Class FormulaParser

java.lang.Object

de.fho.jump.pirol.utilities.FormulaParsing.FormulaParser

public class FormulaParser
extends Object

This class is a utility to parse formulas, that describe how an additional attribute value is to be calculated on a by feature basis. Formulas thereby can contain constant values as well as attribute values, that need to be extracted for each feature.

Formulas are exspected to be space-separated: Each attribute name, constant value, bracket or operator has to be surrounded by empty spaces.

A valid formulas (for a FeatureSchema that has the attributes "yield" and "grain mois") would look like this:
( 4 + 6 ) * yield
or
grain mois / 2.

Version:

$Rev$

Author:

Ole Rahn

FH Osnabrück - University of Applied Sciences Osnabrück,
Project: PIROL (2005),
Subproject: Daten- und Wissensmanagement

See Also:

• FeatureCollectionTools.applyFormulaToFeatureCollection(FeatureCollection, AttributeInfo, FormulaValue, boolean)

Field Summary

Fields

Modifier and Type	Field	Description
static final String	KEY_ACOS
static final String	KEY_ASIN
static final String	KEY_ATAN
static final String	KEY_COS
static final String	KEY_EXP
static final String	KEY_LOG
static final String	KEY_LOG10
static final String	KEY_PI
static final String	KEY_POW
static final String	KEY_SIN
static final String	KEY_SQRT
static final String	KEY_TAN
static final String	KEY_TODEG
static final String	KEY_TORAD
protected static PersonalLogger	logger

Constructor Summary

Constructors

Constructor	Description
FormulaParser()

Method Summary

Modifier and Type	Method	Description
protected static int	findFirstAddSubOperatorOutsideABracket(String formula, int fromIndex)
protected static int	findFirstMultiDivOperatorOutsideABracket(String formula, int fromIndex)
protected static int	findFirstOccuranceOutsideABracket(String toBeFound, String formula, int fromIndex)
protected static String	getFirstCompleteBracketString(String formula, int fromIndex)
static FormulaValue	getValue(String formula, FeatureSchema featSchema)	Recursively parses a given (sub-) formula into a FormulaValue, which can be an operation with sub-FormularValues or a value.
protected static boolean	isBracket(String brack)
protected static boolean	isOperator(String op)
protected static String	kickOutSurroundingBracket(String formula)	deletes a bracket that surrounds the whole formula from the formula.
protected static String[]	splitToFirstLevelOperation(String formula)

Methods inherited from class Object

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

Field Details

logger

protected static PersonalLogger logger

KEY_SQRT

public static final String KEY_SQRT

See Also:

• Constant Field Values

KEY_POW

public static final String KEY_POW

See Also:

• Constant Field Values

KEY_PI

public static final String KEY_PI

See Also:

• Constant Field Values

KEY_LOG

public static final String KEY_LOG

See Also:

• Constant Field Values

KEY_SIN

public static final String KEY_SIN

See Also:

• Constant Field Values

KEY_COS

public static final String KEY_COS

See Also:

• Constant Field Values

KEY_TAN

public static final String KEY_TAN

See Also:

• Constant Field Values

KEY_EXP

public static final String KEY_EXP

See Also:

• Constant Field Values

KEY_ASIN

public static final String KEY_ASIN

See Also:

• Constant Field Values

KEY_ACOS

public static final String KEY_ACOS

See Also:

• Constant Field Values

KEY_ATAN

public static final String KEY_ATAN

See Also:

• Constant Field Values

KEY_LOG10

public static final String KEY_LOG10

See Also:

• Constant Field Values

KEY_TODEG

public static final String KEY_TODEG

See Also:

• Constant Field Values

KEY_TORAD

public static final String KEY_TORAD

See Also:

• Constant Field Values

Constructor Details

FormulaParser

public FormulaParser()

Method Details

getValue

public static FormulaValue getValue(String formula,
 FeatureSchema featSchema)

Recursively parses a given (sub-) formula into a FormulaValue, which can be an operation with sub-FormularValues or a value.

Parameters:

formula - the formula passed as a String

featSchema - The feature schema to check attribute names, if neccessary

Returns:

the given formula parsed into a FormulaValue or null if the given String did not contain formula information

isOperator

protected static boolean isOperator(String op)

isBracket

protected static boolean isBracket(String brack)

findFirstOccuranceOutsideABracket

protected static int findFirstOccuranceOutsideABracket(String toBeFound,
 String formula,
 int fromIndex)

findFirstAddSubOperatorOutsideABracket

protected static int findFirstAddSubOperatorOutsideABracket(String formula,
 int fromIndex)

findFirstMultiDivOperatorOutsideABracket

protected static int findFirstMultiDivOperatorOutsideABracket(String formula,
 int fromIndex)

splitToFirstLevelOperation

protected static String[] splitToFirstLevelOperation(String formula)

getFirstCompleteBracketString

protected static String getFirstCompleteBracketString(String formula,
 int fromIndex)

kickOutSurroundingBracket

protected static String kickOutSurroundingBracket(String formula)

deletes a bracket that surrounds the whole formula from the formula.

Parameters:

formula - formula String

Returns:

formula String without surrounding bracket