adl_COMPUTE_RELATIVE_PATHS(PATH_LIST)
, 

2001-05-25

Alexandre Duret-Lutz <duret_g@epita.fr>

GPLWithACException
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. As a special exception, the respective Autoconf Macro's copyright owner gives unlimited permission to copy, distribute and modify the configure scripts that are the output of Autoconf when processing the Macro. You need not follow the terms of the GNU General Public License when using or distributing such scripts

cryp.to ac-archive's Miscellaneous (released)

PATH_LIST is a space-separated list of colon-separated triplets of the form 'FROM:TO:RESULT'. This function iterates over these triplets and set $RESULT to the relative path from $FROM to $TO. Note that $FROM and $TO needs to be absolute filenames for this macro to success.

For instance,

  first=/usr/local/bin
  second=/usr/local/share
  adl_COMPUTE_RELATIVE_PATHS([first:second:fs second:first:sf])
  # $fs is set to ../share
  # $sf is set to ../bin

$FROM and $TO are both eval'ed recursively and normalized, this means that you can call this macro with autoconf's dirnames like `prefix' or `datadir'. For example:

  adl_COMPUTE_RELATIVE_PATHS([bindir:datadir:bin_to_data])

adl_COMPUTE_RELATIVE_PATHS should also works with DOS filenames.

You may want to use this macro in order to make your package relocatable. Instead of hardcoding $datadir into your programs just encode $bin_to_data and try to determine $bindir at run-time.

This macro requires adl_NORMALIZE_PATH.

AC_DEFUN([adl_COMPUTE_RELATIVE_PATHS],
[for _lcl_i in $1; do
  _lcl_from=\[$]`echo "[$]_lcl_i" | sed 's,:.*$,,'`
  _lcl_to=\[$]`echo "[$]_lcl_i" | sed 's,^[[^:]]*:,,' | sed 's,:[[^:]]*$,,'`
  _lcl_result_var=`echo "[$]_lcl_i" | sed 's,^.*:,,'`
  adl_RECURSIVE_EVAL([[$]_lcl_from], [_lcl_from])
  adl_RECURSIVE_EVAL([[$]_lcl_to], [_lcl_to])
  _lcl_notation="$_lcl_from$_lcl_to"
  adl_NORMALIZE_PATH([_lcl_from],['/'])
  adl_NORMALIZE_PATH([_lcl_to],['/'])
  adl_COMPUTE_RELATIVE_PATH([_lcl_from], [_lcl_to], [_lcl_result_tmp])
  adl_NORMALIZE_PATH([_lcl_result_tmp],["[$]_lcl_notation"])
  eval $_lcl_result_var='[$]_lcl_result_tmp'
done])

## Note:
## *****
## The following helper macros are too fragile to be used out
## of adl_COMPUTE_RELATIVE_PATHS (mainly because they assume that
## paths are normalized), that's why I'm keeping them in the same file.
## Still, some of them maybe worth to reuse.

dnl adl_COMPUTE_RELATIVE_PATH(FROM, TO, RESULT)
dnl ===========================================
dnl Compute the relative path to go from $FROM to $TO and set the value
dnl of $RESULT to that value.  This function work on raw filenames
dnl (for instead it will considerate /usr//local and /usr/local as
dnl two distinct paths), you should really use adl_COMPUTE_REALTIVE_PATHS
dnl instead to have the paths sanitized automatically.
dnl
dnl For instance:
dnl    first_dir=/somewhere/on/my/disk/bin
dnl    second_dir=/somewhere/on/another/disk/share
dnl    adl_COMPUTE_RELATIVE_PATH(first_dir, second_dir, first_to_second)
dnl will set $first_to_second to '../../../another/disk/share'.
AC_DEFUN([adl_COMPUTE_RELATIVE_PATH],
[adl_COMPUTE_COMMON_PATH([$1], [$2], [_lcl_common_prefix])
adl_COMPUTE_BACK_PATH([$1], [_lcl_common_prefix], [_lcl_first_rel])
adl_COMPUTE_SUFFIX_PATH([$2], [_lcl_common_prefix], [_lcl_second_suffix])
$3="[$]_lcl_first_rel[$]_lcl_second_suffix"])

