ax_lua.m4: rewrite _AX_LUA_FND_PREFX_PTH

Rewrite in Lua for robustness and brevity.

Also make it understand the Lua style of ?-pattern path.

Patch from Gary Vaughan (gary@gnu.org)

1 files changed, 14 insertions, 23 deletions

diff --git a/m4/ax_lua.m4 b/m4/ax_lua.m4
index 134bab7..15376af 100644
--- a/m4/ax_lua.m4
+++ b/m4/ax_lua.m4
@@ -180,7 +180,7 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 27
+#serial 28
 
 dnl =========================================================================
 dnl AX_PROG_LUA([MINIMUM-VERSION], [TOO-BIG-VERSION],
@@ -375,28 +375,19 @@ AC_DEFUN([_AX_LUA_FND_PRFX_PTH],
 [
   dnl Invokes the Lua interpreter PROG to print the path variable
   dnl LUA-PATH-VARIABLE, usually package.path or package.cpath. Paths are
-  dnl then matched against PREFIX. The first path to begin with PREFIX is set
-  dnl to ax_lua_prefixed_path.
-
-  ax_lua_prefixed_path=''
-  _ax_package_paths=`$1 -e 'print($3)' 2>/dev/null | sed 's|;|\n|g'`
-  dnl Try the paths in order, looking for the prefix.
-  for _ax_package_path in $_ax_package_paths; do
-    dnl Copy the path, up to the use of a Lua wildcard.
-    _ax_path_parts=`echo "$_ax_package_path" | sed 's|/|\n|g'`
-    _ax_reassembled=''
-    for _ax_path_part in $_ax_path_parts; do
-      echo "$_ax_path_part" | grep '\?' >/dev/null && break
-      _ax_reassembled="$_ax_reassembled/$_ax_path_part"
-    done
-    dnl Check the path against the prefix.
-    _ax_package_path=$_ax_reassembled
-    if echo "$_ax_package_path" | grep "^$2" >/dev/null; then
-      dnl Found it.
-      ax_lua_prefixed_path=$_ax_package_path
-      break
-    fi
-  done
+  dnl then matched against PREFIX. Then ax_lua_prefixed_path is set to the
+  dnl shortest sub path beginning with PREFIX up to the last directory
+  dnl that does not contain a '?', if any.
+
+  ax_lua_prefixed_path=`$1 2>/dev/null -e '
+    $3:gsub ("(@<:@^;@:>@+)",
+      function (p)
+        p = p:gsub ("%?.*$", ""):gsub ("/@<:@^/@:>@*$", "")
+        if p:match ("^$2") and (not shortest or #shortest > #p) then
+          shortest = p
+        end
+      end)
+    print (shortest or "")'`
 ])