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[BGL] obtaining list of edges in a shortest path
by Lars S. Jessen 27 Feb '06

27 Feb '06

Hi. I have an adjacency_list graph where I need to find the shortest path between two vertices. This can be done with the following code (from http://www.boost.org/libs/graph/example/astar-cities.cpp) ... vector<mygraph_t::vertex_descriptor> p(num_vertices(g)); vector<cost> d(num_vertices(g)); try { // call astar named parameter interface astar_search (g, start, distance_heuristic<mygraph_t, cost, location*> (locations, goal), predecessor_map(&p[0]).distance_map(&d[0]). visitor(astar_goal_visitor<vertex>(goal))); } catch(found_goal fg) { // found a path to the goal list<vertex> shortest_path; for(vertex v = goal;; v = p[v]) { shortest_path.push_front(v); if(p[v] == v) break; } ... As you can see, it's easy to obtain the list of vertices that makes the shortest path from start to goal, but how do I obtain the list of edges connecting start to goal? - Lars

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Bjam question
by Drumheller, Michael 27 Feb '06

27 Feb '06

Dear Bjam Experts: For some reason all my source files are getting compiled twice. Below is my Jamfile (stripped to its essentials, and names changed to protect the innocent), and below that is the output (also stripped way down). Sorry for the clutter--I have tried to strip it down to the minimum. Notice how every .obj gets constructed twice. Yet the destination path (vc-7_1\release\threading-multi\ is the same in each case; also, I'm also invoking bjam with precisely that target specified on the command line. Is there anything really obvious to bjam-adjusted eyes going on here? Thank you very much. Michael Drumheller ----------------------------------------------------------cut here: Jamfile--------------------------------------- project-root ; import python ; include python.jam ; FOOCORE_SOURCES = File1 File2 ; FOOCORE_SOURCES = ..\\..\\src\\$(FOOCORE_SOURCES).cpp ; lib Foo : $(FOOCORE_SOURCES) : <include>C:\\Boost\\include\\boost-1_32 <vc-7_1><*><define>WIN32 <include>..\\..\\src <include>C:\\Python24\\include <include>"C:\\Program Files\\Microsoft Visual Studio .NET 2003\\Vc7\\include" ; ----------------------------------------------------------cut here: resulting output --------------------------- 06-02-26:12:22:26:boost/FooBar=> bjam -sTOOLS=vc-7_1 "-sBUILD=release <threading>multi" ...found 3088 targets... ...updating 142 targets... vc-C++ ./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File1.obj File1.cpp vc-C++ ./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File2.obj File2.cpp ...<snip>... vc-Archive ./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\libFoo.lib Microsoft (R) Library Manager Version 7.10.3077 Copyright (C) Microsoft Corporation. All rights reserved. "./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File1.obj" "./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File2.obj" ...<snip>... vc-C++ ./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File1.obj File1.cpp vc-C++ ./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File2.obj File2.cpp ...<snip>... vc-Archive ./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\libFoo.lib Microsoft (R) Library Manager Version 7.10.3077 Copyright (C) Microsoft Corporation. All rights reserved. "./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File1.obj" "./build\bin\FooBar\libFoo.lib\vc-7_1\release\threading-multi\File2.obj" ...<snip>...

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std::map, boost::smart_ptr and std::for_each()
by Pavel Syomin 26 Feb '06

26 Feb '06

Hi to all! How to use for_each() for std::map of boost::smart_ptr items? Thanks.

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Re: [Boost-users] Building 1.33.1 with VC .NET 2003
by Wu Yinghui, Freddie 26 Feb '06

26 Feb '06

> Message: 5 > Date: Sat, 25 Feb 2006 16:50:16 -0700 > From: "D. R. Evans" <doc.evans(a)gmail.com> > Subject: Re: [Boost-users] Building 1.33.1 with VC .NET 2003 > Message-ID: <256f4e900602251550i2cd6f6d3m(a)mail.gmail.com> > > Incidentally, I get the same result if I try: > > C:\boost\boost_1_33_1>bjam "-sTOOLS=vc-7_1" "-sVC71_ROOT=C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7" > > In fact, I get the same result using any reasonable set of parameters > on the command line. > > Doc > > PS This is getting so painful and with no end in sight I'm wondering > whether anyone has a Windows VC 7.1 build of 1_33_1 that I could grab > or they could send? Actually, I only want the debug multi-threaded > date-time library. I do agree the building Boost with MSVC (on Windows platform, of course) is pretty painful. Though I do not have the time the review the actual points here, I do consider it worth taking some time to review the installation doc. It took me 2 full days to do trial&error + research-from-the-web in order to build Boost the first time and to realize all the tricks necessary to make it work. I'll check back to office tomorrow to see if it is possible for me to post some pointers out of the Batch file I wrote to make my own life easier... Cheers, Freddie P.S. I do have a version of Boost 1.33.1 (as well as a Boost 1.34 CVS) built with MSVC71 + STLport 5.0. Do let me know if you want it.

