ModSQL
Class Operator_In

java.lang.Object
  |
  +--ModSQL.AbstractFunction
        |
        +--ModSQL.Operator
              |
              +--ModSQL.Operator_In

All Implemented Interfaces:

Function

final class Operator_In

extends Operator

SQL comparison operators with a table on the RHS.

Author:

chris.studholme@utoronto.ca

Field Summary

private int[]	compare_type Per column comparison type.
static int	EQU Comparison operator (equal).
static int	GT Comparison operator (greater than).
static int	GTE Comparison operator (greater or equal).
private HashSet	hashset Hash table to speedup tests for equality.
private boolean	hashset_hasnull Does the hash table contain a null value.
static int	LT Comparison operator (less than).
static int	LTE Comparison operator (less or equal).
private boolean	match_all True if all rows must match.
private int	ncolumns Number of columns in row-constructor.
static int	NE Comparison operator (not equal).
private int	op Which operator? One of the above constants.
private RowConstructor	row Row-constructor on LHS if needed.
private Table	table Table on right-hand-side (RHS).

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

Operator_In(int op, boolean match_all)
Constructor.

Method Summary

Object	evaluate(boolean aggregate) Evaluate parameters and compare.
Object	evaluate(int match_op, Object match_value) Evaluate parameters and compare.
String	functionName() Returns the name of this function for use by toString() method.
int	getMaxResultSize() Returns -1 as this operator will never return a String object.
int	getSQLType() Returns Types.BIT.
boolean	isAggregate() Determine if this function will return a value that is an aggregate of many database rows.
boolean	isConstant() Determine if this function returns a constant value.
void	optimize() Prepare the function for use.
String	postfixParameters() This method returns ",RHS", provided a table has been specified for the RHS.
void	registerWith(Object o) Since table is not a normal parameter, we need to ensure objects to register with get passed to it.
void	setTable(Table table) Specify the table to be scanned.
Boolean	testRow(Object[] r1, Object[] r2) Compare two rows according to op and using compare_type array.

Methods inherited from class ModSQL.Operator

addAllParameters, addAllParametersNegate, addAllParametersNot, removeDoubleNegation, removeDoubleNot

Methods inherited from class ModSQL.AbstractFunction

addParameter, convertToSQLType, evaluateConstantParameters, evaluateOrder, evaluateParameters, evaluateParameters, getCompatableType, getObjectSQLType, getParameter, getParameterCount, prefixParameters, reset, toString

Methods inherited from class java.lang.Object

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

Field Detail

EQU

public static final int EQU

Comparison operator (equal).

GT

public static final int GT

Comparison operator (greater than).

GTE

public static final int GTE

Comparison operator (greater or equal).

LT

public static final int LT

Comparison operator (less than).

LTE

public static final int LTE

Comparison operator (less or equal).

NE

public static final int NE

Comparison operator (not equal).

op

private int op

Which operator? One of the above constants.

match_all

private boolean match_all

True if all rows must match.

table

private Table table

Table on right-hand-side (RHS).

compare_type

private int[] compare_type

Per column comparison type.

row

private RowConstructor row

Row-constructor on LHS if needed.

ncolumns

private int ncolumns

Number of columns in row-constructor.

hashset

private HashSet hashset

Hash table to speedup tests for equality.

hashset_hasnull

private boolean hashset_hasnull

Does the hash table contain a null value.

Constructor Detail

Operator_In

public Operator_In(int op,
                   boolean match_all)

Constructor.

Parameters:

op - comparison operator

match_all - true to match all rows

Method Detail

setTable

public void setTable(Table table)

Specify the table to be scanned.

Parameters:

table - table on RHS of comparison

registerWith

public void registerWith(Object o)
                  throws SQLException

Since table is not a normal parameter, we need to ensure objects to register with get passed to it. This method also ensures that the LHS gets these objects too.

Overrides:

registerWith in class AbstractFunction

Parameters:

o - object to register with

Throws:

SQLException - if a database error occurs

optimize

public void optimize()
              throws SQLException

Prepare the function for use. This method checks the parameters and figures out how the comparison will take place (what type to use).

If the RHS consists of a single column, the operator is EQU or NE, and the table is constant, a hash table of the rows is created to greatly speed up comparisons.

Overrides:

optimize in class AbstractFunction

Throws:

SQLException - if the parameters are invalid

functionName

public String functionName()

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

Overrides:

functionName in class AbstractFunction

Returns:

name of function

postfixParameters

public String postfixParameters()

This method returns ",RHS", provided a table has been specified for the RHS.

Overrides:

postfixParameters in class AbstractFunction

Returns:

table parameter as a string

isConstant

public boolean isConstant()
                   throws SQLException

Determine if this function returns a constant value. This method returns true if both the LHS and RHS are constant.

Overrides:

isConstant in class AbstractFunction

Returns:

true if the value returned is constant

Throws:

SQLException - if a database-access error occurs

isAggregate

public boolean isAggregate()
                    throws SQLException

Determine if this function will return a value that is an aggregate of many database rows. The function is an aggregate if the LHS is an aggregate and the RHS is constant. If the LHS is an aggregate, but the RHS is not constant, an exception is thrown.

Overrides:

isAggregate in class AbstractFunction

Returns:

true if the function aggregates several rows of data

Throws:

SQLException - if a database-access error occurs

getSQLType

public int getSQLType()

Returns Types.BIT.

Returns:

SQL type of data to be returned

getMaxResultSize

public int getMaxResultSize()

Returns -1 as this operator will never return a String object.

Returns:

maximum size of String returned or -1 if unknown

evaluate

public Object evaluate(boolean aggregate)
                throws SQLException,
                       EndOfTable

Evaluate parameters and compare.

Parameters:

aggregate - passed to parameters

Returns:

result object

Throws:

SQLException - if a database-access error occurs

EndOfTable - if thrown by a parameter

evaluate

public Object evaluate(int match_op,
                       Object match_value)
                throws SQLException,
                       EndOfTable

Evaluate parameters and compare.

Overrides:

evaluate in class AbstractFunction

Parameters:

match_op - how the value should be matched

match_value - desired value

Returns:

result object

Throws:

SQLException - if a database-access error occurs

EndOfTable - if thrown by a parameter

testRow

public Boolean testRow(Object[] r1,
                       Object[] r2)
                throws SQLException

Compare two rows according to op and using compare_type array.

Parameters:

r1 - left row

r2 - right row

Returns:

result of comparison

Throws:

SQLException - if op is invalid or on type mismatch