Fb Query Symbol

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Fb_Query_Symbol

Intrinsic define (macro) performed by the compiler, and its associated sub-macros.

Syntax

__FB_QUERY_SYMBOL__( what, sym )

Parameters

• sym
• b

Description

__FB_QUERY_SYMBOL__ is a generic built-in macro for querying compiler symbol internals.

In the file ./inc/fbc-int/symbol.bi, many convenient and specialized sub-macros with 'is' as name prefix ('isXXXXX') are also defined (where 'XXXXX' stands for the kind of query).
They help the user to indirectly call the generic built-in macro __FB_QUERY_SYMBOL__ without knowing the encoding of its first parameter and its return value, but passing the only sym parameter to those sub-macros which only return -1 (for True) or 0 (for False).

For three of the query types, convenient and specialized sub-macros are available:

• 'class of symbols' (like variable, constant, procedure, namespace, ...),
• 'class of data' (like integer, float, string, UDT, ...),
• 'type of data' (like boolean, byte, ubyte, short, ...).

in order to test whether a symbol matches an element of the considered family.

Remarks

Usage

The ./inc/fbc-int/symbol.bi header exposes internals of the compiler through the built-in macro __FB_QUERY_SYMBOL__.

In addition, many convenient sub-macros with 'is' as name prefix (also defined in the file ./inc/fbc-int/symbol.bi) help the user to indirectly call the generic built-in macro __FB_QUERY_SYMBOL__:

#include once "fbc-int/symbol.bi"

using FBC

' then:

Dim b As Boolean

...

b = isXXXXX( sym )

Differences from QB

• New to FreeBASIC

Examples

Using convenient sub-macros from the ./inc/fbc-int/symbol.bi file (indirectly calling __FB_QUERY_SYMBOL__)

#include Once "fbc-int/symbol.bi"

Using FBC

Type T

    i As Integer

End Type

Dim x As T

Print isUDT( T )       '' returns -1 (true)

Print isVariable( T )  '' returns 0 (false)

Print isUDT( x )       '' returns 0 (false)

Print isVariable( x )  '' returns -1 (true)

Sleep

Using directly __FB_QUERY_SYMBOL__ and some declarations from the ./inc/fbc-int/symbol.bi file to output the data class of a symbol:

#include Once "fbc-int/symbol.bi"

Using FBC

Function dataclassToStr( ByVal classid As fbc.FB_DATACLASS ) As String

    Static As ZString Ptr classnames _

        ( FB_DATACLASS.FB_DATACLASS_INTEGER To FB_DATACLASS.FB_DATACLASS_UDT ) _

        = { @"integer", @"float", @"string", @"udt" }

    Select Case classid

    Case LBound(classnames) To UBound(classnames)

        Return *classnames(classid)

    Case Else

        Return "*invalid*"

    End Select

End Function

#macro show_dataclass( sym )

    Scope

        Var classid = __FB_QUERY_SYMBOL__( FB_QUERY_SYMBOL.dataclass, sym )

        Print Left( "   [" & classid & "] " & dataclassToStr(classid) + Space(16), 16 ) & ": ";

        Print #sym

    End Scope

#endmacro

Dim As Byte b

Dim As Double d

Dim As String s

Type T

    Dim As Long l

End Type

Dim As T t1

Print "EXAMPLES OF '__FB_QUERY_SYMBOL__( FB_QUERY_SYMBOL.dataclass, sym )':"

show_dataclass( b )

show_dataclass( d )

show_dataclass( s )

show_dataclass( T )

show_dataclass( T.l )

show_dataclass( t1 )

show_dataclass( t1.l )

Sleep

Using directly __FB_QUERY_SYMBOL__ and some declarations from the ./inc/fbc-int/symbol.bi file to output the typename as text, the typename as text with special characters replaced with '_', and the decorated (mangled) type name (WIP), of a symbol:

#include Once "fbc-int/symbol.bi"

Using FBC

Namespace NS

    Type T

        Dim As Const String Const Ptr Ptr pps

    End Type

End Namespace

#print TypeOf(NS.T.pps)

Print "type name    : " & __FB_QUOTE__( __FB_QUERY_SYMBOL__( FB_QUERY_SYMBOL.typename, NS.T.pps ) )

Print "type name id : " & __FB_QUOTE__( __FB_QUERY_SYMBOL__( FB_QUERY_SYMBOL.typenameid, NS.T.pps ) )

Print "mangled type : " & __FB_QUOTE__( __FB_QUERY_SYMBOL__( FB_QUERY_SYMBOL.mangletype, NS.T.pps ) )

Sleep

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Category: Intrinsic Defines
Kind: keyword

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.