condor.classad
Class Expr

Object
  |
  +--condor.classad.Expr

Direct Known Subclasses:

AttrRef, CondExpr, Constant, FuncCall, ListExpr, Op, RecordExpr, SelectExpr, SubscriptExpr

public abstract class Expr

extends Object

A node of an expression tree. An Expr is one of

RecordExpr

a "classad" of the form [name = expr, ... ],

SelectExpr

a selection from a record as in a.b,

ListExpr

a list of the form { expr1, expr2, ... },

SubscriptExpr

a selection from a list as in a[i],

CondExpr

a ternary conditional expression as in a ? b : c,

Op

a binary or unary operator applied to operand(s),

FuncCall

a call to a function with a list of argument expressions,

AttrRef

a reference to an attribute of a ClassAd in the form an identifier, or

Constant

a constant (literal) value

Version:

2.0

Author:

Marvin Solomon

See Also:

RecordExpr, SelectExpr, ListExpr, SubscriptExpr, CondExpr, Op, FuncCall, AttrRef, Constant

Nested Class Summary

protected static class

Expr.Env An environment for evaluating expressions.

Field Summary

static int	ABSOLUTE_TIME A type flag indicating that this is an absolute time value
static int	AND Token ID corresponding to the operator &&.
static int	ATTRIBUTE A type flag indicating that this is an attribute reference
static int	BIT_COMPLEMENT Token ID corresponding to the operator unary ~.
static int	BITAND Token ID corresponding to the operator &.
static int	BITOR Token ID corresponding to the operator |.
static int	BITXOR Token ID corresponding to the operator ^.
static int	BOOLEAN A type flag indicating that this is a boolean value
static int	CALL A type flag indicating that this is a function call
static int	COND A type flag indicating that this is a conditional expression
(package private) static SimpleDateFormat	dateAndTimeFormat Format for parsing ISO 8601 date and time
(package private) static SimpleDateFormat	dateFormat Format for parsing ISO 8601 date
static int	dblevel Flag to control level of verbosity of debugging input.
static int	DIFFERENT Token ID corresponding to the operator isnt .
static int	DIV Token ID corresponding to the operator /.
static int	EQUAL Token ID corresponding to the operator ==.
static int	ERROR A type flag indicating that this is an error value
static int	GREATER Token ID corresponding to the operator >.
static int	GREATER_EQ Token ID corresponding to the operator >=.
static int	INTEGER A type flag indicating that this is an integer value
static int	LEFT_SHIFT Token ID corresponding to the operator <<.
static int	LESS Token ID corresponding to the operator <.
static int	LESS_EQ Token ID corresponding to the operator <=.
static int	LIST A type flag indicating that this is a list
protected static int	MAXPREC The maximum precedence in the grammar for ClassAd expressions.
static int	MINUS Token ID corresponding to the operator -.
static int	MOD Token ID corresponding to the operator %.
static int	NOT Token ID corresponding to the operator unary !.
static int	NOT_EQUAL Token ID corresponding to the operator !=.
static int	OP A type flag indicating that this is a unary or binary operator
static String[]	opName A table mapping operator codes to character-string names.
static String[]	opNameXML A table mapping operator codes to character-string names, escaped for XML.
static int	OR Token ID corresponding to the operator ||.
static int	PLUS Token ID corresponding to the operator +.
static int	REAL A type flag indicating that this is a real value
static int	RECORD A type flag indicating that this is a record (classad)
static int	RELATIVE_TIME A type flag indicating that this is a relative time value
static int	RIGHT_SHIFT Token ID corresponding to the operator >>.
static int	SAME Token ID corresponding to the operator is .
static int	SELECTION A type flag indicating that this is a selection (a.b)
static int	STRING A type flag indicating that this is a string value
static int	SUBSCRIPT A type flag indicating that this is a selection (a.b)
static int	TIMES Token ID corresponding to the operator *.
int	type The "type" of this expression.
static int	UMINUS Token ID corresponding to the operator unary -.
static int	UNDEFINED A type flag indicating that this is an undefined value
static int	UPLUS Token ID corresponding to the operator unary +.
static int	URIGHT_SHIFT Token ID corresponding to the operator >>>.

