net.windward.util
Class SimpleEvaluator

java.lang.Object
  |
  +--net.windward.util.SimpleEvaluator

public class SimpleEvaluator

extends java.lang.Object

This will evaluateBoolean an expression and return a boolean result. It supports tokens of type:

• long - 123
• double - 123.45
• boolean - true
• String - "hi there" - supports the escape sequence \\"

It also supports the following operators:

• == eq : equals for any kind of token. String contents are compared in a case sensitive compare.
• != ne : not equals for any kind of token. String contents are compared in a case sensitive compare.
• < lt : arithmetic less than (warning - you must use &lt; instead of < in the template
• > gt : arithmetic greater than
• <= le : arithmetic less than or equal (warning - you must use &lt;= instead of <= in the template
• >= ge : arithmetic greater than or equal
• && and : boolean and
• || or : boolean or
• ! not : boolean not
• + : arithimetic add
• - : arithimetic minus (supports unary operations too)
• * : arithimetic multiply
• /; div : arithimetic divide
• %; mod : arithimetic modulus
• () : paranthesis to force evaluation order.

This class does not support variables. The passed in string must be literals and operators only.

Version:

1.0 Nov 26, 2003

Inner Class Summary

static interface

SimpleEvaluator.VariableEval

Field Summary

static java.lang.String	CIRCULAR Uses a circular reference
static java.lang.String	DIV_0 Divide by 0 in an evaluation.
static java.lang.String	NO_VALUE Need a number and the cell is empty.
static java.lang.String	NOT_A_NUMBER The number got too large or small
static java.lang.String	UNKNOWN_CELL getValue() was asked for a reference that does not exist or makes no sense.
static java.lang.String	WRONG_TYPE The wrong type of argument like "dave" + 3.

Constructor Summary

SimpleEvaluator()

Method Summary

static java.lang.Object	evaluate(java.lang.String expr, SimpleEvaluator.VariableEval evaluator)
static boolean	evaluateBoolean(java.lang.String expr, SimpleEvaluator.VariableEval evaluator)
static void	main(java.lang.String[] args)

Methods inherited from class java.lang.Object

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

Field Detail

DIV_0

public static final java.lang.String DIV_0

Divide by 0 in an evaluation.

UNKNOWN_CELL

public static final java.lang.String UNKNOWN_CELL

getValue() was asked for a reference that does not exist or makes no sense.

NOT_A_NUMBER

public static final java.lang.String NOT_A_NUMBER

The number got too large or small

WRONG_TYPE

public static final java.lang.String WRONG_TYPE

The wrong type of argument like "dave" + 3.

NO_VALUE

public static final java.lang.String NO_VALUE

Need a number and the cell is empty.

CIRCULAR

public static final java.lang.String CIRCULAR

Uses a circular reference

Constructor Detail

SimpleEvaluator

public SimpleEvaluator()

Method Detail

evaluateBoolean

public static boolean evaluateBoolean(java.lang.String expr,
                                      SimpleEvaluator.VariableEval evaluator)

evaluate

public static java.lang.Object evaluate(java.lang.String expr,
                                        SimpleEvaluator.VariableEval evaluator)

main

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