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<HTML><!-- -- Copyright (c) 1996-1999 -- Silicon Graphics Computer Systems, Inc. -- -- Permission to use, copy, modify, distribute and sell this software -- and its documentation for any purpose is hereby granted without fee, -- provided that the above copyright notice appears in all copies and -- that both that copyright notice and this permission notice appear -- in supporting documentation. Silicon Graphics makes no -- representations about the suitability of this software for any -- purpose. It is provided "as is" without express or implied warranty. -- -- Copyright (c) 1994 -- Hewlett-Packard Company -- -- Permission to use, copy, modify, distribute and sell this software -- and its documentation for any purpose is hereby granted without fee, -- provided that the above copyright notice appears in all copies and -- that both that copyright notice and this permission notice appear -- in supporting documentation. 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It is provided "as is" without express or implied warranty. -- --><Head><Title>sequence_buffer<Container, buf_sz></Title><!-- Generated by htmldoc --></HEAD><BODY TEXT="#000000" LINK="#006600" ALINK="#003300" VLINK="#7C7F87" BGCOLOR="#FFFFFF"><A HREF="/"><IMG SRC="/images/common/sgilogo_small.gif" ALT="SGI Logo" WIDTH="80" HEIGHT="72" BORDER="0"></A><P><!--end header--><BR Clear><H1>sequence_buffer<Container, buf_sz></H1><Table CellPadding=0 CellSpacing=0 width=100%><TR><TD Align=left><Img src = "iterators.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD><TD Align=right><Img src = "type.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD></TR><TR><TD Align=left><Img src = "adaptors.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD><TD Align=right></TD></TR><TR><TD Align=left VAlign=top><b>Categories</b>: iterators, adaptors</TD><TD Align=right VAlign=top><b>Component type</b>: type</TD></TR></Table><h3>Description</h3><tt>Sequence_buffer</tt> is similar to <tt><A href="back_insert_iterator.html">back_insert_iterator</A></tt>: it is an <A href="OutputIterator.html">output iterator</A> adaptor that appends elements to the endof a container. <P>The main difference between <tt>sequence_buffer</tt> and <tt><A href="back_insert_iterator.html">back_insert_iterator</A></tt> is that <tt><A href="back_insert_iterator.html">back_insert_iterator</A></tt> inserts elements into a sequence one element at a time; <tt>sequence_buffer</tt>, however, as the "buffer" part of the name suggests, accumulates elements into a buffer and appends theentire buffer in a single operation.<P>Specifically, the expression <tt>*it = v</tt> adds <tt>v</tt>to the end of <tt>it</tt>'s internal buffer. The buffer is automaticallyflushed when it gets full, or when <tt>it</tt> is destroyed; flushing thebuffer means emptying it and appending its contents to<tt>it</tt>'s underlying container. (It is also possible to flush thebuffer manually, by invoking the <tt>flush()</tt> member function.)<P>This difference has two implications. First, <tt>sequence_buffer</tt>is only useful if appending an array of <tt>N</tt> elements is much moreefficient than inserting a single element <tt>N</tt> times. Second,<tt>sequence_buffer</tt> assumes that it can insert elements at theend of a container using an <tt>append</tt> member function. Thismember function is <i>not</i> part of the <A href="Container.html">Container</A> or<A href="Sequence.html">Sequence</A> requirements. The <tt>sequence_buffer</tt> adaptor canbe used with <tt><A href="Rope.html">rope</A></tt>, but not with any of the other containersin the library. (This is the reason why <tt>sequence_buffer</tt> isdefined in the file <A href="rope.h">rope.h</A>, instead of in <A href="iterator.h">iterator.h</A>.)<P>If you want to build up a string one character at a time, it ismuch more efficient to use <tt>sequence_buffer</tt> than to repeatedly add single characters to the end of a <tt>rope</tt>.