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299 lines
13 KiB
299 lines
13 KiB
15 years ago
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<HTML>
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<HEAD>
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<TITLE> DwMessageComponent Man Page </TITLE>
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</HEAD>
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<BODY BGCOLOR="#FFFFFF">
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<H2>
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<FONT COLOR="navy"> NAME </FONT>
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</H2>
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<P>
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DwMessageComponent -- Abstract base class for all message components
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<H2>
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<FONT COLOR="navy"> SYNOPSIS </FONT>
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</H2>
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<PRE>class DW_EXPORT DwMessageComponent {
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public:
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enum componentType {
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kCidError=-1,
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kCidUnknown=0,
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kCidAddress,
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kCidAddressList,
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kCidBody,
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kCidBodyPart,
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kCidDispositionType,
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kCidMechanism,
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kCidMediaType,
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kCidParameter,
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kCidDateTime,
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kCidEntity,
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kCidField,
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kCidFieldBody,
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kCidGroup,
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kCidHeaders,
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kCidMailbox,
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kCidMailboxList,
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kCidMessage,
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kCidMessageComponent,
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kCidMsgId,
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kCidText
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};
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<A HREF="msgcmp.html#DwMessageComponent">DwMessageComponent</A>();
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<A HREF="msgcmp.html#DwMessageComponent">DwMessageComponent</A>(const DwMessageComponent& aCmp);
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<A HREF="msgcmp.html#DwMessageComponent">DwMessageComponent</A>(const DwString& aStr, DwMessageComponent* aParent=0);
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virtual ~DwMessageComponent();
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const DwMessageComponent& <A HREF="msgcmp.html#op_eq">operator =</A> (const DwMessageComponent& aCmp);
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virtual void <A HREF="msgcmp.html#Parse">Parse</A>() = 0;
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virtual void <A HREF="msgcmp.html#Assemble">Assemble</A>() = 0;
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virtual DwMessageComponent* <A HREF="msgcmp.html#Clone">Clone</A>() const = 0;
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void <A HREF="msgcmp.html#FromString">FromString</A>(const DwString& aStr);
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void <A HREF="msgcmp.html#FromString">FromString</A>(const char* aCstr);
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const DwString& <A HREF="msgcmp.html#AsString">AsString</A>();
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DwMessageComponent* <A HREF="msgcmp.html#Parent">Parent</A>();
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void <A HREF="msgcmp.html#SetParent">SetParent</A>(DwMessageComponent* aParent);
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DwBool <A HREF="msgcmp.html#IsModified">IsModified</A>() const;
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void <A HREF="msgcmp.html#SetModified">SetModified</A>();
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int <A HREF="msgcmp.html#ClassId">ClassId</A>() const;
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const char* <A HREF="msgcmp.html#ClassName">ClassName</A>() const;
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int <A HREF="msgcmp.html#ObjectId">ObjectId</A>() const;
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protected:
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DwString mString;
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DwBool mIsModified;
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DwMessageComponent* mParent;
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componentType mClassId;
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const char* mClassName;
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public:
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virtual void <A HREF="msgcmp.html#PrintDebugInfo">PrintDebugInfo</A>(ostream& aStrm, int aDepth=0) const;
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virtual void <A HREF="msgcmp.html#CheckInvariants">CheckInvariants</A>() const;
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protected:
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void _PrintDebugInfo(ostream& aStrm) const;
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};
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</PRE>
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<H2>
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<FONT COLOR="navy"> DESCRIPTION </FONT>
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</H2>
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<P>
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<B><TT>DwMessageComponent</TT></B> is the root of an inheritance hierarchy
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from which all MIME message components are derived. Thus,
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<B><TT>DwMessageComponent</TT></B> defines important features that are inherited
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by nearly all other classes that represent components of a MIME message.
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These features are the following:
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<P>
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<UL>
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<LI>
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A string representation. The <B><TT>DwMessageComponent</TT></B> class provides
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a member function <B><TT>FromString(const DwString&)</TT></B> to set
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the string representation and a member function
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<B><TT>AsString()</TT></B> to get the string representation.
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<P>
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<LI>
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A broken-down, or parsed, representation. An RFC-822 date-time, for example,
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has a year, month, day, hour, minute, second, and time zone as elements of
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its broken-down representation. <B><TT>DwMessageComponent</TT></B> does not
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deal directly with the broken-down representation, since it is
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component-specific. Derived classes bear all the responsibility for their
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broken-down representations.
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<P>
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<LI>
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A parse method to extract the broken-down representation from the string
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representation. In the <B><TT>DwDateTime</TT></B> class, for example, the
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parse method extracts the year, month, day, hour, minute, second, and time
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zone from the RFC-822 <I>date-time</I> contained in the string representation.
