Generalize regex_replace_ex() function

3 files changed, 62 insertions, 12 deletions

diff --git a/libbutl/regex.hxx b/libbutl/regex.hxx
index e4fd6a7..2105f05 100644
--- a/libbutl/regex.hxx
+++ b/libbutl/regex.hxx
@@ -14,13 +14,18 @@
 
 namespace butl
 {
-  // Like std::regex_match() but extends the standard ECMA-262
-  // substitution escape sequences with a subset of Perl sequences:
+  // Call specified append() function for non-matched substrings and matched
+  // substring replacements returning true if search succeeded. The function
+  // must be callable with the following signature:
   //
-  // \\, \u, \l, \U, \L, \E, \1, ..., \9
+  // void
+  // append(basic_string<C>::iterator begin, basic_string<C>::iterator end);
   //
-  // Also return the resulting string as well as whether the search
-  // succeeded.
+  // The regex semantics is like that of std::regex_replace() extended the
+  // standard ECMA-262 substitution escape sequences with a subset of Perl
+  // sequences:
+  //
+  // \\, \u, \l, \U, \L, \E, \1, ..., \9
   //
   // Notes and limitations:
   //
@@ -34,6 +39,19 @@ namespace butl
   //   C++ locale (which is, unless changed, is the same as C locale and
   //   both default to the POSIX locale aka "C").
   //
+  template <typename C, typename F>
+  bool
+  regex_replace_ex (const std::basic_string<C>&,
+                    const std::basic_regex<C>&,
+                    const std::basic_string<C>& fmt,
+                    F&& append,
+                    std::regex_constants::match_flag_type =
+                      std::regex_constants::match_default);
+
+  // As above but concatenate non-matched substrings and matched substring
+  // replacements into a string returning it as well as whether the search
+  // succeeded.
+  //
   template <typename C>
   std::pair<std::basic_string<C>, bool>
   regex_replace_ex (const std::basic_string<C>&,
@@ -52,6 +70,7 @@ namespace std
   operator<< (ostream&, const regex_error&);
 }
 
+#include <libbutl/regex.ixx>
 #include <libbutl/regex.txx>
 
 #endif // LIBBUTL_REGEX_HXX
diff --git a/libbutl/regex.ixx b/libbutl/regex.ixx
new file mode 100644
index 0000000..dd3ad1d
--- /dev/null
+++ b/libbutl/regex.ixx
@@ -0,0 +1,27 @@
+// file      : libbutl/regex.ixx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <utility> // move(), make_pair()
+
+namespace butl
+{
+  template <typename C>
+  inline std::pair<std::basic_string<C>, bool>
+  regex_replace_ex (const std::basic_string<C>& s,
+                    const std::basic_regex<C>& re,
+                    const std::basic_string<C>& fmt,
+                    std::regex_constants::match_flag_type flags)
+  {
+    using namespace std;
+
+    using it = typename basic_string<C>::const_iterator;
+
+    basic_string<C> r;
+    bool match (regex_replace_ex (s, re, fmt,
+                                  [&r] (it b, it e) {r.append (b, e);},
+                                  flags));
+
+    return make_pair (move (r), match);
+  }
+}
diff --git a/libbutl/regex.txx b/libbutl/regex.txx
index 52bddfd..536cabf 100644
--- a/libbutl/regex.txx
+++ b/libbutl/regex.txx
@@ -7,11 +7,12 @@
 
 namespace butl
 {
-  template <typename C>
-  std::pair<std::basic_string<C>, bool>
+  template <typename C, typename F>
+  bool
   regex_replace_ex (const std::basic_string<C>& s,
                     const std::basic_regex<C>& re,
                     const std::basic_string<C>& fmt,
+                    F&& append,
                     std::regex_constants::match_flag_type flags)
   {
     using namespace std;
@@ -24,7 +25,6 @@ namespace butl
     bool no_copy ((flags & std::regex_constants::format_no_copy) != 0);
 
     locale cl; // Copy of the global C++ locale.
-    string_type r;
 
     // Beginning of the last unmatched substring.
     //
@@ -59,7 +59,7 @@ namespace butl
       //
       if (!no_copy)
       {
-        r.append (ub, m.prefix ().second);
+        append (ub, m.prefix ().second);
         ub = m.suffix ().first;
       }
 
@@ -68,7 +68,7 @@ namespace butl
         // Append matched substring.
         //
         if (!no_copy)
-          r.append (m[0].first, m[0].second);
+          append (m[0].first, m[0].second);
       }
       else
       {
@@ -100,6 +100,8 @@ namespace butl
           return c;
         };
 
+        string_type r;
+
         auto append_chr = [&r, &conv_chr] (C c)
         {
           r.push_back (conv_chr (c));
@@ -233,14 +235,16 @@ namespace butl
             }
           }
         }
+
+        append (r.begin (), r.end ());
       }
     }
 
     // Append the rightmost non-matched substring.
     //
     if (!no_copy)
-      r.append (ub, s.end ());
+      append (ub, s.end ());
 
-    return make_pair (move (r), match);
+    return match;
   }
 }