DLV
Class ConversionType

java.lang.Object
  DLV.ConversionType

public final class ConversionType

extends java.lang.Object

The class that defines the constants that are used to identify generic DLV Wrapper types.

The Predicate class implements a JDBC-like interface. In order to implement some JDBC-like methods it is necessary to have some meta-information about types of arguments (see PredicateMetaData).
Datalog languages do not have types; but, from a relational database point of view (predicate are tables), table arguments have a type.
Commercial relational databases handle several types. Sun provided a Java-view of database types for JDBC named JDBC Types. (see java.sql.Types)
Using that convention, JDBC can offer an automatic conversion from Java objects to relational database argument types (Eg. you can handle dates by using the java.sql.Date class).
Like JDBC, this library provide a Java-view of DLV types named DLV Wrapper Types.
Altough in DLV only three types of argument are available, (constant string, positive integer, quoted string)
this library allows to use a richer set of types, by using a standard encoding for types not supported by DLV.
In the following table are described DLV Wrapper Types and their real encoding.

DBNULL_CLASS

DLV Wrapper Types	Conversion	Example
BIGDECIMAL	quoted string	example("102678397373")	102678397373
BOOLEAN	constant string	example(true)	true
CONST_BYTE	positive integer	example(23)	23
CONST_INT	positive integer	example(2400)	2400
CONST_LONG	positive integer	example(25000)	25000
CONST_SHORT	positive integer	example(100)	100
STRING	constant or quoted string (a valid DLV constant)	example(string). example("string").	string
DATE	quoted string	example("2004-01-10")	10 Jan 2004
QUOTED_BYTE	quoted string	example("23")	23
QUOTED_DOUBLE	quoted string	example("23.4")	23.4
QUOTED_FLOAT	quoted string	example("10.5")	10.5
QUOTED_INT	quoted string	example("10")	10
QUOTED_LONG	quoted string	example("10000")	10000
QUOTED_SHORT	quoted string	example("2")	2
QUOTED_STRING	quoted string	example("quoted string")	quoted string
ROUND_DOUBLE	positive integer	example(101)	100.6
ROUND_FLOAT	positive integer	example(11)	10.6
TIME	quoted string	example("17:03:22")	17:03:22
TRUNC_DOUBLE	positive integer	example(100)	100.6
TRUNC_FLOAT	positive integer	example(10)	10.6
NULL	the string constant representing database null values in DLV see DBNULL	example(null)	null
OBJECT	java object (feature not implemented yet)	may throw exceptions when used
UNIMPLEMENTED	feature not implemented yet	may throw exceptions when used
Note that: - if the specified argument must be translated in a positive integer the library always computes the absolute value (eg. -10 is translated in 10) - if the specified argument must be translated in a quoted string the standard java toString() method is used. - real numbers (float and double) can be rounded or truncated (Es. 10.5 rounded is 11, truncated is 10).

Note that DLV Wrapper Types are automatically handled by a Predicate class instance.
The default type is ConversionType.STRING, if you want to customize standard translation you must set a PredicateMetaData descriptor (see PredicateMetaData). (This mechanism allows to handle a java.util.Date object for in-memory operation and you can "save" it in a predicate argument).
An automatic conversion from JDBC Types and DLV Wrapper Types is provided by sqlToDlvTypes(int).

Version:

3.0

Author:

Francesco Ricca

See Also:

java.sql.ResultSet, java.sql.Types, PredicateMetaData

Nested Class Summary

static class

ConversionType.DBNull The static class identifying the DLV term used to identify database null values.

