condor.classad
Class Constant

Object
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  +--condor.classad.Expr
        |
        +--condor.classad.Constant

public class Constant

extends Expr

A constant (Integer, Real, etc.). The constant is wrapped so that it may be used as a node in an expression tree. To conserve space, there is at most one Constant instance with any given value.

Version:

2.0

Author:

Marvin Solomon

See Also:

Expr

Nested Class Summary

Nested classes inherited from class condor.classad.Expr

Expr.Env

Field Summary

static Constant	CyclicRef An undefined constant that represents the result a attempting to resovle a cyclic attribute reference as in [a=b;b=a].
static Constant	Error A default error constant
static Constant	False The unique boolean Constant false
static Constant	True The unique boolean constant true
static Constant	Undef A default undefined constant
Object	value The actual value of this Constant.

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

Method Summary

static Constant	bool(boolean b) Convenience function: Convert a boolean to Constant.True or Constant.False.
static Constant	error(String msg) Convenience function: Create an ERROR constant containing a particular message.
static StringBuffer	escapeString(StringBuffer sb, String s, char quote) Append to sb a quoted version of string, replacing non-printable values by backslash escapes.
protected Expr	eval1(Expr.Env env) Evaluate this Expr.
static Constant	getInstance(char[] buf, int start, int stop) Create a String Constant from a character array, processing backslash escapes.
static Constant	getInstance(Date value) Create an absolute time Constant.
static Constant	getInstance(double value) Returns the unique real constant with value "value", creating one if necessary.
static Constant	getInstance(int value) Returns the unique integer constant with value "value", creating one if necessary.
static Constant	getInstance(long value) Returns the unique time constant with value "value", creating one if necessary.
static Constant	getInstance(String value) Returns the unique String constant with value "value", creating one if necessary.
int	intValue() Get the integer value of this Constant if possible.
boolean	isTrue() Convenience function to test whether an expression is the constant TRUE.
long	milliseconds() Convert a time value to milliseconds.
(package private) static Date	parseAbsTime(String s) Helper function for absTime(String).
(package private) static long	parseRelTime(String s) Helper function for relTime(String).
int	prec() The precedence of this expression node (MAXPREC).
double	realValue() Get the double floating point value of this Constant if possible.
(package private) static String	rel2str(long t) Format a relative time value as a readable String.
String	stringValue() Get the string value of this Constant if possible.
StringBuffer	toString(StringBuffer sb) Convert this Expr to a string, appending the result to the end of "sb".
static Constant	undefined(String msg) Convenience function: Create an UNDEFINED constant containing a particular message.
(package private) static String	unquoteString(char[] buf, int start, int stop) Generate a string from an array of characters, processing backslash escapes.

Methods inherited from class condor.classad.Expr

db, db, eval, eval, isConstant, selectExpr, subExpr, toString, typeName

Methods inherited from class Object

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

Field Detail

value

public final Object value

The actual value of this Constant. Usage depends on type:

UNDEFINED

A String error message.

ERROR

A String error message.

BOOLEAN

null (there are only two Boolean Constants).

INTEGER

An Integer value.

REAL

A Double value.

STRING

A String value.

ABSOLUTE_TIME

A java.util.Date value.

RELATIVE_TIME

A Long value (number of milliseconds).

Undef

public static final Constant Undef

A default undefined constant

CyclicRef

public static final Constant CyclicRef

An undefined constant that represents the result a attempting to resovle a cyclic attribute reference as in [a=b;b=a].

Error

public static final Constant Error

A default error constant

True

public static final Constant True

The unique boolean constant true

False

public static final Constant False

The unique boolean Constant false

Method Detail

getInstance

public static final Constant getInstance(int value)

Returns the unique integer constant with value "value", creating one if necessary.

Parameters:

value - the value of the Constant.

Returns:

a new INTEGER constant.

getInstance

public static final Constant getInstance(double value)

Returns the unique real constant with value "value", creating one if necessary.

Parameters:

value - the value of the Constant.

Returns:

a new REAL constant.

getInstance

public static final Constant getInstance(String value)

Returns the unique String constant with value "value", creating one if necessary.

Parameters:

value - the value of the Constant, not including any surrounding quotes.

Returns:

a new STRING constant.

getInstance

public static final Constant getInstance(char[] buf,
                                         int start,
                                         int stop)

Create a String Constant from a character array, processing backslash escapes. Any surrounding quotes have already been stripped.

Parameters:

buf - the array of characters.

start - the index preceding the first character to be used.

stop - the index following the last characater to be used.

