Package com.prineside.luaj

Class LuaNil

java.lang.Object

com.prineside.luaj.Varargs

com.prineside.luaj.LuaValue

com.prineside.luaj.LuaNil

Direct Known Subclasses:

LuaValue.None

public class LuaNil
extends LuaValue

Class to encapsulate behavior of the singleton instance nil

There will be one instance of this class, LuaValue.NIL, per Java virtual machine. However, the Varargs instance LuaValue.NONE which is the empty list, is also considered treated as a nil value by default.

Although it is possible to test for nil using Java == operator, the recommended approach is to use the method LuaValue.isnil() instead. By using that any ambiguities between LuaValue.NIL and LuaValue.NONE are avoided.

See Also:

• LuaValue
• LuaValue.NIL

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LuaNil.Serializer

Nested classes/interfaces inherited from class com.prineside.luaj.LuaValue

LuaValue.NillableSerializer, LuaValue.None

Nested classes/interfaces inherited from class com.prineside.luaj.Varargs

Varargs.ArrayVarargs

Field Summary

Fields inherited from class com.prineside.luaj.LuaValue

ADD, CALL, CONCAT, DIV, EMPTYSTRING, ENV, EQ, FALSE, INDEX, IPAIRS, LE, LEN, LT, METATABLE, MINUSONE, MOD, MODE, MUL, NEWINDEX, NIL, NILLABLE_SERIALIZER, NILS, NONE, NOVALS, ONE, PAIRS, POW, SUB, TBOOLEAN, TFUNCTION, TINT, TLIGHTUSERDATA, TNIL, TNONE, TNUMBER, TOSTRING, TRUE, TSTRING, TTABLE, TTHREAD, TUSERDATA, TVALUE, TYPE_NAMES, UNM, ZERO

Method Summary

Modifier and Type	Method	Description
final LuaValue	checknotnil()	Check that this is not the value LuaValue.NIL, or throw LuaError if it is
final boolean	equals(Object o)
final LuaValue	getmetatable()	Get the metatable for this LuaValue
final boolean	isnil()	Check if this is #NIL
final boolean	isvalidkey()	Return true if this is a valid key in a table index operation.
final LuaValue	not()	Unary not: return inverse boolean value (~this) as defined by lua not operator
final boolean	optboolean(boolean defval)	Check that optional argument is a boolean and return its boolean value
final LuaClosure	optclosure(LuaClosure defval)	Check that optional argument is a closure and return as LuaClosure
final double	optdouble(double defval)	Check that optional argument is a number or string convertible to number and return as double
final LuaFunction	optfunction(LuaFunction defval)	Check that optional argument is a function and return as LuaFunction
final int	optint(int defval)	Check that optional argument is a number or string convertible to number and return as int
final String	optjstring(String defval)	Check that optional argument is a string or number and return as Java String
final long	optlong(long defval)	Check that optional argument is a number or string convertible to number and return as long
final LuaNumber	optnumber(LuaNumber defval)	Check that optional argument is a number or string convertible to number and return as LuaNumber
final LuaString	optstring(LuaString defval)	Check that optional argument is a string or number and return as LuaString
final LuaTable	opttable(LuaTable defval)	Check that optional argument is a table and return as LuaTable
final Object	optuserdata(Class c, Object defval)	Check that optional argument is a userdata whose instance is of a type and return the Object instance
final Object	optuserdata(Object defval)	Check that optional argument is a userdata and return the Object instance
final LuaValue	optvalue(LuaValue defval)	Perform argument check that this is not nil or none.
final boolean	toboolean()	Convert to boolean false if LuaValue.NIL or LuaValue.FALSE, true if anything else
String	tojstring()	Convert to human readable String for any type.
final String	toString()	Convert the value to a human readable string using LuaValue.tojstring()
final int	type()	Get the enumeration value for the type of this value.
final String	typename()	Get the String name of the type of this value.

