ModSQL
Class Function_Math

java.lang.Object
  |
  +--ModSQL.AbstractFunction
        |
        +--ModSQL.Function_Math

All Implemented Interfaces:

Function

final class Function_Math

extends AbstractFunction

This class implements standard SQL math functions: ABS, CEIL, FLOOR, GREATEST, LEAST, MOD, POWER, ROUND, SIGN, and SQRT.

Author:

chris.studholme@utoronto.ca

Field Summary

static int	ABS Function is ABS().
static int	CEIL Function is CEIL().
static int	FLOOR Function is FLOOR().
static int	GREATEST Function is GREATEST().
static int	LEAST Function is LEAST().
static int	MOD Function is MOD().
private int	op Which function are we? One of the above constants.
static int	POWER Function is POWER().
private int	return_type SQL return type for this function.
static int	ROUND Function is ROUND().
static int	SIGN Function is SIGN().
static int	SQRT Function is SQRT().

Fields inherited from class ModSQL.AbstractFunction

all_constant, constant_non_null, evaluate_order, evaluate_order_array, out_of_order, parameter_constant, parameter_value, parameters, parameters_array

Fields inherited from interface ModSQL.Function

MATCH_BEGINS, MATCH_EQU, MATCH_GT, MATCH_GTE, MATCH_LT, MATCH_LTE, MATCH_NE

Constructor Summary

Function_Math(int op)
Constructor.

Method Summary

Object	evaluate(boolean aggregate) Evaluate parameters and compute function.
static Function	forName(String name) Returns a new instance of this class if name is recognized.
String	functionName() Returns the name of this function for use by toString() method.
int	getMaxResultSize() Returns -1 as this function will never return a String constant.
int	getSQLType() Returns the SQL type of this function.
void	optimize() Prepare the function for use.
static Number	power(Number n, Number e, int return_type) Compute n to the power of e and return a number of the desired type.
static Number	round(Number n) Round number to nearest integer.
static Number	round(Number n, Number d) Round number of specified number of decimal places.

Methods inherited from class ModSQL.AbstractFunction

addParameter, convertToSQLType, evaluate, evaluateConstantParameters, evaluateOrder, evaluateParameters, evaluateParameters, getCompatableType, getObjectSQLType, getParameter, getParameterCount, isAggregate, isConstant, postfixParameters, prefixParameters, registerWith, reset, toString

Methods inherited from class java.lang.Object

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

Field Detail

ABS

public static final int ABS

Function is ABS().

CEIL

public static final int CEIL

Function is CEIL().

FLOOR

public static final int FLOOR

Function is FLOOR().

GREATEST

public static final int GREATEST

Function is GREATEST().

LEAST

public static final int LEAST

Function is LEAST().

MOD

public static final int MOD

Function is MOD().

POWER

public static final int POWER

Function is POWER().

ROUND

public static final int ROUND

Function is ROUND().

SIGN

public static final int SIGN

Function is SIGN().

SQRT

public static final int SQRT

Function is SQRT().

op

private int op

Which function are we? One of the above constants.

return_type

private int return_type

SQL return type for this function.

Constructor Detail

Function_Math

public Function_Math(int op)

Constructor.

Parameters:

op - function type

Method Detail

forName

public static Function forName(String name)

Returns a new instance of this class if name is recognized. The instance is initialized as needed to represent the desired function.

Parameters:

name - name of function to find

Returns:

instance of this class or null if name does not match

optimize

public void optimize()
              throws SQLException

Prepare the function for use. This method figures out the return type of the function.

Overrides:

optimize in class AbstractFunction

Throws:

SQLException - if the parameters are invalid

getSQLType

public int getSQLType()

Returns the SQL type of this function.

Returns:

SQL type of data to be returned

getMaxResultSize

public int getMaxResultSize()

Returns -1 as this function will never return a String constant.

Returns:

maximum size of String returned or -1 if unknown

functionName

public String functionName()

Returns the name of this function for use by toString() method.

Overrides:

functionName in class AbstractFunction

Returns:

name of function

evaluate

public Object evaluate(boolean aggregate)
                throws SQLException,
                       EndOfTable

Evaluate parameters and compute function.

Parameters:

aggregate - passed to parameters

Returns:

result object

Throws:

SQLException - if a database-access error occurs

EndOfTable - if thrown by a parameter

round

public static Number round(Number n)

Round number to nearest integer.

Parameters:

n - number to round

Returns:

Double object with rounded value

round

public static Number round(Number n,
                           Number d)

Round number of specified number of decimal places.

Parameters:

n - number to round

d - number of decimal places to round to (integer)

Returns:

Double object with rounded value

power

public static Number power(Number n,
                           Number e,
                           int return_type)
                    throws SQLException

Compute n to the power of e and return a number of the desired type.

Parameters:

n - base

e - exponent

return_type - SQL type of object to return

Returns:

Number object with computed power

Throws:

SQLException - if type mismatch