water.rapids.ast.params

Class AstConst

java.lang.Object

water.Iced<T>

water.rapids.ast.AstRoot

water.rapids.ast.AstParameter

water.rapids.ast.params.AstConst

All Implemented Interfaces:

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

public class AstConst
extends AstParameter

Class for constants

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static AstConst	E
static AstConst	FALSE
static AstConst	NAN
static AstConst	PI
static AstConst	TRUE

Constructor Summary

Constructors

Constructor and Description
AstConst()
AstConst(java.lang.String name, double d)

Method Summary

Methods

Modifier and Type	Method and Description
ValNum	exec(Env env) "Execute" this AST expression, and return the result.
java.lang.String	str() String representation of this Ast object in the Rapids language.

Methods inherited from class water.rapids.ast.AstParameter

columns, description, example, toJavaString

Methods inherited from class water.rapids.ast.AstRoot

toString

Methods inherited from class water.Iced

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

Methods inherited from class java.lang.Object

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

Field Detail

FALSE

public static final AstConst FALSE

TRUE

public static final AstConst TRUE

NAN

public static final AstConst NAN

PI

public static final AstConst PI

E

public static final AstConst E

Constructor Detail

AstConst

public AstConst()

AstConst

public AstConst(java.lang.String name,
        double d)

Method Detail

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

exec

public ValNum exec(Env env)

Description copied from class: AstRoot

"Execute" this AST expression, and return the result. For different ASTs this may have different interpretation. For example, consider this Rapids expression:

    (mean frame True False)

It will be parsed into the following structure:

 AstExec() instance with
    _asts = [AstMean() singleton instance,
             new AstId(frame),
             AstConst.TRUE,
             AstConst.FALSE]
 

Execution of AstExec will execute its first argument, _asts[0], verify that it produces a function (ValFun), then call AstPrimitive.apply(Env, Env.StackHelp, AstRoot[]) on that function passing down the list of _asts arguments.

The AstMean class will in turn execute all its arguments, where execution of AstId fetches the referred symbol from the environment, and execution of AstConst returns the value of that constant.

Certain other functions may choose not to evaluate all their arguments (for example boolean expressions providing short-circuit evaluation).

Specified by:

exec in class AstRoot