Methods inherited from class com.prineside.luaj.LuaValue

add, add, add, and, arg, arg1, argerror, assert_, buffer, call, call, call, call, call, cBool, cDouble, cFloat, checkboolean, checkclosure, checkdouble, checkfunction, checkglobals, checkint, checkjstring, checklong, checknumber, checknumber, checkstring, checktable, checkuserdata, checkuserdata, cInt, cNcDouble, cNcFloat, cNcInt, cObject, comparemt, concat, concat, concatmt, concatTo, concatTo, concatTo, cRegObject, div, div, div, divInto, eq, eq_b, eqmtcall, error, get, get, get, gt, gt, gt, gt_b, gt_b, gt_b, gteq, gteq, gteq, gteq_b, gteq_b, gteq_b, inext, initupvalue1, invoke, invoke, invoke, invoke, invoke, invokemethod, invokemethod, invokemethod, invokemethod, isboolean, isclosure, isfunction, isint, isinttype, islong, isnumber, isRegObject, isstring, istable, isuserdata, isuserdata, len, length, listOf, listOf, load, lt, lt, lt, lt_b, lt_b, lt_b, lteq, lteq, lteq, lteq_b, lteq_b, lteq_b, metatag, method, method, method, method, method, method, mod, mod, mod, modFrom, mul, mul, mul, narg, neg, neq, neq_b, next, onInvoke, or, pow, pow, pow, powWith, powWith, presize, raweq, raweq, raweq, raweq, raweq, rawget, rawget, rawget, rawlen, rawset, rawset, rawset, rawset, rawset, rawset, rawset, rawsetlist, set, set, set, set, set, set, set, setmetatable, strcmp, strcmp, strongvalue, strvalue, sub, sub, sub, subargs, subFrom, subFrom, tableOf, tableOf, tableOf, tableOf, tableOf, tableOf, tailcallOf, testfor_b, tobyte, tochar, todouble, tofloat, toint, tolong, tonumber, toshort, tostring, touserdata, touserdata, userdataOf, userdataOf, valueOf, valueOf, valueOf, valueOf, valueOf, valueOf, varargsOf, varargsOf, varargsOf, varargsOf, varargsOf, varargsOf

Methods inherited from class com.prineside.luaj.Varargs

argcheck, checkboolean, checkclosure, checkdouble, checkfunction, checkint, checkjstring, checklong, checknotnil, checknumber, checkstring, checktable, checkuserdata, checkuserdata, checkvalue, dealias, eval, isfunction, isnil, isnoneornil, isnumber, isstring, istable, isTailcall, isuserdata, isvalue, optboolean, optclosure, optdouble, optfunction, optint, optjstring, optlong, optnumber, optstring, opttable, optuserdata, optuserdata, optvalue, toboolean, tobyte, tochar, todouble, tofloat, toint, tojstring, tolong, toshort, touserdata, touserdata, type

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Details

type

public final int type()

Description copied from class: LuaValue

Get the enumeration value for the type of this value.

Specified by:

type in class LuaValue

Returns:

value for this type, one of LuaValue.TNIL, LuaValue.TBOOLEAN, LuaValue.TNUMBER, LuaValue.TSTRING, LuaValue.TTABLE, LuaValue.TFUNCTION, LuaValue.TUSERDATA, LuaValue.TTHREAD

See Also:

• LuaValue.typename()

toString

public final String toString()

Description copied from class: LuaValue

Convert the value to a human readable string using LuaValue.tojstring()

Overrides:

toString in class LuaValue

Returns:

String value intended to be human readible.

See Also:

• LuaValue.tostring()
• LuaValue.tojstring()
• LuaValue.optstring(LuaString)
• LuaValue.checkstring()
• LuaValue.toString()

typename

public final String typename()

Description copied from class: LuaValue

Get the String name of the type of this value.

Specified by:

typename in class LuaValue

Returns:

name from type name list LuaValue.TYPE_NAMES corresponding to the type of this value: "nil", "boolean", "number", "string", "table", "function", "userdata", "thread"

See Also:

• LuaValue.type()

tojstring

public String tojstring()

Description copied from class: LuaValue

Convert to human readable String for any type.

Overrides:

tojstring in class LuaValue

Returns:

String for use by human readers based on type.

