[metaconfig.git] / U / modified / Myread.U

?RCS: $Id$
?RCS:
?RCS: Copyright (c) 1991-1997, 2004-2006, Raphael Manfredi
?RCS:
?RCS: You may redistribute only under the terms of the Artistic License,
?RCS: as specified in the README file that comes with the distribution.
?RCS: You may reuse parts of this distribution only within the terms of
?RCS: that same Artistic License; a copy of which may be found at the root
?RCS: of the source tree for dist 4.0.
?RCS:
?RCS: $Log: Myread.U,v $
?RCS: Revision 3.0.1.6  1997/02/28  15:05:39  ram
?RCS: patch61: myread script now starts with a "startsh"
?RCS: patch61: miscellaneous fixes
?RCS:
?RCS: Revision 3.0.1.5  1995/01/11  15:14:22  ram
?RCS: patch45: added & escape allowing user to turn on -d from the prompt
?RCS:
?RCS: Revision 3.0.1.4  1994/10/31  09:48:04  ram
?RCS: patch44: added Options to the MAKE line since it's no longer in Init.U
?RCS:
?RCS: Revision 3.0.1.3  1994/10/29  15:56:20  ram
?RCS: patch36: added ?F: line for metalint file checking
?RCS:
?RCS: Revision 3.0.1.2  1993/08/30  08:57:59  ram
?RCS: patch8: added new visible 'nostick' symbol, mainly for Finish.U
?RCS:
?RCS: Revision 3.0.1.1  1993/08/27  14:39:20  ram
?RCS: patch7: now sticks to the question when no default and empty answer
?RCS:
?RCS: Revision 3.0  1993/08/18  12:05:08  ram
?RCS: Baseline for dist 3.0 netwide release.
?RCS:
?X:
?X: This unit produces a bit of shell code that must be dotted in in order
?X: to do a read.  It allows for shell escapes, default assignment and
?X: parameter evaluation.
?X:
?X: To use this unit, $rp and $dflt must hold the question and the
?X: default answer. The question will be printed by the script itself.
?X:     Neither $rp nor $dflt is altered by the script.
?X:
?X: The myread script will stick to the question if no default is proposed
?X: and the user answer is empty, which prevents mistakes. However, at the
?X: end of Configure, there is an exception to this rule (Finish.U) where we
?X: set nostick to a non-empty value to allow the Return key to play its role!
?X:
?MAKE:Myread: Options startsh n c trnl
?MAKE:  -pick add $@ %<
?V:ans:dflt rp nostick
?F:./myread
?T:COLUMNS xxxm rp dflt answ aok myecho counter
?LINT:change fastread
?X: Some shells (Ultrix) do not understand ${COLUMNS:-80}, sigh!
: compute the number of columns on the terminal for proper question formatting
case "$COLUMNS" in
'') COLUMNS='80';;
esac

: set up the echo used in my read
?X:
?X:     This variable is intended to be eval'ed. It will echo the two
?X:     variables $rp and $dflt (provided this latter has a non null value).
?X:     It is mainly used by the myread script to echo the questions.
?X:
?X: The $n and $c below are substituted before Loc does its silly echo check
?X: so don't put a $ on the echo below so we get builtin, even if $echo is
?X: pointing to /bin/echo.
?X:
myecho="case \"\$xxxm\" in
'') echo $n \"\$rp $c\" >&4;;
*) case \"\$rp\" in
        '') echo $n \"[\$xxxm] $c\";;
        *)
                if test \`echo \"\$rp [\$xxxm]  \" | wc -c\` -ge $COLUMNS; then
                        echo \"\$rp\" >&4
                        echo $n \"[\$xxxm] $c\" >&4
                else
                        echo $n \"\$rp [\$xxxm] $c\" >&4
                fi
                ;;
        esac;;
esac"

: now set up to do reads with possible shell escape and default assignment
cat <<EOSC >myread
$startsh
?X:
?X: Save value of default -- do not alter original in case of eval
?X:
xxxm=\$dflt
$myecho
?X:
?X: If there is no default, then stop, regardless of the value in fastread.
?X: In silent mode, no new-line is to be echoed if the question is empty,
?X: since this is used to wait for the "return" key.
?X:
ans='!'
counter=42
case "\$fastread" in
yes) case "\$dflt" in
        '') ;;
        *) ans='';
                case "\$silent-\$rp" in
                true-) ;;
                *) echo " " >&4;;
                esac;;
        esac;;
*) case "\$silent" in
        true) case "\$rp" in
                '') ans='';;
                esac;;
        esac;;
esac
while expr "X\$ans" : "X!" >/dev/null; do
        read answ
?X:
?X: Run 'eval' on the answer, in order to do variable substitution, in case
?X: the user types $HOME or $WHATEVER. Variables must be evaluated now.
?X: Typing '\$HOME' won't currently prevent from substitution -- use '\\$HOME'
?X: The $1 .. $9 and $*, as well as $@, are available to refer to the
?X: default value.
?X:
        set x \$xxxm
        shift
        aok=''; eval "ans=\\"\$answ\\"" && aok=y
        case  "\$answ" in
?X:
?X: Use "!" and not a plain ! because of a bug in BSD 4.4 shell
?X: (reported by Wayne Davison)
?X: We must handle the shell escapes before dealing with possible variable
?X: substitution, since the shell we're launching in that case will be able
?X: to do it as well as we can -- RAM, 15/03/96
?X
        "!")
                sh 1>&4
                echo " "
                $myecho
                ;;
        !*)
                set x \`expr "X\$ans" : "X!\(.*\)\$"\`
                shift
                sh 1>&4 -c "\$*"
                echo " "
                $myecho
                ;;
        "\$ans")
                case "\$ans" in
?X:
?X: Answers starting with & are hooks allowing to dynamically turn on/off
?X: some Configure options. That's for the future. -- RAM, 09/01/95
?X: Today, we only recognize '& -d' to mean 'go on as if Configure -d, which
?X: is a hardwired behaviour compatible with our general scheme.
?X:
                \\&*)
                        set x \`expr "X\$ans" : "X&\(.*\)\$"\`
                        shift
                        case "\$1" in
                        -d)
                                fastread=yes
                                echo "(OK, I'll run with -d after this question.)" >&4
                                ;;
                        -*)
                                echo "*** Sorry, \$1 not supported yet." >&4
                                ;;
                        esac
                        $myecho
                        ans=!
                        ;;
                esac;;
        *)
                case "\$aok" in
                y)
                        echo "*** Substitution done -- please confirm."
                        xxxm="\$ans"
                        ans=\`echo $n "\$ans$c" | tr '$trnl' ' '\`
                        xxxm="\$ans"
                        ans=!
                        ;;
                *)
                        echo "*** Error -- try again."
                        ans=!
                        ;;
                esac
                $myecho
                ;;
        esac
?X: Stick in myread if no default answer and nothing was answered
        case "\$ans\$xxxm\$nostick" in
        '')
                ans=!
                $myecho
                ;;
        esac
        counter=\`echo \$counter | awk '{ print --\$0 }'\`
        if [ \$counter = 0 ]; then
                echo >&4
                echo >&4 Too many attempts asking the same question.  Giving up.
                exit 1
        fi
done
case "\$ans" in
'') ans="\$xxxm";;
esac
EOSC