org.millscript.millscript.expr
Class NoneExpr

java.lang.Object
  org.millscript.millscript.expr.Expr<NoneAction>
      org.millscript.millscript.expr.NoneExpr

All Implemented Interfaces:

ZeroResults

public final class NoneExpr
extends Expr<NoneAction>
implements ZeroResults

This class implements a none expression. This expression will never return any results.

See Also:

NoneSyntax, NoneAction

Constructor Summary

NoneExpr(Expr<?> x)
Creates a new none expression for the specified expression.

Method Summary

NoneAction	compileIt() Compiles this expression into an action.
static Expr<?>	make(Expr<?> x) Returns the specified expression ensuring it will return zero results.
void	resolve(CompilerState state) Resolves any NameExpr in the tree so that they refer to the correct ident.

Methods inherited from class org.millscript.millscript.expr.Expr

arity, compile, isIntegerExpr, resolveList, setLineNumber, setOrigin, show, show

Methods inherited from class java.lang.Object

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

Constructor Detail

NoneExpr

public NoneExpr(Expr<?> x)

Creates a new none expression for the specified expression.

Parameters:

x - the expression to evaluate

Method Detail

make

public static Expr<?> make(Expr<?> x)

Returns the specified expression ensuring it will return zero results. This method provides some compile-time optimisation, as it avoids creating additional unnecessary objects in the expression tree. If the specified expression is already returns zero results, we simply return it, otherwise we proceed to wrap it in a new none expression.

Parameters:

x - the expression for which to discard results

Returns:

the specified expression if it returns zero results, or a new NoneExpr for the specified expression

compileIt

public NoneAction compileIt()

Description copied from class: Expr

Compiles this expression into an action.

Specified by:

compileIt in class Expr<NoneAction>

Returns:

the Action for this expression

See Also:

Expr.compileIt()

resolve

public void resolve(CompilerState state)

Description copied from class: Expr

Resolves any NameExpr in the tree so that they refer to the correct ident. e.g. This method is responsible for ensuring that references to a function argument in the body of a function actually refer to the correct value.

Specified by:

resolve in class Expr<NoneAction>

Parameters:

state - the compiler state we are resolving in

See Also:

Expr.resolve(org.millscript.millscript.vm.CompilerState)