Class SymbolTable

java.lang.Object
  SymbolTable

public class SymbolTable

extends java.lang.Object

A simple table of symbols for a postscript interpreter. This particular implementation is very expensive, and we'll see improved implementations in the latter part of the semester.

Constructor Summary

SymbolTable()
Constructs an empty symbol table.

Method Summary

void	add(java.lang.String symbol, Token value) Adds a string-value association to the table.
boolean	contains(java.lang.String symbol) Checks for an entry associated with a particular string.
Token	get(java.lang.String symbol) Gets a value associated with a string, from the symbol table.
static void	main(java.lang.String[] args) An example method that makes use of a symbol table.
java.lang.String	toString() Removes a value associated with the a string.

Methods inherited from class java.lang.Object

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

Constructor Detail

SymbolTable

public SymbolTable()

Constructs an empty symbol table.

Method Detail

contains

public boolean contains(java.lang.String symbol)

Checks for an entry associated with a particular string.

Parameters:

symbol - a string potentially associated with a value.

Returns:

true if (and only if) the symbol has an associated value in this table.

add

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

Adds a string-value association to the table. Assumes that the symbol is not null. If string has an associated value already, it is removed before adding the new association.

Parameters:

symbol - a non-null string

value - a Token associated with a string.

get

public Token get(java.lang.String symbol)

Gets a value associated with a string, from the symbol table.

Parameters:

symbol - the string whose value is sought

Returns:

the Token associated with the string, or null, if none.

toString

public java.lang.String toString()

Removes a value associated with the a string.

Returns:

the token associated with the string public Token remove(String symbol) { Association a = new Association(symbol,null); if (table.contains(a)) { a = (Association)table.remove(a); return (Token)a.getValue(); } else { return null; } } /** Returns a string representation of the symbol table.

main

public static void main(java.lang.String[] args)

An example method that makes use of a symbol table.