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docs/typinfo.tex
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docs/typinfo.tex
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% The TYPINFO unit
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\chapter{The TYPINFO unit}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Constants, Types and variables
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\section{Constants, Types and variables}
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\subsection{Constants}
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The following constants are used in the implementation section of the unit.
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\begin{verbatim}
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BooleanIdents: array[Boolean] of String = ('False', 'True');
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DotSep: String = '.';
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\end{verbatim}
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The following constants determine the access method for the \var{Stored}
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identifier of a property as used in the \var{PropProcs} field of the
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\var{TPropInfo} record:
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\begin{verbatim}
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ptField = 0;
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ptStatic = 1;
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ptVirtual = 2;
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ptConst = 3;
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\end{verbatim}
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The following typed constants are used for easy selection of property types.
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\begin{verbatim}
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tkAny = [Low(TTypeKind)..High(TTypeKind)];
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tkMethods = [tkMethod];
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tkProperties = tkAny-tkMethods-[tkUnknown];
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\end{verbatim}
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\subsection{types}
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The following pointer types are defined:
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\begin{verbatim}
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PShortString =^ShortString;
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PByte =^Byte;
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PWord =^Word;
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PLongint =^Longint;
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PBoolean =^Boolean;
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PSingle =^Single;
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PDouble =^Double;
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PExtended =^Extended;
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PComp =^Comp;
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PFixed16 =^Fixed16;
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Variant = Pointer;
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\end{verbatim}
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The \var{TTypeKind} determines the type of a property:
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\begin{verbatim}
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TTypeKind = (tkUnknown,tkInteger,tkChar,tkEnumeration,
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tkFloat,tkSet,tkMethod,tkSString,tkLString,tkAString,
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tkWString,tkVariant,tkArray,tkRecord,tkInterface,
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tkClass,tkObject,tkWChar,tkBool,tkInt64,tkQWord,
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tkDynArray,tkInterfaceRaw);
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tkString = tkSString;
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\end{verbatim}
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\var{tkString} is an alias that is introduced for Delphi compatibility.
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If the property is and ordinal type, then \var{TTOrdType} determines the
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size and sign of the ordinal type:
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\begin{verbatim}
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TTOrdType = (otSByte,otUByte,otSWord,otUWord,otSLong,otULong);
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\end{verbatim}
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The size of a float type is determined by \var{TFloatType}:
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\begin{verbatim}
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TFloatType = (ftSingle,ftDouble,ftExtended,ftComp,ftCurr,
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ftFixed16,ftFixed32);
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\end{verbatim}
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A method property (e.g. an event) can have one of several types:
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\begin{verbatim}
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TMethodKind = (mkProcedure,mkFunction,mkConstructor,mkDestructor,
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mkClassProcedure, mkClassFunction);
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\end{verbatim}
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The kind of parameter to a method is determined by \var{TParamFlags}:
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\begin{verbatim}
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TParamFlags = set of (pfVar,pfConst,pfArray,pfAddress,pfReference,pfOut);
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\end{verbatim}
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Interfaces are described further with \var{TntfFlags}:
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\begin{verbatim}
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TIntfFlags = set of (ifHasGuid,ifDispInterface,ifDispatch);
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\end{verbatim}
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The following defines a set of \var{TTypeKind}:
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\begin{verbatim}
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TTypeKinds = set of TTypeKind;
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\end{verbatim}
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The \var{TypeInfo} function returns a pointer to a \var{TTypeInfo} record:
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\begin{verbatim}
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TTypeInfo = record
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Kind : TTypeKind;
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Name : ShortString;
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end;
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PTypeInfo = ^TTypeInfo;
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PPTypeInfo = ^PTypeInfo;
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\end{verbatim}
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Note that the Name is stored with as much bytes as needed to store the name,
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it is not padded to 255 characters.
