com.dkfqs.tools.interpreter

Class ConditionInterpreter

java.lang.Object

com.dkfqs.tools.interpreter.ConditionInterpreter

public class ConditionInterpreter
extends java.lang.Object

A boolean condition interpreter which supports variables in the format of ${<variable-name>} and returns always true or false.
The values of the variables are inserted/replaced before the boolean expressions are evaluated.

The condition interpreter supports:

1. The simple keywords true and false (without further text) which effects that the condition interpreter always returns true or false.
2. Simple conditional expressions, such as 1 <= 2 | Note: simple expressions are not enfolded by brackets.
3. Boolean expressions with two conditional expressions, such as (5 > 6) || (6 > 5)
4. Multiple boolean expression, such as ((5 > 6) || (6 > 5)) and ("Meier" contains "ei")

Supported comparison operators:

1. <
2. <=
3. ==
4. >=
5. >
6. !=
7. contains
8. !contains

Supported boolean operators:

1. && (or alternative the keyword 'and')
2. || (or alternative the keyword 'or')

Parsing of values:

1. First the interpreter tries to convert values into numbers. If this succeeds for both values of a conditional expression, the comparison is performed with the numbers.
2. If one of the values cannot be converted into a number, both values are interpreted as text and compared as text.
3. Simple text values cannot contain spaces. However, it is supported for text values to be enclosed in double quotes, which circumvents this restriction.
4. Text values enclosed in double quotes are not converted to a number.

See Also:

ReplaceVariableLiteralsInContent, Utils.isFormalValidVariableName(String)

Constructor Summary

Constructors

Constructor and Description
ConditionInterpreter(java.lang.String parserInput) Create a new instance.

Method Summary

Modifier and Type	Method and Description
void	addPredefinedVariable(java.lang.String variableName, java.lang.String value) Add a predefined variable.
boolean	execute() Execute the condition interpreter.
ReplaceVariableLiteralsInContent	getReplaceVariableLiteralsInContent() Get data about the replaced variables.
static java.util.List<java.lang.String>	getRequiredVariableNames(java.lang.String parserInput) Utility: Get the required 'variable names' of a parser input which are formal valid.
static java.util.List<java.lang.String>	getRequiredVariableNames(java.lang.String parserInput, boolean onlyFormalValidVariableNames) Utility: Get the required 'variable names' of a parser input.
static void	main(java.lang.String[] args) Internal test program.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConditionInterpreter

public ConditionInterpreter(java.lang.String parserInput)
                     throws InterpreterException

Create a new instance.

Parameters:

parserInput - the interpreter input

Throws:

InterpreterException - if the parserInput is null or an empty string

Method Detail

addPredefinedVariable

public void addPredefinedVariable(java.lang.String variableName,
                                  java.lang.String value)

Add a predefined variable.

Parameters:

variableName - the variable name

value - the value of the variable (as text)

execute

public boolean execute()
                throws InterpreterException

Execute the condition interpreter.

Returns:

the condition result: true or false

Throws:

InterpreterException - if a syntax error is detected during parsing

getReplaceVariableLiteralsInContent

public ReplaceVariableLiteralsInContent getReplaceVariableLiteralsInContent()

Get data about the replaced variables.

Returns:

data about the replaced variables, or null if the method execute() was not called before

See Also:

execute()

getRequiredVariableNames

public static java.util.List<java.lang.String> getRequiredVariableNames(java.lang.String parserInput,
                                                                        boolean onlyFormalValidVariableNames)

Utility: Get the required 'variable names' of a parser input.

Parameters:

parserInput - the parser input

onlyFormalValidVariableNames - if true get only formal valid 'variable names'

Returns:

a list of required 'variable names'

See Also:

ReplaceVariableLiteralsInContent.DEFAULT_LEFT_SIDE_PATTERN, ReplaceVariableLiteralsInContent.DEFAULT_RIGHT_SIDE_PATTERN, Utils.isFormalValidVariableName(String)

getRequiredVariableNames

public static java.util.List<java.lang.String> getRequiredVariableNames(java.lang.String parserInput)

Utility: Get the required 'variable names' of a parser input which are formal valid.

Parameters:

parserInput - the parser input

Returns:

a list of required and formal valid 'variable names'

See Also:

ReplaceVariableLiteralsInContent.DEFAULT_LEFT_SIDE_PATTERN, ReplaceVariableLiteralsInContent.DEFAULT_RIGHT_SIDE_PATTERN, Utils.isFormalValidVariableName(String)

main

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

Internal test program.

Parameters:

args - [no args]