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How should I do to replace the constant pointer with shared_ptr?
by pegacorn＠jcom.home.ne.jp 26 Feb '06

26 Feb '06

How should I do to replace the constant pointer with shared_ptr? int main() { const int *ip = new int(1); *ip = 2; // NG ip = new int(2); // OK } How should I do to achieve the above-mentioned example by using shared_ptr? ---- pegacorn

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Re: [Boost-users] [spirit] should be a very simple problem, but I'm stumped
by Todd Day 26 Feb '06

26 Feb '06

>> "ParmName: ParmValue" >> I'm looking for certain ParmNames, and I have to grab the associated >> ParmValue. >[Nat] Maybe the Spirit parser is the wrong place to get specific about >the ParmNames you're seeking? Maybe what you should do is parse *every* >item of that form, stuffing the pairs into a std::map. Then you can >extract from that map the specific items you want. Nat, thanks for the reply. In the course of writing a reply to you explaining what I'm really trying to do, I had an "aha" head-slapping moment. You know how it is... sometimes, just trying to explain a problem is enough to generate the answer. In reply to your quoted text above, yes, I should not be specific about which ParmNames I'm seeking at this level. I was actually using a map; I had just removed that from my example to make it a bit easier to understand. There is a bigger problem that the files I'm looking at may have mismatched single quotes in the parts of the file I don't care about. Like this random-text " random-text random-text In other words, to a parser looking for quoted text, these single quotes would appear as damaged, and the parser would still halt like it does now. The only thing I can be sure of is that "ParmName: ParmValue" will be properly quoted and non-damaged and consistent within itself. So it turns out my basic comprehension problem here is similar to one I had actually gone through when I was first learning pattern matching and regular expressions under Perl. I went and dug up some old Perl code of mine that did a similar search to see how I did it back then. My basic problem is thinking that the parser would continue grinding through non-matches just by putting a kleene-star on the front of it. Once I took this into account, a new strategy emerged. First, search for a single quote. Then try and see if there is a match at that point. If a match, move to just beyond the match, else just move to the next character. Repeat. The code is not as simple as my previous non-working version, since now I have to use iterators. This example also looks for multiple types of ParmNames. It comes out looking like the code below. I love that you can load up a complex map assignment right in the middle of the rule. map<string,string> smap; string key; typedef string::const_iterator iterator_t; typedef scanner<iterator_t> scanner_t; typedef rule<scanner_t> rule_t; typedef parse_info<iterator_t> parse_info_t; rule_t quote = ch_p('"'); rule_t colon = ch_p(':'); rule_t eat_all_non_quotes = *~ch_p('"'); rule_t parm_names = str_p(DWARF_DEVICE_NAME) | DWARF_DEVICE_TYPE | DWARF_DEVICE_SOFTWARE_VERSION | DWARF_DEVICE_COMMENTS; rule_t parm_string = quote >> parm_names[assign_a(key)] >> colon >> *blank_p >> eat_all_non_quotes[insert_at_a(smap, key)] >> quote; string str = "\"broken\" (text \"DeviceName: Altera in Controller\" (blah))"; iterator_t first = str.begin(); iterator_t last = str.end(); parse_info_t pi; while (first != last) { // skip to first quote character pi = parse(first, last, eat_all_non_quotes); first = pi.stop; // make sure we haven't gone past the end if (first != last) { // eat up any matching parms here pi = parse(first, last, parm_string); if (pi.hit) first = pi.stop; else first++; } } Thanks for the help, -todd-

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member selector adapter
by Nico Galoppo 25 Feb '06