Field Summary

static byte	BIGDECIMAL The constant identifying the DLV Wrapper type BIGDECIMAL.
static byte	BOOLEAN The constant identifying the DLV Wrapper type BOOLEAN.
static byte	CONST_BYTE The constant identifying the DLV Wrapper type CONST_BYTE.
static byte	CONST_INT The constant identifying the DLV Wrapper type CONST_INT.
static byte	CONST_LONG The constant identifying the DLV Wrapper type CONST_LONG.
static byte	CONST_SHORT The constant identifying the DLV Wrapper type CONST_SHORT.
static byte	DATE The constant identifying the DLV Wrapper type DATE.
static java.lang.String	DBNULL The constant identifying the DLV term used to identify database null values.
static ConversionType.DBNull	DBNULL_CLASS The statc class instance identifying the DLV term used to identify database null values.
static byte	NULL The constant identifying the DLV Wrapper type NULL.
static byte	OBJECT The constant identifying the DLV Wrapper type OBJECT.
static byte	QUOTED_BYTE The constant identifying the DLV Wrapper type QUOTED_BYTE.
static byte	QUOTED_DOUBLE The constant identifying the DLV Wrapper type QUOTED_DOUBLE.
static byte	QUOTED_FLOAT The constant identifying the DLV Wrapper type QUOTED_FLOAT.
static byte	QUOTED_INT The constant identifying the DLV Wrapper type QUOTED_INT.
static byte	QUOTED_LONG The constant identifying the DLV Wrapper type QUOTED_LONG.
static byte	QUOTED_SHORT The constant identifying the DLV Wrapper type QUOTED_SHORT.
static byte	ROUND_DOUBLE The constant identifying the DLV Wrapper type ROUND_DOUBLE.
static byte	ROUND_FLOAT The constant identifying the DLV Wrapper type ROUND_FLOAT.
static byte	STRING The constant identifying the DLV Wrapper type STRING (which is QUOTED_STRING).
static byte	TIME The constant identifying the DLV Wrapper type TIME.
static byte	TRUNC_DOUBLE The constant identifying the DLV Wrapper type TRUNC_DOUBLE.
static byte	TRUNC_FLOAT The constant identifying the DLV Wrapper type TRUNC_FLOAT.
static byte	UNIMPLEMENTED The constant identifying the DLV Wrapper type UNIMPLEMENTED.

Constructor Summary

ConversionType()

Method Summary

static java.lang.String	cutQuotes(java.lang.String s)
static boolean	isConst(java.lang.String s)
static boolean	isQuoted(java.lang.String s)
static boolean	isValid(java.lang.String s)
static byte	sqlToDlvTypes(int sqlType) This function converts SQL type code in a DLV Wrapper type code.

Methods inherited from class java.lang.Object

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

Field Detail

DBNULL_CLASS

public static final ConversionType.DBNull DBNULL_CLASS

The statc class instance identifying the DLV term used to identify database null values.

DBNULL

public static final java.lang.String DBNULL

The constant identifying the DLV term used to identify database null values.

See Also:

Constant Field Values

UNIMPLEMENTED

public static final byte UNIMPLEMENTED

The constant identifying the DLV Wrapper type UNIMPLEMENTED.

See Also:

Constant Field Values

STRING

public static final byte STRING

The constant identifying the DLV Wrapper type STRING (which is QUOTED_STRING).

See Also:

Constant Field Values

BOOLEAN

public static final byte BOOLEAN

The constant identifying the DLV Wrapper type BOOLEAN.

See Also:

Constant Field Values

BIGDECIMAL

public static final byte BIGDECIMAL

The constant identifying the DLV Wrapper type BIGDECIMAL.

See Also:

Constant Field Values

DATE

public static final byte DATE

The constant identifying the DLV Wrapper type DATE.

See Also:

Constant Field Values

TIME

public static final byte TIME

The constant identifying the DLV Wrapper type TIME.

See Also:

Constant Field Values

QUOTED_DOUBLE

public static final byte QUOTED_DOUBLE

The constant identifying the DLV Wrapper type QUOTED_DOUBLE.

See Also:

Constant Field Values

TRUNC_DOUBLE

public static final byte TRUNC_DOUBLE

The constant identifying the DLV Wrapper type TRUNC_DOUBLE.

See Also:

Constant Field Values

ROUND_DOUBLE

public static final byte ROUND_DOUBLE

The constant identifying the DLV Wrapper type ROUND_DOUBLE.

