Package org.basex.query.expr

Class Arr

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.Arr

Direct Known Subclasses:

Arith, CArray, CMap, Cmp, CNode, Delete, Except, FuncCall, If, Insert, Intersect, JavaCall, List, Logical, Lookup, Otherwise, PartFunc, Preds, Range, Rename, Replace, SimpleMap, StandardFunc, SwitchGroup, Transform, TransformWith, Union

public abstract class Arr
extends ParseExpr

Abstract array expression.

Author:

BaseX Team 2005-22, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field	Description
Expr[]	exprs	Expressions.

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

exprType, info

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Arr(InputInfo info, SeqType seqType, Expr... exprs)	Constructor.

Method Summary

Modifier and Type	Method	Description
boolean	accept(ASTVisitor visitor)	Traverses this expression, notifying the visitor of declared and used variables, and checking the tree for other recursive properties.
protected boolean	allAreValues(boolean limit)	Returns true if all arguments are values (possibly of small size).
Expr[]	args()	Returns the arguments/operands of an expression (function, list, etc).
void	checkUp()	Checks if the updating semantics are satisfied.
Expr	compile(CompileContext cc)	Compiles and optimizes the expression, assigns types and cardinalities.
static <T extends Expr> T[]	copyAll(CompileContext cc, IntObjMap<Var> vm, T[] arr)	Creates a deep copy of the given array.
VarUsage	count(Var var)	Checks how often a variable or context reference is used in this expression.
boolean	equals(Object obj)	This function is e.g.
int	exprSize()	Counts the number of expressions in this expression's subtree.
protected void	flatten(CompileContext cc)	Flattens nested expressions.
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.
boolean	inlineable(InlineContext ic)	Checks if inlining is possible.
protected static boolean	mayBePositional(Expr expr)	Checks if the specified expression may be positional.
protected void	removeEmpty(CompileContext cc)	Removes empty expressions.
protected boolean	simplifyAll(CompileContext.Simplify mode, CompileContext cc)	Simplifies all expressions for requests of the specified type.
void	toXml(QueryPlan plan)	Creates a query plan.

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

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

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

arg, atomItem, atomIter, copy, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, mergeEbv, optimize, optimizePos, simplify, simplifyFor, typeCheck, uses, vacuous, visitAll

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

description, toErrorString, toString, toString

Methods inherited from class java.lang.Object

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

Field Detail

exprs

public Expr[] exprs

Expressions.

Constructor Detail

Arr

protected Arr(InputInfo info,
              SeqType seqType,
              Expr... exprs)

Constructor.

Parameters:

info - input info

seqType - sequence type

exprs - expressions

Method Detail

checkUp

public void checkUp()
             throws QueryException

Description copied from class: Expr

Checks if the updating semantics are satisfied. This function is only called if any updating expression was found in the query.

Specified by:

checkUp in class Expr

Throws:

QueryException - query exception

compile

public Expr 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

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.

Specified by:

has in class Expr

Parameters:

flags - flags to be checked

Returns:

result of check

inlineable

public boolean inlineable(InlineContext ic)

Description copied from class: Expr

Checks if inlining is possible. This function is called by InlineContext.inlineable(org.basex.query.expr.Expr...) and: CNode.inlineable(org.basex.query.InlineContext) returns false if the new expression construct new nodes. The following tests might reject inlining if the expression is a context reference:

• Preds.inlineable(org.basex.query.InlineContext)
• Path.inlineable(org.basex.query.InlineContext)
• SimpleMap.inlineable(org.basex.query.InlineContext)
• StaticJavaCall.inlineable(org.basex.query.InlineContext)
• TransformWith.inlineable(org.basex.query.InlineContext)

Specified by:

inlineable in class Expr

Parameters:

ic - inlining context

Returns:

result of check

count

public VarUsage count(Var var)

Description copied from class: Expr

Checks how often a variable or context reference is used in this expression. This function is called by:

• Closure.optimize(org.basex.query.CompileContext)
• GFLWOR.inlineForLet(org.basex.query.CompileContext)
• GFLWOR.optimizePos(org.basex.query.CompileContext)
• GFLWOR.simplify(org.basex.query.CompileContext)
• GFLWOR.unusedVars(org.basex.query.CompileContext)
• SimpleMap.optimize(org.basex.query.CompileContext)
• TypeswitchGroup.optimize(org.basex.query.CompileContext)

Specified by:

count in class Expr

Parameters:

var - variable (Var reference) or context (null) to inline

Returns:

number of usages, see VarUsage

inline

public Expr 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 these 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)
• 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

copyAll

public static <T extends Expr> T[] copyAll(CompileContext cc,
                                           IntObjMap<Var> vm,
                                           T[] arr)

Creates a deep copy of the given array.

Type Parameters:

T - element type

Parameters:

cc - compilation context

vm - variable mapping

arr - array to copy

Returns:

deep copy of the array

allAreValues

protected final boolean allAreValues(boolean limit)

Returns true if all arguments are values (possibly of small size).

Parameters:

limit - check if result size of any expression exceeds CompileContext.MAX_PREEVAL

Returns:

result of check

simplifyAll

protected final boolean simplifyAll(CompileContext.Simplify mode,
                                    CompileContext cc)
                             throws QueryException

Simplifies all expressions for requests of the specified type.

Parameters:

mode - mode of simplification

cc - compilation context

Returns:

true if at least one expression has changed

Throws:

QueryException - query exception

flatten

protected final void flatten(CompileContext cc)

Flattens nested expressions.

Parameters:

cc - compilation context

removeEmpty

protected final void removeEmpty(CompileContext cc)

Removes empty expressions.

Parameters:

cc - compilation context

mayBePositional

protected static boolean mayBePositional(Expr expr)

Checks if the specified expression may be positional.

Parameters:

expr - expression

Returns:

result of check

accept

public boolean accept(ASTVisitor visitor)

Description copied from class: Expr

Traverses this expression, notifying the visitor of declared and used variables, and checking the tree for other recursive properties.

Specified by:

accept in class Expr

Parameters:

visitor - visitor

Returns:

if the walk should be continued

args

public final Expr[] args()

Description copied from class: Expr

Returns the arguments/operands of an expression (function, list, etc).

Overrides:

args in class Expr

Returns:

arguments or null

exprSize

public int exprSize()

Description copied from class: Expr

Counts the number of expressions in this expression's subtree. This method is e.g. called by StaticFunc.inline(org.basex.query.expr.Expr[], org.basex.query.CompileContext) to check if an expression is small enough to be inlined.

Specified by:

exprSize in class Expr

Returns:

number of expressions

equals

public boolean equals(Object obj)

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), in order to compare the start and end value.
• PathCache, in order to find identical root values at runtime.

Must be overwritten by implementing class.

Specified by:

equals in class Expr

toXml

public void toXml(QueryPlan plan)

Description copied from class: ExprInfo

Creates a query plan.

Specified by:

toXml in class ExprInfo

Parameters:

plan - expression plan