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<html>
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<title>Design decisions rationale for Boost Tuple Library</title>
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<body bgcolor="#FFFFFF" text="#000000">
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<IMG SRC="../../../boost.png"
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ALT="C++ Boost" width="277" height="86">
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<h1>Tuple Library : design decisions rationale</h1>
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<h2>About namespaces</h2>
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<p>
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There was a discussion about whether tuples should be in a separate namespace or directly in the <code>boost</code> namespace.
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The common principle is that domain libraries (like <i>graph</i>, <i>python</i>) should be on a separate
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subnamespace, while utility like libraries directly in the <code>boost</code> namespace.
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Tuples are somewhere in between, as the tuple template is clearly a general utility, but the library introduces quite a lot of names in addition to just the tuple template.
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Tuples were originally under a subnamespace.
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As a result of the discussion, tuple definitions were moved directly under the <code>boost</code> namespace.
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As a result of a continued discussion, the subnamespace was reintroduced.
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The final (I truly hope so) solution is now to have all definitions in namespace <code>::boost::tuples</code>, and the most common names in the <code>::boost</code> namespace as well.
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This is accomplished with using declarations (suggested by Dave Abrahams):
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<code><pre>namespace boost {
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namespace tuples {
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...
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// All library code
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...
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}
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using tuples::tuple;
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using tuples::make_tuple;
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using tuples::tie;
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using tuples::get;
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}
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</pre></code>
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With this arrangement, tuple creation with direct constructor calls, <code>make_tuple</code> or <code>tie</code> functions do not need the namespace qualifier.
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Further, all functions that manipulate tuples are found with Koenig-lookup.
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The only exceptions are the <code>get<N></code> functions, which are always called with an explicitly qualified template argument, and thus Koenig-lookup does not apply.
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Therefore, get is lifted to <code>::boost</code> namespace with a using declaration.
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Hence, the interface for an application programmer is in practice under the namespace <code>::boost</code>.
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</p>
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<p>
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The other names, forming an interface for library writers (cons lists, metafunctions manipulating cons lists, ...) remain in the subnamespace <code>::boost::tuples</code>.
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Note, that the names <code>ignore</code>, <code>set_open</code>, <code>set_close</code> and <code>set_delimiter</code> are considered to be part of the application programmer's interface, but are still not under <code>boost</code> namespace.
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The reason being the danger for name clashes for these common names.
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Further, the usage of these features is probably not very frequent.
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</p>
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<h4>For those who are really interested in namespaces</h4>
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<p>
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The subnamespace name <i>tuples</i> raised some discussion.
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The rationale for not using the most natural name 'tuple' is to avoid having an identical name with the tuple template.
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Namespace names are, however, not generally in plural form in boost libraries.
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First, no real trouble was reported for using the same name for a namespace and a class and we considered changing the name 'tuples' to 'tuple'.
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But we found some trouble after all.
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Both gcc and edg compilers reject using declarations where the namespace and class names are identical:
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<code><pre>namespace boost {
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namespace tuple {
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... tie(...);
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class tuple;
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...
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}
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using tuple::tie; // ok
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using tuple::tuple; // error
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...
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}
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</pre></code>
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Note, however, that a corresponding using declaration in the global namespace seems to be ok:
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<code><pre>
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using boost::tuple::tuple; // ok;
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</pre></code>
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<h2>The end mark of the cons list (nil, null_type, ...)</h2>
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<p>
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Tuples are internally represented as <code>cons</code> lists:
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<code><pre>tuple<int, int>
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</pre></code>
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inherits from
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<code><pre>cons<int, cons<int, null_type> >
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</code></pre>
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<code>null_type</code> is the end mark of the list. Original proposition was <code>nil</code>, but the name is used in MacOS, and might have caused problems, so <code>null_type</code> was chosen instead.
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Other names considered were <i>null_t</i> and <i>unit</i> (the empty tuple type in SML).
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<p>
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Note that <code>null_type</code> is the internal representation of an empty tuple: <code>tuple<></code> inherits from <code>null_type</code>.
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</p>
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<h2>Element indexing</h2>
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<p>
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Whether to use 0- or 1-based indexing was discussed more than thoroughly, and the following observations were made:
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<ul>
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<li> 0-based indexing is 'the C++ way' and used with arrays etc.</li>
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<li> 1-based 'name like' indexing exists as well, eg. <code>bind1st</code>, <code>bind2nd</code>, <code>pair::first</code>, etc.</li>
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</ul>
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Tuple access with the syntax <code>get<N>(a)</code>, or <code>a.get<N>()</code> (where <code>a</code> is a tuple and <code>N</code> an index), was considered to be of the first category, hence, the index of the first element in a tuple is 0.
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<p>
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A suggestion to provide 1-based 'name like' indexing with constants like <code>_1st</code>, <code>_2nd</code>, <code>_3rd</code>, ... was made.
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By suitably chosen constant types, this would allow alternative syntaxes:
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<code><pre>a.get<0>() == a.get(_1st) == a[_1st] == a(_1st);
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</pre></code>
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We chose not to provide more than one indexing method for the following reasons:
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<ul>
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<li>0-based indexing might not please everyone, but once its fixed, it is less confusing than having two different methods (would anyone want such constants for arrays?).</li>
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<li>Adding the other indexing scheme doesn't really provide anything new (like a new feature) to the user of the library.</li>
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<li>C++ variable and constant naming rules don't give many possibilities for defining short and nice index constants (like <code>_1st</code>, ...).
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Let the binding and lambda libraries use these for a better purpose.</li>
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<li>The access syntax <code>a[_1st]</code> (or <code>a(_1st)</code>) is appealing, and almost made us add the index constants after all. However, 0-based subscripting is so deep in C++, that we had a fear for confusion.</li>
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<li>
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Such constants are easy to add.
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</li>
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</ul>
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<h2>Tuple comparison</h2>
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The comparison operator implements lexicographical order.
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Other orderings were considered, mainly dominance (<i>a < b iff for each i a(i) < b(i)</i>).
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Our belief is, that lexicographical ordering, though not mathematically the most natural one, is the most frequently needed ordering in everyday programming.
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<h2>Streaming</h2>
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<p>
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The characters specified with tuple stream manipulators are stored within the space allocated by <code>ios_base::xalloc</code>, which allocates storage for <code>long</code> type objects.
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<code>static_cast</code> is used in casting between <code>long</code> and the stream's character type.
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Streams that have character types not convertible back and forth to long thus fail to compile.
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This may be revisited at some point. The two possible solutions are:
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<ul>
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<li>Allow only plain <code>char</code> types as the tuple delimiters and use <code>widen</code> and <code>narrow</code> to convert between the real character type of the stream.
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This would always compile, but some calls to set manipulators might result in a different
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character than expected (some default character).</li>
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<li>Allocate enough space to hold the real character type of the stream.
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This means memory for holding the delimiter characters must be allocated separately, and that pointers to this memory are stored in the space allocated with <code>ios_base::xalloc</code>.
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Any volunteers?</li>
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</ul>
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<A href="tuple_users_guide.html">Back to the user's guide</A>
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<hr><p>© Copyright Jaakko Järvi 2001.
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</body>
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</html>
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@ -1,135 +0,0 @@
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Tuple library advanced features</title>
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<body bgcolor="#FFFFFF" text="#000000">
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<IMG SRC="../../../boost.png"
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ALT="C++ Boost" width="277" height="86">
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</head>
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<body>
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<h1>Tuple library advanced features</h1>
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The advanced features described in this document are all under namespace <code>::boost::tuples</code>
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<h2>Metafunctions for tuple types</h2>
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<p>
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Suppose <code>T</code> is a tuple type, and <code>N</code> is a constant integral expression.
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<code><pre>element<N, T>::type</pre></code>
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gives the type of the <code>N</code>th element in the tuple type <code>T</code>. If <code>T</code> is const, the resulting type is const qualified as well.
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Note that the constness of <code>T</code> does not affect reference type
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elements.
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</p>
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<code><pre>length<T>::value</pre></code>
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gives the length of the tuple type <code>T</code>.
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</p>
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<h2>Cons lists</h2>
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<p>
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Tuples are internally represented as <i>cons lists</i>.
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For example, the tuple
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<code><pre>tuple<A, B, C, D></pre></code>
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inherits from the type
|
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<code><pre>cons<A, cons<B, cons<C, cons<D, null_type> > > >
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</pre></code>
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The tuple template provides the typedef <code>inherited</code> to access the cons list representation. E.g.:
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<code>tuple<A>::inherited</code> is the type <code>cons<A, null_type></code>.
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</p>
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<h4>Empty tuple</h4>
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<p>
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The internal representation of the empty tuple <code>tuple<></code> is <code>null_type</code>.
