Add regex utility functions

1 files changed, 45 insertions, 0 deletions

diff --git a/libbutl/regex.cxx b/libbutl/regex.cxx
new file mode 100644
index 0000000..4e2e26f
--- /dev/null
+++ b/libbutl/regex.cxx
@@ -0,0 +1,45 @@
+// file      : libbutl/regex.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <libbutl/regex.hxx>
+
+#if defined(_MSC_VER) && _MSC_VER <= 1910
+#  include <cstring> // strstr()
+#endif
+
+#include <ostream>
+#include <sstream>
+#include <stdexcept> // runtime_error
+
+#include <libbutl/utility.hxx> // operator<<(ostream, exception)
+
+namespace std
+{
+  // Currently libstdc++ just returns the name of the exception (bug #67361).
+  // So we check that the description contains at least one space character.
+  //
+  // While VC's description is meaningful, it has an undesired prefix that
+  // resembles the following: 'regex_error(error_badrepeat): '. So we skip it.
+  //
+  ostream&
+  operator<< (ostream& o, const regex_error& e)
+  {
+    const char* d (e.what ());
+
+#if defined(_MSC_VER) && _MSC_VER <= 1910
+    const char* rd (strstr (d, "): "));
+    if (rd != nullptr)
+      d = rd + 3;
+#endif
+
+    ostringstream os;
+    os << runtime_error (d); // Sanitize the description.
+
+    string s (os.str ());
+    if (s.find (' ') != string::npos)
+      o << ": " << s;
+
+    return o;
+  }
+}