter(JsonBuilder jsonBuilder, UnaryOperator<RelJson> relJsonTransform)	Creates a RelJsonWriter.

Method Summary

Modifier and Type	Method	Description
String	asString()	Returns a JSON string describing the relational expressions that were just explained.
RelWriter	done(RelNode node)	Writes the completed explanation.
final void	explain(RelNode rel, List<Pair<String,@Nullable Object>> valueList)	Prints an explanation of a node, with a list of (term, value) pairs.
protected void	explain_(RelNode rel, List<Pair<String,@Nullable Object>> values)
SqlExplainLevel	getDetailLevel()	Returns detail level at which plan should be generated.
RelWriter	item(String term, @Nullable Object value)	Adds an attribute to the explanation of the current node.
boolean	nest()	Returns whether the writer prefers nested values.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.calcite.rel.RelWriter

expand, input, itemIf

Field Details

jsonBuilder

protected final JsonBuilder jsonBuilder

relJson

protected final RelJson relJson

relList

protected final List<@Nullable Object> relList

Constructor Details

RelJsonWriter

public RelJsonWriter()

Creates a RelJsonWriter with a private JsonBuilder.

RelJsonWriter

public RelJsonWriter(JsonBuilder jsonBuilder)

Creates a RelJsonWriter with a given JsonBuilder.

RelJsonWriter

public RelJsonWriter(JsonBuilder jsonBuilder,
 UnaryOperator<RelJson> relJsonTransform)

Creates a RelJsonWriter.

Method Details

explain_

protected void explain_(RelNode rel,
 List<Pair<String,@Nullable Object>> values)

explain

public final void explain(RelNode rel,
 List<Pair<String,@Nullable Object>> valueList)

Description copied from interface: RelWriter

Prints an explanation of a node, with a list of (term, value) pairs.

The term-value pairs are generally gathered by calling RelNode.explain(RelWriter). Each sub-class of RelNode calls RelWriter.input(String, org.apache.calcite.rel.RelNode) and RelWriter.item(String, Object) to declare term-value pairs.

Specified by:

explain in interface RelWriter

Parameters:

rel - Relational expression

valueList - List of term-value pairs

getDetailLevel

public SqlExplainLevel getDetailLevel()

Description copied from interface: RelWriter

Returns detail level at which plan should be generated.

Specified by:

getDetailLevel in interface RelWriter

item

public RelWriter item(String term,
 @Nullable Object value)

Description copied from interface: RelWriter

Adds an attribute to the explanation of the current node.

Specified by:

item in interface RelWriter

Parameters:

term - Term for attribute, e.g. "joinType"

value - Attribute value

done

public RelWriter done(RelNode node)

Description copied from interface: RelWriter

Writes the completed explanation.

Specified by:

done in interface RelWriter

nest

public boolean nest()

Description copied from interface: RelWriter

Returns whether the writer prefers nested values. Traditional explain writers prefer flattened values.

Specified by:

nest in interface RelWriter

asString

public String asString()

Returns a JSON string describing the relational expressions that were just explained.