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</p>
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|
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<h4>Head and tail</h4>
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<p>
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Both tuple template and the cons templates provide the typedefs <code>head_type</code> and <code>tail_type</code>.
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The <code>head_type</code> typedef gives the type of the first element of the tuple (or the cons list).
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The
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<code>tail_type</code> typedef gives the remaining cons list after removing the first element.
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The head element is stored in the member variable <code>head</code> and the tail list in the member variable <code>tail</code>.
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Cons lists provide the member function <code>get_head()</code> for getting a reference to the head of a cons list, and <code>get_tail()</code> for getting a reference to the tail.
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There are const and non-const versions of both functions.
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</p>
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||||
<p>
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Note that in a one element tuple, <code>tail_type</code> equals <code>null_type</code> and the <code>get_tail()</code> function returns an object of type <code>null_type</code>.
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</p>
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<p>
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The empty tuple (<code>null_type</code>) has no head or tail, hence the <code>get_head</code> and <code>get_tail</code> functions are not provided.
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</p>
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<p>
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Treating tuples as cons lists gives a convenient means to define generic functions to manipulate tuples. For example, the following pair of function templates assign 0 to each element of a tuple (obviously, the assignments must be valid operations for the element types):
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<pre><code>inline void set_to_zero(const null_type&) {};
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|
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template <class H, class T>
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inline void set_to_zero(cons<H, T>& x) { x.get_head() = 0; set_to_zero(x.get_tail()); }
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</code></pre>
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<p>
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<h4>Constructing cons lists</h4>
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|
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<p>
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A cons list can be default constructed provided that all its elements can be default constructed.
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</p>
|
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<p>
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A cons list can be constructed from its head and tail. The prototype of the constructor is:
|
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<pre><code>cons(typename access_traits<head_type>::parameter_type h,
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const tail_type& t)
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</code></pre>
|
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The traits template for the head parameter selects correct parameter types for different kinds of element types (for reference elements the parameter type equals the element type, for non-reference types the parameter type is a reference to const non-volatile element type).
|
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</p>
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<p>
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For a one-element cons list the tail argument (<code>null_type</code>) can be omitted.
|
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</p>
|
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|
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|
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<h2>Traits classes for tuple element types</h2>
|
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|
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<h4><code>access_traits</code></h4>
|
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<p>
|
||||
The template <code>access_traits</code> defines three type functions. Let <code>T</code> be a type of an element in a tuple:
|
||||
<ol>
|
||||
<li><code>access_traits<T>::type</code> maps <code>T</code> to the return type of the non-const access functions (nonmeber and member <code>get</code> functions, and the <code>get_head</code> function).</li>
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<li><code>access_traits<T>::const_type</code> maps <code>T</code> to the return type of the const access functions.</li>
|
||||
<li><code>access_traits<T>::parameter_type</code> maps <code>T</code> to the parameter type of the tuple constructor.</li>
|
||||
</ol>
|
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<h4><code>make_tuple_traits</code></h4>
|
||||
|
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The element types of the tuples that are created with the <code>make_tuple</code> functions are computed with the type function <code>make_tuple_traits</code>.
|
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The type function call <code>make_tuple_traits<T>::type</code> implements the following type mapping:
|
||||
<ul>
|
||||
<li><i>any reference type</i> -> <i>compile time error</i>
|
||||
</li>
|
||||
<li><i>any array type</i> -> <i>constant reference to the array type</i>
|
||||
</li>
|
||||
<li><code>reference_wrapper<T></code> -> <code>T&</code>
|
||||
</li>
|
||||
<li><code>T</code> -> <code>T</code>
|
||||
</li>
|
||||
</ul>
|
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|
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Objects of type <code>reference_wrapper</code> are created with the <code>ref</code> and <code>cref</code> functions (see <A href="tuple_users_guide.html#make_tuple">The <code>make_tuple</code> function</A>.)
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</p>
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|
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<p>Reference wrappers were originally part of the tuple library, but they are now a general utility of boost.
|
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The <code>reference_wrapper</code> template and the <code>ref</code> and <code>cref</code> functions are defined in a separate file <code>ref.hpp</code> in the main boost include directory; and directly in the <code>boost</code> namespace.
|
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</p>
|
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|
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<A href="tuple_users_guide.html">Back to the user's guide</A>
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<hr>
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|
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<p>© Copyright Jaakko Järvi 2001.</p>
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</body>
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</html>
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@ -1,529 +0,0 @@
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<html>
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<head>
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<title>The Boost Tuple Library</title>
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</head>
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<body bgcolor="#FFFFFF" text="#000000">
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<IMG SRC="../../../boost.png"
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ALT="C++ Boost" width="277" height="86">
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<h1>The Boost Tuple Library</h1>
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<p>
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A tuple (or <i>n</i>-tuple) is a fixed size collection of elements.
|
||||
Pairs, triples, quadruples etc. are tuples.
|
||||
In a programming language, a tuple is a data object containing other objects as elements.
|
||||
These element objects may be of different types.
|
||||
</p>
|
||||
|
||||
<p>Tuples are convenient in many circumstances.
|
||||
For instance, tuples make it easy to define functions that return more than one value.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Some programming languages, such as ML, Python and Haskell, have built-in tuple constructs.
|
||||
Unfortunately C++ does not.
|
||||
To compensate for this "deficiency", the Boost Tuple Library implements a tuple construct using templates.
|
||||
</p>
|
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<h2>Table of Contents</h2>
|
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|
||||
<ol>
|
||||
<li><a href = "#using_library">Using the library</a></li>
|
||||
<li><a href = "#tuple_types">Tuple types</a></li>
|
||||
<li><a href = "#constructing_tuples">Constructing tuples</a></li>
|
||||
<li><a href = "#accessing_elements">Accessing tuple elements</a></li>
|
||||
<li><a href = "#construction_and_assignment">Copy construction and tuple assignment</a></li>
|
||||
<li><a href = "#relational_operators">Relational operators</a></li>
|
||||
<li><a href = "#tiers">Tiers</a></li>
|
||||
<li><a href = "#streaming">Streaming</a></li>
|
||||
<li><a href = "#performance">Performance</a></li>
|
||||
<li><a href = "#portability">Portability</a></li>
|
||||
<li><a href = "#thanks">Acknowledgements</a></li>
|
||||
<li><a href = "#references">References</a></li>
|
||||
</ol>
|
||||
|
||||
<h4>More details</h4>
|
||||
|
||||
<p>
|
||||
<a href = "tuple_advanced_interface.html">Advanced features</a> (describes some metafunctions etc.).</p>
|
||||
<p>
|
||||
<a href = "design_decisions_rationale.html">Rationale behind some design/implementation decisions.</a></p>
|
||||
|
||||
|
||||
<h2><a name="using_library">Using the library</a></h2>
|
||||
|
||||
<p>To use the library, just include:
|
||||
|
||||
<pre><code>#include "boost/tuple/tuple.hpp"</code></pre>
|
||||
|
||||
<p>Comparison operators can be included with:
|
||||
<pre><code>#include "boost/tuple/tuple_comparison.hpp"</code></pre>
|
||||
|
||||
<p>To use tuple input and output operators,
|
||||
|
||||
<pre><code>#include "boost/tuple/tuple_io.hpp"</code></pre>
|
||||
|
||||
Both <code>tuple_io.hpp</code> and <code>tuple_comparison.hpp</code> include <code>tuple.hpp</code>.
|
||||
|
||||
<p>All definitions are in namespace <code>::boost::tuples</code>, but the most common names are lifted to namespace <code>::boost</code> with using declarations. These names are: <code>tuple</code>, <code>make_tuple</code>, <code>tie</code> and <code>get</code>. Further, <code>ref</code> and <code>cref</code> are defined directly under the <code>::boost</code> namespace.
|
||||
|
||||
<h2><a name = "tuple_types">Tuple types</a></h2>
|
||||
|
||||
<p>A tuple type is an instantiation of the <code>tuple</code> template.
|
||||
The template parameters specify the types of the tuple elements.
|
||||
The current version supports tuples with 0-10 elements.
|
||||
If necessary, the upper limit can be increased up to, say, a few dozen elements.
|
||||
The data element can be any C++ type.
|
||||
Note that <code>void</code> and plain function types are valid
|
||||
C++ types, but objects of such types cannot exist.
|
||||
Hence, if a tuple type contains such types as elements, the tuple type
|
||||
can exist, but not an object of that type.
|
||||
There are natural limitations for element types that cannot
|
||||
be be copied, or that are not default constructible (see 'Constructing tuples'
|
||||
below).
