Package org.basex.query.func.fn

Class ContextFn

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.func.StandardFunc

org.basex.query.func.fn.ContextFn

Direct Known Subclasses:

FnBaseUri, FnData, FnDocumentUri, FnElementWithId, FnGenerateId, FnHasChildren, FnId, FnIdref, FnLang, FnNamespaceUri, FnNilled, FnNodeName, FnNormalizeSpace, FnNumber, FnPath, FnRoot, FnString, FnStringLength

public abstract class ContextFn
extends StandardFunc

Context-based function.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Field Summary

Fields inherited from class org.basex.query.func.StandardFunc

definition, sc

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
ContextFn()

Method Summary

Modifier and Type	Method	Description
final boolean	accept(ASTVisitor visitor)	Traverses this expression, notifying the visitor of declared and used variables, and checking the tree for other recursive properties.
final boolean	contextAccess()	Indicates if the function accesses the current context.
int	contextArg()	Argument that provides the context.
final VarUsage	count(Var var)	Checks how often a variable or context reference is used in this expression.
protected final Expr	ctxArg(int i, QueryContext qc)	Returns the specified argument, or the context value if it does not exist.
final boolean	has(Flag... flags)	Indicates if an expression has one of the specified compiler properties.
final Expr	inline(InlineContext ic)	Inlines an expression into this one, replacing all variable or context references.
boolean	inlineable()	Indicates if the function will evaluate the current context.
final Expr	simplifyEbv(Expr expr, CompileContext cc)	Optimizes EBV checks.

Methods inherited from class org.basex.query.func.StandardFunc

checkAdmin, checkArity, checkArity, checkCreate, checkData, checkPath, checkPath, coerceFunc, compileData, copy, data, data, dataLock, dateTimeToMs, description, equals, opt, optFirst, optFirst, optimize, plan, plan, serialize, simplifyArgs, toBaseUri, toBindings, toCollation, toDate, toDBNode, toEncodingOrNull, toNodeOrAtomItem, toOptions, toPath, toPath, toQuery, toQuery, vacuous

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

allAreValues, args, checkUp, compile, copyAll, exprSize, flatten, inline, inlineable, mayBePositional, simplifyAll

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

arg, atomItem, atomIter, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, mergeEbv, simplifyFor, 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

ContextFn

public ContextFn()

Method Details

contextArg

public int contextArg()

Argument that provides the context.

Returns:

context argument.

contextAccess

public final boolean contextAccess()

Indicates if the function accesses the current context.

Returns:

result of check

ctxArg

protected final Expr ctxArg(int i,
 QueryContext qc)
                     throws QueryException

Returns the specified argument, or the context value if it does not exist.

Parameters:

i - index of argument

qc - query context

Returns:

expression

Throws:

QueryException - query exception

has

public final 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 StandardFunc

Parameters:

flags - flags to be checked

Returns:

result of check

accept

public final 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.

Overrides:

accept in class Arr

Parameters:

visitor - visitor

Returns:

if the walk should be continued

inlineable

public boolean inlineable()

Indicates if the function will evaluate the current context.

Returns:

result of check

count

public final 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)

Overrides:

count in class Arr

Parameters:

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

Returns:

number of usages, see VarUsage

inline

public final 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 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:

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

Overrides:

inline in class Arr

Parameters:

ic - inlining context

Returns:

resulting expression if something has changed, null otherwise

Throws:

QueryException - query exception

simplifyEbv

public final Expr simplifyEbv(Expr expr,
 CompileContext cc)
                       throws QueryException

Optimizes EBV checks.

Parameters:

cc - compilation context

expr - context expression (can be null)

Returns:

optimized expression or null

Throws:

QueryException - query exception