Package org.basex.query.expr

Class ItrPos

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.Simple

org.basex.query.expr.ItrPos

All Implemented Interfaces:

CmpPos

public final class ItrPos
extends Simple
implements CmpPos

Integer position range check.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Field Summary

Fields inherited from class org.basex.query.expr.ParseExpr

exprType, info

Method Summary

Modifier and Type	Method	Description
ItrPos	copy(CompileContext cc, IntObjMap<Var> vm)	Copies an expression.
String	description()	Returns a string description of the expression.
boolean	equals(Object obj)	This function is e.g.
boolean	exact()	Checks if minimum and maximum expressions are identical.
static Expr	get(double pos, InputInfo ii)	Returns a position expression for the specified position, or an optimized boolean item.
static Expr	get(long min, long max, InputInfo ii)	Returns a position expression for the specified range, or an optimized boolean item.
boolean	has(Flag... flags)	Indicates if an expression has one of the specified compiler properties.
Expr	inline(InlineContext ic)	Inlines an expression into this one, replacing all variable or context references.
Expr	invert(CompileContext cc)	If possible, returns an optimized expression with inverted operands.
Bln	item(QueryContext qc, InputInfo ii)	Evaluates the expression and returns the resulting item, or Empty.VALUE if the expression yields an empty sequence.
Expr	mergeEbv(Expr ex, boolean or, CompileContext cc)	Tries to merge two expressions that are part of an EBV test.
void	plan(QueryPlan plan)	Creates a query plan.
void	plan(QueryString qs)	Creates a query string.
boolean	simple()	Checks if the positional range is deterministic.
int	test(long pos, QueryContext qc)	Checks the current position.

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

accept, checkUp, compile, count, exprSize, inlineable

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

adoptType, atomValue, checkAllUp, checkNoEmpty, checkNoEmpty, checkNoneUp, checkNoUp, checkType, checkType, checkUp, copyType, ctxValue, ebv, iter, refineType, seqType, size, test, toArray, toArray, toAtomItem, toB64, toB64, toBin, toBin, toBoolean, toBoolean, toBytes, toBytes, toDouble, toDouble, toElem, toFloat, toFunc, toItem, toItem, toLong, toLong, toMap, toMap, toNode, toNode, toNodeOrNull, toNumber, toNumberOrNull, toQNm, toQNm, toToken, toToken, toTokenOrNull, toZeroToken, value

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

arg, args, atomItem, atomIter, data, data, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, optimize, simplifyFor, typeCheck, uses, vacuous, visitAll

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

toErrorString, toString

Methods inherited from class java.lang.Object

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

Method Details

get

public static Expr get(double pos,
 InputInfo ii)

Returns a position expression for the specified position, or an optimized boolean item.

Parameters:

pos - position

ii - input info

Returns:

expression

get

public static Expr get(long min,
 long max,
 InputInfo ii)

Returns a position expression for the specified range, or an optimized boolean item.

Parameters:

min - minimum position

max - minimum position (inclusive)

ii - input info

Returns:

expression

item

public Bln item(QueryContext qc,
 InputInfo ii)
         throws QueryException

Description copied from class: Expr

Evaluates the expression and returns the resulting item, or Empty.VALUE if the expression yields an empty sequence. If this method is not implemented, Expr.value(QueryContext) must be implemented instead.

Overrides:

item in class ParseExpr

Parameters:

qc - query context

ii - input info (only required by Seq instances, which have no input info)

Returns:

item or Empty.VALUE

Throws:

QueryException - query exception

exact

public boolean exact()

Description copied from interface: CmpPos

Checks if minimum and maximum expressions are identical.

Specified by:

exact in interface CmpPos

Returns:

result of check

simple

public boolean simple()

Description copied from interface: CmpPos

Checks if the positional range is deterministic.

Specified by:

simple in interface CmpPos

Returns:

result of check

test

public int test(long pos,
 QueryContext qc)

Description copied from interface: CmpPos

Checks the current position.

• Returns 2 if the test is successful and remaining test can be skipped
• Returns 1 if the test is successful
• Returns 0 otherwise

Should only be called if this is a CmpPos.simple() check.