|
||||
|
||||
<p>
|
||||
For example, the following definitions are valid tuple instantiations (<code>A</code>, <code>B</code> and <code>C</code> are some user defined classes):
|
||||
|
||||
<pre><code>tuple<int>
|
||||
tuple<double&, const double&, const double, double*, const double*>
|
||||
tuple<A, int(*)(char, int), B(A::*)(C&), C>
|
||||
tuple<std::string, std::pair<A, B> >
|
||||
tuple<A*, tuple<const A*, const B&, C>, bool, void*>
|
||||
</code></pre>
|
||||
|
||||
<h2><a name = "constructing_tuples">Constructing tuples</a></h2>
|
||||
|
||||
<p>
|
||||
The tuple constructor takes the tuple elements as arguments.
|
||||
For an <i>n</i>-element tuple, the constructor can be invoked with <i>k</i> arguments, where 0 <= <i>k</i> <= <i>n</i>.
|
||||
For example:
|
||||
<pre><code>tuple<int, double>()
|
||||
tuple<int, double>(1)
|
||||
tuple<int, double>(1, 3.14)
|
||||
</code></pre>
|
||||
|
||||
<p>
|
||||
If no initial value for an element is provided, it is default initialized (and hence must be default initializable).
|
||||
For example.
|
||||
|
||||
<pre><code>class X {
|
||||
X();
|
||||
public:
|
||||
X(std::string);
|
||||
};
|
||||
|
||||
tuple<X,X,X>() // error: no default constructor for X
|
||||
tuple<X,X,X>(string("Jaba"), string("Daba"), string("Duu")) // ok
|
||||
</code></pre>
|
||||
|
||||
In particular, reference types do not have a default initialization:
|
||||
|
||||
<pre><code>tuple<double&>() // error: reference must be
|
||||
// initialized explicitly
|
||||
|
||||
double d = 5;
|
||||
tuple<double&>(d) // ok
|
||||
|
||||
tuple<double&>(d+3.14) // error: cannot initialize
|
||||
// non-const reference with a temporary
|
||||
|
||||
tuple<const double&>(d+3.14) // ok, but dangerous:
|
||||
// the element becomes a dangling reference
|
||||
</code></pre>
|
||||
|
||||
<p>Using an initial value for an element that cannot be copied, is a compile
|
||||
time error:
|
||||
|
||||
<pre><code>class Y {
|
||||
Y(const Y&);
|
||||
public:
|
||||
Y();
|
||||
};
|
||||
|
||||
char a[10];
|
||||
|
||||
tuple<char[10], Y>(a, Y()); // error, neither arrays nor Y can be copied
|
||||
tuple<char[10], Y>(); // ok
|
||||
</code></pre>
|
||||
|
||||
Note particularly that the following is perfectly ok:
|
||||
<code><pre>Y y;
|
||||
tuple<char(&)[10], Y&>(a, y);
|
||||
</code></pre>
|
||||
|
||||
It is possible to come up with a tuple type that cannot be constructed.
|
||||
This occurs if an element that cannot be initialized has a lower
|
||||
index than an element that requires initialization.
|
||||
For example: <code>tuple<char[10], int&></code>.
|
||||
|
||||
<p>In sum, the tuple construction is semantically just a group of individual elementary constructions.
|
||||
</p>
|
||||
|
||||
<h4><a name="make_tuple">The <code>make_tuple</code> function</a></h4>
|
||||
|
||||
<p>
|
||||
Tuples can also be constructed using the <code>make_tuple</code> (cf. <code>std::make_pair</code>) helper functions.
|
||||
This makes the construction more convenient, saving the programmer from explicitly specifying the element types:
|
||||
<pre><code>tuple<int, int, double> add_multiply_divide(int a, int b) {
|
||||
return make_tuple(a+b, a*b, double(a)/double(b));
|
||||
}
|
||||
</code></pre>
|
||||
|
||||
<p>
|
||||
By default, the element types are deduced to the plain non-reference types. E.g:
|
||||
<pre><code>void foo(const A& a, B& b) {
|
||||
...
|
||||
make_tuple(a, b);
|
||||
</code></pre>
|
||||
The <code>make_tuple</code> invocation results in a tuple of type <code>tuple<A, B></code>.
|
||||
|
||||
<p>
|
||||
Sometimes the plain non-reference type is not desired, e.g. if the element type cannot be copied.
|
||||
Therefore, the programmer can control the type deduction and state that a reference to const or reference to
|
||||
non-const type should be used as the element type instead.
|
||||
This is accomplished with two helper template functions: <code>ref</code> and <code>cref</code>.
|
||||
Any argument can be wrapped with these functions to get the desired type.
|
||||
The mechanism does not compromise const correctness since a const object wrapped with <code>ref</code> results in a tuple element with const reference type (see the fifth code line below).
|
||||
For example:
|
||||
|
||||
<pre><code>A a; B b; const A ca = a;
|
||||
make_tuple(cref(a), b); // creates tuple<const A&, B>
|
||||
make_tuple(ref(a), b); // creates tuple<A&, B>
|
||||
make_tuple(ref(a), cref(b)); // creates tuple<A&, const B&>
|
||||
make_tuple(cref(ca)); // creates tuple<const A&>
|
||||
make_tuple(ref(ca)); // creates tuple<const A&>
|
||||
</code></pre>
|
||||
|
||||
|
||||
<p>
|
||||
Array arguments to <code>make_tuple</code> functions are deduced to reference to const types by default; there is no need to wrap them with <code>cref</code>. For example:
|
||||
<pre><code>make_tuple("Donald", "Daisy");
|
||||
</code></pre>
|
||||
|
||||
This creates an object of type <code>tuple<const char (&)[7], const char (&)[6]></code>
|
||||
(note that the type of a string literal is an array of const characters, not <code>const char*</code>).
|
||||
However, to get <code>make_tuple</code> to create a tuple with an element of a
|
||||
non-const array type one must use the <code>ref</code> wrapper.
|
||||
|
||||
<p>
|
||||
Function pointers are deduced to the plain non-reference type, that is, to plain function pointer.
|
||||
A tuple can also hold a reference to a function,
|
||||
but such a tuple cannot be constructed with <code>make_tuple</code> (a const qualified function type would result, which is illegal):
|
||||
<pre><code>void f(int i);
|
||||
...
|
||||
make_tuple(&f); // tuple<void (*)(int)>
|
||||
...
|
||||
tuple<tuple<void (&)(int)> > a(f) // ok
|
||||
make_tuple(f); // not ok
|
||||
</code></pre>
|
||||
|
||||
<h2><a name = "accessing_elements">Accessing tuple elements</a></h2>
|
||||
|
||||
<p>
|
||||
Tuple elements are accessed with the expression:
|
||||
|
||||
<pre><code>t.get<N>()
|
||||
</code></pre>
|
||||
or
|
||||
<pre><code>get<N>(t)
|
||||
</code></pre>
|
||||
where <code>t</code> is a tuple object and <code>N</code> is a constant integral expression specifying the index of the element to be accessed.
|
||||
Depending on whether <code>t</code> is const or not, <code>get</code> returns the <code>N</code>th element as a reference to const or
|
||||
non-const type.
|
||||
The index of the first element is 0 and thus<code>
|
||||
N</code> must be between 0 and <code>k-1</code>, where <code>k</code> is the number of elements in the tuple.
|
||||
Violations of these constrains are detected at compile time. Examples:
|
||||
|
||||
<pre><code>double d = 2.7; A a;
|
||||
tuple<int, double&, const A&> t(1, d, a);
|
||||
const tuple<int, double&, const A&> ct = t;
|
||||
...
|
||||
int i = get<0>(t); i = t.get<0>(); // ok
|
||||
int j = get<0>(ct); // ok
|
||||
get<0>(t) = 5; // ok
|
||||
get<0>(ct) = 5; // error, can't assign to const
|
||||
...
|
||||
double e = get<1>(t); // ok
|
||||
get<1>(t) = 3.14; // ok
|
||||
get<2>(t) = A(); // error, can't assign to const
|
||||
A aa = get<3>(t); // error: index out of bounds
|
||||
...
|
||||
++get<0>(t); // ok, can be used as any variable
|
||||
</code></pre>
|
||||
|
||||
Note! The member get functions are not supported with MS Visual C++ compiler.
|
||||
Further, the compiler has trouble with finding the non-member get functions without an explicit namespace qualifier.
|
||||
Hence, all <code>get</code> calls should be qualified as: <code>tuples::get<N>(a_tuple)</code> when writing code that shoud compile with MSVC++ 6.0.
|
||||
|
||||
<h2><a name = "construction_and_assignment">Copy construction and tuple assignment</a></h2>
|
||||
|
||||
<p>
|
||||
A tuple can be copy constructed from another tuple, provided that the element types are element-wise copy constructible.
