Followup patch: compute dirname and basename at once, when both are needed

[Charles Wilson]

When reviewing one of my earlier patches, Ralf said:
> Side note: there should be a function that does both dirname and
> basename at once, for speed.  (Not in this patch, but later.)
> Another instance below.

This patch adds that new function, and adjusts several locations to take 
advantage of it.  Tested on cygwin and linux with no regressions.

I deliberately re-used the same return variables as func_dirname() and 
func_basename() to minimize ripple, and so that this combo function 
could be a drop-in replacement for calls to the two separate funcs.

ChangeLog:

2007-07-11  Charles Wilson  <...>

        * libltdl/m4/libtool.m4 (func_dirname_and_basename): New
        function
        * libltdl/config/ltmain.m4sh (func_ltwrapper_scriptname):
        Call it.  Also, take advantage of missed optimization using
        func_dirname's additional arguments.
        (func_mode_compile): Call it.
        (func_mode_install): Call it.
        (func_mode_link): Call it.

--
Chuck

Index: libltdl/config/ltmain.m4sh
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/config/ltmain.m4sh,v
retrieving revision 1.83
diff -u -r1.83 ltmain.m4sh
--- libltdl/config/ltmain.m4sh  7 Jul 2007 05:09:10 -0000       1.83
+++ libltdl/config/ltmain.m4sh  12 Jul 2007 03:04:20 -0000
@@ -692,14 +692,9 @@
 {
     func_ltwrapper_scriptname_result=""
     if func_ltwrapper_executable_p "$1"; then
-       func_dirname "$1"
-       func_basename "$1"
+       func_dirname_and_basename "$1" "" "."
        func_stripname '' '.exe' "$func_basename_result"
-       if test -z "$func_dirname_result"; then
-           
func_ltwrapper_scriptname_result="./$objdir/${func_stripname_result}_ltshwrapper"
-       else
-           
func_ltwrapper_scriptname_result="$func_dirname_result/$objdir/${func_stripname_result}_ltshwrapper"
-       fi
+       
func_ltwrapper_scriptname_result="$func_dirname_result/$objdir/${func_stripname_result}_ltshwrapper"
     fi
 }
 
@@ -1422,9 +1417,8 @@
     test "X$libobj" != "X$func_quote_for_eval_result" \
       && $ECHO "X$libobj" | $GREP '[@:>@~#^*{};<>?"'"'"'       &()|`$@<:@]' \
       && func_warning "libobj name \`$libobj' may not contain shell special 
characters."
-    func_basename "$obj"
+    func_dirname_and_basename "$obj" "/" ""
     objname="$func_basename_result"
-    func_dirname "$obj" "/" ""
     xdir="$func_dirname_result"
     lobj=${xdir}$objdir/$objname
 
@@ -1921,9 +1915,8 @@
       destdir="$dest"
       destname=
     else
-      func_dirname "$dest" "" "."
+      func_dirname_and_basename "$dest" "" "."
       destdir="$func_dirname_result"
-      func_basename "$dest"
       destname="$func_basename_result"
 
       # Not a directory, so check to see that there is only one file specified.
@@ -6785,13 +6778,9 @@
        esac
        case $host in
          *cygwin* | *mingw* )
-           func_basename "$output"
+           func_dirname_and_basename "$output" "" "."
            output_name=$func_basename_result
-           func_dirname "$output"
            output_path=$func_dirname_result
-           if test -z "$output_path"; then
-             output_path=.
-           fi
            cwrappersource="$output_path/$objdir/lt-$output_name.c"
            cwrapper="$output_path/$output_name.exe"
            $RM $cwrappersource $cwrapper
Index: libltdl/m4/libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/m4/libtool.m4,v
retrieving revision 1.111
diff -u -r1.111 libtool.m4
--- libltdl/m4/libtool.m4       3 Jul 2007 05:09:40 -0000       1.111
+++ libltdl/m4/libtool.m4       12 Jul 2007 03:04:24 -0000
@@ -7056,6 +7056,27 @@
   func_basename_result="${1##*/}"
 }
 
+# func_dirname_and_basename file append nondir_replacement
+# perform func_basename and func_dirname in a single function
+# call:
+#   dirname:  Compute the dirname of FILE.  If nonempty,
+#             add APPEND to the result, otherwise set result 
+#             to NONDIR_REPLACEMENT.
+#             value returned in "$func_dirname_result"
+#   basename: Compute filename of FILE.
+#             value retuned in "$func_basename_result"
+# Implementation must be kept synchronized with func_dirname
+# and func_basename. For efficiency, we do not delegate to
+# those functions but instead duplicate the functionality here.
+func_dirname_and_basename ()
+{
+  case ${1} in
+    */*) func_dirname_result="${1%/*}${2}" ;;
+    *  ) func_dirname_result="${3}" ;;
+  esac
+  func_basename_result="${1##*/}"
+}
+
 # func_stripname prefix suffix name
 # strip PREFIX and SUFFIX off of NAME.
 # PREFIX and SUFFIX must not contain globbing or regex special