dnl adl_COMPUTE_COMMON_PATH(LEFT, RIGHT, RESULT)
dnl ============================================
dnl Compute the common path to $LEFT and $RIGHT and set the result to $RESULT.
dnl
dnl For instance:
dnl    first_path=/somewhere/on/my/disk/bin
dnl    second_path=/somewhere/on/another/disk/share
dnl    adl_COMPUTE_COMMON_PATH(first_path, second_path, common_path)
dnl will set $common_path to '/somewhere/on'.
AC_DEFUN([adl_COMPUTE_COMMON_PATH],
[$3=''
_lcl_second_prefix_match=''
while test "[$]_lcl_second_prefix_match" != 0; do
  _lcl_first_prefix=`expr "x[$]$1" : "x\([$]$3/*[[^/]]*\)"`
  _lcl_second_prefix_match=`expr "x[$]$2" : "x[$]_lcl_first_prefix"`
  if test "[$]_lcl_second_prefix_match" != 0; then
    if test "[$]_lcl_first_prefix" != "[$]$3"; then
      $3="[$]_lcl_first_prefix"
    else
      _lcl_second_prefix_match=0
    fi
  fi
done])

dnl adl_COMPUTE_SUFFIX_PATH(PATH, SUBPATH, RESULT)
dnl ==============================================
dnl Substrack $SUBPATH from $PATH, and set the resulting suffix
dnl (or the empty string if $SUBPATH is not a subpath of $PATH)
dnl to $RESULT.
dnl
dnl For instace:
dnl    first_path=/somewhere/on/my/disk/bin
dnl    second_path=/somewhere/on
dnl    adl_COMPUTE_SUFFIX_PATH(first_path, second_path, common_path)
dnl will set $common_path to '/my/disk/bin'.
AC_DEFUN([adl_COMPUTE_SUFFIX_PATH],
[$3=`expr "x[$]$1" : "x[$]$2/*\(.*\)"`])

dnl adl_COMPUTE_BACK_PATH(PATH, SUBPATH, RESULT)
dnl ============================================
dnl Compute the relative path to go from $PATH to $SUBPATH, knowing that
dnl $SUBPATH is a subpath of $PATH (any other words, only repeated '../'
dnl should be needed to move from $PATH to $SUBPATH) and set the value
dnl of $RESULT to that value.  If $SUBPATH is not a subpath of PATH,
dnl set $RESULT to the empty string.
dnl
dnl For instance:
dnl    first_path=/somewhere/on/my/disk/bin
dnl    second_path=/somewhere/on
dnl    adl_COMPUTE_BACK_PATH(first_path, second_path, back_path)
dnl will set $back_path to '../../../'.
AC_DEFUN([adl_COMPUTE_BACK_PATH],
[adl_COMPUTE_SUFFIX_PATH([$1], [$2], [_lcl_first_suffix])
$3=''
_lcl_tmp='xxx'
while test "[$]_lcl_tmp" != ''; do
  _lcl_tmp=`expr "x[$]_lcl_first_suffix" : "x[[^/]]*/*\(.*\)"`
  if test "[$]_lcl_first_suffix" != ''; then
     _lcl_first_suffix="[$]_lcl_tmp"
     $3="../[$]$3"
  fi
done])


dnl adl_RECURSIVE_EVAL(VALUE, RESULT)
dnl =================================
dnl Interpolate the VALUE in loop until it doesn't change,
dnl and set the result to $RESULT.
dnl WARNING: It's easy to get an infinite loop with some unsane input.
AC_DEFUN([adl_RECURSIVE_EVAL],
[_lcl_receval="$1"
$2=`(test "x$prefix" = xNONE && prefix="$ac_default_prefix"
     test "x$exec_prefix" = xNONE && exec_prefix="${prefix}"
     _lcl_receval_old=''
     while test "[$]_lcl_receval_old" != "[$]_lcl_receval"; do
       _lcl_receval_old="[$]_lcl_receval"
       eval _lcl_receval="\"[$]_lcl_receval\""
     done
     echo "[$]_lcl_receval")`])