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The type data immediatly follows the \var{TTypeInfo} record as a \var{TTypeData} record:
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\begin{verbatim}
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PTypeData = ^TTypeData;
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TTypeData = packed record
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case TTypeKind of
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tkUnKnown,tkLString,tkWString,tkAString,tkVariant:
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();
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tkInteger,tkChar,tkEnumeration,tkWChar:
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(OrdType : TTOrdType;
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case TTypeKind of
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tkInteger,tkChar,tkEnumeration,tkBool,tkWChar : (
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MinValue,MaxValue : Longint;
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case TTypeKind of
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tkEnumeration: (
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BaseType : PTypeInfo;
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NameList : ShortString
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)
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);
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tkSet: (
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CompType : PTypeInfo
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)
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);
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tkFloat: (
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FloatType : TFloatType
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);
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tkSString:
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(MaxLength : Byte);
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tkClass:
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(ClassType : TClass;
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ParentInfo : PTypeInfo;
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PropCount : SmallInt;
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UnitName : ShortString
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);
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tkMethod:
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(MethodKind : TMethodKind;
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ParamCount : Byte;
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ParamList : array[0..1023] of Char
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{in reality ParamList is a array[1..ParamCount] of:
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record
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Flags : TParamFlags;
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ParamName : ShortString;
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TypeName : ShortString;
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end;
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followed by
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ResultType : ShortString}
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);
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tkInt64:
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(MinInt64Value, MaxInt64Value: Int64);
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tkQWord:
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(MinQWordValue, MaxQWordValue: QWord);
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tkInterface:
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();
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end;
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\end{verbatim}
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If the typeinfo kind is \var{tkClass}, then the property
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information follows the \var{UnitName} string, as an array of \var{TPropInfo} records.
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The \var{TPropData} record is not used, but is provided for completeness.
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\begin{verbatim}
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TPropData = packed record
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PropCount : Word;
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PropList : record end;
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end;
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\end{verbatim}
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The \var{TPropInfo} record describes one published property of a class:
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\begin{verbatim}
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PPropInfo = ^TPropInfo;
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TPropInfo = packed record
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PropType : PTypeInfo;
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GetProc : Pointer;
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SetProc : Pointer;
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StoredProc : Pointer;
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Index : Integer;
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Default : Longint;
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NameIndex : SmallInt;
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PropProcs : Byte;
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Name : ShortString;
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end;
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\end{verbatim}
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The \var{Name} field is stored not with 255 characters, but with just as many characters
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as required to store the name.
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\begin{verbatim}
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TProcInfoProc = procedure(PropInfo : PPropInfo) of object;
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\end{verbatim}
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The following pointer and array types are used for typecasts:
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\begin{verbatim}
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PPropList = ^TPropList;
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TPropList = array[0..65535] of PPropInfo;
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\end{verbatim}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Functions and procedures
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\section{Functions and Procedures}
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\begin{function}{GetTypeData}
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\Declaration
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Function GetTypeData(TypeInfo : PTypeInfo) : PTypeData;
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\Description
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\var{GetTypeData} returns a pointer to the \var{TTypeData} record that
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follows after the \var{TTypeInfo} record pointed to by \var{TypeInfo}.
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It essentially skips the \var{Kind} and \var{Name} fields in the
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\var{TTypeInfo} record.
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\Errors
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None.
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\SeeAlso
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\end{function}
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\begin{function}{GetPropInfo}
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\Declaration
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function GetPropInfo(TypeInfo: PTypeInfo;
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const PropName: string) : PPropInfo;
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\Description
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\var{GetPropInfo} returns a pointer to the \var{TPropInfo} record for a the \var{PropName}
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property of a class that has \var{TypeInfo} as class info.
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\Errors
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If the property \var{PropName} does not exist, \var{Nil} is returned.
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\SeeAlso
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\seep{GetPropInfos},\seef{GetPropList}
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\end{function}
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\begin{procedure}{GetPropInfos}
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\Declaration
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Procedure GetPropInfos(TypeInfo: PTypeInfo;PropList: PPropList);
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\Description
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\var{GetPropInfos} stores pointers to the property information of all published
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properties of a class with class info \var{TypeInfo} in the list pointed to by
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\var{Proplist}. The \var{PropList} pointer must point to a memory location that
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contains enough space to hold all properties of the class and its parent classes.
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\Errors
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No checks are done to see whether \var{PropList} points to a memory area that
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is big enough to hold all pointers.
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\SeeAlso
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\seef{GetPropInfo},\seef{GetPropList}
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\end{procedure}
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\begin{function}{GetPropList}
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\Declaration
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Function GetPropList(TypeInfo : PTypeInfo;
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TypeKinds : TTypeKinds;
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PropList : PPropList) : Integer;
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\Description
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\var{GetPropList} stores pointers to property information of the class with class
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info \var{TypeInfo} for properties of kind \var{TypeKinds} in the list pointed to
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by \var{Proplist}. \var{PropList} must contain enough space to hold all properties.
