org.basex.query.expr.gflwor

Class Let

java.lang.Object

org.basex.query.expr.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.gflwor.Clause

org.basex.query.expr.gflwor.ForLet

org.basex.query.expr.gflwor.Let

public final class Let
extends ForLet

FLWOR let clause, binding an expression to a variable.

Author:

BaseX Team 2005-21, BSD License, Leo Woerteler

Field Summary

Fields inherited from class org.basex.query.expr.gflwor.ForLet

expr, var

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

exprType, info

Constructor Summary

Constructors

Constructor and Description
Let(Var var, Expr expr) Constructor.
Let(Var var, Expr expr, boolean scoring) Constructor.

Method Summary

Modifier and Type	Method and Description
boolean	accept(ASTVisitor visitor) Traverses this expression, notifying the visitor of declared and used variables, and checking the tree for other recursive properties.
Let	copy(CompileContext cc, IntObjMap<Var> vm) Copies an expression.
boolean	equals(Object obj) This function is e.g.
Let	optimize(CompileContext cc) Optimizes an already compiled expression without recompiling its sub-expressions.
void	plan(QueryPlan plan) Creates a query plan.
void	plan(QueryString qs) Creates a query string.

Methods inherited from class org.basex.query.expr.gflwor.ForLet

checkUp, compile, count, exprSize, has, inline, inlineable

Methods inherited from class org.basex.query.expr.gflwor.Clause

calcSize, declares, vars

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, args, atomItem, atomIter, data, data, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, mergeEbv, simplifyFor, 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

Constructor Detail

Let

public Let(Var var,
           Expr expr)

Constructor.

Parameters:

var - variable

expr - expression

Let

public Let(Var var,
           Expr expr,
           boolean scoring)

Constructor.

Parameters:

var - variable

expr - expression

scoring - scoring flag

Method Detail

optimize

public Let optimize(CompileContext cc)
             throws QueryException

Description copied from class: Expr

Optimizes an already compiled expression without recompiling its sub-expressions.

Specified by:

optimize in class Clause

Parameters:

cc - compilation context

Returns:

optimized expression

Throws:

QueryException - query exception

copy

public Let 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 Clause

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

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.

Specified by:

accept in class Expr

Parameters:

visitor - visitor

Returns:

if the walk should be continued

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) 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.

Overrides:

equals in class ForLet

plan

public void plan(QueryPlan plan)

Description copied from class: ExprInfo

Creates a query plan.

Specified by:

plan in class ExprInfo

Parameters:

plan - expression plan

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