ptolemy.data.expr

Class Constants

java.lang.Object

ptolemy.data.expr.Constants

public class Constants
extends java.lang.Object

A table of named constants that are recognized by the expression parser.

A named constant in an expression is substituted by its associated value when the expression is evaluated. The constants are stored in a hash table, using their names as key. The value of each constant is wrapped in a data token.

Since:

Ptolemy II 2.0

Version:

$Id$

Author:

Xiaojun Liu

See Also:

PtParser

Pt.AcceptedRating:

Red (liuxj)

Pt.ProposedRating:

Red (liuxj)

Method Summary

Modifier and Type	Method and Description
static void	add(java.lang.String name, Token value) Add a constant with the given name and value to the table.
static RecordToken	constants() Return a record representation of the constants.
static Token	get(java.lang.String name) Look up the value of the constant with the given name.
static Type	nameToType(java.lang.String name) Given a name defining a type, return the type, or null if there is no such type.
static void	remove(java.lang.String name) Remove the constant with the given name from the table.
static java.util.TreeMap	types() Return a map from names to types, with the names sorted alphabetically.

Methods inherited from class java.lang.Object

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

Method Detail

add

public static void add(java.lang.String name,
                       Token value)

Add a constant with the given name and value to the table. If a constant with this same name had been previously added, then that value is replaced with the new one. Neither the name nor the value can be null, otherwise a NullPointerException will be thrown.

Parameters:

name - The name of the constant.

value - The value of the constant, wrapped in a data token.

constants

public static RecordToken constants()

Return a record representation of the constants.

Returns:

A record with the constants and their values.

Since:

Ptolemy II 2.1

get

public static Token get(java.lang.String name)

Look up the value of the constant with the given name.

Parameters:

name - The name of the constant.

Returns:

The value of the constant, wrapped in a data token, or null if there is no constant with the given name in the table.

nameToType

public static Type nameToType(java.lang.String name)

Given a name defining a type, return the type, or null if there is no such type.

Parameters:

name - The type name.

remove

public static void remove(java.lang.String name)

Remove the constant with the given name from the table. If there is no constant with the given name in the table, the table is not changed.

Parameters:

name - The name of the constant to be removed from the table.

types

public static java.util.TreeMap types()

Return a map from names to types, with the names sorted alphabetically.

Returns:

A copy of the table of named types.