Package org.basex.query.expr

Class SimpleMap

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.SimpleMap

Direct Known Subclasses:

CachedMap, DualMap, ItemMap, IterMap

public abstract class SimpleMap
extends Arr

Simple map operator.

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

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 void	checkUp()	Checks if the updating semantics are satisfied.
final Expr	compile(CompileContext cc)	Compiles and optimizes the expression, assigns types and cardinalities.
final VarUsage	count(Var var)	Checks how often a variable or context reference is used in this 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 map expression, or the first expression if only one was specified.
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.
final boolean	inlineable(InlineContext ic)	Checks if inlining is possible.
void	markTailCalls(CompileContext cc)	Finds and marks tail calls, enabling TCO.
final Expr	optimize(CompileContext cc)	Optimizes an already compiled expression without recompiling its sub-expressions.
void	plan(QueryString qs)	Creates a query string.
final Expr	simplifyFor(CompileContext.Simplify mode, CompileContext cc)	This function is called at compile time for expressions whose operands might be simplified.
Expr	toPath(CompileContext cc)	Converts the map to a path expression.
boolean	vacuous()	Tests if this is a vacuous expression (empty sequence or error function).

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

allAreValues, args, copyAll, exprSize, flatten, inline, 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, 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, copy, data, ddo, funcType, hasFreeVars, indexAccessible, isSimple, 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

Method Details

get

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

Creates a new, optimized map 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 final 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

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

compile

public final 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 final 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

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)

toPath

public Expr toPath(CompileContext cc)
            throws QueryException

Converts the map to a path expression.

Parameters:

cc - compilation context

Returns:

converted or original expression

Throws:

QueryException - query context

simplifyFor

public final 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

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 Arr

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

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)
• 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

inlineable

public final 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)
• inlineable(org.basex.query.InlineContext)
• StaticJavaCall.inlineable(org.basex.query.InlineContext)
• TransformWith.inlineable(org.basex.query.InlineContext)

Overrides:

inlineable in class Arr

Parameters:

ic - inlining context

Returns:

result of check

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:

• ContextFn.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

markTailCalls

public void markTailCalls(CompileContext cc)

Description copied from class: Expr

Finds and marks tail calls, enabling TCO.

Overrides:

markTailCalls in class Expr

Parameters:

cc - compilation context, null if the changes should not be reported

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