NAME

DwHeaders -- Class representing the collection of header fields in a message or body part

SYNOPSIS

class DW_CORE_EXPORT DwHeaders : public DwMessageComponent {

public:

    DwHeaders();
    DwHeaders(const DwHeaders& aHeaders);
    DwHeaders(const DwString& aStr, DwMessageComponent* aParent=0);
    virtual ~DwHeaders();
    const DwHeaders& operator = (const DwHeaders& aHeaders);
    virtual void Parse();
    virtual void Assemble();
    virtual DwMessageComponent* Clone() const;
    DwBool HasBcc() const;
    DwBool HasCc() const;
    DwBool HasComments() const;
    DwBool HasDate() const;
    DwBool HasEncrypted() const;
    DwBool HasFrom() const;
    DwBool HasInReplyTo() const;
    DwBool HasKeywords() const;
    DwBool HasMessageId() const;
    DwBool HasReceived() const;
    DwBool HasReferences() const;
    DwBool HasReplyTo() const;
    DwBool HasResentBcc() const;
    DwBool HasResentCc() const;
    DwBool HasResentDate() const;
    DwBool HasResentFrom() const;
    DwBool HasResentMessageId() const;
    DwBool HasResentReplyTo() const;
    DwBool HasResentSender() const;
    DwBool HasResentTo() const;
    DwBool HasReturnPath() const;
    DwBool HasSender() const;
    DwBool HasSubject() const;
    DwBool HasTo() const;
    DwBool HasApproved() const;
    DwBool HasControl() const;
    DwBool HasDistribution() const;
    DwBool HasExpires() const;
    DwBool HasFollowupTo() const;
    DwBool HasLines() const;
    DwBool HasNewsgroups() const;
    DwBool HasOrganization() const;
    DwBool HasPath() const;
    DwBool HasSummary() const;
    DwBool HasXref() const;
    DwBool HasContentDescription() const;
    DwBool HasContentId() const;
    DwBool HasContentTransferEncoding() const;
    DwBool HasCte() const;
    DwBool HasContentType() const;
    DwBool HasMimeVersion() const;
    DwBool HasContentDisposition() const;
    DwBool HasField(const char* aFieldName) const;
    DwBool HasField(const DwString& aFieldName) const;
    DwAddressList&  Bcc();
    DwAddressList&  Cc();
    DwText&         Comments();
    DwDateTime&     Date();
    DwText&         Encrypted();
    DwMailboxList&  From();
    DwText&         InReplyTo();
    DwText&         Keywords();
    DwMsgId&        MessageId();
    DwStamp&        Received();
    DwText&         References();
    DwAddressList&  ReplyTo();
    DwAddressList&  ResentBcc();
    DwAddressList&  ResentCc();
    DwDateTime&     ResentDate();
    DwMailboxList&  ResentFrom();
    DwMsgId&        ResentMessageId();
    DwAddressList&  ResentReplyTo();
    DwMailbox&      ResentSender();
    DwAddressList&  ResentTo();
    DwAddress&      ReturnPath();
    DwMailbox&      Sender();
    DwText&         Subject();
    DwAddressList&  To();
    DwText& Approved();
    DwText& Control();
    DwText& Distribution();
    DwText& Expires();
    DwText& FollowupTo();
    DwText& Lines();
    DwText& Newsgroups();
    DwText& Organization();
    DwText& Path();
    DwText& Summary();
    DwText& Xref();
    DwText&         ContentDescription();
    DwMsgId&        ContentId();
    DwMechanism&    ContentTransferEncoding();
    DwMechanism&    Cte();
    DwMediaType&    ContentType();
    DwText&         MimeVersion();
    DwDispositionType& ContentDisposition();
    DwFieldBody& FieldBody(const char* aFieldName);
    int NumFields() const;
    void AddField(DwField* aField);
    void DeleteAllFields();
    DwField& FieldAt(int aIndex) const;
    void InsertFieldAt(int aIndex, DwField* aField);
    DwField* RemoveFieldAt(int aIndex);
    DwField* FindField(const char* aFieldName) const;
    DwField* FindField(const DwString& aFieldName) const;
    static DwHeaders* NewHeaders(const DwString& aStr,
        DwMessageComponent* aParent);
    static DwHeaders* (*sNewHeaders)(const DwString&, DwMessageComponent*);

protected:

    void _CopyFields(const DwHeaders& aHeaders);
    void _InsertFieldAt(int aIndex, DwField* aField);
    void _DeleteAllFields();

public:

    virtual void PrintDebugInfo(DW_STD ostream& aStrm, int aDepth=0) const;
    virtual void CheckInvariants() const;
};

DESCRIPTION

DwHeaders represents the collection of header fields (often called just headers) in an entity (either a message or body part), as described in RFC-822 and RFC-2045. A DwHeaders object manages a list of DwField objects, which represent the individual header fields.

In the tree (broken-down) representation of a message, a DwHeaders object is an intermediate node, having both a parent node and several child nodes. The parent node is the DwEntity object that contains it. The child nodes are the DwField objects in the list it manages. (See the man page for DwMessageComponent for a discussion of the tree representation of a message.)