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<B><TT>DwMessageComponent</TT></B> provides a pure virtual function
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<B><TT>Parse()</TT></B>, which executes the parse method for a derived class.
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<P>
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<LI>
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An assemble method to convert the broken-down representation to a string
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representation. This is the opposite of the parse method. In the
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<B><TT>DwDateTime</TT></B> class, for example, the assemble method creates
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an RFC-822 <I>date-time</I> string from values of the year, month, day, hour,
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minute, second, and time zone. <B><TT>DwMessageComponent</TT></B> provides
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a pure virtual function <B><TT>Assemble()</TT></B>, which executes the assemble
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method for a derived class.
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<P>
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<LI>
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An is-modified flag. When the string representation and the broken-down
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representation are consistent, the assemble method does not need to be executed.
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The is-modified flag is cleared when the two representations are consistent,
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and is set when they are inconsistent. The flag is set automatically whenever
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a <B><TT>DwMessageComponent</TT></B> object's broken-down representation
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is changed by calling one of the object's member functions, and it is cleared
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when the assemble or parse method is executed.
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<B><TT>DwMessageComponent</TT></B> also provides a member function
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<B><TT>SetModified()</TT></B> which forces the is-modified flag to be set.
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<P>
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<LI>
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A parent. Most message components are part of another component. A collection
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of headers is part of a message or body part, a header field is part of a
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collection of headers, a field-body is part of a header field, and so on.
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The parent of a component is the component that contains it. This tree structure
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is important, since a component's parent must be parsed before the component
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can be. Also, a component's string representation must be assembled before
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its parent's. To maintain consistency in the tree, whenever a component's
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is-modified flag is set, the component notifies its parent to also set its
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is-modified flag. In this way, an is-modified flag set anywhere in the tree
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always propagates up to the root component.
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<P>
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<LI>
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Children. The preceding discussion about a component's parent is relevant
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to an understanding of a component's children. A component's parse method
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calls the parse methods of its children after it has executed its own parse
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method (and, in some cases, created all of its children). Also, a component
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typically calls the assemble method of its children before it executes its
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own. A component's child may request that the component set its is-modified
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flag. <B><TT>DwMessageComponent</TT></B> does not deal directly with children.
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Derived classes bear all the responsibility for handling their children.
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</UL>
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<H2>
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<FONT COLOR="navy"> Public Member Functions </FONT>
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</H2>
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<P>
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<FONT COLOR="teal"><B> <A NAME="DwMessageComponent">DwMessageComponent</A>()
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<BR>
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DwMessageComponent(const DwMessageComponent& aCmp) <BR>
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DwMessageComponent(const DwString& aStr, DwMessageComponent* aParent=0)
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</B></FONT>
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<P>
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The first constructor is the default constructor, which sets the
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<B><TT>DwMessageComponent</TT></B> object's string representation to the
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empty string and sets its parent to NULL.
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<P>
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The second constructor is the copy constructor, which performs a deep copy
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of <B><TT>aCmp</TT></B>. The parent of the new
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<B><TT>DwMessageComponent</TT></B> object is set to NULL.
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<P>
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The third constructor copies <B><TT>aStr</TT></B> to the new
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<B><TT>DwMessageComponent</TT></B> object's string representation and sets
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<B><TT>aParent</TT></B> as its parent. In typical cases, the virtual member
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function <B><TT>Parse()</TT></B> should be called immediately after this
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constructor to parse the new <B><TT>DwMessageComponent</TT></B> object and
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all of its children into their broken-down representations.
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<P>
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<FONT COLOR="teal"><B> const DwMessageComponent& <A NAME="op_eq">operator
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=</A> (const DwMessageComponent& aCmp) </B></FONT>
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<P>
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This is the assignment operator, which performs a deep copy of
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<B><TT>aCmp</TT></B>.
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<P>
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<FONT COLOR="teal"><B> virtual void <A NAME="Parse">Parse</A>() = 0
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</B></FONT>
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<P>
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A pure virtual function which provides an interface to the parse method.
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The parse method, implemented in derived classes, is responsible for extracting
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the broken-down representation from the string representation. In some derived
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classes, such as <B><TT>DwHeaders</TT></B>, the parse method is also responsible
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for creating the children of the object. (In the case of
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<B><TT>DwHeaders</TT></B>, the children created are the
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<B><TT>DwField</TT></B> objects that represent the <I>field</I>s contained
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in the <I>headers</I>.) The <B><TT>Parse()</TT></B> function always calls
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the <B><TT>Parse()</TT></B> function of all of its children.
