Module com.darkcollective.relix.ast

Package com.darkcollective.relix.ast

Record Class IterateNode

java.lang.Object

java.lang.Record

com.darkcollective.relix.ast.IterateNode

Record Components:

name - the bound relation name; must not be blank

base - the relation the first round reads; must not be null

step - the body computing each round from the previous one; must not be null

stop - when the iteration stops; must not be null

location - the source location of this node; never null

All Implemented Interfaces:

RelNode

public record IterateNode(String name, RelNode base, RelNode step, IterateStop stop, SourceLocation location)
extends Record
implements RelNode

Replace-each-round iteration — the binder ITERATE.

ITERATE name (base, step) <stop> binds name over step exactly as FixpointNode does: occurrences of name inside step are RecursiveRefNode leaves, and name is not in scope in base. What differs is what a round does with the step's output. FIX adds it to everything derived so far; ITERATE replaces the relation with it. The relation bound to name in a round is the whole of the previous round's output, and the result is the last round's output.

Because nothing accumulates, the step is free of FIX's restrictions: it may reference name any number of times and through any operator — aggregation, outer joins and difference included — which is what numeric iterations such as PageRank and state machines such as cellular automata need. The price is that nothing guarantees it stops, so stop() says when it does (see IterateStop).

The operator materialises a set: each round is deduplicated, and IterateStop.Stable compares rounds as sets. It never pushes down to a source.

Surface syntax: ITERATE R (base, step) ROUNDS n, … UNTIL STABLE MAX n ROUNDS, or … UNTIL c WITHIN ε PER k MAX n ROUNDS (keyword-only, no glyph).

Constructor Summary

Constructors

Constructor	Description
IterateNode(String name, RelNode base, RelNode step, IterateStop stop)	Convenience constructor for tests: SourceLocation.UNKNOWN.
IterateNode(String name, RelNode base, RelNode step, IterateStop stop, SourceLocation location)	Creates an instance of a IterateNode record class.

Method Summary

Modifier and Type	Method	Description
<R> R	accept(RelNodeVisitor<R> visitor)
RelNode	base()	Returns the value of the base record component.
final boolean	equals(Object o)	Indicates whether some other object is "equal to" this one.
final int	hashCode()	Returns a hash code value for this object.
SourceLocation	location()	Returns the value of the location record component.
String	name()	Returns the value of the name record component.
RelNode	step()	Returns the value of the step record component.
IterateStop	stop()	Returns the value of the stop record component.
final String	toString()	Returns a string representation of this record class.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.darkcollective.relix.ast.RelNode

children, mapChildren, materializationMode, prettyPrint

Constructor Details

IterateNode

public IterateNode(String name,
 RelNode base,
 RelNode step,
 IterateStop stop,
 SourceLocation location)

Creates an instance of a IterateNode record class.

Parameters:

name - the value for the name record component

base - the value for the base record component

step - the value for the step record component

stop - the value for the stop record component

location - the value for the location record component

IterateNode

public IterateNode(String name,
 RelNode base,
 RelNode step,
 IterateStop stop)

Convenience constructor for tests: SourceLocation.UNKNOWN.

Method Details

accept

public <R> R accept(RelNodeVisitor<R> visitor)

Specified by:

accept in interface RelNode

toString

public final String toString()

Returns a string representation of this record class. The representation contains the name of the class, followed by the name and value of each of the record components.

Specified by:

toString in class Record

Returns:

a string representation of this object

hashCode

public final int hashCode()

Returns a hash code value for this object. The value is derived from the hash code of each of the record components.

Specified by:

hashCode in class Record

Returns:

a hash code value for this object

equals

public final boolean equals(Object o)

Indicates whether some other object is "equal to" this one. The objects are equal if the other object is of the same class and if all the record components are equal. All components in this record class are compared with Objects::equals(Object,Object).

Specified by:

equals in class Record

Parameters:

o - the object with which to compare

Returns:

true if this object is the same as the o argument; false otherwise.

name

public String name()

Returns the value of the name record component.

Returns:

the value of the name record component

base

public RelNode base()

Returns the value of the base record component.

Returns:

the value of the base record component

step

public RelNode step()

Returns the value of the step record component.

Returns:

the value of the step record component

stop

public IterateStop stop()

Returns the value of the stop record component.

Returns:

the value of the stop record component

location

public SourceLocation location()

Returns the value of the location record component.

Specified by:

location in interface RelNode

Returns:

the value of the location record component