Normally, you do not create a DwHeaders object directly, but you access it through the Headers() member function of DwEntity, which creates the DwHeaders object for you.

While DwHeaders has public member functions for managing the list of DwField objects it contains, you will normally use convenience functions to access the field bodies of the header fields directly. You can access the field body for a specific well-known header field by using the member function <Field>(), where <Field> is the field name of the header field with hyphens removed and the first word following a hyphen capitalized. For example, to access the field body for the "MIME-version" header field, use MimeVersion(). The member function <Field>() will create a header field with field name <Field> if such a header field does not already exist. You can check for the existence of a particular well-known header field by using the member function Has<Field>(). For example, to check for the existence of the MIME-version header field, use HasMimeVersion(). Well-known header fields are those documented in RFC-822 (standard email), RFC-1036 (USENET messages), RFC-2045 (MIME messages), and possibly other RFCs.

In the case of an extension field or user-defined field, you can access the field body of the header field by calling the member function FieldBody() with the field name as its argument. If the extension field or user-defined field does not exist, FieldBody() will create it. You can check for the existence of an extension field or user-defined field by using the member function HasField() with the field name as its argument.

DwHeaders has several other member functions provided for the sake of completeness that are not required for most applications. These functions are documented below.

Public Member Functions

DwHeaders()
DwHeaders(const DwHeaders& aHeaders)
DwHeaders(const DwString& aStr, DwMessageComponent* aParent=0)

The first constructor is the default constructor, which sets the DwHeaders object's string representation to the empty string and sets its parent to NULL.

The second constructor is the copy constructor, which performs a deep copy of aHeaders. The parent of the new DwHeaders object is set to NULL.

The third constructor copies aStr to the DwHeaders object's string representation and sets aParent as its parent. The virtual member function Parse() should be called immediately after this constructor in order to parse the string representation. Unless it is NULL, aParent should point to an object of a class derived from DwEntity.

const DwHeaders& operator = (const DwHeaders& aHeaders)

This is the assignment operator, which performs a deep copy of aHeaders. The parent node of the DwHeaders object is not changed.

virtual void Parse()

This virtual function, inherited from DwMessageComponent, executes the parse method for DwHeaders objects. The parse method creates or updates the broken-down representation from the string representation. For DwHeaders objects, DwHeaders::Parse() parses the string representation to create a list of DwField objects. This member function also calls the Parse() member function of each DwField object in its list.

You should call this member function after you set or modify the string representation, and before you access any of the header fields.

This function clears the is-modified flag.

virtual void Assemble()

This virtual function, inherited from DwMessageComponent, executes the assemble method for DwHeaders objects. The assemble method creates or updates the string representation from the broken-down representation. That is, the assemble method builds the string representation from its list of DwField objects. Before it builds the string representation, this function first calls the Assemble() member function of each DwField object in its list.

You should call this member function after you set or modify any of the header fields, and before you retrieve the string representation.

This function clears the is-modified flag.

virtual DwMessageComponent* Clone() const

This virtual function, inherited from DwMessageComponent, creates a new DwHeaders on the free store that has the same value as this DwHeaders object. The basic idea is that of a virtual copy constructor.

DwBool HasBcc() const
DwBool HasCc() const
DwBool HasComments() const
DwBool HasDate() const
DwBool HasEncrypted() const
DwBool HasFrom() const
DwBool HasInReplyTo() const
DwBool HasKeywords() const
DwBool HasMessageId() const
DwBool HasReceived() const
DwBool HasReferences() const
DwBool HasReplyTo() const
DwBool HasResentBcc() const
DwBool HasResentCc() const
DwBool HasResentDate() const
DwBool HasResentFrom() const
DwBool HasResentMessageId() const
DwBool HasResentReplyTo() const
DwBool HasResentSender() const
DwBool HasResentTo() const
DwBool HasReturnPath() const
DwBool HasSender() const
DwBool HasSubject() const
DwBool HasTo() const
DwBool HasApproved() const
DwBool HasControl() const
DwBool HasDistribution() const
DwBool HasExpires() const
DwBool HasFollowupTo() const
DwBool HasLines() const
DwBool HasNewsgroups() const
DwBool HasOrganization() const
DwBool HasPath() const
DwBool HasSummary() const
DwBool HasXref() const
DwBool HasContentDescription() const
DwBool HasContentId() const
DwBool HasContentTransferEncoding() const
DwBool HasCte() const
DwBool HasContentType() const
DwBool HasMimeVersion() const
DwBool HasContentDisposition() const

Each member function in this group returns a boolean value indicating whether a particular well-known header field is present in this object's collection of header fields.

DwBool HasField(const char* aFieldName) const
DwBool HasField(const DwString& aFieldName) const

Returns true if the header field specified by aFieldName is present in this object's collection of header fields. These member functions are used for extension fields or user-defined fields.

