Package org.basex.query.expr.gflwor

Class Clause

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.gflwor.Clause

Direct Known Subclasses:

Count, ForLet, GroupBy, OrderBy, Where, Window

public abstract class Clause
extends ParseExpr

A FLWOR clause.

Author:

BaseX Team 2005-21, BSD License, Leo Woerteler

Field Summary

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

exprType, info

Method Summary

Modifier and Type	Method	Description
void	calcSize(long[] minMax)	Calculates the minimum and maximum number of results.
abstract Clause	compile(CompileContext cc)	Compiles and optimizes the expression, assigns types and cardinalities.
abstract Clause	copy(CompileContext cc, IntObjMap<Var> vm)	Copies an expression.
final boolean	declares(Var var)	Checks if the given variable is declared by this clause.
abstract Clause	inline(InlineContext ic)	Inlines an expression into this one, replacing all variable or context references.
abstract Clause	optimize(CompileContext cc)	Optimizes an already compiled expression without recompiling its sub-expressions.
final Var[]	vars()	All declared variables of this clause.

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

adoptType, atomValue, checkAllUp, checkNoEmpty, checkNoEmpty, checkNoneUp, checkNoUp, checkType, checkType, checkUp, copyType, ctxValue, ebv, item, 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

accept, arg, args, atomItem, atomIter, checkUp, count, data, data, ddo, equals, exprSize, funcType, has, hasFreeVars, indexAccessible, inlineable, isSimple, markTailCalls, mergeEbv, simplifyFor, typeCheck, uses, vacuous, visitAll

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

description, plan, plan, toErrorString, toString

Methods inherited from class java.lang.Object

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

Method Details

compile

public abstract Clause compile(CompileContext cc)
                        throws QueryException

Description copied from class: Expr

Compiles and optimizes the expression, assigns types and cardinalities.

Specified by:

compile in class Expr

Parameters:

cc - compilation context

Returns:

optimized expression

Throws:

QueryException - query exception

optimize

public abstract Clause optimize(CompileContext cc)
                         throws QueryException

Description copied from class: Expr

Optimizes an already compiled expression without recompiling its sub-expressions.

Overrides:

optimize in class Expr

Parameters:

cc - compilation context

Returns:

optimized expression

Throws:

QueryException - query exception

inline

public abstract Clause inline(InlineContext ic)
                       throws QueryException

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

Throws:

QueryException - query exception

copy

public abstract Clause 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

vars

public final Var[] vars()

All declared variables of this clause.

Returns:

declared variables

declares

public final boolean declares(Var var)

Checks if the given variable is declared by this clause.

Parameters:

var - variable

Returns:

{code true} if the variable was declared here, false otherwise

calcSize

public void calcSize(long[] minMax)

Calculates the minimum and maximum number of results.

Parameters:

minMax - minimum and maximum number of incoming tuples