com.trassare.calculator.engine
Class Token

java.lang.Object
  com.trassare.calculator.engine.Token

Direct Known Subclasses:

Token.ERROR, Token.IDENTIFIER, Token.NUMBER

public class Token
extends Object

A Token class for use in a scanner for simple arithmetic expressions.
CS 152, Fall, 2005
Programming Assignment #1

Version:

10 September 2006

Author:

Kenneth C. Louden, Samuel T Trassare

Nested Class Summary

static class	Token.ERROR Token matching an erroneous character in input. CS 152, Fall, 2005 Programming Assignment #1
static class	Token.IDENTIFIER Token matching regular expression [A-Z]+ in input. This token is used for variable names in the input expression.
static class	Token.NUMBER Token matching regular expression [0-9]+(\.[0-9]*)? in input. CS 152, Fall, 2005 Programming Assignment #1

Field Summary

static Token	ACOS Token matching 'acos' in input.
static Token	ASIN Token matching 'asin' in input.
static Token	ASSIGN Token matching '>>' in input.
static Token	ATAN Token matching 'atan' in input.
static Token	COS Token matching 'cos' in input.
static Token	EOL Token matching end of line.
static Token	ERROR A dummy ERROR token for equality testing.
static Token	IDENTIFIER A dummy IDENTIFIER token for equality testing.
static Token	LN Token matching 'ln' in input.
static Token	LPAREN Token matching '(' in input.
static Token	MINUS Token matching '-' in input.
static Token	NUMBER A dummy NUMBER token for equality testing.
static Token	OVER Token matching '/' in input.
static Token	PLUS Token matching '+' in input.
static Token	POW Token matching '^' in input.
static Token	RECALL Deprecated. Do not use this token. It will be removed in future versions of this class.
static Token	RPAREN Token matching ')' in input.
static Token	SIN Token matching 'sin' in input.
static Token	STORE Deprecated. Do not use this token. It will be removed in future versions of this class. Instead use Token.ASSIGN. This token was originally used as a command to send the evaluated expression to a single memory cell. The use of Token.ASSIGN signals an assignment to a variable. Beginning with the 10 September 2006 version of this class the com.trassare.calculator.engine package now supports infinite memory storage.
static Token	TAN Token matching 'tan' in input.
static Token	TIMES Token matching '*' in input.

Constructor Summary

protected

Token(String inValue) Make the constructor protected so that only limited kinds of tokens can be generated.

Method Summary

boolean	equals(Object obj) Overrides Object.equals: all tokens in the same token subclass are implicitly equal.
int	hashCode() Dummy hash code implementation.
String	stringValue() An accessor method for the stringValue field.

Methods inherited from class java.lang.Object

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

Field Detail

ACOS

public static final Token ACOS

Token matching 'acos' in input. This is the arccosine operator.

ASIN

public static final Token ASIN

Token matching 'asin' in input. This is the arcsine operator.

ASSIGN

public static final Token ASSIGN

Token matching '>>' in input. This token is used to indicate that an evaluated expression will be stored to a variable as in:
2+2>>VAR

ATAN

public static final Token ATAN

Token matching 'atan' in input. This is the arctangent operator.

COS

public static final Token COS

Token matching 'cos' in input. This is the cosine operator.

EOL

public static final Token EOL

Token matching end of line.

ERROR

public static final Token ERROR

A dummy ERROR token for equality testing. Since the constructor for the Token class is protected, a dummy error token needs to be constructed. Tokens from the input stream can be compared against the dummies to verify the type of token in the input.

LN

public static final Token LN

Token matching 'ln' in input. This is the natural logarithm operator.

LPAREN

public static final Token LPAREN

Token matching '(' in input.

MINUS

public static final Token MINUS

Token matching '-' in input. This token is both the binary subtraction operator and the unary negation operator. It's usage depends upon it's location in the expression and is determined by the expression evaluator.

NUMBER

public static final Token NUMBER

A dummy NUMBER token for equality testing. Since the constructor for the Token class is protected, a dummy number token needs to be constructed. Tokens from the input stream can be compared against the dummies to verify the type of token in the input.

IDENTIFIER

public static final Token IDENTIFIER

A dummy IDENTIFIER token for equality testing. Since the constructor for the Token class is protected, a dummy identifier token needs to be constructed. Tokens from the input stream can be compared against the dummies to verify the type of token in the input.

OVER

public static final Token OVER

Token matching '/' in input. This is the division operator.

PLUS

public static final Token PLUS

Token matching '+' in input. This is the addition operator.

POW

public static final Token POW

Token matching '^' in input. This is the power operator.

RECALL

public static final Token RECALL

Deprecated. Do not use this token. It will be removed in future versions of this class.

Token matching '@' in input. This is the recall operator.

RPAREN

public static final Token RPAREN

Token matching ')' in input.

SIN

public static final Token SIN

Token matching 'sin' in input. This is the sine operator.

STORE

public static final Token STORE

Deprecated. Do not use this token. It will be removed in future versions of this class. Instead use Token.ASSIGN. This token was originally used as a command to send the evaluated expression to a single memory cell. The use of Token.ASSIGN signals an assignment to a variable. Beginning with the 10 September 2006 version of this class the com.trassare.calculator.engine package now supports infinite memory storage.

Token matching '!' in input.

TAN

public static final Token TAN

Token matching 'tan' in input. This is the tangent operator.

TIMES

public static final Token TIMES

Token matching '*' in input. This is the multiplication operator.

Constructor Detail

Token

protected Token(String inValue)

Make the constructor protected so that only limited kinds of tokens can be generated.

Parameters:

inValue - the string value of the token

Method Detail

equals

public final boolean equals(Object obj)

Overrides Object.equals: all tokens in the same token subclass are implicitly equal.

Overrides:

equals in class Object

Parameters:

obj - the object against which this object is tested for equality

Returns:

true if obj is in the same class as this object

hashCode

public final int hashCode()

Dummy hash code implementation.

Overrides:

hashCode in class Object

Returns:

the hash code of the super object.

stringValue

public final String stringValue()

An accessor method for the stringValue field.

Returns:

the stringValue of the token