See Also:

Constant Field Values

QUOTED_FLOAT

public static final byte QUOTED_FLOAT

The constant identifying the DLV Wrapper type QUOTED_FLOAT.

See Also:

Constant Field Values

TRUNC_FLOAT

public static final byte TRUNC_FLOAT

The constant identifying the DLV Wrapper type TRUNC_FLOAT.

See Also:

Constant Field Values

ROUND_FLOAT

public static final byte ROUND_FLOAT

The constant identifying the DLV Wrapper type ROUND_FLOAT.

See Also:

Constant Field Values

QUOTED_INT

public static final byte QUOTED_INT

The constant identifying the DLV Wrapper type QUOTED_INT.

See Also:

Constant Field Values

CONST_INT

public static final byte CONST_INT

The constant identifying the DLV Wrapper type CONST_INT.

See Also:

Constant Field Values

QUOTED_LONG

public static final byte QUOTED_LONG

The constant identifying the DLV Wrapper type QUOTED_LONG.

See Also:

Constant Field Values

CONST_LONG

public static final byte CONST_LONG

The constant identifying the DLV Wrapper type CONST_LONG.

See Also:

Constant Field Values

QUOTED_SHORT

public static final byte QUOTED_SHORT

The constant identifying the DLV Wrapper type QUOTED_SHORT.

See Also:

Constant Field Values

CONST_SHORT

public static final byte CONST_SHORT

The constant identifying the DLV Wrapper type CONST_SHORT.

See Also:

Constant Field Values

QUOTED_BYTE

public static final byte QUOTED_BYTE

The constant identifying the DLV Wrapper type QUOTED_BYTE.

See Also:

Constant Field Values

CONST_BYTE

public static final byte CONST_BYTE

The constant identifying the DLV Wrapper type CONST_BYTE.

See Also:

Constant Field Values

OBJECT

public static final byte OBJECT

The constant identifying the DLV Wrapper type OBJECT.

See Also:

Constant Field Values

NULL

public static final byte NULL

The constant identifying the DLV Wrapper type NULL.

See Also:

Constant Field Values

Constructor Detail

ConversionType

public ConversionType()

Method Detail

sqlToDlvTypes

public static byte sqlToDlvTypes(int sqlType)

This function converts SQL type code in a DLV Wrapper type code.
The performed translation is described in the following table:

SQL Type	DLV Wrapper type
CHAR	STRING
DATE	DATE
FLOAT	ROUND_FLOAT
DECIMAL	ROUND_FLOAT
DOUBLE	ROUND_FLOAT
NUMERIC	ROUND_FLOAT
REAL	ROUND_FLOAT
BIGINT	CONST_LONG
VARBINARY	CONST_LONG
LONGVARBINARY	CONST_LONG
INTEGER	CONST_INT
SMALLINT	CONST_INT
TINYINT	CONST_INT
BINARY	STRING
BIT	STRING
TIME	TIME
VARCHAR	STRING
LONGVARCHAR	STRING
NULL	UNIMPLEMENTED
DISTINCT	UNIMPLEMENTED
OTHER	UNIMPLEMENTED
JAVA_OBJECT	OBJECT
REF	UNIMPLEMENTED
STRUCT	UNIMPLEMENTED
TIMESTAMP	UNIMPLEMENTED
BLOB	UNIMPLEMENTED
CLOB	UNIMPLEMENTED
ARRAY	UNIMPLEMENTED
NULL	NULL

Parameters:

sqlType - an SQL type from java.sql.Types

Returns:

The DLV Wrapper type which corresponds tho the specified JDBC Type.

See Also:

java.sql.Types.

isValid

public static boolean isValid(java.lang.String s)

isConst

public static boolean isConst(java.lang.String s)

isQuoted

public static boolean isQuoted(java.lang.String s)

cutQuotes

public static java.lang.String cutQuotes(java.lang.String s)