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## org.basex.query.expr
Class Pred

    java.lang.Object
      org.basex.query.ExprInfo
          org.basex.query.expr.Expr
              org.basex.query.expr.Preds
                  org.basex.query.expr.Pred

Direct Known Subclasses:
  IterPred

    public class Pred

extends Preds

Predicate expression.

Author:
  Workgroup DBIS, University of Konstanz 2005-10, ISC License, Christian Gruen

Nested Class Summary

Nested classes/interfaces inherited from class org.basex.query.expr.Expr
`Expr.Use`

Field Summary

Fields inherited from class org.basex.query.expr.Preds
`pred`

Constructor Summary
`Pred(Expr r, Expr... p)` Constructor.

Method Summary
`Expr` | `comp(QueryContext ctx)` Optimizes and compiles the expression.
`Iter` | `iter(QueryContext ctx)` Evaluates the expression and returns an iterator on the resulting items.
`void` | `plan(Serializer ser)` Recursively sends the abstract syntax of this expression to the specified serializer.
`boolean` | `removable(Var v, QueryContext ctx)` Checks if the specified variable is removable.
`Expr` | `remove(Var v)` Removes the specified variable in a sub expression.
`String` | `toString()`
`boolean` | `uses(Expr.Use u, QueryContext ctx)` Indicates if an expression uses the specified type.

Methods inherited from class org.basex.query.expr.Preds
`color`

Methods inherited from class org.basex.query.expr.Expr
`addText, atomic, checkCtx, checkDbl, checkItr, duplicates, e, ebv, i, indexAccessible, indexEquivalent, returned, sameAs, size, test, v`

Methods inherited from class org.basex.query.ExprInfo
`info, name`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### Pred

    public Pred(Expr r,
                Expr... p)

  Constructor.

  Parameters:
    `r` - expression
    `p` - predicates

Method Detail

### comp

    public final Expr comp(QueryContext ctx)
                    throws QueryException

  Description copied from class: `Expr`
  Optimizes and compiles the expression.

  Overrides:
    `comp` in class `Preds`
  Parameters:
    `ctx` - query context
  Returns:
    optimized Expression
  Throws:
    `QueryException` - query exception

### iter

    public Iter iter(QueryContext ctx)
              throws QueryException

  Description copied from class: `Expr`
  Evaluates the expression and returns an iterator on the resulting items. If this method is not overwritten, `Expr.atomic(org.basex.query.QueryContext)` must be implemented.

  Overrides:
    `iter` in class `Expr`
  Parameters:
    `ctx` - query context
  Returns:
    resulting item
  Throws:
    `QueryException` - query exception

### uses

    public final boolean uses(Expr.Use u,
                              QueryContext ctx)

  Description copied from class: `Expr`
  Indicates if an expression uses the specified type. Called by the compiler to perform certain optimizations. `true` is returned by default and thus assumed as "worst-case".

  Overrides:
    `uses` in class `Preds`
  Parameters:
    `u` - use type to be checked
    `ctx` - query context
  Returns:
    result of check

### removable

    public final boolean removable(Var v,
                                   QueryContext ctx)

  Description copied from class: `Expr`
  Checks if the specified variable is removable.

  Overrides:
    `removable` in class `Preds`
  Parameters:
    `v` - variable to be removed
    `ctx` - query context
  Returns:
    result of check

### remove

    public final Expr remove(Var v)

  Description copied from class: `Expr`
  Removes the specified variable in a sub expression.

  Overrides:
    `remove` in class `Preds`
  Parameters:
    `v` - variable to be removed
  Returns:
    expression with removed variable

### plan

    public final void plan(Serializer ser)
                    throws IOException

  Description copied from class: `ExprInfo`
  Recursively sends the abstract syntax of this expression to the specified serializer.

  Overrides:
    `plan` in class `Preds`
  Parameters:
    `ser` - serializer
  Throws:
    `IOException` - I/O exception

### toString

    public final String toString()

  Overrides:
    `toString` in class `Preds`

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