See Also:

• LuaValue.tostring()
• LuaValue.optjstring(String)
• LuaValue.checkjstring()
• LuaValue.isstring()
• LuaValue.TSTRING

not

public final LuaValue not()

Description copied from class: LuaValue

Unary not: return inverse boolean value (~this) as defined by lua not operator

Overrides:

not in class LuaValue

Returns:

LuaValue.TRUE if LuaValue.NIL or LuaValue.FALSE, otherwise LuaValue.FALSE

toboolean

public final boolean toboolean()

Description copied from class: LuaValue

Convert to boolean false if LuaValue.NIL or LuaValue.FALSE, true if anything else

Overrides:

toboolean in class LuaValue

Returns:

Value cast to byte if number or string convertible to number, otherwise 0

See Also:

• LuaValue.optboolean(boolean)
• LuaValue.checkboolean()
• LuaValue.isboolean()
• LuaValue.TBOOLEAN

isnil

public final boolean isnil()

Description copied from class: LuaValue

Check if this is #NIL

Overrides:

isnil in class LuaValue

Returns:

true if this is #NIL, otherwise false

See Also:

• LuaValue.NIL
• LuaValue.NONE
• LuaValue.checknotnil()
• LuaValue.optvalue(LuaValue)
• Varargs.isnoneornil(int)
• LuaValue.TNIL
• LuaValue.TNONE

getmetatable

public final LuaValue getmetatable()

Description copied from class: LuaValue

Get the metatable for this LuaValue

For LuaTable and LuaUserdata instances, the metatable returned is this instance metatable. For all other types, the class metatable value will be returned.

Overrides:

getmetatable in class LuaValue

Returns:

metatable, or null if it there is none

equals

public final boolean equals(Object o)

Overrides:

equals in class LuaValue

checknotnil

public final LuaValue checknotnil()

Description copied from class: LuaValue

Check that this is not the value LuaValue.NIL, or throw LuaError if it is

Overrides:

checknotnil in class LuaValue

Returns:

this if it is not LuaValue.NIL

See Also:

• LuaValue.optvalue(LuaValue)

isvalidkey

public final boolean isvalidkey()

Description copied from class: LuaValue

Return true if this is a valid key in a table index operation.

Overrides:

isvalidkey in class LuaValue

Returns:

true if valid as a table key, otherwise false

See Also:

• LuaValue.isnil()
• LuaValue.isinttype()

optboolean

public final boolean optboolean(boolean defval)

Description copied from class: LuaValue

Check that optional argument is a boolean and return its boolean value

Overrides:

optboolean in class LuaValue

Parameters:

defval - boolean value to return if this is nil or none

Returns:

this cast to boolean if a LuaBoolean, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.checkboolean()
• LuaValue.isboolean()
• LuaValue.TBOOLEAN

optclosure

public final LuaClosure optclosure(LuaClosure defval)

Description copied from class: LuaValue

Check that optional argument is a closure and return as LuaClosure

A LuaClosure is a LuaFunction that executes lua byteccode.

Overrides:

optclosure in class LuaValue

Parameters:

defval - LuaClosure to return if this is nil or none

Returns:

this cast to LuaClosure if a function, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.checkclosure()
• LuaValue.isclosure()
• LuaValue.TFUNCTION

optdouble

public final double optdouble(double defval)

Description copied from class: LuaValue

Check that optional argument is a number or string convertible to number and return as double

Overrides:

optdouble in class LuaValue

Parameters:

defval - double to return if this is nil or none

Returns:

this cast to double if numeric, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.optint(int)
• LuaValue.checkdouble()
• LuaValue.todouble()
• LuaValue.tonumber()
• LuaValue.isnumber()
• LuaValue.TNUMBER

optfunction

public final LuaFunction optfunction(LuaFunction defval)

Description copied from class: LuaValue

Check that optional argument is a function and return as LuaFunction

A LuaFunction may either be a Java function that implements functionality directly in Java, or a LuaClosure which is a LuaFunction that executes lua bytecode.

Overrides:

optfunction in class LuaValue

Parameters:

defval - LuaFunction to return if this is nil or none

Returns:

this cast to LuaFunction if a function, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.checkfunction()
• LuaValue.isfunction()
• LuaValue.TFUNCTION

optint

public final int optint(int defval)

Description copied from class: LuaValue

Check that optional argument is a number or string convertible to number and return as int

Overrides:

optint in class LuaValue

Parameters:

defval - int to return if this is nil or none

Returns:

this cast to int if numeric, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.optdouble(double)
• LuaValue.optlong(long)
• LuaValue.checkint()
• LuaValue.toint()
• LuaValue.tonumber()
• LuaValue.isnumber()
• LuaValue.TNUMBER

optlong

public final long optlong(long defval)