Returns:

a new STRING constant.

getInstance

public static final Constant getInstance(Date value)

Create an absolute time Constant.

Parameters:

value - the value of the Constant.

Returns:

a new ABSTIME constant.

getInstance

public static final Constant getInstance(long value)

Returns the unique time constant with value "value", creating one if necessary.

Parameters:

value - the value of the constant in milliseconds

Returns:

a new RELTIME constant.

eval1

protected Expr eval1(Expr.Env env)

Evaluate this Expr. This is the internal method used to implement Expr.eval().

Specified by:

eval1 in class Expr

Parameters:

env - an environment used to evaluate the operands. It is cleared to the null environment before return.

Returns:

this Constant.

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

error

public static Constant error(String msg)

Convenience function: Create an ERROR constant containing a particular message.

Parameters:

msg - the message.

Returns:

the Constant.

undefined

public static Constant undefined(String msg)

Convenience function: Create an UNDEFINED constant containing a particular message.

Parameters:

msg - the message.

Returns:

the Constant.

bool

public static Constant bool(boolean b)

Convenience function: Convert a boolean to Constant.True or Constant.False.

Parameters:

b - the boolean value.

Returns:

the Constant.

intValue

public int intValue()
             throws ArithmeticException

Get the integer value of this Constant if possible.

Overrides:

intValue in class Expr

Returns:

the integer value of this IntegerConstant.

Throws:

ArithmeticException - if this Constant is not an integer.

realValue

public double realValue()
                 throws ArithmeticException

Get the double floating point value of this Constant if possible.

Overrides:

realValue in class Expr

Returns:

the real value of this RealConstant or the value of this IntegerConstant converted to double.

Throws:

ArithmeticException - if this Constant is not an instance of IntegerConstant or RealConstant.

stringValue

public String stringValue()
                   throws ArithmeticException

Get the string value of this Constant if possible.

Overrides:

stringValue in class Expr

Returns:

the string value of this StringConstant.

Throws:

ArithmeticException - if this Constant is not an instance of StringConstant.

isTrue

public boolean isTrue()

Convenience function to test whether an expression is the constant TRUE. Note that unlike inValue, etc., this method never throws an exception.

Overrides:

isTrue in class Expr

Returns:

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

milliseconds

public long milliseconds()
                  throws ArithmeticException

Convert a time value to milliseconds.

Returns:

the number of milliseconds (since 1/1/70 for ABSOLUTE_TIME values).

Throws:

ArithmeticException - if this Constant is not a time value.

prec

public int prec()

The precedence of this expression node (MAXPREC). Used to print expressions without superfluous parentheses.

Specified by:

prec in class Expr

Returns:

the precendence of this node.

See Also:

ClassAdWriter.MINIMAL_PARENTHESES

unquoteString

static final String unquoteString(char[] buf,
                                  int start,
                                  int stop)

Generate a string from an array of characters, processing backslash escapes. The the characters buf[start+1] ... buf[stop-1] are converted to a String, after replacing backslash escapes such as \n by their values.

Parameters:

buf - the array of characters.

start - the index of the first character to be used.

stop - the index following the last characater to be used.

Returns:

the converted String.

escapeString

public static StringBuffer escapeString(StringBuffer sb,
                                        String s,
                                        char quote)

Append to sb a quoted version of string, replacing non-printable values by backslash escapes. The result starts and ends with quote; any embedded occurrences of quote are preceded by backslashes. Any non-printing characters are escaped with a single-character escape (such as \n) if possible, otherwise \ooo, where ooo is a three-digit octal code.

Note that Unicode is not supported: We assume the value of every character is in the range 0..0377.

Parameters:

sb - a place to put the result.

s - the string to be quoted.

quote - the quote character (' or ").

Returns:

sb.

rel2str

static final String rel2str(long t)

Format a relative time value as a readable String. The result is a string of of the form days+hh:mm:ss.mmm, where leading components are omitted if they are zero. For example,

• ten milliseconds becomes ".010".
• twelve minutes and thirty-four seconds becomes "12:34.000"

Parameters:

t - the number to be converted, in milliseconds.

Returns:

the resulting String.

parseRelTime

static long parseRelTime(String s)

Helper function for relTime(String). Convert a relative time pattern of the form days+hh:mm:ss[.msec] into a number of milliseconds.

Parameters:

s - the string to parse.

Returns:

a number of milliseconds, or -1 for errors.

parseAbsTime

static Date parseAbsTime(String s)

Helper function for absTime(String). Convert an absolute time pattern of the form yyyymmddThhmmss to a Date.

Parameters:

s - the string to parse.

Returns:

the corresponding Date, or null for errors.