one.world.io
Class Query

java.lang.Object
  |
  +--one.world.core.Tuple
        |
        +--one.world.io.Query

All Implemented Interfaces:

Cloneable, Serializable

public class Query

extends Tuple

Implementation of a query. Queries are used to select specific tuples when performing input operations. Queries are either empty, unary, binary, or comparison queries. Empty queries are always true. Unary queries apply a unary operator on another query. Binary queries apply a binary operator on two other queries. Finally, comparison queries compare the field of a tuple to a value. The field of a tuple is specified as a string, giving the field's name. The tuple itself can be specified by using the empty string. Nested fields of nested tuples can be specified by using the corresponding chain of field names, where the individual field names are separated by dots ('.').

Whether a comparison query is valid for a given field, depends on the type of the field. For the tuple itself, only queries for its type, subtype, or declared type are valid. For arbitrary objects, only queries for the type, subtype, declared type, equality, or inequality are valid. For numeric types, either in their primitive or in their boxed form, all comparisons besides begins-with, contains, ends-with are valid. Finally, for strings and binary data, all comparisons are valid.

Version:

$Revision: 1.11 $

See Also:

Serialized Form

Field Summary

static int	BINARY_AND The and binary operator.
static int	BINARY_OR The or binary operator.
static int	COMPARE_BEGINS_WITH The begins with comparison operator.
static int	COMPARE_CONTAINS The contains comparison operator.
static int	COMPARE_ENDS_WITH The ends with comparison operator.
static int	COMPARE_EQUAL The equal comparison operator.
static int	COMPARE_GREATER The greater than comparison operator.
static int	COMPARE_GREATER_EQUAL The greater equal comparison operator.
static int	COMPARE_HAS_DECLARED_TYPE The has declared type comparison operation.
static int	COMPARE_HAS_FIELD The has field comparison operator.
static int	COMPARE_HAS_SUBTYPE The has subtype comparison operator.
static int	COMPARE_HAS_TYPE The has type comparison operator.
static int	COMPARE_LESS The less than comparison operator.
static int	COMPARE_LESS_EQUAL The less equal comparison operator.
static int	COMPARE_NOT_EQUAL The not equal comparison operator.
String	field The field specifier for comparison queries.
int	op The operator for unary, binary, and comparison queries.
Query	query1 The first query for unary and binary queries.
Query	query2 The second query for binary queries.
int	type The type of this query.
static int	TYPE_BINARY The binary type.
static int	TYPE_COMPARE The comparison type.
static int	TYPE_EMPTY The empty type.
static int	TYPE_UNARY The unary type.
static int	UNARY_NOT The not unary operator.
Object	value The value for comparison queries.

Fields inherited from class one.world.core.Tuple

CLOSURE, id, ID, META_DATA, metaData, SOURCE

Constructor Summary

Query()
Create a new empty query.

Query(int op, Query query1)
Create a new unary query.

Query(Query query1, int op, Query query2)
Create a new binary query.

Query(String field, int op, Object value)
Create a new comparison query.

Method Summary

void	validate() Validate this query.

Methods inherited from class one.world.core.Tuple

clone, containsNonSymbolicHandler, equals, fields, get, getMetaData, getType, hasField, hashCode, hasMetaData, remove, set, setMetaData, toString, wrap

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

TYPE_EMPTY

public static final int TYPE_EMPTY

The empty type.

TYPE_UNARY

public static final int TYPE_UNARY

The unary type.

TYPE_BINARY

public static final int TYPE_BINARY

The binary type.

TYPE_COMPARE

public static final int TYPE_COMPARE

The comparison type.

UNARY_NOT

public static final int UNARY_NOT

The not unary operator.

BINARY_AND

public static final int BINARY_AND

The and binary operator.

BINARY_OR

public static final int BINARY_OR

The or binary operator.

COMPARE_EQUAL

public static final int COMPARE_EQUAL

The equal comparison operator.

COMPARE_NOT_EQUAL

public static final int COMPARE_NOT_EQUAL

The not equal comparison operator.

COMPARE_GREATER

public static final int COMPARE_GREATER

The greater than comparison operator.

COMPARE_GREATER_EQUAL

public static final int COMPARE_GREATER_EQUAL

The greater equal comparison operator.

COMPARE_LESS

public static final int COMPARE_LESS

The less than comparison operator.

COMPARE_LESS_EQUAL

public static final int COMPARE_LESS_EQUAL

The less equal comparison operator.

COMPARE_BEGINS_WITH

public static final int COMPARE_BEGINS_WITH

The begins with comparison operator.

COMPARE_CONTAINS

public static final int COMPARE_CONTAINS

The contains comparison operator.

COMPARE_ENDS_WITH

public static final int COMPARE_ENDS_WITH

The ends with comparison operator.

COMPARE_HAS_TYPE

public static final int COMPARE_HAS_TYPE

The has type comparison operator. Has type comparisons compare the actual value of a tuple or field with the specified type.

COMPARE_HAS_SUBTYPE

public static final int COMPARE_HAS_SUBTYPE

The has subtype comparison operator. Has subtype comparisons compare the actual value of a tuple or field with the specified type.

COMPARE_HAS_DECLARED_TYPE

public static final int COMPARE_HAS_DECLARED_TYPE

The has declared type comparison operation. Has declared type comparisons compare the declared type of a field with the specified type. The declared type of a tuple is the type of the tuple. The declared type of the dynamically typed fields of a dynamic tuple is java.lang.Object.

COMPARE_HAS_FIELD

public static final int COMPARE_HAS_FIELD

The has field comparison operator. Has field comparisons return true if the tuple has a field with the given fieldname. The value parameter is unused and should be set to null.

type

public int type

The type of this query.

op

public int op

The operator for unary, binary, and comparison queries.

query1

public Query query1

The first query for unary and binary queries.

query2

public Query query2

The second query for binary queries.

field

public String field

The field specifier for comparison queries.

value

public Object value

The value for comparison queries.

Constructor Detail

Query

public Query()

Create a new empty query.

Query

public Query(int op,
             Query query1)

Create a new unary query.

Parameters:

op - The unary operator.

query1 - The query to operate on.

Query

public Query(Query query1,
             int op,
             Query query2)

Create a new binary query.

Parameters:

query1 - The first query to operate on.

op - The binary operator.

query2 - The second query to operate on.

Query

public Query(String field,
             int op,
             Object value)

Create a new comparison query.

Parameters:

field - The field for the comparison.

op - The comparison operator.

value - The value for the comparison.

Method Detail

validate

public void validate()
              throws TupleException

Validate this query.

Overrides:

validate in class Tuple

Following copied from class: one.world.core.Tuple

Throws:

TupleException - Signals that the tuple is either malformed (i.e., does not conform to the tuple specification) or invalid (i.e., does not conform to the semantic constraints of its type).

See Also:

MalformedTupleException, InvalidTupleException, Type.validate(Class)