Package org.basex.query.expr

Class TypeCheck

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.Single

org.basex.query.expr.TypeCheck

Direct Known Subclasses:

Treat

public class TypeCheck
extends Single

Checks the argument expression's result type.

Author:

BaseX Team 2005-21, BSD License, Leo Woerteler

Field Summary

Fields

Modifier and Type	Field	Description
final boolean	promote	Flag for function conversion.

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

expr

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

exprType, info

Constructor Summary

Constructors

Constructor	Description
TypeCheck(StaticContext sc, InputInfo info, Expr expr, SeqType seqType, boolean promote)	Constructor.

Method Summary

Modifier and Type	Method	Description
final Expr	check(Expr ex, CompileContext cc)	Creates an expression that checks the given expression's return type.
final Expr	compile(CompileContext cc)	Compiles and optimizes the expression, assigns types and cardinalities.
final Expr	copy(CompileContext cc, IntObjMap<Var> vm)	Copies an expression.
final Data	data()	Returns the data reference bound to this expression.
final boolean	equals(Object obj)	This function is e.g.
QueryError	error()	Returns the used error code.
final boolean	isRedundant(Var var)	Checks if this type check is redundant if the result is bound to the given variable.
final Iter	iter(QueryContext qc)	Evaluates the expression and returns an iterator on the resulting items.
final Expr	optimize(CompileContext cc)	Optimizes an already compiled expression without recompiling its sub-expressions.
final void	plan(QueryPlan plan)	Creates a query plan.
final 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.
final Value	value(QueryContext qc)	Evaluates the expression and returns the resulting value.

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

accept, checkUp, count, exprSize, has, inline, inlineable

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, args, atomItem, atomIter, data, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, mergeEbv, typeCheck, uses, vacuous, visitAll

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

description, toErrorString, toString

Methods inherited from class java.lang.Object

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

Field Details

promote

public final boolean promote

Flag for function conversion.

Constructor Details

TypeCheck

public TypeCheck(StaticContext sc,
 InputInfo info,
 Expr expr,
 SeqType seqType,
 boolean promote)

Constructor.

Parameters:

sc - static context

info - input info

expr - expression to be promoted

seqType - type to promote to

promote - flag for function promotion

Method Details

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 Single

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 Single

Parameters:

cc - compilation context

Returns:

optimized expression

Throws:

QueryException - query exception

iter

public final Iter iter(QueryContext qc)
                throws QueryException

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

Throws:

QueryException - query exception

value

public final 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 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

isRedundant

public final boolean isRedundant(Var var)

Checks if this type check is redundant if the result is bound to the given variable.

Parameters:

var - variable

Returns:

result of check

check

public final Expr check(Expr ex,
 CompileContext cc)
                 throws QueryException

Creates an expression that checks the given expression's return type.

Parameters:

ex - expression to check

cc - compilation context

Returns:

the resulting expression, or null if no type check is necessary

Throws:

QueryException - query exception

error

public QueryError error()

Returns the used error code.

Returns:

error code

copy

public final 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 final 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)

equals

public final boolean equals(Object obj)

Description copied from class: Single

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 Single

plan

public final void plan(QueryPlan plan)

Description copied from class: ExprInfo

Creates a query plan.

Overrides:

plan in class Single

Parameters:

plan - expression plan

plan

public final void plan(QueryString qs)

Description copied from class: ExprInfo

Creates a query string.

Specified by:

plan in class ExprInfo

Parameters:

qs - query string builder