Package net.hydromatic.morel.ast

Class Core.Scan

java.lang.Object

net.hydromatic.morel.ast.AstNode

net.hydromatic.morel.ast.Core.BaseNode

net.hydromatic.morel.ast.Core.FromStep

net.hydromatic.morel.ast.Core.Scan

Enclosing class:

Core

public static class Core.Scan
extends Core.FromStep

A join or v in listExpr or v = expr clause in a from expression.

Field Summary

Fields

Modifier and Type	Field	Description
final Core.Exp	condition
final Core.Exp	exp
final Core.Pat	pat

Fields inherited from class net.hydromatic.morel.ast.Core.FromStep

env

Fields inherited from class net.hydromatic.morel.ast.AstNode

op, pos

Constructor Summary

Constructors

Constructor	Description
Scan(Core.StepEnv env, Core.Pat pat, Core.Exp exp, Core.Exp condition)

Method Summary

Modifier and Type	Method	Description
Core.Scan	accept(Shuttle shuttle)	Accepts a shuttle, calling the Shuttle.visit(net.hydromatic.morel.ast.Ast.Literal) method appropriate to the type of this node, and returning the result.
void	accept(Visitor visitor)	Accepts a visitor, calling the Shuttle.visit(net.hydromatic.morel.ast.Ast.Literal) method appropriate to the type of this node, and returning the result.
private static boolean	canAssign(Type fromType, Type toType)	Returns whether you can assign a value of fromType to a variable of type toType.
Core.Scan	copy(Core.StepEnv env, Core.Pat pat, Core.Exp exp, Core.Exp condition)
private boolean	isLiteralTrue()
boolean	isOrdered(boolean inputIsOrdered)	Returns whether the output of this step is ordered, given whether the input is ordered.
protected AstWriter	unparse(AstWriter w, Core.From from, int ordinal, int left, int right)

Methods inherited from class net.hydromatic.morel.ast.Core.FromStep

unparse

Methods inherited from class net.hydromatic.morel.ast.AstNode

toString, unparse

Methods inherited from class java.lang.Object

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

Field Details

pat

public final Core.Pat pat

exp

public final Core.Exp exp

condition

public final Core.Exp condition

Constructor Details

Scan

Scan(Core.StepEnv env,
 Core.Pat pat,
 Core.Exp exp,
 Core.Exp condition)

Method Details

canAssign

private static boolean canAssign(Type fromType,
 Type toType)

Returns whether you can assign a value of fromType to a variable of type toType.

isOrdered

public boolean isOrdered(boolean inputIsOrdered)

Returns whether the output of this step is ordered, given whether the input is ordered.

For example, Core.Where and Core.Yield are ordered if and only if their input is ordered; Core.Order is always ordered; Core.Group is unordered.

A Scan is ordered only if the input is ordered and exp is ordered. Think of it as like nested loops join.

If a Scan is the first step in the from, we think of its input as an ordered list containing unit. Therefore, its output is ordered if exp is a list.

Overrides:

isOrdered in class Core.FromStep

accept

public Core.Scan accept(Shuttle shuttle)

Description copied from class: AstNode

Accepts a shuttle, calling the Shuttle.visit(net.hydromatic.morel.ast.Ast.Literal) method appropriate to the type of this node, and returning the result.

Specified by:

accept in class Core.FromStep

accept

public void accept(Visitor visitor)

Description copied from class: AstNode

Accepts a visitor, calling the Shuttle.visit(net.hydromatic.morel.ast.Ast.Literal) method appropriate to the type of this node, and returning the result.

Overrides:

accept in class Core.BaseNode

unparse

protected AstWriter unparse(AstWriter w,
 Core.From from,
 int ordinal,
 int left,
 int right)

Specified by:

unparse in class Core.FromStep

isLiteralTrue

private boolean isLiteralTrue()

copy

public Core.Scan copy(Core.StepEnv env,
 Core.Pat pat,
 Core.Exp exp,
 Core.Exp condition)