Constructor Summary

protected

Expr(int type) Create an Expr node of a given type.

Method Summary

static void	db(boolean newline, Object msg) Debugging print.
static void	db(Object msg) Debugging print.
Expr	eval() Evaluate this Expr in a "top-level" (empty) environment.
Expr	eval(Expr.Env env) Evaluate this Expr in a given environment.
protected abstract Expr	eval1(Expr.Env env) Evaluate this Expr.
int	intValue() Convert to an integer constant if possible.
protected boolean	isConstant() Check whether this Expr is a constant.
boolean	isTrue() Convert to a boolean value.
(package private) abstract int	prec() The precedence of the operator in this expression node.
double	realValue() Convert to a double value if possible.
SelectExpr	selectExpr(String selector) A convenience function for creating a SelectExpression corresponding to ``this.selector''
String	stringValue() Convert to a String value, if possible.
SubscriptExpr	subExpr(int subscript) A convenience function for creating a SubscriptExpression corresponding to ``this[subscript]''
String	toString() Convert this Expr to a string.
abstract StringBuffer	toString(StringBuffer sb) Convert this Expr to a string, appending the result to the end of "sb".
protected String	typeName() Determine the type of this expression (for printing messages).

Methods inherited from class Object

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

Field Detail

type

public final int type

The "type" of this expression. For constants, the type is one of UNDEFINED, ERROR, BOOLEAN, INTEGER, REAL, STRING, ABSOLUTE_TIME, or RELATIVE_TIME.

For non-atomic values, the type is one of COND, OP, CALL, SELECTION, SUBSCRIPT, ATTRIBUTE, LIST, or RECORD.

The values of these constants are chosen to facilitate classifying an expression as a constant, constructed value (LIST or RECORD) or other expression.

See Also:

isConstant(), eval(condor.classad.Expr.Env)

COND

public static final int COND

A type flag indicating that this is a conditional expression

See Also:

Constant Field Values

OP

public static final int OP

A type flag indicating that this is a unary or binary operator

See Also:

Constant Field Values

CALL

public static final int CALL

A type flag indicating that this is a function call

See Also:

Constant Field Values

SELECTION

public static final int SELECTION

A type flag indicating that this is a selection (a.b)

See Also:

Constant Field Values

SUBSCRIPT

public static final int SUBSCRIPT

A type flag indicating that this is a selection (a.b)

See Also:

Constant Field Values

ATTRIBUTE

public static final int ATTRIBUTE

A type flag indicating that this is an attribute reference

See Also:

Constant Field Values

LIST

public static final int LIST

A type flag indicating that this is a list

See Also:

Constant Field Values

RECORD

public static final int RECORD

A type flag indicating that this is a record (classad)

See Also:

Constant Field Values

UNDEFINED

public static final int UNDEFINED

A type flag indicating that this is an undefined value

See Also:

Constant Field Values

ERROR

public static final int ERROR

A type flag indicating that this is an error value

See Also:

Constant Field Values

BOOLEAN

public static final int BOOLEAN

A type flag indicating that this is a boolean value

See Also:

Constant Field Values

INTEGER

public static final int INTEGER

A type flag indicating that this is an integer value

See Also:

Constant Field Values

REAL

public static final int REAL

A type flag indicating that this is a real value

See Also:

Constant Field Values

STRING

public static final int STRING

A type flag indicating that this is a string value

See Also:

Constant Field Values

ABSOLUTE_TIME

public static final int ABSOLUTE_TIME

A type flag indicating that this is an absolute time value

See Also:

Constant Field Values

RELATIVE_TIME

public static final int RELATIVE_TIME

A type flag indicating that this is a relative time value

See Also:

Constant Field Values

dateAndTimeFormat

static SimpleDateFormat dateAndTimeFormat

Format for parsing ISO 8601 date and time

dateFormat

static SimpleDateFormat dateFormat

Format for parsing ISO 8601 date

MAXPREC

protected static final int MAXPREC

The maximum precedence in the grammar for ClassAd expressions.