25 Feb '06

Hi, is there some utility (templated) adapter type class that I could use to construct an adapter such that an (associative) array of (pointers to) objects behaves like an (associative) array of a member variable of the objects? Something like class A { int val; }; std::map<int, shared_ptr<A> > container_type; container_type amap; shared_ptr<A> elem(new A()); amap[2] = elem; amap[4] = elem; amap[6] = elem; selector_adapter<container_type, &A::val> val_container(&amap); std::cout << val_container[4]; // should output amap[4]->val; --nico -- nico galoppo von borries @ address: 105 creel st., chapel hill comp. graphics phd. student @ north carolina, 27516 USA UNC, chapel hill @ phone: +1 (919) 962-1898 (office) @ +1 (919) 942-7609 (home) @ email: nico at cs dot unc dot edu @ homepage: http://www.cs.unc.edu/~nico --- debian linux :: vim powered

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Boost build problems in Scratchbox, mkdir fails
by Rohit Chaudhri 25 Feb '06

25 Feb '06

Hello, I have recently started to work with Boost 1.33 on Linux. I have an X86 based Ubuntu Linux machine. I have installed Scratchbox 1.0 (www.scratchbox.org) on this machine for embedded linux development. I'm able to build boost on Ubuntu, however when I try to do the same within Scratchbox using an arm-gcc-glibc toolchain, the Boost build scripts fail because mkdir commands are failing. I was able to build Boost.Jam by manually creating the required directories within Scratchbox. Now while building Boost 1.33, I'm trying to build the Boost.Python module and it fails in a similar way on MKDIR. I want to fix this mkdir failure problem because I can't manually keep creating each required directory. Would appreciate it someone could help me out with this. Looking at the archives I've read emails that indicate Boost has been successfully built within Scratchbox. This is probably a problem in my Scratchbox environment, but don't know how to fix it. I'll post a similar email on Scratchbox forums too. Thanks in advance. Rohit

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iterator_adaptor question
by Nico Galoppo 25 Feb '06

25 Feb '06

Hi, regarding iterator_adaptor<>, I've created a custom iterator over a map as below. Basically, it allows to iterate over map values without being worried with key values. Anyway, if I would want to do something like this: typedef map<int,int> map_type; typedef map_data_iterator<map_type::iterator> map_iterator; map_type map; map_iterator it = map_data_iterator(map.begin()); for (; it != map.end(); ++map) ... I'd have to add an equal method to the map_data_iterator class that takes the base type iterator, right? I tried to do so below, but it still complains about not being able to convert: binary '!=' : no operator found which takes a left-hand operand of type 'OpenTissue::DepthFirstTesselator<Types>::prism_iterator' (or there is no acceptable conversion) I know this is probably not the right thing(tm) to do , but I basically need to be able to do this comparison for backward compatibility with deprecated code. Thanks, --nico template <class Iterator> class map_data_iterator : public iterator_adaptor< map_data_iterator<Iterator>, Iterator, typename Iterator::value_type::second_type > { typedef typename map_data_iterator::iterator_adaptor_ super_t; typedef typename Iterator::value_type pair_type; typedef typename pair_type::second_type second_type; friend class iterator_core_access; public: map_data_iterator() {} // should be explicit, but removed to give OpenTissue backwards compatibility map_data_iterator(Iterator x) : super_t(x) {} template<class OtherIterator> map_data_iterator( map_data_iterator<OtherIterator> const& r , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0 ) : super_t(r.base()) {} private: second_type & dereference() const { return this->base()->second; } // added to give support for comparison with base type iterators //bool equal(Iterator const& other) const //{ // return (this->base() == other); //} //bool equal(super_t const& other) const //{ // return (*this == other); //} }; -- nico galoppo von borries @ address: 105 creel st., chapel hill comp. graphics phd. student @ north carolina, 27516 USA UNC, chapel hill @ phone: +1 (919) 962-1898 (office) @ +1 (919) 942-7609 (home) @ email: nico at cs dot unc dot edu @ homepage: http://www.cs.unc.edu/~nico --- debian linux :: vim powered

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Re: [Boost-users] [mpl] newbie question
by james.jones＠firstinvestors.com 24 Feb '06

24 Feb '06

Andy Little wrote: > What can I say? I acknowledge that mpl is a monumental piece of work . > Wonderful... but far from perfect. You can say, "Sorry, that was terribly rude of me. Here's a patch and some test code so that we can work together to make MPL even better." - James

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