util

Class TokenDispenser

java.lang.Object

java.io.StreamTokenizer

util.TokenDispenser

public class TokenDispenser
extends java.io.StreamTokenizer

This class extends java.io.StreamTokenizer for the Calculator application. It provides methods for advancing through expression strings and returning the relevant tokens. It also provides methods for testing for a token's type (number, operator, etc.)

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	EOF

Fields inherited from class java.io.StreamTokenizer

nval, sval, TT_EOF, TT_EOL, TT_NUMBER, TT_WORD, ttype

Constructor Summary

Constructors

Constructor and Description
TokenDispenser(java.lang.String input) Creates a token dispenser for a given string input.

Method Summary

Modifier and Type	Method and Description
void	advance() Parses the next token in the input.
char	getChar() Returns the most recently parsed token as a single character.
double	getNumber() Returns the most recently parsed token as a number.
java.lang.Object	getToken() Returns the most recently parsed token in the input.
java.lang.String	getWord() Returns the most recently parsed token as a word.
boolean	tokenIsEOF() Tests for whether the most recently parsed token is EOF (end of file).
boolean	tokenIsLeftParen() Tests for whether the most recently parsed token is a left parenthesis.
boolean	tokenIsNumber() Tests for whether the most recently parsed token is a number.
boolean	tokenIsOperator() Tests for whether the most recently parsed token is a binary operator (+, -, *, /).
boolean	tokenIsRightParen() Tests for whether the most recently parsed token is a right parenthesis.
boolean	tokenIsWord() Tests for whether the most recently parsed token is a word (string of alphabetic characters).

Methods inherited from class java.io.StreamTokenizer

commentChar, eolIsSignificant, lineno, lowerCaseMode, nextToken, ordinaryChar, ordinaryChars, parseNumbers, pushBack, quoteChar, resetSyntax, slashSlashComments, slashStarComments, toString, whitespaceChars, wordChars

Methods inherited from class java.lang.Object

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

Field Detail

EOF

public static final java.lang.String EOF

See Also:

Constant Field Values

Constructor Detail

TokenDispenser

public TokenDispenser(java.lang.String input)

Creates a token dispenser for a given string input.

Parameters:

input - the string input

Method Detail

advance

public void advance()

Parses the next token in the input.

getToken

public java.lang.Object getToken()

Returns the most recently parsed token in the input.

Returns:

an object that is either a number, a word (string of alphabetic characters), a single non-alphabetic character, or a string indicating EOF

tokenIsNumber

public boolean tokenIsNumber()

Tests for whether the most recently parsed token is a number.

Returns:

true if the most recently parsed token is a number, or false otherwise

getNumber

public double getNumber()

Returns the most recently parsed token as a number.

Returns:

a number

tokenIsWord

public boolean tokenIsWord()

Tests for whether the most recently parsed token is a word (string of alphabetic characters).

Returns:

true if the most recently parsed token is a word, or false otherwise

getWord

public java.lang.String getWord()

Returns the most recently parsed token as a word.

Returns:

a string of alphabetic characters

tokenIsEOF

public boolean tokenIsEOF()

Tests for whether the most recently parsed token is EOF (end of file).

Returns:

true if the most recently parsed token is EOF, or false otherwise

tokenIsOperator

public boolean tokenIsOperator()

Tests for whether the most recently parsed token is a binary operator (+, -, *, /).

Returns:

true if the most recently parsed token is an operator, or false otherwise

tokenIsLeftParen

public boolean tokenIsLeftParen()

Tests for whether the most recently parsed token is a left parenthesis.

Returns:

true if the most recently parsed token is a left parenthesis, or false otherwise

tokenIsRightParen

public boolean tokenIsRightParen()

Tests for whether the most recently parsed token is a right parenthesis.

Returns:

true if the most recently parsed token is a right parenthesis, or false otherwise

getChar

public char getChar()

Returns the most recently parsed token as a single character.

Returns:

a single character