water.rapids.ast.prims.operators

Class AstIfElse

java.lang.Object

water.Iced<T>

water.rapids.ast.AstRoot<T>

water.rapids.ast.AstPrimitive

water.rapids.ast.prims.operators.AstIfElse

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, java.lang.Cloneable, Freezable

public class AstIfElse
extends AstPrimitive

If-Else -- ternary conditional operator, equivalent of "?:" in C++ and Java.

"NaNs poison". If the test is a NaN, evaluate neither side and return a NaN

"Frames poison". If the test is a Frame, both sides are evaluated and selected between according to the test. The result is a Frame. All Frames must be compatible, and scalars and 1-column Frames are widened to match the widest frame. NaN test values produce NaN results.

If the test is a scalar, then only the returned side is evaluated. If both sides are scalars or frames, then the evaluated result is returned. The unevaluated side is not checked for being a compatible frame. It is an error if one side is typed as a scalar and the other as a Frame.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AstIfElse()

Method Summary

Modifier and Type	Method and Description
Val	apply(Env env, Env.StackHelp stk, AstRoot[] asts) Primary method to invoke this function, passing all the parameters as the `asts` list.
java.lang.String[]	args() List of argument names.
int	nargs() Number of function's arguments + 1.
java.lang.String	str() String representation of this Ast object in the Rapids language.

Methods inherited from class water.rapids.ast.AstPrimitive

description, example, exec

Methods inherited from class water.rapids.ast.AstRoot

toString

Methods inherited from class water.Iced

asBytes, clone, copyOver, frozenType, read, readExternal, readJSON, reloadFromBytes, toJsonBytes, toJsonString, write, writeExternal, writeJSON

Methods inherited from class java.lang.Object

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

Constructor Detail

AstIfElse

public AstIfElse()

Method Detail

args

public java.lang.String[] args()

Description copied from class: AstPrimitive

List of argument names. The length of the returned array should be equal to `nargs() - 1` (unless `nargs()` returns -1, in which case this function may return {"..."} or something similar).

Specified by:

args in class AstPrimitive

nargs

public int nargs()

Description copied from class: AstPrimitive

Number of function's arguments + 1. Thus, a binary operator like '+' should be declared with 3 nargs: ["+", lhs, rhs]. For variable-argument functions this method should return -1.

Specified by:

nargs in class AstPrimitive

str

public java.lang.String str()

Description copied from class: AstRoot

String representation of this Ast object in the Rapids language. For AstPrimitives this is the name of the function; for AstParameters this is either the name of the variable, or the value of the numeric constant that the parameter represents. For more complicated constructs such as AstExec or AstFunction this method should return those objects as a Rapids string.

Specified by:

str in class AstRoot

apply

public Val apply(Env env,
                 Env.StackHelp stk,
                 AstRoot[] asts)

Description copied from class: AstPrimitive

Primary method to invoke this function, passing all the parameters as the `asts` list.

Specified by:

apply in class AstPrimitive

Parameters:

env - Current execution environment. Variables are looked up here.

stk - TODO need clarification

asts - List of AstRoot expressions that are arguments to the function. First element in this list is the function itself.

Returns:

value resulting from calling the function with the provided list of arguments.