Package org.basex.query.expr

Class List

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.Arr

org.basex.query.expr.List

public final class List
extends Arr

List of expressions that have been separated by commas.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Field Summary

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

exprs

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

exprType, info

Constructor Summary

Constructors

Constructor	Description
List(InputInfo info, Expr... exprs)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	checkUp()	Checks if the updating semantics are satisfied.
Expr	compile(CompileContext cc)	Compiles and optimizes the expression, assigns types and cardinalities.
Expr	copy(CompileContext cc, IntObjMap<Var> vm)	Copies an expression.
Data	data()	Returns the data reference bound to this expression.
String	description()	Returns a string description of the expression.
boolean	equals(Object obj)	This function is e.g.
static Expr	get(CompileContext cc, InputInfo ii, Expr... exprs)	Creates a new, optimized list expression, or the first expression if only one was specified.
Iter	iter(QueryContext qc)	Evaluates the expression and returns an iterator on the resulting items.
Expr	optimize(CompileContext cc)	Optimizes an already compiled expression without recompiling its sub-expressions.
void	plan(QueryString qs)	Creates a query string.
Expr	simplifyFor(CompileContext.Simplify mode, CompileContext cc)	This function is called at compile time for expressions whose operands might be simplified.
Expr	toDistinctRange()	If possible, rewrites the list to a distinct range expression.
Expr	toUnion(CompileContext cc)	If possible, rewrites the list to a union expression.
boolean	vacuous()	Tests if this is a vacuous expression (empty sequence or error function).
Value	value(QueryContext qc)	Evaluates the expression and returns the resulting value.

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

accept, allAreValues, args, copyAll, count, exprSize, flatten, has, inline, inline, inlineable, mayBePositional, plan, simplifyAll

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

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

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

arg, atomItem, atomIter, data, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, mergeEbv, typeCheck, uses, 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

Constructor Details

List

public List(InputInfo info,
 Expr... exprs)

Constructor.

Parameters:

info - input info

exprs - expressions

Method Details

get

public static Expr get(CompileContext cc,
 InputInfo ii,
 Expr... exprs)
                throws QueryException

Creates a new, optimized list expression, or the first expression if only one was specified.

Parameters:

cc - compilation context

ii - input info

exprs - one or more expressions

Returns:

filter root, path or filter expression

Throws:

QueryException - query exception

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.

Overrides:

checkUp in class Arr

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.

Overrides:

compile in class Arr

Parameters:

cc - compilation context

Returns:

optimized expression

Throws:

QueryException - query exception

optimize

public Expr 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

iter

public Iter iter(QueryContext qc)

Description copied from class: Expr

Evaluates the expression and returns an iterator on the resulting items. The implementation of this method is optional.

Overrides:

iter in class ParseExpr

Parameters:

qc - query context

Returns:

iterator

value

public Value value(QueryContext qc)
            throws QueryException

Description copied from class: Expr

Evaluates the expression and returns the resulting value. If this method is not implemented, Expr.item(QueryContext, InputInfo) must be implemented instead.

Overrides:

value in class ParseExpr

Parameters:

qc - query context

Returns:

value

Throws:

QueryException - query exception

simplifyFor

public Expr simplifyFor(CompileContext.Simplify mode,
 CompileContext cc)
                 throws QueryException

Description copied from class: Expr

This function is called at compile time for expressions whose operands might be simplified.

Overrides:

simplifyFor in class Expr

Parameters:

mode - mode of simplification

cc - compilation context

Returns:

simplified or original expression

Throws:

QueryException - query exception

See Also:

• CompileContext.Simplify

toUnion

public Expr toUnion(CompileContext cc)
             throws QueryException

If possible, rewrites the list to a union expression.

Parameters:

cc - compilation context

Returns:

union or original expression

Throws:

QueryException - query exception

toDistinctRange

public Expr toDistinctRange()

If possible, rewrites the list to a distinct range expression.

Returns:

range or original expression

copy

public Expr 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

data

public Data data()

Description copied from class: Expr

Returns the data reference bound to this expression. This method is currently overwritten by DBNode, DBNodeSeq, AxisPath and VarRef.

Overrides:

data in class Expr

Returns:

data reference (can be null)

vacuous

public boolean vacuous()

Description copied from class: Expr

Tests if this is a vacuous expression (empty sequence or error function). This check is needed for updating queries.

Overrides:

vacuous in class Expr

Returns:

result of check

equals

public boolean equals(Object obj)

Description copied from class: Arr

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.

Must be overwritten by implementing class.

Overrides:

equals in class Arr

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(QueryString qs)

Description copied from class: ExprInfo

Creates a query string.

Specified by:

plan in class ExprInfo

Parameters:

qs - query string builder