AS_CASE [was: AS_IF whitespace cleanup]

[Eric Blake]

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According to Eric Blake on 10/21/2008 12:24 PM:
> 
> Eric Blake (4):
>       Allow AS_CASE in shell lists.

And here's a followup patch for AS_CASE, which makes it more robust in the
face of underquoting (as long as it's easy, we might as well be nice to
users in spite of their bugs).

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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>From edd82b60cbf48f12067c36d0f92244704e7eeaf8 Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Wed, 22 Oct 2008 14:24:02 -0600
Subject: [PATCH] Formatting tweak: balance () with m4sh case statements.

* lib/m4sugar/m4sh.m4 (_AS_DETECT_BETTER_SHELL)
(_AS_SHELL_SANITIZE, _AS_ECHO_N_PREPARE, _AS_ECHO_PREPARE)
(AS_SET_CATFILE, _AS_TEST_PREPARE): Add strategic shell comments.
(_AS_CASE, _AS_CASE_DEFAULT, AS_CASE): Rearrange newlines, to
allow output of strategic shell comments.
(AS_VERSION_COMPARE): Use AS_CASE.
* tests/m4sh.at (AS@&address@hidden and AS@&address@hidden): Enhance test.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog           |   11 +++++++++++
 lib/m4sugar/m4sh.m4 |   49 +++++++++++++++++++++++++------------------------
 tests/m4sh.at       |    5 ++++-
 3 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index bdc3244..df85fbf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2008-10-23  Eric Blake  <address@hidden>
+
+       Formatting tweak: balance () with m4sh case statements.
+       * lib/m4sugar/m4sh.m4 (_AS_DETECT_BETTER_SHELL)
+       (_AS_SHELL_SANITIZE, _AS_ECHO_N_PREPARE, _AS_ECHO_PREPARE)
+       (AS_SET_CATFILE, _AS_TEST_PREPARE): Add strategic shell comments.
+       (_AS_CASE, _AS_CASE_DEFAULT, AS_CASE): Rearrange newlines, to
+       allow output of strategic shell comments.
+       (AS_VERSION_COMPARE): Use AS_CASE.
+       * tests/m4sh.at (AS@&address@hidden and AS@&address@hidden): Enhance 
test.
+
 2008-10-22  Paolo Bonzini  <address@hidden>
        and Eric Blake  <address@hidden>
 
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index c2c4afd..09fbee6 100644
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -209,7 +209,7 @@ dnl Remove any tests from suggested that are also required
     [],
     [as_candidate_shells=
     _AS_PATH_WALK([/bin$PATH_SEPARATOR/usr/bin$PATH_SEPARATOR$PATH],
-      [case $as_dir in
+      [case $as_dir in @%:@(
         /*)
           for as_base in sh bash ksh sh5; do
             as_candidate_shells="$as_candidate_shells $as_dir/$as_base"
@@ -423,7 +423,7 @@ _AS_PATH_SEPARATOR_PREPARE
 IFS=" ""       $as_nl"
 
 # Find who we are.  Look in the path if we contain no directory separator.
-case $[0] in
+case $[0] in @%:@((
   *[[\\/]]* ) as_myself=$[0] ;;
   *) _AS_PATH_WALK([],
                   [test -r "$as_dir/$[0]" && as_myself=$as_dir/$[0] && break])
@@ -486,20 +486,22 @@ _AS_UNSET_PREPARE
 # AS_CASE(WORD, [PATTERN1], [IF-MATCHED1]...[DEFAULT])
 # ----------------------------------------------------
 # Expand into
-# | case WORD in
-# | PATTERN1) IF-MATCHED1 ;;
-# | ...
-# | *) DEFAULT ;;
+# | case WORD in #(
+# |   PATTERN1) IF-MATCHED1 ;; #(
+# |   ...
+# |   *) DEFAULT ;;
 # | esac
+# The shell comments are intentional, to work around people who don't
+# realize the impacts of using insufficient m4 quoting.
 m4_define([_AS_CASE],
-[  $1[)] m4_default([$2], [:]) ;;
-])
+[ address@hidden:@(]
+  $1[)] $2 ;;])
 m4_define([_AS_CASE_DEFAULT],
-[  *[)] $1 ;;
-])
+[ address@hidden:@(]
+  *[)] $1 ;;])
+
 m4_defun([AS_CASE],
-[case $1 in
-m4_map_args_pair([_$0], [_$0_DEFAULT], m4_shift($@))dnl
+[case $1 in[]m4_map_args_pair([_$0], [_$0_DEFAULT], m4_shift($@))
 esac])# AS_CASE
 