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<P>
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<FONT COLOR="teal"><B> virtual void <A NAME="Assemble">Assemble</A>() = 0
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</B></FONT>
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<P>
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A pure virtual function which provides an interface to the assemble method.
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The assemble method, implemented in derived classes, is responsible for creating
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the string representation from the broken-down representation. In other words,
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the assemble method is the opposite of the parse method. Before assembling
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its string representation, the assemble method calls the assemble method
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of each of its children. In this way, the entire tree structure that represents
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a message may be traversed. If the is-modifed flag for a
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<B><TT>DwMessageComponent</TT></B> is cleared, the
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<B><TT>Assemble()</TT></B> function will return immediately without calling
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the <B><TT>Assemble()</TT></B> function of any of its children.
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<P>
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<FONT COLOR="teal"><B> virtual DwMessageComponent*
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<A NAME="Clone">Clone</A>() const = 0 </B></FONT>
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<P>
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Creates a new <B><TT>DwMessageComponent</TT></B> on the free store that is
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of the same type as, and has the same value as, this object. The basic idea
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is that of a ``virtual copy constructor.''
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<P>
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<FONT COLOR="teal"><B> void <A NAME="FromString">FromString</A>(const
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DwString& aStr) <BR>
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void FromString(const char* aCstr) </B></FONT>
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<P>
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Sets the object's string representation. <B><TT>aCstr</TT></B> must be
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NUL-terminated. This member function does not invoke the parse method. Typically,
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the virtual member function <B><TT>Parse()</TT></B> should be called immediately
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after this member function to parse the
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<B><TT>DwMessageComponent</TT></B> object and all of its children into their
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broken-down representations. See also
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<B><TT>DwMessageComponent::Parse()</TT></B>
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<P>
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<FONT COLOR="teal"><B> const DwString& <A NAME="AsString">AsString</A>()
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</B></FONT>
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<P>
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Returns the <B><TT>DwMessageComponent</TT></B> object's string representation.
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The assemble method is not called automatically. Typically, the
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<B><TT>Assemble()</TT></B> member function should be called immediately before
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this member function to insure that the broken-down representation and the
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string representation are consistent. See also
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<B><TT>DwMessageComponent::Assemble()</TT></B>.
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<P>
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<FONT COLOR="teal"><B> DwMessageComponent* <A NAME="Parent">Parent</A>()
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</B></FONT>
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<P>
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Returns the <B><TT>DwMessageComponent</TT></B> object that is the parent
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of this object.
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<P>
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<FONT COLOR="teal"><B> void
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<A NAME="SetParent">SetParent</A>(DwMessageComponent* aParent) </B></FONT>
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<P>
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Sets <B><TT>aParent</TT></B> as the <B><TT>DwMessageComponent</TT></B> object's
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parent.
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<P>
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<FONT COLOR="teal"><B> DwBool <A NAME="IsModified">IsModified</A>() const
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</B></FONT>
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<P>
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Returns 1 if the is-modified flag is set for this
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<B><TT>DwMessageComponent</TT></B> object.
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<P>
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<FONT COLOR="teal"><B> void <A NAME="SetModified">SetModified</A>()
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</B></FONT>
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<P>
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Sets the is-modified (dirty) flag for this
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<B><TT>DwMessageComponent</TT></B> object and notifies the object's parent
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to also set its is-modified flag.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="ClassId">ClassId</A>() const </B></FONT>
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<P>
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Returns an integer id for the object's class.
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<P>
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<FONT COLOR="teal"><B> const char* <A NAME="ClassName">ClassName</A>() const
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</B></FONT>
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<P>
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Returns the name of the class as a NUL-terminated char string.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="ObjectId">ObjectId</A>() const
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</B></FONT>
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<P>
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Returns a object id that is unique among all DwMessageComponent objects.
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<P>
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<FONT COLOR="teal"><B> virtual void
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<A NAME="PrintDebugInfo">PrintDebugInfo</A>(ostream& aStrm, int aDepth=0)
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const </B></FONT>
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<P>
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This virtual function prints debugging information about this object to
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<B><TT>aStrm</TT></B>. It will also call <B><TT>PrintDebugInfo()</TT></B>
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for any of its child components down to a level of
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<B><TT>aDepth</TT></B>.
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<P>
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This member function is available only in the debug version of the library.
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<P>
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<FONT COLOR="teal"><B> virtual void
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<A NAME="CheckInvariants">CheckInvariants</A>() const </B></FONT>
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<P>
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Aborts if one of the invariants of the object fails. Use this member function
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to track down bugs.
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<P>
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This member function is available only in the debug version of the library.
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</BODY></HTML>
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