ENH: improvements to stringOps format and split functions

- split now optionally retains empty substrings.
  Added split on fixed field width.

- Foam::name() now formats directly into string buffer, which a
  removes one layer of copying and also avoids using a non-constexpr
  in the temporary.

STYLE: explicit type narrowing on zero-padded output for ensight

applications/test/string/Test-string.C

@@ -62,6 +62,18 @@ int main(int argc, char *argv[])
     dict.add("FOAM_RUN", subDict);
 
 
+    // Test Foam::name with formatting string
+    {
+        word formatted = Foam::name("formatted=<%X>", 0xdeadbeef);
+        Info<<"formatted: " << formatted << nl;
+    }
+
+    Info<<"formatted: "
+        << Foam::name("formatted not checked for validity=<%X>", 0xdeadbeef)
+        << nl
+        << endl
+
+
     Info<< "string:" << test << nl << "hash:"
         << unsigned(string::hash()(test)) << endl;
 

applications/test/stringSplit/Test-stringSplit.C

@@ -71,6 +71,18 @@ int main(int argc, char *argv[])
         "string",
         "test split on substring"
     );
+    argList::addOption
+    (
+        "char",
+        "delim",
+        "test split on specified delimiter character"
+    );
+    argList::addOption
+    (
+        "fixed",
+        "int",
+        "test split on fixed width"
+    );
     argList::addBoolOption
     (
         "slash",
@@ -81,6 +93,11 @@ int main(int argc, char *argv[])
         "space",
         "test split on space"
     );
+    argList::addBoolOption
+    (
+        "empty",
+        "preserve empty strings in split"
+    );
     argList args(argc, argv, false, true);
 
     if (args.size() <= 1 && args.options().empty())
@@ -88,8 +105,10 @@ int main(int argc, char *argv[])
         args.printUsage();
     }
 
+    const bool keepEmpty = args.optionFound("empty");
+
     int nopts = 0;
-    for (auto optName : { "any", "slash", "space", "sub" })
+    for (auto optName : { "any", "slash", "space", "sub", "fixed", "char" })
     {
         if (args.optionFound(optName))
         {
@@ -152,15 +171,55 @@ int main(int argc, char *argv[])
         }
     }
 
+    if (args.optionFound("char"))
+    {
+        const char delim = args["char"][0];
+
+        Info<< "split on char=" << delim << nl
+            << "~~~~~~~~~~~~~~" << nl;
+
+        for (label argi=1; argi < args.size(); ++argi)
+        {
+            const auto split = stringOps::split(args[argi], delim, keepEmpty);
+            printSubStrings(args[argi], split);
+        }
+
+        if (nopts == 1)
+        {
+            return 0;
+        }
+    }
+
+    if (args.optionFound("fixed"))
+    {
+        const label width = readLabel(args["fixed"]);
+
+        Info<< "split on fixed width = " << width << nl
+            << "~~~~~~~~~~~~~~" << nl;
+
+        for (label argi=1; argi < args.size(); ++argi)
+        {
+            const auto split = stringOps::splitFixed(args[argi], width);
+            printSubStrings(args[argi], split);
+        }
+
+        if (nopts == 1)
+        {
+            return 0;
+        }
+    }
+
     // Default
     if (!nopts || args.optionFound("slash"))
     {
+        const char delim = '/';
+
         Info<< "split on slash" << nl
             << "~~~~~~~~~~~~~~" << nl;
 
         for (label argi=1; argi < args.size(); ++argi)
         {
-            const auto split = stringOps::split(args[argi], '/');
+            const auto split = stringOps::split(args[argi], delim, keepEmpty);
             printSubStrings(args[argi], split);
         }
     }

src/OpenFOAM/primitives/strings/stringOps/stringOps.H

@@ -335,26 +335,29 @@ namespace stringOps
 
 
     //- Split string into sub-strings at the delimiter character.
-    //  Empty sub-strings are suppressed.
+    //  Empty sub-strings are normally suppressed.
+    //  Behaviour is ill-defined if delim is a NUL character.
     template<class StringType>
     Foam::SubStrings<StringType> split
     (
         const StringType& str,
-        const char delim
+        const char delim,
+        const bool keepEmpty = false
     );
 
     //- Split string into sub-strings using delimiter string.
-    //  Empty sub-strings are suppressed.
+    //  Empty sub-strings are normally suppressed.
     template<class StringType>
     Foam::SubStrings<StringType> split
     (
         const StringType& str,
-        const std::string& delim
+        const std::string& delim,
+        const bool keepEmpty = false
     );
 
-
     //- Split string into sub-strings using any characters in delimiter.
-    //  Empty sub-strings are suppressed.
+    //  Empty sub-strings are normally suppressed.
+    //  Behaviour is ill-defined if delim is an empty string.
     template<class StringType>
     Foam::SubStrings<StringType> splitAny
     (
@@ -362,6 +365,14 @@ namespace stringOps
         const std::string& delim
     );
 
+    //- Split string into sub-strings using a fixed field width
+    //  Behaviour is ill-defined if width is zero.
+    template<class StringType>
+    Foam::SubStrings<StringType> splitFixed
+    (
+        const StringType& str,
+        const std::string::size_type width
+    );
 
     //- Split string into sub-strings at whitespace (TAB, NL, VT, FF, CR, SPC)
     //  Empty sub-strings are suppressed.