DwAddressList& Bcc()
DwAddressList& Cc()
DwText& Comments()
DwDateTime& Date()
DwText& Encrypted()
DwMailboxList& From()
DwText& InReplyTo()
DwText& Keywords()
DwMsgId& MessageId()
DwStamp& Received()
DwText& References()
DwAddressList& ReplyTo()
DwAddressList& ResentBcc()
DwAddressList& ResentCc()
DwDateTime& ResentDate()
DwMailboxList& ResentFrom()
DwMsgId& ResentMessageId()
DwAddressList& ResentReplyTo()
DwMailbox& ResentSender()
DwAddressList& ResentTo()
DwAddress& ReturnPath()
DwMailbox& Sender()
DwText& Subject()
DwAddressList& To()
DwText& Approved()
DwText& Control()
DwText& Distribution()
DwText& Expires()
DwText& FollowupTo()
DwText& Lines()
DwText& Newsgroups()
DwText& Organization()
DwText& Path()
DwText& Summary()
DwText& Xref()
DwText& ContentDescription()
DwMsgId& ContentId()
DwMechanism& ContentTransferEncoding()
DwMechanism& Cte()
DwMediaType& ContentType()
DwText& MimeVersion()
DwDispositionType& ContentDisposition()

Each member function in this group returns a reference to a DwFieldBody object for a particular header field. If the header field does not already exist, it is created. Use the corresponding Has<Field>() function to test if the header field already exists without creating it.

DwFieldBody& FieldBody(const char* aFieldName)

Returns a reference to the DwFieldBody object for a particular header field with field name aFieldName. If the header field does not already exist, it is created. Use HasField() to test if the header field already exists without creating it. This member function allows access to extension fields or user-defined fields.

int NumFields() const

Returns the number of DwField objects contained in this DwHeaders object.

void AddField(DwField* aField)

Appends a DwField object to the list managed by this DwHeaders object.

Any DwField objects contained in a DwHeaders object's list will be deleted by the DwHeaders object's destructor.

void DeleteAllFields()

Removes and deletes all DwField objects contained in this DwHeaders object.

DwField& FieldAt(int aIndex) const

Returns the DwField object at position aIndex in this DwHeaders object's list.

If the library is compiled to throw exceptions, the function will throw a DwBoundsException if aIndex is out of range. Otherwise, (if the library is compiled not to throw exceptions) the behavior is undefined if aIndex is out of range. Valid values for aIndex are 0 <= aIndex < NumFields().

void InsertFieldAt(int aIndex, DwField* aField)

Inserts aField into the list of DwField objects at the position given by aIndex. A value of zero for aIndex will insert aField as the first one in the list; a value of NumFields() will insert it as the last one in the list. If aIndex is less than NumFields(), the DwField objects at position aIndex or greater will be shifted down the list to make room to insert aField.

Any DwField objects contained in a DwHeaders object's list will be deleted by the DwHeaders object's destructor.

If the library is compiled to throw exceptions, the function will throw a DwBoundsException if aIndex is out of range. Otherwise, (if the library is compiled not to throw exceptions) the behavior is undefined if aIndex is out of range. Valid values for aIndex are 0 <= aIndex <= NumFields().

DwField* RemoveFieldAt(int aIndex)

Removes the DwField object at position aIndex from the list and returns it. If aIndex is less than NumFields()-1, then any DwField objects at a position greater than aIndex will be shifted up in the list after the requested DwField is removed.

If the library is compiled to throw exceptions, the function will throw a DwBoundsException if aIndex is out of range. Otherwise, (if the library is compiled not to throw exceptions) the behavior is undefined if aIndex is out of range. Valid values for aIndex are 0 <= aIndex < NumFields().

DwField* FindField(const char* aFieldName) const
DwField* FindField(const DwString& aFieldName) const

Searches for a header field by its field name. Returns NULL if the field is not found. This is an advanced function: most applications should use the <Field>() or Has<Field>() family of functions.

static DwHeaders* NewHeaders(const DwString& aStr, DwMessageComponent* aParent)

Creates a new DwHeaders object on the free store. If the static data member sNewHeaders is NULL, this member function will create a new DwHeaders and return it. Otherwise, NewHeaders() will call the user-supplied function pointed to by sNewHeaders, which is assumed to return an object from a class derived from DwHeaders, and return that object.

virtual void PrintDebugInfo(DW_STD ostream& aStrm, int aDepth=0) const

This virtual function, inherited from DwMessageComponent, prints debugging information about this object to aStrm. It will also call PrintDebugInfo() for any of its child components down to a level of aDepth.

This member function is available only in the debug version of the library.

virtual void CheckInvariants() const

Aborts if one of the invariants of the object fails. Use this member function to track down bugs.

This member function is available only in the debug version of the library.

Public Data Members

static DwHeaders* (*sNewHeaders)(const DwString&, DwMessageComponent*)

If sNewHeaders is not NULL, it is assumed to point to a user-supplied function that returns an object from a class derived from DwHeaders.

Protected Member Functions

void _CopyFields(const DwHeaders& aHeaders)

Copies the list of DwField objects from aHeaders.

void _InsertFieldAt(int aIndex, DwField* aField)

Performs all the work of adding DwField objects to the list. This function does not set the is-modified flag.

void _DeleteAllFields()

Deletes all fields. Differs from DeleteAllFields() in that it does not set the is-modified flag.