ENH: adapter for a list of C++ strings <-> a list of C-style strings

- Translate a list of C++ strings into C-style (argc, argv) pair.
- Translate C-style (argc, argv) pair to list of C++ strings.

Useful when interfacing to external C-code and some libraries

applications/test/cstring/Make/files

@@ -0,0 +1,3 @@
+Test-cstring.C
+
+EXE = $(FOAM_USER_APPBIN)/Test-cstring

applications/test/cstring/Make/options

@@ -0,0 +1,2 @@
+/* EXE_INC = -I$(LIB_SRC)/cfdTools/include */
+/* EXE_LIBS = -lfiniteVolume */

applications/test/cstring/Test-cstring.C

@@ -0,0 +1,99 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Description
+    Test some string functionality
+
+\*---------------------------------------------------------------------------*/
+
+#include "CStringList.H"
+#include "DynamicList.H"
+#include "IOstreams.H"
+#include "fileNameList.H"
+#include "stringList.H"
+#include "wordList.H"
+
+using namespace Foam;
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+int print(int argc, char *argv[])
+{
+    Info<< "argc=" << argc << endl;
+    for (int i=0; i<argc; ++i)
+    {
+        Info<< "  argv[" << i << "] = \"" << argv[i] << "\"" << endl;
+    }
+    return argc;
+}
+
+int print(const CStringList& cstrLst)
+{
+    return print(cstrLst.size(), cstrLst.strings());
+}
+
+
+// Main program:
+
+int main(int argc, char *argv[])
+{
+    DynamicList<string> dynlst;
+    dynlst.reserve(16);
+
+    dynlst.append("string1 with content");
+    dynlst.append("string2 other content");
+    dynlst.append("string3 done");
+
+    {
+        CStringList inC(dynlst);
+
+        Info<< "input: " << dynlst << endl;
+        print(inC);
+    }
+
+    Info<<"command-line with " << CStringList::count(argv) << " items"<< endl;
+
+    print(argc, argv);
+    {
+        dynlst.clear();
+        for (int i=0; i<argc; ++i)
+        {
+            dynlst.append(argv[i]);
+        }
+
+        Info<< "input: " << dynlst << endl;
+        CStringList inC(dynlst);
+        inC.reset(dynlst);
+
+        print(inC);
+        Info<< "length: " << inC.length() << endl;
+        std::cout.write(inC.data(), inC.length());
+    }
+
+
+    Info<< "\nEnd\n" << endl;
+    return 0;
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/strings/lists/CStringList.H

@@ -0,0 +1,175 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::CStringList
+
+Description
+    An adapter for copying a list of C++ strings into a list of C-style
+    strings for passing to C code that expects argc/argv parameters.
+
+    In addition to providing a C-compatible list of C-strings,
+    the string lists are flattened into a single string of data that can be
+    also be passed en mass.
+
+    Example use:
+    \code
+        wordList myStrings;  ...
+        CStringList cstr(myStrings);
+
+        // pass as argc, argv:
+        someMain(cstr.size(), cstr.strings());
+
+        // access the raw characters:
+        os.write(cstr.data(), cstr.length());
+    \endcode
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef CStringList_H
+#define CStringList_H
+
+#include "fileNameList.H"
+#include "stringList.H"
+#include "wordList.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                         Class CStringList Declaration
+\*---------------------------------------------------------------------------*/
+
+class CStringList
+{
+    // Private data
+
+        //- Number of strings
+        int argc_;
+
+        //- Overall length of the raw content
+        //  Does not include the final nul-character
+        size_t len_;
+
+        //- List of strings, including trailing NULL pointer
+        char** argv_;
+
+        //- Flattened content with interspersed nul-characters
+        char* data_;
+
+
+    // Private Member Functions
+
+        //- Disallow default bitwise copy construct
+        CStringList(const CStringList&) = delete;
+
+        //- Disallow default bitwise assignment
+        void operator=(const CStringList&) = delete;
+
+
+public:
+
+    // Constructors
+
+        //- Construct empty, adding content later (via reset).
+        inline CStringList();
+
+
+        //- Construct from a list of strings
+        //  Copies the input characters.
+        template<class StringType>
+        CStringList(const UList<StringType>& input);
+
+
+    //- Destructor
+    inline ~CStringList();
+
+
+    // Public Members
+
+        //- Count the number of parameters until the first NULL pointer.
+        //  Return 0 if argv is NULL.
+        static inline int count(const char * const argv[]);
+
+
+    // Access
+
+        //- Return the number of C-strings (ie, argc)
+        inline int size() const;
+
+        //- Return the list of C-strings (ie, argv)
+        //  The position at argc is a NULL pointer
+        inline char** strings() const;
+
+
+        //- Overall length of the flattened character (data) content
+        inline size_t length() const;
+
+        //- The flattened character content, with interspersed nul-chars
+        inline char* data() const;
+
+
+    // Edit
+
+        //- Clear contents and free memory
+        inline void clear();
+
+        //- Copy the input list of strings.
+        template<class StringType>
+        void reset(const UList<StringType>& input);
+
+
+    // Other
+
+        //- Create a list from argc/argv parameters.
+        //  A null pointer for argv is permissible when argc is zero.
+        template<class StringType>
+        static List<StringType> asList(int argc, const char * const argv[]);
+
+        //- Create a list from a NULL-terminated list of argv parameters.
+        //  A null pointer for argv is permissible.
+        template<class StringType>
+        static inline List<StringType> asList(const char * const argv[]);
+
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "CStringListI.H"
+
+#ifdef NoRepository
+#   include "CStringListTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/primitives/strings/lists/CStringListI.H