See Also:

Constant Field Values

dblevel

public static int dblevel

Flag to control level of verbosity of debugging input. Higher values are more verbose. If the value is zero, no debugging output is printed.

opName

public static final String[] opName

A table mapping operator codes to character-string names. For example, opName[NOT_EQUAL] = "!=".

opNameXML

public static final String[] opNameXML

A table mapping operator codes to character-string names, escaped for XML. For example, opName[LEFT_SHIFT] = "<<".

OR

public static final int OR

Token ID corresponding to the operator ||.

See Also:

Constant Field Values

AND

public static final int AND

Token ID corresponding to the operator &&.

See Also:

Constant Field Values

BITOR

public static final int BITOR

Token ID corresponding to the operator |.

See Also:

Constant Field Values

BITXOR

public static final int BITXOR

Token ID corresponding to the operator ^.

See Also:

Constant Field Values

BITAND

public static final int BITAND

Token ID corresponding to the operator &.

See Also:

Constant Field Values

EQUAL

public static final int EQUAL

Token ID corresponding to the operator ==.

See Also:

Constant Field Values

NOT_EQUAL

public static final int NOT_EQUAL

Token ID corresponding to the operator !=.

See Also:

Constant Field Values

SAME

public static final int SAME

Token ID corresponding to the operator is .

See Also:

Constant Field Values

DIFFERENT

public static final int DIFFERENT

Token ID corresponding to the operator isnt .

See Also:

Constant Field Values

LESS

public static final int LESS

Token ID corresponding to the operator <.

See Also:

Constant Field Values

GREATER

public static final int GREATER

Token ID corresponding to the operator >.

See Also:

Constant Field Values

LESS_EQ

public static final int LESS_EQ

Token ID corresponding to the operator <=.

See Also:

Constant Field Values

GREATER_EQ

public static final int GREATER_EQ

Token ID corresponding to the operator >=.

See Also:

Constant Field Values

LEFT_SHIFT

public static final int LEFT_SHIFT

Token ID corresponding to the operator <<.

See Also:

Constant Field Values

RIGHT_SHIFT

public static final int RIGHT_SHIFT

Token ID corresponding to the operator >>.

See Also:

Constant Field Values

URIGHT_SHIFT

public static final int URIGHT_SHIFT

Token ID corresponding to the operator >>>.

See Also:

Constant Field Values

PLUS

public static final int PLUS

Token ID corresponding to the operator +.

See Also:

Constant Field Values

MINUS

public static final int MINUS

Token ID corresponding to the operator -.

See Also:

Constant Field Values

TIMES

public static final int TIMES

Token ID corresponding to the operator *.

See Also:

Constant Field Values

DIV

public static final int DIV

Token ID corresponding to the operator /.

See Also:

Constant Field Values

MOD

public static final int MOD

Token ID corresponding to the operator %.

See Also:

Constant Field Values

UPLUS

public static final int UPLUS

Token ID corresponding to the operator unary +.

See Also:

Constant Field Values

UMINUS

public static final int UMINUS

Token ID corresponding to the operator unary -.

See Also:

Constant Field Values

BIT_COMPLEMENT

public static final int BIT_COMPLEMENT

Token ID corresponding to the operator unary ~.

See Also:

Constant Field Values

NOT

public static final int NOT

Token ID corresponding to the operator unary !.

See Also:

Constant Field Values

Constructor Detail

Expr

protected Expr(int type)

Create an Expr node of a given type. Used in constructors of subclasses.

Method Detail

typeName

protected String typeName()

Determine the type of this expression (for printing messages).