 
@@ -664,7 +666,7 @@ _AS_ECHO([$as_me:${as_lineno-$LINENO}: $1], 
[AS_MESSAGE_LOG_FD])])
 # failed there is also a newline to match.
 m4_defun([_AS_ECHO_N_PREPARE],
 [ECHO_C= ECHO_N= ECHO_T=
-case `echo -n x` in
+case `echo -n x` in @%:@((((
 -n*)
   case `echo 'x\c'` in
   *c*) ECHO_T='        ';;     # ECHO_T is single tab character.
@@ -881,7 +883,7 @@ else
     as_echo_body='eval expr "X$][1" : "X\\(.*\\)"'
     as_echo_n_body='eval
       arg=$][1;
-      case $arg in
+      case $arg in @%:@(
       *"$as_nl"*)
        expr "X$arg" : "X\\(.*\\)$as_nl";
        arg=`expr "X$arg" : ".*$as_nl\\(.*\\)"`;;
@@ -1154,10 +1156,10 @@ IFS=$as_save_IFS
 # Set VAR to DIR-NAME/FILE-NAME.
 # Optimize the common case where $2 or $3 is '.'.
 m4_define([AS_SET_CATFILE],
-[case $2 in
+[case $2 in @%:@((
 .) $1=$3;;
 *)
-  case $3 in
+  case $3 in @%:@(((
   .) $1=$2;;
   [[\\/]]* | ?:[[\\/]]* ) $1=$3;;
   *) $1=$2/$3;;
@@ -1192,10 +1194,10 @@ else
       if test -d "$[]1"; then
        test -d "$[]1/.";
       else
-       case $[]1 in
+       case $[]1 in @%:@(
        -*)set "./$[]1";;
        esac;
-       case `ls -ld'$as_ls_L_option' "$[]1" 2>/dev/null` in
+       case `ls -ld'$as_ls_L_option' "$[]1" 2>/dev/null` in @%:@((
        ???[[sx]]*):;;*)false;;esac;fi
     '\'' sh
   '
@@ -1512,12 +1514,11 @@ as_arg_v2=$2
 dnl This usage is portable even to ancient awk,
 dnl so don't worry about finding a "nice" awk version.
 awk "$as_awk_strverscmp" v1="$as_arg_v1" v2="$as_arg_v2" /dev/null
-case $? in
-1) $3;;
-0) $4;;
-2) $5;;
-esac[]dnl
-])# _AS_VERSION_COMPARE
+AS_CASE([$?],
+       [1], [$3],
+       [0], [$4],
+       [2], [$5])[]dnl
+])# AS_VERSION_COMPARE
 
 
 
diff --git a/tests/m4sh.at b/tests/m4sh.at
index 49c2b7e..badc668 100644
--- a/tests/m4sh.at
+++ b/tests/m4sh.at
@@ -799,7 +799,7 @@ AS_CASE([foo],
         [foo], [echo ten],
         [*],   [echo wrong])
 
-# check for nesting, lists, and side effects
+# check for nesting, lists, and side effects, and quoting robustness
 empty=
 AS_IF([AS_IF([$empty], [echo eleven])]) && AS_CASE([foo]) && echo twelve
 rm -f file
@@ -807,6 +807,8 @@ AS_IF([touch file; false]) && echo thirteen
 test -f file && echo fourteen
 rm -f file
 AS_CASE([`touch file; false`]) && test -f file && echo fifteen
+dnl The next line is badly underquoted; don't intentionally copy this style.
+AS_CASE([foo], [foo], m4_do(AS_CASE([bar], [bar], [echo sixteen])))
 
 # check that require works correctly
 m4_for([n], 1, 9, [],
@@ -858,6 +860,7 @@ twelve
 thirteen
 fourteen
 fifteen
+sixteen
 foo1=1 bar1=1
 foo2=2 bar2=
 foo3=3 bar3=
-- 
1.6.0.2