|
||||
Analogously, a tuple can be assigned to another tuple, provided that the element types are element-wise assignable.
|
||||
For example:
|
||||
|
||||
<pre><code>class A {};
|
||||
class B : public A {};
|
||||
struct C { C(); C(const B&); };
|
||||
struct D { operator C() const; };
|
||||
tuple<char, B*, B, D> t;
|
||||
...
|
||||
tuple<int, A*, C, C> a(t); // ok
|
||||
a = t; // ok
|
||||
</code></pre>
|
||||
|
||||
In both cases, the conversions performed are: <code>char -> int</code>, <code>B* -> A*</code> (derived class pointer to base class pointer), <code>B -> C</code> (a user defined conversion) and <code>D -> C</code> (a user defined conversion).
|
||||
|
||||
<p>
|
||||
Note that assignment is also defined from <code>std::pair</code> types:
|
||||
|
||||
<pre><code>tuple<float, int> a = std::make_pair(1, 'a');
|
||||
</code></pre>
|
||||
|
||||
<h2><a name = "relational_operators">Relational operators</a></h2>
|
||||
<p>
|
||||
Tuples reduce the operators <code>==, !=, <, >, <=</code> and <code>>=</code> to the corresponding elementary operators.
|
||||
This means, that if any of these operators is defined between all elements of two tuples, then the same operator is defined between the tuples as well.
|
||||
|
||||
The equality operators for two tuples <code>a</code> and <code>b</code> are defined as:
|
||||
<ul>
|
||||
<li><code>a == b</code> iff for each <code>i</code>: <code>a<sub>i</sub> == b<sub>i</sub></code></li>
|
||||
<li><code>a != b</code> iff exists <code>i</code>: <code>a<sub>i</sub> != b<sub>i</sub></code></li>
|
||||
</ul>
|
||||
|
||||
The operators <code><, >, <=</code> and <code>>=</code> implement a lexicographical ordering.
|
||||
|
||||
<p>
|
||||
Note that an attempt to compare two tuples of different lengths results in a compile time error.</p>
|
||||
Also, the comparison operators are <i>"short-circuited"</i>: elementary comparisons start from the first elements and are performed only until the result is clear.
|
||||
|
||||
<p>Examples:
|
||||
|
||||
<pre><code>tuple<std::string, int, A> t1(std::string("same?"), 2, A());
|
||||
tuple<std::string, long, A> t2(std::string("same?"), 2, A());
|
||||
tuple<std::string, long, A> t3(std::string("different"), 3, A());
|
||||
|
||||
bool operator==(A, A) { std::cout << "All the same to me..."; return true; }
|
||||
|
||||
t1 == t2; // true
|
||||
t1 == t3; // false, does not print "All the..."
|
||||
</code></pre>
|
||||
|
||||
|
||||
<h2><a name = "tiers">Tiers</a></h2>
|
||||
|
||||
<p>
|
||||
<i>Tiers</i> are tuples, where all elements are of non-const reference types.
|
||||
They are constructed with a call to the <code>tie</code> function template (cf. <code>make_tuple</code>):
|
||||
|
||||
<pre><code>int i; char c; double d;
|
||||
...
|
||||
tie(i, c, a);
|
||||
</code></pre>
|
||||
|
||||
<p>
|
||||
The above <code>tie</code> function creates a tuple of type <code>tuple<int&, char&, double&></code>.
|
||||
The same result could be achieved with the call <code>make_tuple(ref(i), ref(c), ref(a))</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
A tuple that contains non-const references as elements can be used to 'unpack' another tuple into variables. E.g.:
|
||||
|
||||
<pre><code>int i; char c; double d;
|
||||
tie(i, c, d) = make_tuple(1,'a', 5.5);
|
||||
std::cout << i << " " << c << " " << d;
|
||||
</code></pre>
|
||||
This code prints <code>1 a 5.5</code> to the standard output stream.
|
||||
|
||||
A tuple unpacking operation like this is found for example in ML and Python.
|
||||
It is convenient when calling functions which return tuples.
|
||||
|
||||
<p>
|
||||
The tying mechanism works with <code>std::pair</code> templates as well:
|
||||
|
||||
<pre><code>int i; char c;
|
||||
tie(i, c) = std::make_pair(1, 'a');
|
||||
</code></pre>
|
||||
<h4>Ignore</h4>
|
||||
There is also an object called <code>ignore</code> which allows you to ignore an element assigned by a tuple.
|
||||
The idea is that a function may return a tuple, only part of which you are interested in. For example (note, that <code>ignore</code> is under the <code>tuples</code> subnamespace):
|
||||
|
||||
<pre><code>char c;
|
||||
tie(tuples::ignore, c) = std::make_pair(1, 'a');
|
||||
</code></pre>
|
||||
|
||||
<h2><a name = "streaming">Streaming</a></h2>
|
||||
|
||||
<p>
|
||||
The global <code>operator<<</code> has been overloaded for <code>std::ostream</code> such that tuples are
|
||||
output by recursively calling <code>operator<<</code> for each element.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Analogously, the global <code>operator>></code> has been overloaded to extract tuples from <code>std::istream</code> by recursively calling <code>operator>></code> for each element.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
The default delimiter between the elements is space, and the tuple is enclosed
|
||||
in parenthesis.
|
||||
For Example:
|
||||
|
||||
<pre><code>tuple<float, int, std::string> a(1.0f, 2, std::string("Howdy folks!");
|
||||
|
||||
cout << a;
|
||||
</code></pre>
|
||||
outputs the tuple as: <code>(1.0 2 Howdy folks!)</code>
|
||||
|
||||
<p>
|
||||
The library defines three <i>manipulators</i> for changing the default behavior:
|
||||
<ul>
|
||||
<li><code>set_open(char)</code> defines the character that is output before the first
|
||||
element.</li>
|
||||
<li><code>set_close(char)</code> defines the character that is output after the
|
||||
last element.</li>
|
||||
<li><code>set_delimiter(char)</code> defines the delimiter character between
|
||||
elements.</li>
|
||||
</ul>
|
||||
|
||||
Note, that these manipulators are defined in the <code>tuples</code> subnamespace.
|
||||
For example:
|
||||
<code><pre>cout << tuples::set_open('[') << tuples::set_close(']') << tuples::set_delimiter(',') << a;
|
||||
</code></pre>
|
||||
outputs the same tuple <code>a</code> as: <code>[1.0,2,Howdy folks!]</code>
|
||||
|
||||
<p>The same manipulators work with <code>operator>></code> and <code>istream</code> as well. Suppose the <code>cin</code> stream contains the following data:
|
||||
|
||||
<pre><code>(1 2 3) [4:5]</code></pre>
|
||||
|
||||
The code:
|
||||
|
||||
<code><pre>tuple<int, int, int> i;
|
||||
tuple<int, int> j;
|
||||
|
||||
cin >> i;
|
||||
cin >> tuples::set_open('[') >> tuples::set_close(']') >> tules::set_delimiter(':');
|
||||
cin >> j;
|
||||
</code></pre>
|
||||
|
||||
reads the data into the tuples <code>i</code> and <code>j</code>.
|
||||
|
||||
<p>
|
||||
Note that extracting tuples with <code>std::string</code> or C-style string
|
||||
elements does not generally work, since the streamed tuple representation may not be unambiguously
|
||||
parseable.
|
||||
</p>
|
||||
|
||||
<h2><a name = "performance">Performance</a></h2>
|
||||
|
||||
All tuple access and construction functions are small inlined one-liners.
|
||||
Therefore, a decent compiler can eliminate any extra cost of using tuples compared to using hand written tuple like classes.
|
||||
Particularly, with a decent compiler there is no performance difference between this code:
|
||||
|
||||
<pre><code>class hand_made_tuple {
|
||||
A a; B b; C c;
|
||||
public:
|
||||
hand_made_tuple(const A& aa, const B& bb, const C& cc)
|
||||
: a(aa), b(bb), c(cc) {};
|
||||
A& getA() { return a; };
|
||||
B& getB() { return b; };
|
||||
C& getC() { return c; };
|
||||
};
|
||||
|
||||
hand_made_tuple hmt(A(), B(), C());
|
||||
hmt.getA(); hmt.getB(); hmt.getC();
|
||||
</code></pre>
|
||||
|
||||
and this code:
|
||||
|
||||
<pre><code>tuple<A, B, C> t(A(), B(), C());
|
||||
t.get<0>(); t.get<1>(); t.get<2>();
|
||||
</code></pre>
|
||||
|
||||
<p>Note, that there are widely used compilers (e.g. bcc 5.5.1) which fail to optimize this kind of tuple usage.
|
||||
</p>
|
||||
<p>
|
||||
Depending on the optimizing ability of the compiler, the tier mechanism may have a small performance penalty compared to using
|
||||
non-const reference parameters as a mechanism for returning multiple values from a function.
