Add find_stem() utility function

3 files changed, 39 insertions, 23 deletions

diff --git a/libbuild2/cc/guess.cxx b/libbuild2/cc/guess.cxx
index f40bb88..b18c516 100644
--- a/libbuild2/cc/guess.cxx
+++ b/libbuild2/cc/guess.cxx
@@ -306,38 +306,19 @@ namespace build2
       size_t s_p (path::traits_type::find_leaf (s));
       size_t s_n (s.size ());
 
-      // Name separator characters (e.g., '-' in 'g++-4.8').
-      //
-      auto sep = [] (char c) -> bool
-      {
-        return c == '-' || c == '_' || c == '.';
-      };
-
-      auto stem = [&sep, &s, s_p, s_n] (const char* x) -> size_t
-      {
-        size_t m (strlen (x));
-        size_t p (s.find (x, s_p, m));
-
-        return (p != string::npos &&
-                (      p == s_p || sep (s[p - 1])) && // Separated beginning.
-                ((p + m) == s_n || sep (s[p + m])))   // Separated end.
-        ? p
-        : string::npos;
-      };
-
       using type = compiler_type;
 
       // If the user specified the compiler id, then only check the stem for
       // that compiler.
       //
-      auto check = [&xi, &stem] (type t,
-                                 const char* s,
-                                 const char* v = nullptr)
+      auto check = [&xi, &s, s_p, s_n] (type t,
+                                        const char* stem,
+                                        const char* v = nullptr)
         -> optional<pre_guess_result>
       {
         if (!xi || (xi->type == t && (v == nullptr || xi->variant == v)))
         {
-          size_t p (stem (s));
+          size_t p (find_stem (s, s_p, s_n, stem));
 
           if (p != string::npos)
           {
diff --git a/libbuild2/utility.hxx b/libbuild2/utility.hxx
index 0422786..536898e 100644
--- a/libbuild2/utility.hxx
+++ b/libbuild2/utility.hxx
@@ -686,6 +686,20 @@ namespace build2
                         const cstrings&,
                         bool = false);
 
+  // Find in the string the stem separated from other characters with the
+  // specified separators or begin/end of the string. Return the stem's
+  // position or npos if not found.
+  //
+  size_t
+  find_stem (const string&, size_t pos, size_t n,
+             const char* stem, const char* seps = "-_.");
+
+  inline size_t
+  find_stem (const string& s, const char* stem, const char* seps = "-_.")
+  {
+    return find_stem (s, 0, s.size (), stem, seps);
+  }
+
   // Apply the specified substitution (stem) to a '*'-pattern. If pattern is
   // NULL or empty, then return the stem itself. Assume the pattern is valid,
   // i.e., contains a single '*' character.
diff --git a/libbuild2/utility.ixx b/libbuild2/utility.ixx
index 2846756..514d4ee 100644
--- a/libbuild2/utility.ixx
+++ b/libbuild2/utility.ixx
@@ -2,6 +2,8 @@
 // copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
+#include <cstring> // strlen() strchr()
+
 namespace build2
 {
   inline void
@@ -152,4 +154,23 @@ namespace build2
   {
     return find_option_prefixes (ps, s[var], ic);
   }
+
+  inline size_t
+  find_stem (const string& s, size_t s_p, size_t s_n,
+             const char* stem, const char* seps)
+  {
+    auto sep = [seps] (char c) -> bool
+    {
+      return strchr (seps, c) != nullptr;
+    };
+
+    size_t m (strlen (stem));
+    size_t p (s.find (stem, s_p, m));
+
+    return (p != string::npos &&
+            (      p == s_p || sep (s[p - 1])) && // Separated beginning.
+            ((p + m) == s_n || sep (s[p + m])))   // Separated end.
+      ? p
+      : string::npos;
+  }
 }