condor.classad
Class SubscriptExpr

Object
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  +--condor.classad.Expr
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        +--condor.classad.SubscriptExpr

public class SubscriptExpr

extends Expr

A selection from a list. An internal (non-leaf) node of an expression tree representing a subscript applied to base expression: base[selector]. Two combinations of types are possible: Either the base is a ListExpr and the selector evaluates to an integer, or the base is a RecordExpr and the subscript evaluates to a string. In the latter case, base["x"] is equivalent to base.x except that the "selector" does not have to be a literal string.

Version:

2.0

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 subscript operator.
Expr	selector The right argument (subscript) of the selection operator.

Fields inherited from class condor.classad.Expr

ABSOLUTE_TIME, AND, ATTRIBUTE, BIT_COMPLEMENT, BITAND, BITOR, BITXOR, BOOLEAN, CALL, COND, dateAndTimeFormat, dateFormat, 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

SubscriptExpr(Expr base, Expr selector)
Create a new SubscriptExpr.

Method Summary

protected Expr	eval1(Expr.Env env) Evaluate this Expr.
int	prec() The precedence of the operator in this expression node.
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 subscript operator.

selector

public final Expr selector

The right argument (subscript) of the selection operator.

Constructor Detail

SubscriptExpr

public SubscriptExpr(Expr base,
                     Expr selector)

Create a new SubscriptExpr.

Parameters:

base - the left argument (base expression).

selector - the right argument (subscript).

Method Detail

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".

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 and selector should evaluate to a List and an integer or a Record and a string. In the latter case, this SubscriptExpr is semantically equivalent to a SelectExpr. In either case, the appropriate component of the base value is then returned. If the types of the base and selector do not mactch, the result is the ERROR constant.

Specified by:

eval1 in class Expr

Parameters:

env - an environment used to evaluate the base and selector; it is updated to the resulting environment from the evaluation of the base.

Returns:

the result of the subscripting operation.