@@ -0,0 +1,106 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * * //
+
+inline int Foam::CStringList::count(const char * const argv[])
+{
+    int nElem = 0;
+    if (argv)
+    {
+        while (argv[nElem])
+        {
+            ++nElem;
+        }
+    }
+
+    return nElem;
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+inline Foam::CStringList::CStringList()
+:
+    argc_(0),
+    len_(0),
+    argv_(0),
+    data_(0)
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+inline Foam::CStringList::~CStringList()
+{
+    clear();
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+inline void Foam::CStringList::clear()
+{
+    argc_ = 0;
+    len_  = 0;
+
+    if (data_)
+    {
+        delete[] data_;
+        data_ = 0;
+    }
+    if (argv_)
+    {
+        delete[] argv_;
+        argv_ = 0;
+    }
+}
+
+
+inline int Foam::CStringList::size() const
+{
+    return argc_;
+}
+
+
+inline size_t Foam::CStringList::length() const
+{
+    return len_;
+}
+
+
+inline char** Foam::CStringList::strings() const
+{
+    return argv_;
+}
+
+
+inline char* Foam::CStringList::data() const
+{
+    return data_;
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/strings/lists/CStringListTemplates.C

@@ -0,0 +1,115 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template<class StringType>
+Foam::CStringList::CStringList
+(
+    const UList<StringType>& input
+)
+:
+    argc_(0),
+    len_(0),
+    argv_(0),
+    data_(0)
+{
+    reset(input);
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class StringType>
+void Foam::CStringList::reset
+(
+    const UList<StringType>& input
+)
+{
+    clear();
+
+    argc_ = input.size();
+    forAll(input, argI)
+    {
+        len_ += input[argI].size();
+        ++len_;  // nul terminator for C-strings
+    }
+
+    argv_ = new char*[argc_+1];
+    argv_[argc_] = NULL; // extra terminator
+
+    if (argc_ > 0)
+    {
+        // allocation includes final nul terminator,
+        // but overall count does not
+        data_ = new char[len_--];
+
+        char* ptr = data_;
+        forAll(input, argI)
+        {
+            argv_[argI] = ptr;
+
+            const std::string& str =
+                static_cast<const std::string&>(input[argI]);
+
+            for
+            (
+                std::string::const_iterator iter = str.begin();
+                iter != str.end();
+                ++iter
+            )
+            {
+                *(ptr++) = *iter;
+            }
+            *(ptr++) = '\0';
+        }
+    }
+}
+
+
+template<class StringType>
+Foam::List<StringType>
+Foam::CStringList::asList(int argc, const char * const argv[])
+{
+    List<StringType> lst(argc);
+
+    for (int i=0; i < argc; ++i)
+    {
+        lst[i] = argv[i];
+    }
+
+    return lst;
+}
+
+
+template<class StringType>
+Foam::List<StringType>
+Foam::CStringList::asList(const char * const argv[])
+{
+    return asList<StringType>(count(argv), argv);
+}
+
+
+// ************************************************************************* //