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The function returns the number of pointers that matched the criteria and were stored
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in \var{PropList}.
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\Errors
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No checks are done to see whether \var{PropList} points to a memory area that is big enough
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to hold all pointers.
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\SeeAlso
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\seep{GetPropInfos}, \seef{GetPropInfo}
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\end{function}
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\begin{function}{IsStoredProp}
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\Declaration
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Function IsStoredProp(Instance : TObject;PropInfo : PPropInfo) : Boolean;
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\Description
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\var{IsStoredProp} returns \var{True} if the \var{Stored} modifier evaluates
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to \var{True} for the property described by \var{PropInfo} for object
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\var{Instance}. It returns \var{False} otherwise. If the function returns
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\var{True}, this indicates that the property should be written when
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streaming the object \var{Instance}.
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If there was no \var{stored} modifier in the declaration of the property,
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\var{True} will be returned.
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\Errors
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No checking is done whether \var{Instance} is non-nil, or whether
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\var{PropInfo} describes a valid property of \var{Instance}.
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\SeeAlso
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\end{function}
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\begin{function}{GetOrdProp}
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\Declaration
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Function GetOrdProp(Instance : TObject;PropInfo : PPropInfo) : Longint;
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\Description
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\var{GetOrdProp} returns the value of the ordinal property described by
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\var{PropInfo} for the object \var{Instance}. The value is returned as a
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longint, which should be typecasted to the needed type.
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Ordinal properties that can be retrieved include:
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\begin{description}
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\item[Integers and subranges of integers] The value of the integer will be
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returned.
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\item[Enumerated types and subranges of enumerated types] The ordinal value
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of the enumerated type will be returned.
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\item[Sets] If the base type of the set has less than 31 possible values.
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If a bit is set in the return value, then the corresponding element of the
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base ordinal class of the set type must be included in the set.
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\end{description}
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\Errors
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No checking is done whether \var{Instance} is non-nil, or whether
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\var{PropInfo} describes a valid ordinal property of \var{Instance}
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\SeeAlso
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\seep{SetOrdProp}, \seef{GetStrProp}, \seef{GetFloatProp},
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\seef{GetInt64Prop},\seef{GetMethodProp}
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\end{function}
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\begin{procedure}{SetOrdProp}
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\Declaration
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Procedure SetOrdProp(Instance : TObject;PropInfo : PPropInfo; Value : Longint);
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\Description
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\var{SetOrdProp} assigns \var{Value} to the the ordinal property described by
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\var{PropInfo} for the object \var{Instance}.
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Ordinal properties that can be set include:
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\begin{description}
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\item[Integers and subranges of integers] The actual value of the integer must be
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passed.
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\item[Enumerated types and subranges of enumerated types] The ordinal value
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of the enumerated type must be passed.
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\item[Subrange types] of integers or enumerated types. Here the ordinal
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value must be passed.
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\item[Sets] If the base type of the set has less than 31 possible values.
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For each possible value; the corresponding bit of \var{Value} must be set.
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\end{description}
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\Errors
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No checking is done whether \var{Instance} is non-nil, or whether
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\var{PropInfo} describes a valid ordinal property of \var{Instance}.
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No range checking is performed.
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\SeeAlso
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\seef{GetOrdProp}, \seep{SetStrProp}, \seep{SetFloatProp},
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\seep{SetInt64Prop},\seep{SetMethodProp}
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\end{procedure}
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\begin{function}{GetStrProp}
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\Declaration
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Function GetStrProp(Instance : TObject;PropInfo : PPropInfo) : Ansistring;
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\Description
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\var{GetStrProp} returns the value of the string property described by
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\var{PropInfo} for object \var{Instance}.
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\Errors
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No checking is done whether \var{Instance} is non-nil, or whether
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\var{PropInfo} describes a valid string property of \var{Instance}.
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\SeeAlso
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\seep{SetStrProp}, \seef{GetOrdProp}, \seef{GetFloatProp},
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\seef{GetInt64Prop},\seef{GetMethodProp}
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\end{function}
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\begin{procedure}{SetStrProp}
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\Declaration
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procedure SetStrProp(Instance : TObject;PropInfo : PPropInfo;
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const Value : Ansistring);
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\Description
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\var{GetStrProp} assigns \var{Value} to the string property described by
|
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\var{PropInfo} for object \var{Instance}.
