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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<title>Autoconf Macro: relpaths</title>
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<link rel="stylesheet" type="text/css" href="ac-archive.css">
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<table summary="web navigation" style="width:100%;">
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<td style="width:50%;" align="center">[<a href="index.html">Macro Index
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<td style="width:50%;" align="center">[<a href=
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"../m4source/relpaths.m4">Download M4 Source</a>]</td>
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<p style="text-align:left; white-space:nowrap;">
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<code>adl_COMPUTE_RELATIVE_PATHS(PATH_LIST)</code></p>
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<p>PATH_LIST is a space-separated list of colon-separated triplets of the
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form 'FROM:TO:RESULT'. This function iterates over these triplets and set
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$RESULT to the relative path from $FROM to $TO. Note that $FROM and $TO
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needs to be absolute filenames for this macro to success.</p>
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second=/usr/local/share
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adl_COMPUTE_RELATIVE_PATHS([first:second:fs second:first:sf])
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# $fs is set to ../share
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# $sf is set to ../bin
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<p>$FROM and $TO are both eval'ed recursively and normalized, this means
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that you can call this macro with autoconf's dirnames like `prefix' or
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`datadir'. For example:</p>
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adl_COMPUTE_RELATIVE_PATHS([bindir:datadir:bin_to_data])
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<p>adl_COMPUTE_RELATIVE_PATHS should also works with DOS filenames.</p>
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<p>You may want to use this macro in order to make your package
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relocatable. Instead of hardcoding $datadir into your programs just encode
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$bin_to_data and try to determine $bindir at run-time.</p>
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<p>This macro requires adl_NORMALIZE_PATH.</p>
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<p>1.1 (last modified: 2001-05-25)</p>
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<p>Alexandre Duret-Lutz <duret_g@epita.fr></p>
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<h2>M4 Source Code</h2>
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<pre class="m4source">
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AC_DEFUN([adl_COMPUTE_RELATIVE_PATHS],
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_lcl_from=\[$]`echo "[$]_lcl_i" | sed 's,:.*$,,'`
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_lcl_to=\[$]`echo "[$]_lcl_i" | sed 's,^[[^:]]*:,,' | sed 's,:[[^:]]*$,,'`
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_lcl_result_var=`echo "[$]_lcl_i" | sed 's,^.*:,,'`
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adl_RECURSIVE_EVAL([[$]_lcl_from], [_lcl_from])
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adl_RECURSIVE_EVAL([[$]_lcl_to], [_lcl_to])
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_lcl_notation="$_lcl_from$_lcl_to"
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adl_NORMALIZE_PATH([_lcl_from],['/'])
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adl_NORMALIZE_PATH([_lcl_to],['/'])
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adl_COMPUTE_RELATIVE_PATH([_lcl_from], [_lcl_to], [_lcl_result_tmp])
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adl_NORMALIZE_PATH([_lcl_result_tmp],["[$]_lcl_notation"])
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eval $_lcl_result_var='[$]_lcl_result_tmp'
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## The following helper macros are too fragile to be used out
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## of adl_COMPUTE_RELATIVE_PATHS (mainly because they assume that
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## paths are normalized), that's why I'm keeping them in the same file.
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## Still, some of them maybe worth to reuse.
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dnl adl_COMPUTE_RELATIVE_PATH(FROM, TO, RESULT)
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dnl ===========================================
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dnl Compute the relative path to go from $FROM to $TO and set the value
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dnl of $RESULT to that value. This function work on raw filenames
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dnl (for instead it will considerate /usr//local and /usr/local as
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dnl two distinct paths), you should really use adl_COMPUTE_REALTIVE_PATHS
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dnl instead to have the paths sanitized automatically.
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dnl first_dir=/somewhere/on/my/disk/bin
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dnl second_dir=/somewhere/on/another/disk/share
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dnl adl_COMPUTE_RELATIVE_PATH(first_dir, second_dir, first_to_second)
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dnl will set $first_to_second to '../../../another/disk/share'.
