org.basex.query.var

Class Var

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.var.Var

public final class Var
extends ExprInfo

Variable expression.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen, Leo Woerteler

Field Summary

Fields

Modifier and Type	Field and Description
SeqType	declType Declared type, null if not specified.
int	id Variable ID.
InputInfo	info Input info.
QNm	name Variable name.
boolean	promote Flag for function conversion.

Constructor Summary

Constructors

Constructor and Description
Var(QNm name, SeqType declType, boolean param, int slot, QueryContext qc, StaticContext sc, InputInfo info) Constructor for a variable with an already known stack slot.
Var(QNm name, SeqType declType, boolean param, QueryContext qc, StaticContext sc, InputInfo info) Constructor.
Var(Var var, QueryContext qc, StaticContext sc) Copy constructor.

Method Summary

Modifier and Type	Method and Description
boolean	adoptCheck(SeqType st, boolean prom) Tries to adopt the given type check.
Expr	checked(Expr expr, CompileContext cc) Returns an equivalent to the given expression that checks this variable's type.
boolean	checksType() Determines if this variable checks the type of the expression bound to it.
void	checkType(Expr expr) Checks if the type of the specified expression could be converted to the sequence type of this variable.
Value	checkType(Value value, QueryContext qc, boolean opt) Checks the type of this value and casts/promotes it when necessary.
Data	data() Returns the data reference bound to this variable.
boolean	ddo() Returns the distinct document order flag.
SeqType	declaredType() Declared type of this variable.
boolean	equals(Object obj)
void	expr(Expr expr) Attaches an input expression.
int	hashCode()
byte[]	id() Returns a unique representation of the variable.
boolean	is(Var var) Checks whether the given variable is identical to this one, i.e.
void	plan(QueryPlan plan) Creates a query plan.
void	plan(QueryString qs) Creates a query string.
boolean	promotes() Checks if this variable performs function conversion on its bound values.
void	refineType(SeqType st, CompileContext cc) Tries to refine the type of this variable through the type of the bound expression.
void	refineType(SeqType st, long size, CompileContext cc) Tries to refine the type of this variable through the type of the bound expression.
SeqType	seqType() Sequence type of values bound to this variable.
long	size() Returns the result size.
String	toErrorString() Returns a string representation of the expression that can be embedded in error messages.

Methods inherited from class org.basex.query.expr.ExprInfo

description, toString

Methods inherited from class java.lang.Object

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

Field Detail

name

public final QNm name

Variable name.

id

public final int id

Variable ID.

info

public final InputInfo info

Input info.

declType

public SeqType declType

Declared type, null if not specified.

promote

public boolean promote

Flag for function conversion.

Constructor Detail

Var

public Var(QNm name,
           SeqType declType,
           boolean param,
           int slot,
           QueryContext qc,
           StaticContext sc,
           InputInfo info)

Constructor for a variable with an already known stack slot.

Parameters:

name - variable name

declType - declared type, null for no check

param - function parameter flag

slot - stack slot

qc - query context, used for generating a variable ID

sc - static context

info - input info

Var

public Var(QNm name,
           SeqType declType,
           boolean param,
           QueryContext qc,
           StaticContext sc,
           InputInfo info)

Constructor.

Parameters:

name - variable name

declType - declared sequence type, null for no check

param - function parameter flag

qc - query context, used for generating a variable ID

sc - static context

info - input info

Var

public Var(Var var,
           QueryContext qc,
           StaticContext sc)

Copy constructor.

Parameters:

var - variable to copy

qc - query context

sc - static context

Method Detail

seqType

public SeqType seqType()

Sequence type of values bound to this variable.

Returns:

sequence type

expr

public void expr(Expr expr)

Attaches an input expression.

Parameters:

expr - input expression

size

public long size()

Returns the result size.

Returns:

result size

ddo

public boolean ddo()

Returns the distinct document order flag. See Expr.ddo() for details.

Returns:

result of check

data

public Data data()

Returns the data reference bound to this variable. See Expr.data() for details.

Returns:

data reference (can be null)

declaredType

public SeqType declaredType()

Declared type of this variable.

Returns:

declared type

refineType

public void refineType(SeqType st,
                       CompileContext cc)
                throws QueryException

Tries to refine the type of this variable through the type of the bound expression.

Parameters:

st - sequence type of the bound expression

cc - compilation context (can be null)

Throws:

QueryException - query exception

refineType

public void refineType(SeqType st,
                       long size,
                       CompileContext cc)
                throws QueryException

Tries to refine the type of this variable through the type of the bound expression.

Parameters:

st - sequence type of the bound expression

size - size (can be -1)

cc - compilation context (can be null)

Throws:

QueryException - query exception

checksType

public boolean checksType()

Determines if this variable checks the type of the expression bound to it.

Returns:

true if the type is checked or promoted, false otherwise

checked

public Expr checked(Expr expr,
                    CompileContext cc)
             throws QueryException

Returns an equivalent to the given expression that checks this variable's type.

Parameters:

expr - expression

cc - compilation context

Returns:

checked expression

Throws:

QueryException - query exception

checkType

public Value checkType(Value value,
                       QueryContext qc,
                       boolean opt)
                throws QueryException

Checks the type of this value and casts/promotes it when necessary.

Parameters:

value - value to be checked

qc - query context

opt - if the result should be optimized

Returns:

checked and possibly cast value

Throws:

QueryException - if the check failed

checkType

public void checkType(Expr expr)
               throws QueryException

Checks if the type of the specified expression could be converted to the sequence type of this variable. Due to insufficient typing, the check will only be performed if:

• The variable type is an instance of the specified type. This way, expressions with super types like item() will not be rejected.
• The expression is to be promoted, and it is not of type node (eg: function-declaration-016)

Parameters:

expr - expression

Throws:

QueryException - query exception

is

public boolean is(Var var)

Checks whether the given variable is identical to this one, i.e. has the same id.

Parameters:

var - variable to check

Returns:

true if the IDs are equal, false otherwise

promotes

public boolean promotes()

Checks if this variable performs function conversion on its bound values.

Returns:

result of check

hashCode

public int hashCode()

Overrides:

hashCode in class Object

adoptCheck

public boolean adoptCheck(SeqType st,
                          boolean prom)

Tries to adopt the given type check.

Parameters:

st - type to check

prom - if function conversion should be applied

Returns:

true if the check could be adopted, false otherwise

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

plan

public void plan(QueryPlan plan)

Description copied from class: ExprInfo

Creates a query plan.

Specified by:

plan in class ExprInfo

Parameters:

plan - expression plan

id

public byte[] id()

Returns a unique representation of the variable.

Returns:

variable id

plan

public void plan(QueryString qs)

Description copied from class: ExprInfo

Creates a query string.

Specified by:

plan in class ExprInfo

Parameters:

qs - query string builder

toErrorString

public String toErrorString()

Description copied from class: ExprInfo

Returns a string representation of the expression that can be embedded in error messages. Defaults to ExprInfo.toString().

Overrides:

toErrorString in class ExprInfo

Returns:

class name