<h3>Example</h3><pre>int main(){ const char* const s = "this is a test"; const int N = strlen(s); crope r; transform(s, s + N, sequence_buffer<crope>(r), toupper); cout << "r = " << r << endl;}</pre><h3>Definition</h3>Defined in the header <A href="rope">rope</A>, and in the backward-compatibilityheader <A href="rope.h">rope.h</A>. The <tt>sequence_buffer</tt> class, and the <A href="rope">rope</A>header, are SGI extensions; they are not part of the C++ standard.<h3>Template parameters</h3><Table border><TR><TH>Parameter</TH><TH>Description</TH><TH>Default</TH></TR><TR><TD VAlign=top><tt>Container</tt></TD><TD VAlign=top>The type of the underlying container that elements are being written to. <A href="#1">[1]</A></TD><TD VAlign=top> </TD></TR><TR><TD VAlign=top><tt>buf_sz</tt></TD><TD VAlign=top>Number of elements in the buffer. This is a number, not a type. <tt>buf_sz</tt> has type <tt>size_t</tt>.</TD><TD VAlign=top>100</TD></tr></table><h3>Model of</h3><A href="OutputIterator.html">Output Iterator</A>.<h3>Type requirements</h3><UL><LI><tt>Container</tt> is a variable-sized <A href="ForwardContainer.html">Forward Container</A><LI><tt>Container</tt>'s value type <tt>T</tt> is a model of <A href="DefaultConstructible.html">Default Constructible</A>, as well as <A href="Assignable.html">Assignable</A>.<LI><tt>Container</tt> has a member function that appends a range. Specifically: If <tt>x</tt> is an object of type <tt>Container</tt> and <tt>f</tt> and <tt>l</tt> are of type <tt>T*</tt>, then <tt>x.append(f, l)</tt> appends the range <tt>[f, l)</tt> to <tt>x</tt>. <A href="#1">[1]</A></UL><h3>Public base classes</h3><tt>output_iterator</tt><h3>Members</h3><Table border><TR><TH>Member</TH><TH>Where defined</TH><TH>Description</TH></TR><TR><TD VAlign=top><tt>value_type</tt></TD><TD VAlign=top><tt>sequence_buffer</tt></TD><TD VAlign=top>The underlying container's value type.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer(Container& C)</tt></TD><TD VAlign=top><tt>sequence_buffer</tt></TD><TD VAlign=top>Create a <tt>sequence_buffer</tt> whose underlying container is <tt>C</tt>.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer()</tt></TD><TD VAlign=top><tt><A href="DefaultConstructible.html">Default Constructible</A></tt></TD><TD VAlign=top>The default constructor. The resulting iterator is singular.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer(const sequence_buffer&)</tt></TD><TD VAlign=top> <A href="Assignable.html">Assignable</A></TD><TD VAlign=top>Copy constructor.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer& operator=(const sequence_buffer& s)</tt></TD><TD VAlign=top> <A href="Assignable.html">Assignable</A></TD><TD VAlign=top>Assignment operator.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer& operator=(sequence_buffer& s)</tt></TD><TD VAlign=top> <A href="Assignable.html">Assignable</A></TD><TD VAlign=top>Faster version of assignment operator.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer& operator=(const value_type&)</tt></TD><TD VAlign=top> <A href="OutputIterator.html">Output Iterator</A></TD><TD VAlign=top>Used to implement the <A href="OutputIterator.html">Output Iterator</A> requirement <tt>*i = t</tt>. <A href="#2">[2]</A></TD></TR><TR><TD VAlign=top><tt>sequence_buffer& operator*()</tt></TD><TD VAlign=top> <A href="OutputIterator.html">Output Iterator</A></TD><TD VAlign=top>Used to implement the <A href="OutputIterator.html">Output Iterator</A> requirement <tt>*i = t</tt>. <A href="#2">[2]</A></TD></TR><TR><TD VAlign=top><tt>sequence_buffer& operator++()</tt></TD><TD VAlign=top> <A href="OutputIterator.html">Output Iterator</A></TD><TD VAlign=top>Preincrement</TD></TR><TR><TD VAlign=top><tt>sequence_buffer& operator++(int)</tt></TD><TD VAlign=top> <A href="OutputIterator.html">Output Iterator</A></TD><TD VAlign=top>Postincrement</TD></TR><TR><TD VAlign=top><tt>void flush()</tt></TD><TD VAlign=top><tt>sequence_buffer</tt></TD><TD VAlign=top>Flush the buffer.</TD></TR><TR><TD VAlign=top><tt>void push_back(value_type)</tt></TD><TD VAlign=top><tt>sequence_buffer</tt></TD><TD VAlign=top><tt>i.push_back(x)</tt> is equivalent to <tt>*i = x</tt>.