src/OpenFOAM/primitives/strings/stringOps/stringOpsTemplates.C

@@ -37,20 +37,21 @@ Foam::word Foam::stringOps::name
     const PrimitiveType& val
 )
 {
-    // same concept as GNU/BSD asprintf()
-    // use snprintf with zero to determine the number of characters required
+    word output;
 
-    const int n = ::snprintf(nullptr, 0, fmt, val);
+    // snprintf with zero to find size (without '\0') required
+    int n = ::snprintf(nullptr, 0, fmt, val);
     if (n > 0)
     {
-        char buf[n+1];
-        ::snprintf(buf, n+1, fmt, val);
-        buf[n] = 0;
+        output.resize(n+1);
+        char* buf = &(output[0]);
 
-        return word(buf, false); // no stripping desired
+        // Print directly into buffer, no stripping desired
+        n = ::snprintf(buf, n+1, fmt, val);
+        output.resize(n);
     }
 
-    return word::null;
+    return output;
 }
 
 
@@ -69,28 +70,32 @@ template<class StringType>
 Foam::SubStrings<StringType> Foam::stringOps::split
 (
     const StringType& str,
-    const char delim
+    const char delim,
+    const bool keepEmpty
 )
 {
     Foam::SubStrings<StringType> lst;
+    if (str.empty() || !delim)
+    {
+        return lst;
+    }
+
     lst.reserve(20);
 
     std::string::size_type beg = 0, end = 0;
-
     while ((end = str.find(delim, beg)) != std::string::npos)
     {
-        if (beg < end)
+        if (keepEmpty || (beg < end))
         {
-            // (Non-empty) intermediate element
             lst.append(str.cbegin() + beg, str.cbegin() + end);
         }
         beg = end + 1;
     }
 
-    // (Non-empty) trailing element
-    if (beg < str.size())
+    // Trailing element
+    if (keepEmpty ? (beg == str.size()) : (beg < str.size()))
     {
-        lst.append(str.cbegin() + beg, str.cbegin() + str.size());
+        lst.append(str.cbegin() + beg, str.cend());
     }
 
     return lst;
@@ -101,28 +106,32 @@ template<class StringType>
 Foam::SubStrings<StringType> Foam::stringOps::split
 (
     const StringType& str,
-    const std::string& delim
+    const std::string& delim,
+    const bool keepEmpty
 )
 {
     Foam::SubStrings<StringType> lst;
+    if (str.empty() || delim.empty())
+    {
+        return lst;
+    }
+
     lst.reserve(20);
 
     std::string::size_type beg = 0, end = 0;
-
     while ((end = str.find(delim, beg)) != std::string::npos)
     {
-        if (beg < end)
+        if (keepEmpty || (beg < end))
         {
-            // (Non-empty) intermediate element
             lst.append(str.cbegin() + beg, str.cbegin() + end);
         }
         beg = end + delim.size();
     }
 
-    // (Non-empty) trailing element
-    if (beg < str.size())
+    // Trailing element
+    if (keepEmpty ? (beg == str.size()) : (beg < str.size()))
     {
-        lst.append(str.cbegin() + beg, str.cbegin() + str.size());
+        lst.append(str.cbegin() + beg, str.cend());
     }
 
     return lst;
@@ -137,30 +146,67 @@ Foam::SubStrings<StringType> Foam::stringOps::splitAny
 )
 {
     Foam::SubStrings<StringType> lst;
+    if (str.empty() || delim.empty())
+    {
+        return lst;
+    }
+
     lst.reserve(20);
 
-    std::string::size_type beg = 0;
-
-    while
+    for
     (
-        (beg = str.find_first_not_of(delim, beg))
-     != std::string::npos
+        std::string::size_type pos = 0;
+        (pos = str.find_first_not_of(delim, pos)) != std::string::npos;
+        /*nil*/
     )
     {
-        const auto end = str.find_first_of(delim, beg);
+        const auto end = str.find_first_of(delim, pos);
 
         if (end == std::string::npos)
         {
             // Trailing element
-            lst.append(str.cbegin() + beg, str.cbegin() + str.size());
+            lst.append(str.cbegin() + pos, str.cend());
             break;
         }
-        else
-        {
+
         // Intermediate element
-            lst.append(str.cbegin() + beg, str.cbegin() + end);
-            beg = end + 1;
+        lst.append(str.cbegin() + pos, str.cbegin() + end);
+
+        pos = end + 1;
     }
+
+    return lst;
+}
+
+
+template<class StringType>
+Foam::SubStrings<StringType> Foam::stringOps::splitFixed
+(
+    const StringType& str,
+    const std::string::size_type width
+)
+{
+    Foam::SubStrings<StringType> lst;
+    if (str.empty() || !width)
+    {
+        return lst;
+    }
+
+    const auto len = str.size();
+    lst.reserve(1 + (len / width));
+
+    for (std::string::size_type pos = 0; pos < len; pos += width)
+    {
+        const auto end = (pos + width);
+
+        if (end >= len)
+        {
+            // Trailing element
+            lst.append(str.cbegin() + pos, str.cend());
+            break;
+        }
+
+        lst.append(str.cbegin() + pos, str.cbegin() + end);
     }
 
     return lst;

src/fileFormats/ensight/file/ensightCaseOptions.C

@@ -59,7 +59,7 @@ Foam::word Foam::ensightCase::options::padded(const label i) const
     // As per Foam::name, but with fixed length
     char buf[32];
 
-    ::snprintf(buf, 32, printf_.c_str(), i);
+    ::snprintf(buf, 32, printf_.c_str(), static_cast<int>(i));
     buf[31] = 0;
 
     // no stripping required