|
||||
For example, suppose that the following functions <code>f1</code> and <code>f2</code> have equivalent functionalities:
|
||||
|
||||
<pre><code>void f1(int&, double&);
|
||||
tuple<int, double> f2();
|
||||
</code></pre>
|
||||
|
||||
Then, the call #1 may be slightly faster than #2 in the code below:
|
||||
|
||||
<pre><code>int i; double d;
|
||||
...
|
||||
f1(i,d); // #1
|
||||
tie(i,d) = f2(); // #2
|
||||
</code></pre>
|
||||
See
|
||||
[<a href="#publ_1">1</a>,
|
||||
<a href="#publ_2">2</a>]
|
||||
for more in-depth discussions about efficiency.
|
||||
|
||||
<h4>Effect on Compile Time</h4>
|
||||
|
||||
<p>
|
||||
Compiling tuples can be slow due to the excessive amount of template instantiations.
|
||||
Depending on the compiler and the tuple length, it may be more than 10 times slower to compile a tuple construct, compared to compiling an equivalent explicitly written class, such as the <code>hand_made_tuple</code> class above.
|
||||
However, as a realistic program is likely to contain a lot of code in addition to tuple definitions, the difference is probably unnoticeable.
|
||||
Compile time increases between 5 to 10 percentages were measured for programs which used tuples very frequently.
|
||||
With the same test programs, memory consumption of compiling increased between 22% to 27%. See
|
||||
[<a href="#publ_1">1</a>,
|
||||
<a href="#publ_2">2</a>]
|
||||
for details.
|
||||
</p>
|
||||
|
||||
<h2><a name = "portability">Portability</a></h2>
|
||||
|
||||
<p>The library code is(?) standard C++ and thus the library works with a standard conforming compiler.
|
||||
Below is a list of compilers and known problems with each compiler:
|
||||
</p>
|
||||
<table>
|
||||
<tr><td><u>Compiler</u></td><td><u>Problems</u></td></tr>
|
||||
<tr><td>gcc 2.95</td><td>-</td></tr>
|
||||
<tr><td>edg 2.44</td><td>-</td></tr>
|
||||
<tr><td>Borland 5.5</td><td>Can't use function pointers or member pointers as tuple elements</td></tr>
|
||||
<tr><td>Metrowerks 6.2</td><td>Can't use <code>ref</code> and <code>cref</code> wrappers</td></tr>
|
||||
<tr><td>MS Visual C++</td><td>No reference elements (<code>tie</code> still works). Can't use <code>ref</code> and <code>cref</code> wrappers</td></tr>
|
||||
</table>
|
||||
|
||||
<h2><a name = "thanks">Acknowledgements</a></h2>
|
||||
Gary Powell has been an indispensable helping hand. In particular, stream manipulators for tuples were his idea. Doug Gregor came up with a working version for MSVC, David Abrahams found a way to get rid of most of the restrictions for compilers not supporting partial specialization. Thanks to Jeremy Siek, William Kempf and Jens Maurer for their help and suggestions.
|
||||
The comments by Vesa Karvonen, John Max Skaller, Ed Brey, Beman Dawes, David Abrahams and Hartmut Kaiser helped to improve the
|
||||
library.
|
||||
The idea for the tie mechanism came from an old usenet article by Ian McCulloch, where he proposed something similar for std::pairs.
|
||||
<h2><a name = "references">References</a></h2>
|
||||
|
||||
<p>
|
||||
<a name="publ_1"></a>[1]
|
||||
Järvi J.: <i>Tuples and multiple return values in C++</i>, TUCS Technical Report No 249, 1999<!-- (<a href="http://www.tucs.fi/Publications">http://www.tucs.fi/Publications</a>)-->.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
<a name="publ_2"></a>[2]
|
||||
Järvi J.: <i>ML-Style Tuple Assignment in Standard C++ - Extending the Multiple Return Value Formalism</i>, TUCS Technical Report No 267, 1999<!-- (<a href="http://www.tucs.fi/Publications">http://www.tucs.fi/Publications</a>)-->.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
[3] Järvi J.:<i>Tuple Types and Multiple Return Values</i>, C/C++ Users Journal, August 2001.
|
||||
</p>
|
||||
|
||||
<hr>
|
||||
|
||||
<p>Last modified 2003-09-07</p>
|
||||
|
||||
<p>© Copyright <a href="../../../people/jaakko_jarvi.htm"> Jaakko Järvi</a> 2001.
|
||||
|
||||
Permission to copy, use, modify, sell and distribute this software and its documentation is granted provided this copyright notice appears in all copies.
|
||||
This software and its documentation is provided "as is" without express or implied warranty, and with no claim as to its suitability for any purpose.
|
||||
</p>
|
||||
</body>
|
||||
</html>
|
||||
|
||||
|
||||
|
||||
|
||||
@ -1,8 +0,0 @@
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="refresh" content="0; URL=doc/tuple_users_guide.html">
|
||||
</head>
|
||||
<body>
|
||||
Automatic redirection failed, please go to <a href="doc/tuple_users_guide.html">doc/tuple_users_guide.html</a>
|
||||
</body>
|
||||
</html>
|
||||
20
test/Jamfile
20
test/Jamfile
@ -1,20 +0,0 @@
|
||||
subproject libs/tuple/test ;
|
||||
|
||||
unit-test tuple_test_bench
|
||||
: tuple_test_bench.cpp
|
||||
<lib>../../test/build/boost_test_exec_monitor
|
||||
: <sysinclude>$(BOOST_ROOT)
|
||||
;
|
||||
|
||||
unit-test io_test
|
||||
: io_test.cpp
|
||||
<lib>../../test/build/boost_test_exec_monitor
|
||||
: <sysinclude>$(BOOST_ROOT)
|
||||
;
|
||||
|
||||
unit-test another_tuple_test_bench
|
||||
: another_tuple_test_bench.cpp
|
||||
<lib>../../test/build/boost_test_exec_monitor
|
||||
: <sysinclude>$(BOOST_ROOT)
|
||||
;
|
||||
|
||||
16
test/README
16
test/README
@ -1,16 +0,0 @@
|
||||
To compile the
|
||||
|
||||
libs/tuple/test/*.cpp
|
||||
|
||||
files, you need to set include paths
|
||||
for boost.
|
||||
For example, in libs/tuple/test directory you would type (using g++):
|
||||
|
||||
g++ -I../../.. tuple_test_bench.cpp
|
||||
|
||||
The following is not true anymore:
|
||||
|
||||
If you want to use tuple_io, you need to compile and link src/tuple.cpp:
|
||||
g++ -I../../.. ../src/tuple.cpp io_test.cpp
|
||||
|
||||
Thanks to Hartmut Kaiser's suggestion, the tuple.cpp is not needed anymore.
|
||||
@ -1,164 +0,0 @@
|
||||
// Copyright (C) 1999, 2000 Jaakko J<>rvi (jaakko.jarvi@cs.utu.fi)
|
||||
//
|
||||
// Distributed under the Boost Software License, Version 1.0. (See
|
||||
// accompanying file LICENSE_1_0.txt or copy at
|
||||
// http://www.boost.org/LICENSE_1_0.txt)
|
||||
|
||||
// For more information, see http://www.boost.org
|
||||
|
||||
|
||||
// another_test_bench.cpp --------------------------------
|
||||
|
||||
// This file has various tests to see that things that shouldn't
|
||||
// compile, don't compile.
|
||||
|
||||
// Defining any of E1 to E5 or E7 to E11 opens some illegal code that
|
||||
// should cause the compliation to fail.