</TD></TR><TR><TD VAlign=top><tt>void append(value_type* s, size_t len)</tt></TD><TD VAlign=top><tt>sequence_buffer</tt></TD><TD VAlign=top>Append multiple values.</TD></tr></table><h3>New members</h3>These members are not defined in the <A href="OutputIterator.html">Output Iterator</A> requirements,but are specific to <tt>sequence_buffer</tt>.<Table border><TR><TH>Function</TH><TH>Description</TH></TR><TR><TD VAlign=top><tt>value_type</tt></TD><TD VAlign=top>The underlying container's value type. That is, <tt>typename Container::value_type</tt>.</TD></TR><TR><TD VAlign=top><tt>sequence_buffer(Container& C)</tt></TD><TD VAlign=top>Create a <tt>sequence_buffer</tt> whose underlying container is <tt>C</tt>. Elements appended to the <tt>sequence_buffer</tt> will be appended to <tt>C</tt> whenever the <tt>sequence_buffer</tt> is flushed.</TD></TR><TR><TD VAlign=top><tt>void flush()</tt></TD><TD VAlign=top>Append all elements in the buffer to the underlying container, and empty the buffer. That is, make the underlying container consistent with the <tt>sequence_buffer</tt>. Note that <tt>flush</tt> is called automatically whenever the buffer is full, and also by <tt>sequence_buffer</tt>'s destructor. Sometimes, however, it is useful to be sure that the buffer is flushed at a particular time.</TD></TR><TR><TD VAlign=top><tt>void push_back(value_type x)</tt></TD><TD VAlign=top>Append <tt>x</tt> to the <tt>sequence_buffer</tt>. Note that this member function is strictly unnecessary: <tt>i.push_back(x)</tt> is just alternate syntax for <tt>*i = x</tt>.</TD></TR><TR><TD VAlign=top><tt>void append(value_type* s, size_t len)</tt></TD><TD VAlign=top>Append the range <tt>[s, s + len)</tt> to the <tt>sequence_buffer</tt>. Note that <tt>i.append(s, n)</tt> is just the same as <tt><A href="copy.html">copy</A>(s, s + n, i)</tt>. The <tt>append</tt> member function, however, is faster.</TD></tr></table><h3>Notes</h3><P><A name="1">[1]</A>Despite the name "sequence_buffer", this adaptor cannotactually be used with arbitrary sequences: it requires that thetemplate argument <tt>Container</tt> have an <tt>append</tt> member function thatcan insert multiple elements at the end of the container. Thismember function is not part of the <A href="Sequence.html">Sequence</A> requirements. Thismeans that <tt>sequence_buffer</tt> can be used with <tt><A href="Rope.html">rope</A></tt>, butnot with any of the other predefined container classes.<P><A name="2">[2]</A>Note how assignment through a <tt>sequence_buffer</tt> is implemented.In general, unary <tt>operator*</tt> must be defined so that it returns aproxy object, where the proxy object defines <tt>operator=</tt> to performthe output operation. In this case, for the sake of simplicity, theproxy object is the <tt>sequence_buffer</tt> itself. That is, <tt>*i</tt> simplyreturns <tt>i</tt>, and <tt>*i = t</tt> is equivalent to <tt>i = t</tt>. You should not,however, rely on this behavior. It is an implementation detail,and it is not guaranteed to remain the same in future versions.<h3>See also</h3><A href="OutputIterator.html">Output Iterator</A>, <tt><A href="Rope.html">rope</A></tt>,<tt><A href="front_insert_iterator.html">front_insert_iterator</A></tt>, <tt><A href="back_insert_iterator.html">back_insert_iterator</A></tt>,<tt><A href="insert_iterator.html">insert_iterator</A></tt><!-- start footer --><!-- Footer Begins --><STYLE TYPE="text/css"><!--TD.footer, TD.footer A{ font-family: Arial, helvetica, sans-serif; font-size: 8pt;}A.home {font-family: Arial, helvetica, sans-serif;}--></STYLE><P><A CLASS="home" HREF="index.html">STL Home</A><P><TABLE WIDTH="600" CELLPADDING="0" CELLPADDING="0" BORDER="0"> <TR> <TD ALIGN="RIGHT" CLASS="footer"><A HREF="/company_info/terms.html" TARGET="_top">terms of use</A> | <A HREF="/company_info/privacy.html" TARGET="_top">privacy policy</A></TD> <TD ALIGN="CENTER" CLASS="footer"> | </TD> <TD ALIGN="LEFT" CLASS="footer"><A HREF="/cgi-bin/feedback/" TARGET="_top">contact us</A></TD> </TR><TR> <TD ALIGN="RIGHT" CLASS="footer">Copyright © 1993-2003 Silicon Graphics, Inc. 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