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\Errors
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No checking is done whether \var{Instance} is non-nil, or whether
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\var{PropInfo} describes a valid string property of \var{Instance}.
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\SeeAlso
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\seef{GetStrProp}, \seep{SetOrdProp}, \seep{SetFloatProp},
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\seep{SetInt64Prop},\seep{SetMethodProp}
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\end{procedure}
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\begin{function}{GetFloatProp}
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\Declaration
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Function GetFloatProp(Instance : TObject;PropInfo : PPropInfo) : Extended;
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\Description
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\var{GetFloatProp} returns the value of the float property described by
|
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\var{PropInfo} for the object \var{Instance}. All float types are converted
|
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to extended.
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||||
\Errors
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No checking is done whether \var{Instance} is non-nil, or whether
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\var{PropInfo} describes a valid float property of \var{Instance}.
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\SeeAlso
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\seep{SetFloatProp}, \seef{GetOrdProp}, \seef{GetStrProp},
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\seef{GetInt64Prop},\seef{GetMethodProp}
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\end{function}
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\begin{procedure}{SetFloatProp}
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\Declaration
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||||
Procedure SetFloatProp(Instance : TObject;
|
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PropInfo : PPropInfo;
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||||
Value : Extended);
|
||||
\Description
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||||
\var{SetFloatProp} assigns \var{Value} to the property described by
|
||||
\var{PropInfo} for the object \var{Instance}.
|
||||
\Errors
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||||
No checking is done whether \var{Instance} is non-nil, or whether
|
||||
\var{PropInfo} describes a valid float property of \var{Instance}.
|
||||
\SeeAlso
|
||||
\seef{GetFloatProp}, \seep{SetOrdProp}, \seep{SetStrProp},
|
||||
\seep{SetInt64Prop},\seep{SetMethodProp}
|
||||
|
||||
\end{procedure}
|
||||
|
||||
|
||||
\begin{function}{GetVariantProp}
|
||||
\Declaration
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||||
Function GetVariantProp(Instance : TObject;PropInfo : PPropInfo): Variant;
|
||||
\Description
|
||||
Not yet implemented. Provided for Delphi compatibility only.
|
||||
\Errors
|
||||
\SeeAlso
|
||||
\end{function}
|
||||
|
||||
|
||||
\begin{procedure}{SetVariantProp}
|
||||
\Declaration
|
||||
Procedure SetVariantProp(Instance : TObject;
|
||||
PropInfo : PPropInfo;
|
||||
Const Value: Variant);
|
||||
\Description
|
||||
Not yet implemented. Provided for Delphi compatibility only.
|
||||
\Errors
|
||||
\SeeAlso
|
||||
\end{procedure}
|
||||
|
||||
|
||||
\begin{function}{GetMethodProp}
|
||||
\Declaration
|
||||
Function GetMethodProp(Instance : TObject;PropInfo : PPropInfo) : TMethod;
|
||||
\Description
|
||||
\var{GetMethodProp} returns the method the property described by
|
||||
\var{PropInfo} for object \var{Instance}.
|
||||
The return type \var{TMethod} is defined in the \file{SysUtils} unit as:
|
||||
\begin{verbatim}
|
||||
TMethod = packed record
|
||||
Code, Data: Pointer;
|
||||
end;
|
||||
\end{verbatim}
|
||||
\var{Data} points to the instance of the class with the method \var{Code}.
|
||||
|
||||
\Errors
|
||||
No checking is done whether \var{Instance} is non-nil, or whether
|
||||
\var{PropInfo} describes a valid method property of \var{Instance}.
|
||||
\SeeAlso
|
||||
\seep{SetMethodProp}, \seef{GetOrdProp}, \seef{GetStrProp},
|
||||
\seef{GetFloatProp}, \seef{GetInt64Prop}
|
||||
\end{function}
|
||||
|
||||
|
||||
\begin{procedure}{SetMethodProp}
|
||||
\Declaration
|
||||
Procedure SetMethodProp(Instance : TObject;PropInfo : PPropInfo; const Value : TMethod);
|
||||
\Description
|
||||
\var{SetMethodProp} assigns \var{Value} to the method the property described
|
||||
by \var{PropInfo} for object \var{Instance}.