|
||||
|
||||
#define BOOST_INCLUDE_MAIN // for testing, include rather than link
|
||||
#include <boost/test/test_tools.hpp> // see "Header Implementation Option"
|
||||
|
||||
#include "boost/tuple/tuple.hpp"
|
||||
|
||||
#include <string>
|
||||
#include <utility>
|
||||
|
||||
using namespace std;
|
||||
using namespace boost;
|
||||
using namespace boost::tuples;
|
||||
|
||||
|
||||
template<class T> void dummy(const T&) {}
|
||||
|
||||
class A {}; class B {}; class C {};
|
||||
|
||||
// A non-copyable class
|
||||
class no_copy {
|
||||
no_copy(const no_copy&) {}
|
||||
public:
|
||||
no_copy() {};
|
||||
};
|
||||
|
||||
no_copy y;
|
||||
|
||||
#ifdef E1
|
||||
tuple<no_copy> v1; // should faild
|
||||
#endif
|
||||
|
||||
|
||||
#ifdef E2
|
||||
char cs[10];
|
||||
tuple<char[10]> v3; // should fail, arrays must be stored as references
|
||||
#endif
|
||||
|
||||
// a class without a public default constructor
|
||||
class no_def_constructor {
|
||||
no_def_constructor() {}
|
||||
public:
|
||||
no_def_constructor(std::string) {} // can be constructed with a string
|
||||
};
|
||||
|
||||
void foo1() {
|
||||
|
||||
#ifdef E3
|
||||
dummy(tuple<no_def_constructor, no_def_constructor, no_def_constructor>());
|
||||
// should fail
|
||||
|
||||
#endif
|
||||
}
|
||||
|
||||
void foo2() {
|
||||
// testing default values
|
||||
#ifdef E4
|
||||
dummy(tuple<double&>()); // should fail, not defaults for references
|
||||
dummy(tuple<const double&>()); // likewise
|
||||
#endif
|
||||
|
||||
#ifdef E5
|
||||
double dd = 5;
|
||||
dummy(tuple<double&>(dd+3.14)); // should fail, temporary to non-const reference
|
||||
#endif
|
||||
}
|
||||
|
||||
|
||||
|
||||
// make_tuple ------------------------------------------
|
||||
|
||||
|
||||
void foo3() {
|
||||
#ifdef E7
|
||||
std::make_pair("Doesn't","Work"); // fails
|
||||
#endif
|
||||
// make_tuple("Does", "Work"); // this should work
|
||||
}
|
||||
|
||||
|
||||
|
||||
// - testing element access
|
||||
|
||||
void foo4()
|
||||
{
|
||||
double d = 2.7;
|
||||
A a;
|
||||
tuple<int, double&, const A&> t(1, d, a);
|
||||
const tuple<int, double&, const A> ct = t;
|
||||
(void)ct;
|
||||
#ifdef E8
|
||||
get<0>(ct) = 5; // can't assign to const
|
||||
#endif
|
||||
|
||||
#ifdef E9
|
||||
get<4>(t) = A(); // can't assign to const
|
||||
#endif
|
||||
#ifdef E10
|
||||
dummy(get<5>(ct)); // illegal index
|
||||
#endif
|
||||
}
|
||||
|
||||
// testing copy and assignment with implicit conversions between elements
|
||||
// testing tie
|
||||
|
||||
class AA {};
|
||||
class BB : public AA {};
|
||||
struct CC { CC() {} CC(const BB& b) {} };
|
||||
struct DD { operator CC() const { return CC(); }; };
|
||||
|
||||
void foo5() {
|
||||
tuple<char, BB*, BB, DD> t;
|
||||
(void)t;
|
||||
tuple<char, char> aaa;
|
||||
tuple<int, int> bbb(aaa);
|
||||
(void)bbb;
|
||||
// tuple<int, AA*, CC, CC> a = t;
|
||||
// a = t;
|
||||
}
|
||||
|
||||
|
||||
// testing tie
|
||||
// testing assignment from std::pair
|
||||
void foo7() {
|
||||
|
||||
tuple<int, int, float> a;
|
||||
#ifdef E11
|
||||
a = std::make_pair(1, 2); // should fail, tuple is of length 3, not 2
|
||||
#endif
|
||||
|
||||
dummy(a);
|
||||
}
|
||||
|
||||
|
||||
|
||||
// --------------------------------
|
||||
// ----------------------------
|
||||
int test_main(int, char *[]) {
|
||||
|
||||
foo1();
|
||||
foo2();
|
||||
foo3();
|
||||
foo4();
|
||||
foo5();
|
||||
|
||||
foo7();
|
||||
|
||||
return 0;
|
||||
}
|
||||
115
test/io_test.cpp
115
test/io_test.cpp
@ -1,115 +0,0 @@
|
||||
// Copyright (C) 1999, 2000 Jaakko J<>rvi (jaakko.jarvi@cs.utu.fi)
|
||||
//
|
||||
// Distributed under the Boost Software License, Version 1.0. (See
|
||||
// accompanying file LICENSE_1_0.txt or copy at
|
||||
// http://www.boost.org/LICENSE_1_0.txt)
|
||||
|
||||
// For more information, see http://www.boost.org
|
||||
|
||||
// -- io_test.cpp -----------------------------------------------
|
||||
//
|
||||
// Testing the I/O facilities of tuples
|
||||
|
||||
#define BOOST_INCLUDE_MAIN // for testing, include rather than link
|
||||
#include "boost/test/test_tools.hpp" // see "Header Implementation Option"
|
||||
|
||||
#include "boost/tuple/tuple_io.hpp"
|
||||
#include "boost/tuple/tuple_comparison.hpp"
|
||||
|
||||
#include <fstream>
|
||||
#include <iterator>
|
||||
#include <algorithm>
|
||||
#include <string>
|
||||
|
||||
#if defined BOOST_NO_STRINGSTREAM
|
||||
#include <strstream>
|
||||
#else
|
||||
#include <sstream>
|
||||
#endif
|
||||
|
||||
using namespace std;
|
||||
using namespace boost;
|
||||
|
||||
#if defined BOOST_NO_STRINGSTREAM
|
||||
typedef ostrstream useThisOStringStream;
|
||||
typedef istrstream useThisIStringStream;
|
||||
#else
|
||||
typedef ostringstream useThisOStringStream;
|
||||
typedef istringstream useThisIStringStream;
|
||||
#endif
|
||||
|
||||
int test_main(int argc, char * argv[] ) {
|
||||
(void)argc;
|
||||
(void)argv;
|
||||
using boost::tuples::set_close;
|
||||
using boost::tuples::set_open;
|
||||
using boost::tuples::set_delimiter;
|
||||
|
||||
useThisOStringStream os1;
|
||||
|
||||
// Set format [a, b, c] for os1
|
||||
os1 << set_open('[');
|
||||
os1 << set_close(']');
|
||||
os1 << set_delimiter(',');
|
||||
os1 << make_tuple(1, 2, 3);
|
||||
BOOST_CHECK (os1.str() == std::string("[1,2,3]") );
|
||||
|
||||
{
|
||||
useThisOStringStream os2;
|
||||
// Set format (a:b:c) for os2;
|
||||
os2 << set_open('(');
|
||||
os2 << set_close(')');
|
||||
os2 << set_delimiter(':');
|
||||
#if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
|
||||
os2 << make_tuple("TUPU", "HUPU", "LUPU", 4.5);
|
||||
BOOST_CHECK (os2.str() == std::string("(TUPU:HUPU:LUPU:4.5)") );
|
||||
#endif
|
||||
}
|
||||
|
||||
// The format is still [a, b, c] for os1
|
||||
os1 << make_tuple(1, 2, 3);
|
||||
BOOST_CHECK (os1.str() == std::string("[1,2,3][1,2,3]") );
|
||||
|
||||
ofstream tmp("temp.tmp");
|
||||
|
||||
#if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
|
||||
tmp << make_tuple("One", "Two", 3);
|
||||
#endif
|
||||
tmp << set_delimiter(':');
|
||||
tmp << make_tuple(1000, 2000, 3000) << endl;
|
||||
|
||||
tmp.close();
|
||||
|
||||
// When teading tuples from a stream, manipulators must be set correctly:
|
||||
ifstream tmp3("temp.tmp");
|
||||
tuple<string, string, int> j;
|
||||
|
||||
#if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
|
||||
tmp3 >> j;
|
||||
BOOST_CHECK (tmp3.good() );
|
||||
#endif
|
||||
|
||||
tmp3 >> set_delimiter(':');
|
||||
tuple<int, int, int> i;
|
||||
tmp3 >> i;
|
||||
BOOST_CHECK (tmp3.good() );
|
||||
|
||||
tmp3.close();
|
||||
|
||||
|
||||
// reading tuple<int, int, int> in format (a b c);
|
||||
useThisIStringStream is("(100 200 300)");
|
||||
|
||||
tuple<int, int, int> ti;
|
||||
BOOST_CHECK(bool(is >> ti));
|
||||
BOOST_CHECK(ti == make_tuple(100, 200, 300));
|
||||
|
||||
|
||||
// Note that strings are problematic:
|
||||
// writing a tuple on a stream and reading it back doesn't work in
|
||||
// general. If this is wanted, some kind of a parseable string class
|
||||
// should be used.
