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

Constructor Summary

Constructors

Constructor and Description
RelJsonWriter()

Method Summary

Methods

Modifier and Type	Method and Description
String	asString() Returns a JSON string describing the relational expressions that were just explained.
RelWriter	done(RelNode node) Writes the completed explanation.
protected void	explain_(RelNode rel, List<Pair<String,Object>> values)
void	explain(RelNode rel, List<Pair<String,Object>> valueList) Prints an explanation of a node, with a list of (term, value) pairs.
SqlExplainLevel	getDetailLevel()
RelWriter	input(String term, RelNode input) Adds an input to the explanation of the current node.
RelWriter	item(String term, Object value) Adds an attribute to the explanation of the current node.
RelWriter	itemIf(String term, Object value, boolean condition) Adds an input to the explanation of the current node, if a condition holds.
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

Constructor Detail

RelJsonWriter

public RelJsonWriter()

Method Detail

explain_

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

explain

public final void explain(RelNode rel,
           List<Pair<String,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()

Specified by:

getDetailLevel in interface RelWriter

Returns:

detail level at which plan should be generated

input

public RelWriter input(String term,
              RelNode input)

Description copied from interface: RelWriter

Adds an input to the explanation of the current node.

Specified by:

input in interface RelWriter

Parameters:

term - Term for input, e.g. "left" or "input #1".

input - Input relational expression

item

public RelWriter item(String term,
             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

itemIf

public RelWriter itemIf(String term,
               Object value,
               boolean condition)

Description copied from interface: RelWriter

Adds an input to the explanation of the current node, if a condition holds.

Specified by:

itemIf in interface RelWriter

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.