condor.classad
Class SelectExpr

Object
  condor.classad.Expr
      condor.classad.SelectExpr

public class SelectExpr

extends Expr

An internal (non-leaf) node of an expression tree, representing a selection of component of a record. It has the form from a class ad in the form

    <expr> . <identifier>.
 

Version:

2.1

Author:

Marvin Solomon

See Also:

Expr

Nested Class Summary

Nested classes inherited from class condor.classad.Expr

Expr.Env

Field Summary

Expr	base The left argument (base expression) of the selection operator.
AttrName	selector The right argument (identifier) of the selection operator.

Fields inherited from class condor.classad.Expr

ABSOLUTE_TIME, AND, ATTRIBUTE, BIT_COMPLEMENT, BITAND, BITOR, BITXOR, BOOLEAN, CALL, COND, dblevel, DIFFERENT, DIV, EQUAL, ERROR, GREATER, GREATER_EQ, INTEGER, LEFT_SHIFT, LESS, LESS_EQ, LIST, MAXPREC, MINUS, MOD, NOT, NOT_EQUAL, OP, opName, opNameXML, OR, PLUS, REAL, RECORD, RELATIVE_TIME, RIGHT_SHIFT, SAME, SELECTION, STRING, SUBSCRIPT, TIMES, type, UMINUS, UNDEFINED, UPLUS, URIGHT_SHIFT

Constructor Summary

SelectExpr(Expr base, AttrName selector)
Create a new SelectExpr corresponding to base.selector.

SelectExpr(Expr base, String selector)
Create a new SelectExpr corresponding to base.selector.

Method Summary

protected Expr	eval1(Expr.Env env) Evaluate this Expr.
int	prec() The precedence of the operator in this expression node.
static Expr	select(Expr base, String[] sel) A convenience function for creating a SelectExpression corresponding to "base.a.b.c".
StringBuffer	toString(StringBuffer sb) Convert this Expr to a string, appending the result to the end of "sb".
protected String	typeName() The type of the expression.

Methods inherited from class condor.classad.Expr

db, db, eval, eval, intValue, isConstant, isTrue, realValue, selectExpr, stringValue, subExpr, toString

Methods inherited from class Object

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

Field Detail

base

public final Expr base

The left argument (base expression) of the selection operator.

selector

public final AttrName selector

The right argument (identifier) of the selection operator.

Constructor Detail

SelectExpr

public SelectExpr(Expr base,
                  String selector)

Create a new SelectExpr corresponding to base.selector.

Parameters:

base - the left argument (base expression).

selector - the right argument (identifier).

SelectExpr

public SelectExpr(Expr base,
                  AttrName selector)

Create a new SelectExpr corresponding to base.selector.

Parameters:

base - the left argument (base expression).

selector - the right argument (identifier).

Method Detail

select

public static Expr select(Expr base,
                          String[] sel)

A convenience function for creating a SelectExpression corresponding to "base.a.b.c".

Parameters:

base - the base Expr.

sel - the sequence of selectors {"a", "b", "c"}

Returns:

a new SelectExpr or base if sel is empty.

typeName

protected String typeName()

The type of the expression. This should never be called!

Overrides:

typeName in class Expr

Returns:

the string "selection".

toString

public StringBuffer toString(StringBuffer sb)

Convert this Expr to a string, appending the result to the end of "sb". The representation is the "canonical native format": base '.' selector, with no extra spaces.

Specified by:

toString in class Expr

Parameters:

sb - a place to put the result.

Returns:

sb.

See Also:

ClassAdWriter

prec

public int prec()

The precedence of the operator in this expression node. Used to print expressions without superfluous parentheses.

Specified by:

prec in class Expr

Returns:

the precendence of this node.

See Also:

ClassAdWriter.MINIMAL_PARENTHESES

eval1

protected Expr eval1(Expr.Env env)

Evaluate this Expr. This is the internal method used to implement Expr.eval(). The base is evaluated to yield a record or list. In the case of a record, the selector is used to choose the appropriate component, and the record is added to the environment. In the case of a list, the selection is distributed across the list. In all other cases, the result is the ERROR constant.

Specified by:

eval1 in class Expr

Parameters:

env - an environment used to evaluate the base. If the base evaluates to a RecordExpr, it is added to the env (as the first (innermost) scope) before returning.

Returns:

the result of the selection.