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AC_DEFUN([adl_COMPUTE_RELATIVE_PATH],
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[adl_COMPUTE_COMMON_PATH([$1], [$2], [_lcl_common_prefix])
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adl_COMPUTE_BACK_PATH([$1], [_lcl_common_prefix], [_lcl_first_rel])
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adl_COMPUTE_SUFFIX_PATH([$2], [_lcl_common_prefix], [_lcl_second_suffix])
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$3="[$]_lcl_first_rel[$]_lcl_second_suffix"])
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dnl adl_COMPUTE_COMMON_PATH(LEFT, RIGHT, RESULT)
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dnl ============================================
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dnl Compute the common path to $LEFT and $RIGHT and set the result to $RESULT.
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dnl first_path=/somewhere/on/my/disk/bin
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dnl second_path=/somewhere/on/another/disk/share
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dnl adl_COMPUTE_COMMON_PATH(first_path, second_path, common_path)
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dnl will set $common_path to '/somewhere/on'.
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AC_DEFUN([adl_COMPUTE_COMMON_PATH],
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_lcl_second_prefix_match=''
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while test "[$]_lcl_second_prefix_match" != 0; do
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_lcl_first_prefix=`expr "x[$]$1" : "x\([$]$3/*[[^/]]*\)"`
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_lcl_second_prefix_match=`expr "x[$]$2" : "x[$]_lcl_first_prefix"`
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if test "[$]_lcl_second_prefix_match" != 0; then
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if test "[$]_lcl_first_prefix" != "[$]$3"; then
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$3="[$]_lcl_first_prefix"
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_lcl_second_prefix_match=0
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dnl adl_COMPUTE_SUFFIX_PATH(PATH, SUBPATH, RESULT)
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dnl ==============================================
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dnl Substrack $SUBPATH from $PATH, and set the resulting suffix
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dnl (or the empty string if $SUBPATH is not a subpath of $PATH)
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dnl first_path=/somewhere/on/my/disk/bin
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dnl second_path=/somewhere/on
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dnl adl_COMPUTE_SUFFIX_PATH(first_path, second_path, common_path)
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dnl will set $common_path to '/my/disk/bin'.
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AC_DEFUN([adl_COMPUTE_SUFFIX_PATH],
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[$3=`expr "x[$]$1" : "x[$]$2/*\(.*\)"`])
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dnl adl_COMPUTE_BACK_PATH(PATH, SUBPATH, RESULT)
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dnl ============================================
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dnl Compute the relative path to go from $PATH to $SUBPATH, knowing that
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dnl $SUBPATH is a subpath of $PATH (any other words, only repeated '../'
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dnl should be needed to move from $PATH to $SUBPATH) and set the value
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dnl of $RESULT to that value. If $SUBPATH is not a subpath of PATH,
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dnl set $RESULT to the empty string.
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dnl first_path=/somewhere/on/my/disk/bin
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dnl second_path=/somewhere/on
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dnl adl_COMPUTE_BACK_PATH(first_path, second_path, back_path)
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dnl will set $back_path to '../../../'.
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AC_DEFUN([adl_COMPUTE_BACK_PATH],
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[adl_COMPUTE_SUFFIX_PATH([$1], [$2], [_lcl_first_suffix])
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while test "[$]_lcl_tmp" != ''; do
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_lcl_tmp=`expr "x[$]_lcl_first_suffix" : "x[[^/]]*/*\(.*\)"`
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if test "[$]_lcl_first_suffix" != ''; then
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_lcl_first_suffix="[$]_lcl_tmp"
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dnl adl_RECURSIVE_EVAL(VALUE, RESULT)
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dnl =================================
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dnl Interpolate the VALUE in loop until it doesn't change,
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dnl and set the result to $RESULT.
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dnl WARNING: It's easy to get an infinite loop with some unsane input.
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AC_DEFUN([adl_RECURSIVE_EVAL],
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$2=`(test "x$prefix" = xNONE && prefix="$ac_default_prefix"
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test "x$exec_prefix" = xNONE && exec_prefix="${prefix}"
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while test "[$]_lcl_receval_old" != "[$]_lcl_receval"; do
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_lcl_receval_old="[$]_lcl_receval"
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eval _lcl_receval="\"[$]_lcl_receval\""
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echo "[$]_lcl_receval")`])
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<a href="COPYING.html">GNU General Public License</a> with this special
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<a href="COPYING-Exception.html">exception</a>.
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htmldoc/relpaths.html
