adams.parser
Class TwitterFilter

java.lang.Object
  adams.core.ConsoleObject
      adams.core.option.AbstractOptionHandler
          adams.parser.AbstractExpressionEvaluator<T>
              adams.parser.AbstractSymbolEvaluator<Boolean>
                  adams.parser.TwitterFilter

All Implemented Interfaces:

Debuggable, Destroyable, OptionHandler, SizeOfHandler, GrammarSupplier, Serializable

public class TwitterFilter
extends AbstractSymbolEvaluator<Boolean>

Evaluates Twitter filter expressions.

The expressions use the following grammar:

expr_list ::= expr_list expr | expr;
expr ::= ( expr )
| boolexpr
;

boolexpr ::= BOOLEAN
| ( boolexpr )
| not boolexpr
| boolexpr and boolexpr
| boolexpr or boolexpr
| boolexpr xor boolexpr

| langcode <match> pattern
| country <match> pattern
| countrycode <match> pattern
| place <match> pattern
| source <match> pattern
| text <match> pattern
| user <match> pattern

| ifelse ( boolexpr:test , boolexpr:test_true , boolexpr:test_false )
;

The '<match>' operator can be one of the following:
1. '=' - exact match (the twitter field must be the exact 'pattern' string)
2. ':' - substring match (the 'pattern' can occur anywhere in the twitter field)
3. '~' - regular expression match (the 'pattern' is a regular expression that the twitter field must match)

Please note, all strings are converted to lower case before the filter is applied.

Valid options are:

-D <int> (property: debugLevel)
    The greater the number the more additional info the scheme may output to
    the console (0 = off).
    default: 0
    minimum: 0
 

-env <java.lang.String> (property: environment)
    The class to use for determining the environment.
    default: adams.env.Environment
 

-expression <java.lang.String> (property: expression)
    The filter expression to evaluate.
    default: text~\".*\"
 

-symbol <adams.core.base.BaseString> [-symbol ...] (property: symbols)
    The symbols to initialize the parser with, key-value pairs: name=value.
    default:
 

Version:

$Revision: 4584 $

Author:

FracPete (fracpete at waikato dot ac dot nz)

See Also:

Serialized Form

Field Summary

Fields inherited from class adams.parser.AbstractSymbolEvaluator

m_Symbols

Fields inherited from class adams.parser.AbstractExpressionEvaluator

m_Environment, m_Expression

Fields inherited from class adams.core.option.AbstractOptionHandler

m_DebugLevel, m_OptionManager

Constructor Summary

TwitterFilter()

Method Summary

protected Boolean	doEvaluate(HashMap symbols) Performs the actual evaluation.
static boolean	evaluate(String expr, HashMap symbols) Parses and evaluates the given expression.
String	expressionTipText() Returns the tip text for this property.
protected String	getDefaultExpression() Returns the default expression to use.
String	getGrammar() Returns a string representation of the grammar.
String	globalInfo() Returns a string describing the object.
protected Object	initializeSymbol(String name, String value) Initializes the symbol.
static void	main(String[] args) Runs the evaluator from command-line.

Methods inherited from class adams.parser.AbstractSymbolEvaluator

defineOptions, evaluate, getSymbols, initialize, initializeSymbols, setSymbols, symbolsTipText

Methods inherited from class adams.parser.AbstractExpressionEvaluator

environmentTipText, forCommandLine, forName, getEnvironment, getExpression, runEvaluator, setEnvironment, setExpression

Methods inherited from class adams.core.option.AbstractOptionHandler

cleanUpOptions, debug, debug, debugLevelTipText, destroy, finishInit, getDebugLevel, getOptionManager, isDebugOn, newOptionManager, reset, setDebugLevel, toCommandLine, toString

Methods inherited from class adams.core.ConsoleObject

getDebugging, getSystemErr, getSystemOut, sizeOf

Methods inherited from class java.lang.Object

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

Constructor Detail

TwitterFilter

public TwitterFilter()

Method Detail

globalInfo

public String globalInfo()

Returns a string describing the object.

Specified by:

globalInfo in class AbstractOptionHandler

Returns:

a description suitable for displaying in the gui

getGrammar

public String getGrammar()

Returns a string representation of the grammar.

Returns:

the grammar, null if not available

getDefaultExpression

protected String getDefaultExpression()

Returns the default expression to use.

Specified by:

getDefaultExpression in class AbstractExpressionEvaluator<Boolean>

Returns:

the default expression

expressionTipText

public String expressionTipText()

Returns the tip text for this property.

Specified by:

expressionTipText in class AbstractExpressionEvaluator<Boolean>

Returns:

tip text for this property suitable for displaying in the GUI or for listing the options.

initializeSymbol

protected Object initializeSymbol(String name,
                                  String value)

Initializes the symbol.

Specified by:

initializeSymbol in class AbstractSymbolEvaluator<Boolean>

Parameters:

name - the name of the symbol

value - the string representation of the symbol

Returns:

the object representation of the symbol

doEvaluate

protected Boolean doEvaluate(HashMap symbols)
                      throws Exception

Performs the actual evaluation.

Specified by:

doEvaluate in class AbstractSymbolEvaluator<Boolean>

Parameters:

symbols - the symbols to use

Returns:

the evaluation, or null in case of error

Throws:

Exception - if evaluation fails

evaluate

public static boolean evaluate(String expr,
                               HashMap symbols)
                        throws Exception

Parses and evaluates the given expression. Returns the result of the boolean expression, based on the given values of the symbols.

Parameters:

expr - the expression to evaluate

symbols - the symbol/value mapping

Returns:

the evaluated result

Throws:

Exception - if something goes wrong

main

public static void main(String[] args)

Runs the evaluator from command-line.

Parameters:

args - the command-line options, use "-help" to list them