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
@ -1,477 +0,0 @@
|
||||
// Copyright (C) 1999, 2000 Jaakko J<>rvi (jaakko.jarvi@cs.utu.fi)
|
||||
//
|
||||
// Distributed under the Boost Software License, Version 1.0. (See
|
||||
// accompanying file LICENSE_1_0.txt or copy at
|
||||
// http://www.boost.org/LICENSE_1_0.txt)
|
||||
|
||||
// For more information, see http://www.boost.org
|
||||
|
||||
// tuple_test_bench.cpp --------------------------------
|
||||
|
||||
#define BOOST_INCLUDE_MAIN // for testing, include rather than link
|
||||
#include <boost/test/test_tools.hpp> // see "Header Implementation Option"
|
||||
|
||||
#include "boost/tuple/tuple.hpp"
|
||||
|
||||
#include "boost/tuple/tuple_comparison.hpp"
|
||||
|
||||
#include "boost/type_traits/is_const.hpp"
|
||||
|
||||
#include "boost/ref.hpp"
|
||||
#include <string>
|
||||
#include <utility>
|
||||
|
||||
using namespace std;
|
||||
using namespace boost;
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// helpers
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
class A {};
|
||||
class B {};
|
||||
class C {};
|
||||
|
||||
// classes with different kinds of conversions
|
||||
class AA {};
|
||||
class BB : public AA {};
|
||||
struct CC { CC() {} CC(const BB&) {} };
|
||||
struct DD { operator CC() const { return CC(); }; };
|
||||
|
||||
// something to prevent warnings for unused variables
|
||||
template<class T> void dummy(const T&) {}
|
||||
|
||||
// no public default constructor
|
||||
class foo {
|
||||
public:
|
||||
explicit foo(int v) : val(v) {}
|
||||
|
||||
bool operator==(const foo& other) const {
|
||||
return val == other.val;
|
||||
}
|
||||
|
||||
private:
|
||||
foo() {}
|
||||
int val;
|
||||
};
|
||||
|
||||
// another class without a public default constructor
|
||||
class no_def_constructor {
|
||||
no_def_constructor() {}
|
||||
public:
|
||||
no_def_constructor(std::string) {}
|
||||
};
|
||||
|
||||
// A non-copyable class
|
||||
class no_copy {
|
||||
no_copy(const no_copy&) {}
|
||||
public:
|
||||
no_copy() {};
|
||||
};
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// Testing different element types --------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
|
||||
typedef tuple<int> t1;
|
||||
|
||||
typedef tuple<double&, const double&, const double, double*, const double*> t2;
|
||||
typedef tuple<A, int(*)(char, int), C> t3;
|
||||
typedef tuple<std::string, std::pair<A, B> > t4;
|
||||
typedef tuple<A*, tuple<const A*, const B&, C>, bool, void*> t5;
|
||||
typedef tuple<volatile int, const volatile char&, int(&)(float) > t6;
|
||||
|
||||
# if !defined(__BORLANDC__) || __BORLAND__ > 0x0551
|
||||
typedef tuple<B(A::*)(C&), A&> t7;
|
||||
#endif
|
||||
|
||||
// -----------------------------------------------------------------------
|
||||
// -tuple construction tests ---------------------------------------------
|
||||
// -----------------------------------------------------------------------
|
||||
|
||||
|
||||
no_copy y;
|
||||
tuple<no_copy&> x = tuple<no_copy&>(y); // ok
|
||||
|
||||
char cs[10];
|
||||
tuple<char(&)[10]> v2(cs); // ok
|
||||
|
||||
void
|
||||
construction_test()
|
||||
{
|
||||
|
||||
// Note, the get function can be called without the tuples:: qualifier,
|
||||
// as it is lifted to namespace boost with a "using tuples::get" but
|
||||
// MSVC 6.0 just cannot find get without the namespace qualifier
|
||||
|
||||
tuple<int> t1;
|
||||
BOOST_CHECK(get<0>(t1) == int());
|
||||
|
||||
tuple<float> t2(5.5f);
|
||||
BOOST_CHECK(get<0>(t2) > 5.4f && get<0>(t2) < 5.6f);
|
||||
|
||||
tuple<foo> t3(foo(12));
|
||||
BOOST_CHECK(get<0>(t3) == foo(12));
|
||||
|
||||
tuple<double> t4(t2);
|
||||
BOOST_CHECK(get<0>(t4) > 5.4 && get<0>(t4) < 5.6);
|
||||
|
||||
tuple<int, float> t5;
|
||||
BOOST_CHECK(get<0>(t5) == int());
|
||||
BOOST_CHECK(get<1>(t5) == float());
|
||||
|
||||
tuple<int, float> t6(12, 5.5f);
|
||||
BOOST_CHECK(get<0>(t6) == 12);
|
||||
BOOST_CHECK(get<1>(t6) > 5.4f && get<1>(t6) < 5.6f);
|
||||
|
||||
tuple<int, float> t7(t6);
|
||||
BOOST_CHECK(get<0>(t7) == 12);
|
||||
BOOST_CHECK(get<1>(t7) > 5.4f && get<1>(t7) < 5.6f);
|
||||
|
||||
tuple<long, double> t8(t6);
|
||||
BOOST_CHECK(get<0>(t8) == 12);
|
||||
BOOST_CHECK(get<1>(t8) > 5.4f && get<1>(t8) < 5.6f);
|
||||
|
||||
dummy(
|
||||
tuple<no_def_constructor, no_def_constructor, no_def_constructor>(
|
||||
std::string("Jaba"), // ok, since the default
|
||||
std::string("Daba"), // constructor is not used
|
||||
std::string("Doo")
|
||||
)
|
||||
);
|
||||
|
||||
// testing default values
|
||||
dummy(tuple<int, double>());
|
||||
dummy(tuple<int, double>(1));
|
||||
dummy(tuple<int, double>(1,3.14));
|
||||
|
||||
|
||||
// dummy(tuple<double&>()); // should fail, not defaults for references
|
||||
// dummy(tuple<const double&>()); // likewise
|
||||
|
||||
double dd = 5;
|
||||
dummy(tuple<double&>(dd)); // ok
|
||||
|
||||
dummy(tuple<const double&>(dd+3.14)); // ok, but dangerous
|
||||
|
||||
// dummy(tuple<double&>(dd+3.14)); // should fail,
|
||||
// // temporary to non-const reference
|
||||
}
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - testing element access ---------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
void element_access_test()
|
||||
{
|
||||
double d = 2.7;
|
||||
A a;
|
||||
tuple<int, double&, const A&, int> t(1, d, a, 2);
|
||||
const tuple<int, double&, const A, int> ct = t;
|
||||
|
||||
int i = get<0>(t);
|
||||
int i2 = get<3>(t);
|
||||
|
||||
BOOST_CHECK(i == 1 && i2 == 2);
|
||||
|
||||
int j = get<0>(ct);
|
||||
BOOST_CHECK(j == 1);
|
||||
|
||||
get<0>(t) = 5;
|
||||
BOOST_CHECK(t.head == 5);
|
||||
|
||||
// get<0>(ct) = 5; // can't assign to const
|
||||
|
||||
double e = get<1>(t);
|
||||
BOOST_CHECK(e > 2.69 && e < 2.71);
|
||||
|
||||
get<1>(t) = 3.14+i;
|
||||
BOOST_CHECK(get<1>(t) > 4.13 && get<1>(t) < 4.15);
|
||||
|
||||
// get<4>(t) = A(); // can't assign to const
|
||||
// dummy(get<5>(ct)); // illegal index
|
||||
|
||||
++get<0>(t);
|
||||
BOOST_CHECK(get<0>(t) == 6);
|
||||
|
||||
BOOST_STATIC_ASSERT((boost::is_const<boost::tuples::element<0, tuple<int, float> >::type>::value != true));
|
||||
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
|
||||
BOOST_STATIC_ASSERT((boost::is_const<boost::tuples::element<0, const tuple<int, float> >::type>::value));
|
||||
#endif
|
||||
|
||||
BOOST_STATIC_ASSERT((boost::is_const<boost::tuples::element<1, tuple<int, float> >::type>::value != true));
|
||||
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
|
||||
BOOST_STATIC_ASSERT((boost::is_const<boost::tuples::element<1, const tuple<int, float> >::type>::value));
|
||||
#endif
|
||||
|
||||
|
||||
dummy(i); dummy(i2); dummy(j); dummy(e); // avoid warns for unused variables
|
||||
}
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - copying tuples -----------------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
|
||||
|
||||
void
|
||||
copy_test()
|
||||
{
|
||||
tuple<int, char> t1(4, 'a');
|
||||
tuple<int, char> t2(5, 'b');
|
||||
t2 = t1;
|
||||
BOOST_CHECK(get<0>(t1) == get<0>(t2));
|
||||
BOOST_CHECK(get<1>(t1) == get<1>(t2));
|
||||