Specified by:

test in interface CmpPos

Parameters:

pos - current position

qc - query context

Returns:

result of check

inline

public Expr inline(InlineContext ic)

Description copied from class: Expr

Inlines an expression into this one, replacing all variable or context references. This function is called by InlineContext.inline(Expr) (see invocations of this functions for further inlinings). The variable reference is replaced in:

• OrderBy.inline(org.basex.query.InlineContext)
• VarRef.inline(org.basex.query.InlineContext)

The context is replaced in:

• ContextFn.inline(org.basex.query.InlineContext)
• ContextValue.inline(org.basex.query.InlineContext)
• Arr.inline(org.basex.query.InlineContext)

Specified by:

inline in class Expr

Parameters:

ic - inlining context

Returns:

resulting expression if something has changed, null otherwise

copy

public ItrPos copy(CompileContext cc,
 IntObjMap<Var> vm)

Description copied from class: Expr

Copies an expression. Used for inlining functions, or for copying static queries. It is utilized by VarRef.inline(org.basex.query.InlineContext), FuncItem.inline(org.basex.query.expr.Expr[], org.basex.query.CompileContext), Closure.inline(org.basex.query.InlineContext) and StaticFunc.inline(org.basex.query.expr.Expr[], org.basex.query.CompileContext).

Specified by:

copy in class Expr

Parameters:

cc - compilation context

vm - mapping from old variable IDs to new variable copies. Required by Closure.copy(org.basex.query.CompileContext, org.basex.util.hash.IntObjMap<org.basex.query.var.Var>) and VarRef.copy(org.basex.query.CompileContext, org.basex.util.hash.IntObjMap<org.basex.query.var.Var>)

Returns:

copied expression

invert

public Expr invert(CompileContext cc)
            throws QueryException

Description copied from interface: CmpPos

If possible, returns an optimized expression with inverted operands.

Specified by:

invert in interface CmpPos

Parameters:

cc - compilation context

Returns:

original or modified expression

Throws:

QueryException - query exception

mergeEbv

public Expr mergeEbv(Expr ex,
 boolean or,
 CompileContext cc)

Description copied from class: Expr

Tries to merge two expressions that are part of an EBV test. Called by And, Or), Step and Filter. Overwritten by CmpG, CmpIR, CmpR, CmpSR, ItrPos, Pos and others.

Overrides:

mergeEbv in class Expr

Parameters:

ex - second expression

or - union or intersection

cc - compilation context

Returns:

optimized expression or null

has

public boolean has(Flag... flags)

Description copied from class: Expr

Indicates if an expression has one of the specified compiler properties. This method must only be called at compile time. It is invoked to test properties of sub-expressions. It returns true if at least flag matches an expression.

Overrides:

has in class Simple

Parameters:

flags - flags to be checked

Returns:

result of check

equals

public boolean equals(Object obj)

Description copied from class: Expr

This function is e.g. called by:

• If.optimize(CompileContext), Switch.optimize(CompileContext), Typeswitch.optimize(CompileContext), in order to discard identical expressions.
• CmpR.mergeEbv(Expr, boolean, CompileContext) or CmpSR.mergeEbv(Expr, boolean, CompileContext), in order to merge expressions with identical input.
• CmpG.optimize(CompileContext) or CmpV.optimize(CompileContext), in order to pre-evaluate equality tests.
• CmpG.optimize(CompileContext) or Pos.get(Expr, CmpV.OpV, InputInfo, CompileContext), in order to compare the start and end value.
• PathCache, in order to find identical root values at runtime.

Specified by:

equals in class Expr

description

public String description()

Description copied from class: ExprInfo

Returns a string description of the expression. This method is only called by error messages. Contrary to the ExprInfo.toString() method, arguments are not included in the output.

Overrides:

description in class ExprInfo

Returns:

result of check

plan

public void plan(QueryPlan plan)

Description copied from class: ExprInfo

Creates a query plan.

Overrides:

plan in class Simple

Parameters:

plan - expression plan

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