From d6427addaf7de41d401dd2a871b4789022e5f7cf Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 5 Jan 2018 15:06:24 +0200
Subject: Extend find_option_prefix() to return option

---
 build2/utility.cxx | 40 ++++++++++++++++++++--------------------
 build2/utility.hxx | 25 ++++++++++++++-----------
 build2/utility.ixx |  8 ++++----
 3 files changed, 38 insertions(+), 35 deletions(-)

diff --git a/build2/utility.cxx b/build2/utility.cxx
index 8d63059..280edd3 100644
--- a/build2/utility.cxx
+++ b/build2/utility.cxx
@@ -397,73 +397,73 @@ namespace build2
     return false;
   }
 
-  bool
+  const string*
   find_option_prefix (const char* p, const lookup& l, bool ic)
   {
-    return l && find_option_prefix (p, cast<strings> (l), ic);
+    return l ? find_option_prefix (p, cast<strings> (l), ic) : nullptr;
   }
 
-  bool
+  const string*
   find_option_prefix (const char* p, const strings& strs, bool ic)
   {
     size_t n (strlen (p));
 
-    for (const string& s: strs)
+    for (const string& s: reverse_iterate (strs))
       if ((ic ? casecmp (s, p, n) : s.compare (0, n, p)) == 0)
-        return true;
+        return &s;
 
-    return false;
+    return nullptr;
   }
 
-  bool
+  const char*
   find_option_prefix (const char* p, const cstrings& cstrs, bool ic)
   {
     size_t n (strlen (p));
 
-    for (const char* s: cstrs)
+    for (const char* s: reverse_iterate (cstrs))
       if (s != nullptr && (ic ? casecmp (s, p, n) : strncmp (s, p, n)) == 0)
-        return true;
+        return s;
 
-    return false;
+    return nullptr;
   }
 
-  bool
+  const string*
   find_option_prefixes (initializer_list<const char*> ps,
                         const lookup& l,
                         bool ic)
   {
-    return l && find_option_prefixes (ps, cast<strings> (l), ic);
+    return l ? find_option_prefixes (ps, cast<strings> (l), ic) : nullptr;
   }
 
-  bool
+  const string*
   find_option_prefixes (initializer_list<const char*> ps,
                         const strings& strs,
                         bool ic)
   {
-    for (const string& s: strs)
+    for (const string& s: reverse_iterate (strs))
       for (const char* p: ps)
         if ((ic
              ? casecmp (s, p, strlen (p))
              : s.compare (0, strlen (p), p)) == 0)
-          return true;
+          return &s;
 
-    return false;
+    return nullptr;
   }
 
-  bool
+  const char*
   find_option_prefixes (initializer_list<const char*> ps,
                         const cstrings& cstrs,
                         bool ic)
   {
-    for (const char* s: cstrs)
+    for (const char* s: reverse_iterate (cstrs))
       if (s != nullptr)
         for (const char* p: ps)
           if ((ic
                ? casecmp (s, p, strlen (p))
                : strncmp (s, p, strlen (p))) == 0)
-            return true;
+            return s;
 
-    return false;
+    return nullptr;
   }
 
   string
diff --git a/build2/utility.hxx b/build2/utility.hxx
index db6460c..cfdaee0 100644
--- a/build2/utility.hxx
+++ b/build2/utility.hxx
@@ -511,51 +511,54 @@ namespace build2
   bool
   find_options (initializer_list<const char*>, const cstrings&, bool = false);
 
-  // As above but look for an option that has the specified prefix.
+  // As above but look for an option that has the specified prefix. Return the
+  // pointer to option or NULL if not found (thus can be used as bool).
+  // Search backward (which is normall consistent with how options override
+  // each other).
   //
   template <typename T>
-  bool
+  const string*
   find_option_prefix (const char* prefix, T&, const variable&, bool = false);
 
   template <typename T>
-  bool
+  const string*
   find_option_prefix (const char* prefix, T&, const char*, bool = false);
 
-  bool
+  const string*
   find_option_prefix (const char* prefix, const lookup&, bool = false);
 
-  bool
+  const string*
   find_option_prefix (const char* prefix, const strings&, bool = false);
 
-  bool
+  const char*
   find_option_prefix (const char* prefix, const cstrings&, bool = false);
 
   // As above but look for several option prefixes.
   //
   template <typename T>
-  bool
+  const string*
   find_option_prefixes (initializer_list<const char*>,
                         T&,
                         const variable&,
                         bool = false);
 
   template <typename T>
-  bool
+  const string*
   find_option_prefixes (initializer_list<const char*>,
                         T&,
                         const char*,
                         bool = false);
 
-  bool
+  const string*
   find_option_prefixes (initializer_list<const char*>,
                         const lookup&, bool = false);
 
-  bool
+  const string*
   find_option_prefixes (initializer_list<const char*>,
                         const strings&,
                         bool = false);
 
-  bool
+  const char*
   find_option_prefixes (initializer_list<const char*>,
                         const cstrings&,
                         bool = false);
diff --git a/build2/utility.ixx b/build2/utility.ixx
index 0622e99..a726b0c 100644
--- a/build2/utility.ixx
+++ b/build2/utility.ixx
@@ -131,21 +131,21 @@ namespace build2
   }
 
   template <typename T>
-  inline bool
+  inline const string*
   find_option_prefix (const char* p, T& s, const variable& var, bool ic)
   {
     return find_option_prefix (p, s[var], ic);
   }
 
   template <typename T>
-  inline bool
+  inline const string*
   find_option_prefix (const char* p, T& s, const char* var, bool ic)
   {
     return find_option_prefix (p, s[var], ic);
   }
 
   template <typename T>
-  inline bool
+  inline const string*
   find_option_prefixes (initializer_list<const char*> ps,
                         T& s,
                         const variable& var,
@@ -155,7 +155,7 @@ namespace build2
   }
 
   template <typename T>
-  inline bool
+  inline const string*
   find_option_prefixes (initializer_list<const char*> ps,
                         T& s,
                         const char* var,
-- 
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