|
||||
|
||||
The type \var{TMethod} of the \var{Value} parameter is defined in the
|
||||
\file{SysUtils} unit as:
|
||||
\begin{verbatim}
|
||||
TMethod = packed record
|
||||
Code, Data: Pointer;
|
||||
end;
|
||||
\end{verbatim}
|
||||
\var{Data} should point to the instance of the class with the method \var{Code}.
|
||||
|
||||
\Errors
|
||||
No checking is done whether \var{Instance} is non-nil, or whether
|
||||
\var{PropInfo} describes a valid method property of \var{Instance}.
|
||||
\SeeAlso
|
||||
\seef{GetMethodProp}, \seep{SetOrdProp}, \seep{SetStrProp},
|
||||
\seep{SetFloatProp}, \seep{SetInt64Prop}
|
||||
\end{procedure}
|
||||
|
||||
\begin{function}{GetInt64Prop}
|
||||
\Declaration
|
||||
Function GetInt64Prop(Instance: TObject; PropInfo: PPropInfo): Int64;
|
||||
\Description
|
||||
\var{GetInt64Prop} returns the value of the property of type
|
||||
\var{Int64} that is described by \var{PropInfo} for the object
|
||||
\var{Instance}.
|
||||
|
||||
\Errors
|
||||
No checking is done whether \var{Instance} is non-nil, or whether
|
||||
\var{PropInfo} describes a valid \var{Int64} property of \var{Instance}.
|
||||
\SeeAlso
|
||||
\seep{SetInt64Prop}, \seef{GetOrdProp}, \seef{GetStrProp},
|
||||
\seef{GetFloatProp}, \seef{GetMethodProp}
|
||||
|
||||
\end{function}
|
||||
|
||||
\begin{procedure}{SetInt64Prop}
|
||||
\Declaration
|
||||
Procedure SetInt64Prop(Instance: TObject; PropInfo: PPropInfo; const Value: Int64);
|
||||
\Description
|
||||
\var{SetInt64Prop} assigns \var{Value} to the property of type
|
||||
\var{Int64} that is described by \var{PropInfo} for the object
|
||||
\var{Instance}.
|
||||
\Errors
|
||||
No checking is done whether \var{Instance} is non-nil, or whether
|
||||
\var{PropInfo} describes a valid \var{Int64} property of \var{Instance}.
|
||||
\SeeAlso
|
||||
\seef{GetInt64Prop}, \seef{GetMethodProp}, \seep{SetOrdProp}, \seep{SetStrProp},
|
||||
\seep{SetFloatProp}
|
||||
\end{procedure}
|
||||
|
||||
\begin{function}{GetEnumName}
|
||||
\Declaration
|
||||
Function GetEnumName(TypeInfo : PTypeInfo;Value : Integer) : string;
|
||||
\Description
|
||||
\var{GetEnumName} scans the type information for the enumeration type
|
||||
desribed by \var{TypeInfo} and returns the name of the enumeration
|
||||
constant for the element with ordinal value equal to \var{Value}.
|
||||
|
||||
If \var{Value} is out of range, the first element of the enumeration type
|
||||
is returned. The result is lowercased, but this may change in the future.
|
||||
|
||||
This can be used in combination with \var{GetOrdProp} to stream a property
|
||||
of an enumerated type.
|
||||
\Errors
|
||||
No check is done whether \var{TypeInfo} points to the type information
|
||||
for an enumerated type.
|
||||
\SeeAlso
|
||||
\seef{GetOrdProp}, \seef{GetEnumValue}
|
||||
\end{function}
|
||||
|
||||
\begin{function}{GetEnumValue}
|
||||
\Declaration
|
||||
Function GetEnumValue(TypeInfo : PTypeInfo;const Name : string) : Integer;
|
||||
\Description
|
||||
\var{GetEnumValue} scans the type information for the enumeration type
|
||||
described by \var{TypeInfor} and returns the ordinal value for the element
|
||||
in the enumerated type that has identifier \var{Name}. The identifier is
|
||||
searched in a case-insensitive manner.
|
||||
|
||||
This can be used to set the value of enumerated properties from a stream.
|
||||
\Errors
|
||||
If \var{Name} is not found in the list of enumerated values, then -1 is
|
||||
returned. No check is done whether \var{TypeInfo} points to the type information
|
||||
for an enumerated type.
|
||||
\SeeAlso
|
||||
\seef{GetEnumName}, \seep{SetOrdProp}
|
||||
\end{function}
|
||||
Loading…
Reference in New Issue
Block a user