CONFIG: use C++11 regex instead of POSIX for newer compilers

BUG: The ok_ flag was not being updated in the regExpCxx::set() method

applications/test/regex1/Test-regex1.C

@@ -27,12 +27,16 @@ Description
 \*---------------------------------------------------------------------------*/
 
 #include "argList.H"
+#include "IOobject.H"
 #include "IOstreams.H"
 #include "IFstream.H"
 #include "Switch.H"
 
+#include "SubStrings.H"
 #include "regExpCxx.H"
+#ifndef _WIN32
 #include "regExpPosix.H"
+#endif
 
 using namespace Foam;
 
@@ -83,6 +87,7 @@ static Ostream& operator<<(Ostream& os, const regExpCxx::results_type& sm)
 
 
 // Simple output of match groups
+#ifndef _WIN32
 static Ostream& operator<<(Ostream& os, const regExpPosix::results_type& sm)
 {
     for (std::smatch::size_type i = 1; i < sm.size(); ++i)
@@ -92,6 +97,7 @@ static Ostream& operator<<(Ostream& os, const regExpPosix::results_type& sm)
 
     return os;
 }
+#endif
 
 
 template<class RegexType>
@@ -209,7 +215,6 @@ void generalTests()
 }
 
 
-
 template<class RegexType>
 void testExpressions(const UList<regexTest>& tests)
 {
@@ -293,11 +298,13 @@ int main(int argc, char *argv[])
         "Test C++11 regular expressions"
     );
 
+    #ifndef _WIN32
     argList::addBoolOption
     (
         "posix",
         "Test POSIX regular expressions"
     );
+    #endif
 
     argList::addArgument("file");
     argList::addArgument("...");
@@ -306,6 +313,17 @@ int main(int argc, char *argv[])
 
     #include "setRootCase.H"
 
+    if (std::is_same<regExp, regExpCxx>::value)
+    {
+        Info<<"Foam::regExp uses C++11 regex" << nl << nl;
+    }
+    #ifndef _WIN32
+    if (std::is_same<regExp, regExpPosix>::value)
+    {
+        Info<<"Foam::regExp uses POSIX regex" << nl << nl;
+    }
+    #endif
+
     if (!args.count({"cxx", "posix"}))
     {
         Info<< "Specified one or more of -cxx, -posix" << nl;
@@ -321,10 +339,12 @@ int main(int argc, char *argv[])
             generalTests<regExpCxx>();
         }
 
+        #ifndef _WIN32
         if (args.found("posix"))
         {
             generalTests<regExpPosix>();
         }
+        #endif
     }
 
     for (label argi = 1; argi < args.size(); ++argi)
@@ -339,10 +359,12 @@ int main(int argc, char *argv[])
             testExpressions<regExpCxx>(tests);
         }
 
+        #ifndef _WIN32
         if (args.found("posix"))
         {
             testExpressions<regExpPosix>(tests);
         }
+        #endif
     }
 
     Info<< "\nDone" << nl << endl;

applications/test/regex1/testRegexps2

@@ -0,0 +1,19 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  v1812                                 |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// Pattern, String
+(
+    ( true  "(U|k|epsilon)"  "U" )
+    ( false "(U|k|epsilon)"  "alpha" )
+    ( true  "ab.*"  "abc" )
+    ( true  ".*"  "abc" )
+)
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

src/OSspecific/POSIX/regExp/regExp.H

@@ -32,6 +32,7 @@ Description
 #ifndef regExp_H
 #define regExp_H
 
+#include "regExpCxx.H"
 #include "regExpPosix.H"
 #include "regExpFwd.H"
 

src/OSspecific/POSIX/regExp/regExpFwd.H

@@ -39,7 +39,12 @@ namespace Foam
     class regExpCxx;
     class regExpPosix;
 
+    // Newer compilers support regex directly
+    #if (_GLIBCXX_RELEASE >= 7) || (__clang_major__ >= 7)
+    typedef regExpCxx regExp;
+    #else
     typedef regExpPosix regExp;
+    #endif
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

src/OSspecific/POSIX/regExp/regExpPosix.H

@@ -120,7 +120,7 @@ public:
     inline ~regExpPosix();
 
 
-    // Member functions
+    // Member Functions
 
     // Access
 

src/OpenFOAM/primitives/strings/regex/regExpCxx.C

@@ -108,7 +108,7 @@ static std::string error_string(const std::regex_error& err)
 
 bool Foam::regExpCxx::set(const char* pattern, bool ignoreCase)
 {
-    clear();
+    clear();  // Also sets ok_ = false
 
     size_t len = (pattern ? strlen(pattern) : 0);
 
@@ -139,7 +139,7 @@ bool Foam::regExpCxx::set(const char* pattern, bool ignoreCase)
         try
         {
             re_.assign(pat, flags);
-            return true;
+            ok_ = true;
         }
         catch (const std::regex_error& err)
         {
@@ -151,13 +151,13 @@ bool Foam::regExpCxx::set(const char* pattern, bool ignoreCase)
         }
     }
 
-    return false;
+    return ok_;
 }
 
 
 bool Foam::regExpCxx::set(const std::string& pattern, bool ignoreCase)
 {
-    clear();
+    clear();  // Also sets ok_ = false
 
     auto len = pattern.size();
 
@@ -188,7 +188,7 @@ bool Foam::regExpCxx::set(const std::string& pattern, bool ignoreCase)
         try
         {
             re_.assign(pat, pattern.end(), flags);
-            return true;
+            ok_ = true;
         }
         catch (const std::regex_error& err)
         {
@@ -200,7 +200,7 @@ bool Foam::regExpCxx::set(const std::string& pattern, bool ignoreCase)
         }
     }
 
-    return false;
+    return ok_;
 }
 
 

src/OpenFOAM/primitives/strings/regex/regExpCxx.H

@@ -41,7 +41,7 @@ Description
 Note
     The C++11 regular expressions may be broken on some compilers.
     For example, gcc 4.8 is known to fail.
-    For these systems the POSIX implementation should be used.
+    For these systems the POSIX implementation or alternative must be used.
 
 SourceFiles
     regExpCxxI.H
@@ -66,7 +66,7 @@ namespace Foam
 
 class regExpCxx
 {
-    // Private data
+    // Private Data
 
         //- Regular expression (using char type)
         std::regex re_;
@@ -132,7 +132,7 @@ public:
     ~regExpCxx() = default;
 
 
-    // Member functions
+    // Member Functions
 
     // Access
 

src/OpenFOAM/primitives/strings/regex/regExpCxxI.H

@@ -157,7 +157,8 @@ inline void Foam::regExpCxx::swap(regExpCxx& rgx)
 }
 
 
-inline std::string::size_type Foam::regExpCxx::find(const std::string& text) const
+inline std::string::size_type
+Foam::regExpCxx::find(const std::string& text) const
 {
     std::smatch mat;
     if (!text.empty() && std::regex_search(text, mat, re_))