Description copied from class: LuaValue

Check that optional argument is a number or string convertible to number and return as long

Overrides:

optlong in class LuaValue

Parameters:

defval - long to return if this is nil or none

Returns:

this cast to long if numeric, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.optdouble(double)
• LuaValue.optint(int)
• LuaValue.checkint()
• LuaValue.toint()
• LuaValue.tonumber()
• LuaValue.isnumber()
• LuaValue.TNUMBER

optnumber

public final LuaNumber optnumber(LuaNumber defval)

Description copied from class: LuaValue

Check that optional argument is a number or string convertible to number and return as LuaNumber

Overrides:

optnumber in class LuaValue

Parameters:

defval - LuaNumber to return if this is nil or none

Returns:

this cast to LuaNumber if numeric, defval if nil or none, throws LuaError otherwise

See Also:

• LuaValue.optdouble(double)
• LuaValue.optlong(long)
• LuaValue.optint(int)
• LuaValue.checkint()
• LuaValue.toint()
• LuaValue.tonumber()
• LuaValue.isnumber()
• LuaValue.TNUMBER

opttable

public final LuaTable opttable(LuaTable defval)

Description copied from class: LuaValue

Check that optional argument is a table and return as LuaTable

Overrides:

opttable in class LuaValue

Parameters:

defval - LuaTable to return if this is nil or none

Returns:

this cast to LuaTable if a table, defval if nil or none, throws LuaError if some other type

See Also:

• LuaValue.checktable()
• LuaValue.istable()
• LuaValue.TTABLE

optjstring

public final String optjstring(String defval)

Description copied from class: LuaValue

Check that optional argument is a string or number and return as Java String

Overrides:

optjstring in class LuaValue

Parameters:

defval - LuaString to return if this is nil or none

Returns:

this converted to String if a string or number, defval if nil or none, throws LuaError if some other type

See Also:

• LuaValue.tojstring()
• LuaValue.optstring(LuaString)
• LuaValue.checkjstring()
• LuaValue.toString()
• LuaValue.TSTRING

optstring

public final LuaString optstring(LuaString defval)

Description copied from class: LuaValue

Check that optional argument is a string or number and return as LuaString

Overrides:

optstring in class LuaValue

Parameters:

defval - LuaString to return if this is nil or none

Returns:

this converted to LuaString if a string or number, defval if nil or none, throws LuaError if some other type

See Also:

• LuaValue.tojstring()
• LuaValue.optjstring(String)
• LuaValue.checkstring()
• LuaValue.toString()
• LuaValue.TSTRING

optuserdata

public final Object optuserdata(Object defval)

Description copied from class: LuaValue

Check that optional argument is a userdata and return the Object instance

Overrides:

optuserdata in class LuaValue

Parameters:

defval - Object to return if this is nil or none

Returns:

Object instance of the userdata if a LuaUserdata, defval if nil or none, throws LuaError if some other type

See Also:

• LuaValue.checkuserdata()
• LuaValue.isuserdata()
• LuaValue.optuserdata(Class, Object)
• LuaValue.TUSERDATA

optuserdata

public final Object optuserdata(Class c,
 Object defval)

Description copied from class: LuaValue

Check that optional argument is a userdata whose instance is of a type and return the Object instance

Overrides:

optuserdata in class LuaValue

Parameters:

c - Class to test userdata instance against

defval - Object to return if this is nil or none

Returns:

Object instance of the userdata if a LuaUserdata and instance is assignable to c, defval if nil or none, throws LuaError if some other type

See Also:

• LuaValue.checkuserdata(Class)
• LuaValue.isuserdata(Class)
• LuaValue.optuserdata(Object)
• LuaValue.TUSERDATA

optvalue

public final LuaValue optvalue(LuaValue defval)

Description copied from class: LuaValue

Perform argument check that this is not nil or none.

Overrides:

optvalue in class LuaValue

Parameters:

defval - LuaValue to return if this is nil or none

Returns:

this if not nil or none, else defval

See Also:

• LuaValue.NIL
• LuaValue.NONE
• LuaValue.isnil()
• Varargs.isnoneornil(int)
• LuaValue.TNIL
• LuaValue.TNONE