|
||||
tuple<long, std::string> t3(2, "a");
|
||||
t3 = t1;
|
||||
BOOST_CHECK((double)get<0>(t1) == get<0>(t3));
|
||||
BOOST_CHECK(get<1>(t1) == get<1>(t3)[0]);
|
||||
|
||||
// testing copy and assignment with implicit conversions between elements
|
||||
// testing tie
|
||||
|
||||
tuple<char, BB*, BB, DD> t;
|
||||
tuple<int, AA*, CC, CC> a(t);
|
||||
a = t;
|
||||
|
||||
int i; char c; double d;
|
||||
tie(i, c, d) = make_tuple(1, 'a', 5.5);
|
||||
|
||||
BOOST_CHECK(i==1);
|
||||
BOOST_CHECK(c=='a');
|
||||
BOOST_CHECK(d>5.4 && d<5.6);
|
||||
}
|
||||
|
||||
void
|
||||
mutate_test()
|
||||
{
|
||||
tuple<int, float, bool, foo> t1(5, 12.2f, true, foo(4));
|
||||
get<0>(t1) = 6;
|
||||
get<1>(t1) = 2.2f;
|
||||
get<2>(t1) = false;
|
||||
get<3>(t1) = foo(5);
|
||||
|
||||
BOOST_CHECK(get<0>(t1) == 6);
|
||||
BOOST_CHECK(get<1>(t1) > 2.1f && get<1>(t1) < 2.3f);
|
||||
BOOST_CHECK(get<2>(t1) == false);
|
||||
BOOST_CHECK(get<3>(t1) == foo(5));
|
||||
}
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// make_tuple tests -----------------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
void
|
||||
make_tuple_test()
|
||||
{
|
||||
tuple<int, char> t1 = make_tuple(5, 'a');
|
||||
BOOST_CHECK(get<0>(t1) == 5);
|
||||
BOOST_CHECK(get<1>(t1) == 'a');
|
||||
|
||||
tuple<int, std::string> t2;
|
||||
t2 = make_tuple((short int)2, std::string("Hi"));
|
||||
BOOST_CHECK(get<0>(t2) == 2);
|
||||
BOOST_CHECK(get<1>(t2) == "Hi");
|
||||
|
||||
|
||||
A a = A(); B b;
|
||||
const A ca = a;
|
||||
make_tuple(boost::cref(a), b);
|
||||
make_tuple(boost::ref(a), b);
|
||||
make_tuple(boost::ref(a), boost::cref(b));
|
||||
|
||||
make_tuple(boost::ref(ca));
|
||||
|
||||
// the result of make_tuple is assignable:
|
||||
BOOST_CHECK(make_tuple(2, 4, 6) ==
|
||||
(make_tuple(1, 2, 3) = make_tuple(2, 4, 6)));
|
||||
|
||||
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
|
||||
make_tuple("Donald", "Daisy"); // should work;
|
||||
#endif
|
||||
// std::make_pair("Doesn't","Work"); // fails
|
||||
|
||||
// You can store a reference to a function in a tuple
|
||||
tuple<void(&)()> adf(make_tuple_test);
|
||||
|
||||
dummy(adf); // avoid warning for unused variable
|
||||
|
||||
// But make_tuple doesn't work
|
||||
// with function references, since it creates a const qualified function type
|
||||
|
||||
// make_tuple(make_tuple_test);
|
||||
|
||||
// With function pointers, make_tuple works just fine
|
||||
|
||||
#if !defined(__BORLANDC__) || __BORLAND__ > 0x0551
|
||||
make_tuple(&make_tuple_test);
|
||||
#endif
|
||||
|
||||
// NOTE:
|
||||
//
|
||||
// wrapping it the function reference with ref helps on gcc 2.95.2.
|
||||
// on edg 2.43. it results in a catastrophic error?
|
||||
|
||||
// make_tuple(ref(foo3));
|
||||
|
||||
// It seems that edg can't use implicitly the ref's conversion operator, e.g.:
|
||||
// typedef void (&func_t) (void);
|
||||
// func_t fref = static_cast<func_t>(ref(make_tuple_test)); // works fine
|
||||
// func_t fref = ref(make_tuple_test); // error
|
||||
|
||||
// This is probably not a very common situation, so currently
|
||||
// I don't know how which compiler is right (JJ)
|
||||
}
|
||||
|
||||
void
|
||||
tie_test()
|
||||
{
|
||||
int a;
|
||||
char b;
|
||||
foo c(5);
|
||||
|
||||
tie(a, b, c) = make_tuple(2, 'a', foo(3));
|
||||
BOOST_CHECK(a == 2);
|
||||
BOOST_CHECK(b == 'a');
|
||||
BOOST_CHECK(c == foo(3));
|
||||
|
||||
tie(a, tuples::ignore, c) = make_tuple((short int)5, false, foo(5));
|
||||
BOOST_CHECK(a == 5);
|
||||
BOOST_CHECK(b == 'a');
|
||||
BOOST_CHECK(c == foo(5));
|
||||
|
||||
// testing assignment from std::pair
|
||||
int i, j;
|
||||
tie (i, j) = std::make_pair(1, 2);
|
||||
BOOST_CHECK(i == 1 && j == 2);
|
||||
|
||||
tuple<int, int, float> ta;
|
||||
#ifdef E11
|
||||
ta = std::make_pair(1, 2); // should fail, tuple is of length 3, not 2
|
||||
#endif
|
||||
|
||||
dummy(ta);
|
||||
}
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - testing tuple equality -------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
void
|
||||
equality_test()
|
||||
{
|
||||
tuple<int, char> t1(5, 'a');
|
||||
tuple<int, char> t2(5, 'a');
|
||||
BOOST_CHECK(t1 == t2);
|
||||
|
||||
tuple<int, char> t3(5, 'b');
|
||||
tuple<int, char> t4(2, 'a');
|
||||
BOOST_CHECK(t1 != t3);
|
||||
BOOST_CHECK(t1 != t4);
|
||||
BOOST_CHECK(!(t1 != t2));
|
||||
}
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - testing tuple comparisons -----------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
void
|
||||
ordering_test()
|
||||
{
|
||||
tuple<int, float> t1(4, 3.3f);
|
||||
tuple<short, float> t2(5, 3.3f);
|
||||
tuple<long, double> t3(5, 4.4);
|
||||
BOOST_CHECK(t1 < t2);
|
||||
BOOST_CHECK(t1 <= t2);
|
||||
BOOST_CHECK(t2 > t1);
|
||||
BOOST_CHECK(t2 >= t1);
|
||||
BOOST_CHECK(t2 < t3);
|
||||
BOOST_CHECK(t2 <= t3);
|
||||
BOOST_CHECK(t3 > t2);
|
||||
BOOST_CHECK(t3 >= t2);
|
||||
|
||||
}
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - testing cons lists -------------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
void cons_test()
|
||||
{
|
||||
using tuples::cons;
|
||||
using tuples::null_type;
|
||||
|
||||
cons<volatile float, null_type> a(1, null_type());
|
||||
cons<const int, cons<volatile float, null_type> > b(2,a);
|
||||
int i = 3;
|
||||
cons<int&, cons<const int, cons<volatile float, null_type> > > c(i, b);
|
||||
BOOST_CHECK(make_tuple(3,2,1)==c);
|
||||
|
||||
cons<char, cons<int, cons<float, null_type> > > x;
|
||||
dummy(x);
|
||||
}
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - testing const tuples -----------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
void const_tuple_test()
|
||||
{
|
||||
const tuple<int, float> t1(5, 3.3f);
|
||||
BOOST_CHECK(get<0>(t1) == 5);
|
||||
BOOST_CHECK(get<1>(t1) == 3.3f);
|
||||
}
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - testing length -----------------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
void tuple_length_test()
|
||||
{
|
||||
typedef tuple<int, float, double> t1;
|
||||
using tuples::cons;
|
||||
typedef cons<int, cons< float, cons <double, tuples::null_type> > > t1_cons;
|
||||
typedef tuple<> t2;
|
||||
typedef tuples::null_type t3;
|
||||
|
||||
BOOST_STATIC_ASSERT(tuples::length<t1>::value == 3);
|
||||
BOOST_STATIC_ASSERT(tuples::length<t1_cons>::value == 3);
|
||||
BOOST_STATIC_ASSERT(tuples::length<t2>::value == 0);
|
||||
BOOST_STATIC_ASSERT(tuples::length<t3>::value == 0);
|
||||
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
// ----------------------------------------------------------------------------
|
||||
// - main ---------------------------------------------------------------------
|
||||
// ----------------------------------------------------------------------------
|
||||
|
||||
int test_main(int, char *[]) {
|
||||
|
||||
construction_test();
|
||||
element_access_test();
|
||||
copy_test();
|
||||
mutate_test();
|
||||
make_tuple_test();
|
||||
tie_test();
|
||||
equality_test();
|
||||
ordering_test();
|
||||
cons_test();
|
||||
const_tuple_test();
|
||||
tuple_length_test();
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user