Returns:

a string identifing the type of this constant.

eval1

protected abstract Expr eval1(Expr.Env env)

Evaluate this Expr. This is the internal method used to implement eval(). Each type of expression implements it differently. Lists, records, and constants evaluate to themselves. Function calls and operators evaluate to the result of applying the operartor or function to the (recursively evaluated) arguments. Attribute references are evaluated by looking up the reference in the env.

Parameters:

env - an environment consisting of a list of RecordExprs (innermost first) used to resolve AttrRefs. In the case of AttrRef, env is updated to remove all scopes preceding the one where the reference was resovled.

Returns:

a Constant, AttrRef, ListExpr, or RecordExpr representing the value.

eval

public Expr eval(Expr.Env env)

Evaluate this Expr in a given environment. Lists, records, and constants evaluate to themselves. Function calls and operators evaluate to the result of applying the operartor or function to the (recursively evaluated) arguments. Attribute references are evaluated by looking up the reference in the env. If the result is an AttrRef, it is re-evalutated. If this re-evaluation leads to a cycle (an attribute defined in terms of itself), the result is the UNDEFINED constant.

Parameters:

env - an environment consisting of a list of RecordExprs (innermost first) used to resolve AttrRefs. In the case of AttrRef, env is updated to remove all scopes preceding the one where the reference was resovled.

Returns:

a Constant, ListExpr, or RecordExpr representing the value.

eval

public Expr eval()

Evaluate this Expr in a "top-level" (empty) environment. Lists, records, and constants evaluate to themselves. Function calls and operators evaluate to the result of applying the operartor or function to the (recursively evaluated) arguments. Attribute references evaluate to the UNDEFINED constant.

Returns:

a Constant, ListExpr, or RecordExpr representing the value.

selectExpr

public SelectExpr selectExpr(String selector)

A convenience function for creating a SelectExpression corresponding to ``this.selector''

Parameters:

selector - a selector.

Returns:

a new SelectExpr corresponding to ``this.selector''.

subExpr

public SubscriptExpr subExpr(int subscript)

A convenience function for creating a SubscriptExpression corresponding to ``this[subscript]''

Returns:

a new SelectExpr corresponding to ``this[subscript]''.

isConstant

protected final boolean isConstant()

Check whether this Expr is a constant.

Returns:

true if this Expr is a constant.

toString

public String toString()

Convert this Expr to a string. The representation is the "canonical native format".

Overrides:

toString in class Object

Returns:

a string representation of this Expr

See Also:

ClassAdWriter

toString

public abstract 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".

Parameters:

sb - a place to put the result.

Returns:

sb.

See Also:

ClassAdWriter

intValue

public int intValue()
             throws ArithmeticException

Convert to an integer constant if possible.

Returns:

the integer value of this Expr.

Throws:

ArithmeticException - if this Expr is not an integer Constant.

realValue

public double realValue()
                 throws ArithmeticException

Convert to a double value if possible.

Returns:

the value of of this Expr, converted to double.

Throws:

ArithmeticException - if this Expr is not an integer or real constant.

stringValue

public String stringValue()
                   throws ArithmeticException

Convert to a String value, if possible.

Returns:

the string value of this Expr.

Throws:

ArithmeticException - if this Expr is not an String Constant.

isTrue

public boolean isTrue()

Convert to a boolean value. Note that unlike intValue, etc., this method never throws an exception.

Returns:

true if this Expr is a constant of type boolean with value true, and false in all other cases.

prec

abstract int prec()

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

Returns:

the precendence of this node.

See Also:

ClassAdWriter.MINIMAL_PARENTHESES

db

public static void db(Object msg)

Debugging print. The message is printed to System.out, followed by a newline. Intended usage is something like

    if (dblevel > 1) db("The value of foo is " +foo);
 

Parameters:

msg - the message to be printed.

See Also:

dblevel

db

public static void db(boolean newline,
                      Object msg)

Debugging print. The message is printed to System.out.

Parameters:

newline - if true, terminate the message with a newline.

msg - the message to be printed.

See Also:

db(java.lang.Object)