Package org.basex.query.var
Class VarRef
- java.lang.Object
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- org.basex.query.expr.ExprInfo
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- org.basex.query.expr.Expr
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- org.basex.query.expr.ParseExpr
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- org.basex.query.var.VarRef
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public final class VarRef extends ParseExpr
Local Variable Reference expression.- Author:
- BaseX Team 2005-23, BSD License, Christian Gruen, Leo Woerteler
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Method Summary
All Methods Instance Methods Concrete Methods 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.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.VarUsage
count(Var v)
Checks how often a variable or context reference is used in this expression.boolean
ddo()
Indicates if this expression returns items in document order without duplicates.String
description()
Returns a string description of the expression.boolean
equals(Object obj)
This function is e.g.int
exprSize()
Counts the number of expressions in this expression's subtree.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 v)
Checks if inlining is possible.Expr
optimize(CompileContext cc)
Optimizes an already compiled expression without recompiling its sub-expressions.String
toErrorString()
Returns a string representation of the expression that can be embedded in error messages.void
toString(QueryString qs)
Creates a query string.void
toXml(QueryPlan plan)
Creates a query plan.Value
value(QueryContext qc)
Evaluates the expression and returns the resulting value.-
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, toB64OrNull, toBin, toBin, toBoolean, toBoolean, toBooleanOrFalse, toBytes, toBytes, toDouble, toDouble, toElem, toElem, toFloat, toFunction, toItem, toItem, toLong, toLong, toMap, toMap, toNode, toNode, toNodeOrNull, toNumber, toNumberOrNull, toQNm, toQNmOrNull, toString, toString, toStringOrNull, toToken, toToken, toTokenOrNull, toZeroToken
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Methods inherited from class org.basex.query.expr.Expr
arg, args, atomItem, atomIter, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, mergeEbv, optimizePos, simplify, simplifyFor, typeCheck, uses, vacuous, visitAll
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Field Detail
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var
public final Var var
Variable name.
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Method Detail
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compile
public Expr compile(CompileContext cc)
Description copied from class:Expr
Compiles and optimizes the expression, assigns types and cardinalities.
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optimize
public Expr optimize(CompileContext cc)
Description copied from class:Expr
Optimizes an already compiled expression without recompiling its sub-expressions.
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value
public Value value(QueryContext qc)
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.
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ddo
public boolean ddo()
Description copied from class:Expr
Indicates if this expression returns items in document order without duplicates.
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inlineable
public boolean inlineable(InlineContext v)
Description copied from class:Expr
Checks if inlining is possible. This function is called byInlineContext.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:- Specified by:
inlineable
in classExpr
- Parameters:
v
- inlining context- Returns:
- result of check
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count
public VarUsage count(Var v)
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)
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GFLWOR.inlineForLet(org.basex.query.CompileContext)
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GFLWOR.optimizePos(org.basex.query.CompileContext)
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GFLWOR.simplify(org.basex.query.CompileContext)
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GFLWOR.unusedVars(org.basex.query.CompileContext)
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SimpleMap.optimize(org.basex.query.CompileContext)
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TypeswitchGroup.optimize(org.basex.query.CompileContext)
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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 byInlineContext.inline(Expr)
(see invocations of these functions for further inlinings). The variable reference is replaced in: The context is replaced in:- Specified by:
inline
in classExpr
- Parameters:
ic
- inlining context- Returns:
- resulting expression if something has changed,
null
otherwise - Throws:
QueryException
- query exception
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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 byinline(org.basex.query.InlineContext)
,FuncItem.inline(org.basex.query.expr.Expr[], org.basex.query.CompileContext)
,Closure.inline(org.basex.query.InlineContext)
andStaticFunc.inline(org.basex.query.expr.Expr[], org.basex.query.CompileContext)
.- Specified by:
copy
in classExpr
- Parameters:
cc
- compilation contextvm
- mapping from old variable IDs to new variable copies. Required byClosure.copy(org.basex.query.CompileContext, org.basex.util.hash.IntObjMap<org.basex.query.var.Var>)
andcopy(org.basex.query.CompileContext, org.basex.util.hash.IntObjMap<org.basex.query.var.Var>)
- Returns:
- copied expression
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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.
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checkUp
public void checkUp()
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.
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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 returnstrue
if at least flag matches an expression.
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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 byStaticFunc.inline(org.basex.query.expr.Expr[], org.basex.query.CompileContext)
to check if an expression is small enough to be inlined.
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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)
orCmpSR.mergeEbv(Expr, boolean, CompileContext)
, in order to merge expressions with identical input.CmpG.optimize(CompileContext)
orCmpV.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.
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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 theExprInfo.toString()
method, arguments are not included in the output.- Overrides:
description
in classExprInfo
- Returns:
- result of check
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toXml
public void toXml(QueryPlan plan)
Description copied from class:ExprInfo
Creates a query plan.
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toString
public void toString(QueryString qs)
Description copied from class:ExprInfo
Creates a query string.
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toErrorString
public String toErrorString()
Description copied from class:ExprInfo
Returns a string representation of the expression that can be embedded in error messages. Defaults toExprInfo.toString()
.- Overrides:
toErrorString
in classExprInfo
- Returns:
- class name
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