#!/usr/local/bin/perl
#
#  ebcalc - 再計算電卓
#
#  $Date: 1998/01/28 19:38:25 $
#  $Revision: 1.1 $
#
#  増井俊之 @ ソニーコンピュータサイエンス研究所
#
require 'cbreak2.pl';

&cbreak;
$| = 1;

while(1){
  $s = getc;
  next if $s eq '';
  last if $s eq "\003";
  &calculator($s);
}
&cooked;
print "\n";

sub calculator {
  local($_) = @_;
  if(/[\d\.]/){
    if($prev =~ /=/){
      $value = $operator = '';
      $exp = $rest = '' unless $undomode;
    }
    $arg = '' if $prev !~ /[\d\.]/;
    $arg .= $_;
    $exp .= $_ unless $undomode;
    &display($arg);
  }
  elsif(/[\010\177]/){
    if($prev =~ /[\d\.\010\177]/ &&
       ! $undomode){
      if(length($arg) > 0){
        chop($arg);
        &display($arg);
      }
    }
    else {
      if(! $undomode){
        $undomode = 1;
        $rest = $d = '';
      }
      if($exp =~
       /^(.*[^\d\.])?([\d\.]+)([^\d\.]*)$/){
        $exp = $1; $rest = $3.$d.$rest;
        $d = $2;
        &display($d);
      }
    }
  }
  elsif(/[\+\*\-\/]/){
    if($undomode){
      $undomode = 0;
      $value = $operator = '';
      $exp = $arg; $rest = '';
    }
    unless($prev =~ /=/){
      $value = $operator ? 
        eval "$value $operator $arg" : $arg;
    }
    $operator = $_;
    $exp .= $_;
    &display($value);
  }
  elsif(/=/){
    if(! $undomode){
      $value = eval "$value $operator $arg";
      $exp .= $_;
      &display($value);
    }
    else {
      $expbak = $exp; $restbak = $rest;
      $t = $exp . $arg . $rest;
      $exp = $rest = $value = 
      $operator = $arg = '';
      $undomode = 0;
      $prev = '';
      while($t =~ s/.//){
        &calculator($&);
      }
      $exp = $expbak; $rest = $restbak;
      $undomode = 1;
    }
  }
  elsif(/c/i){
    $value = $operator = '';
    $exp = $rest = '';
    $undomode = 0;
    &display(0);
  }
  $prev = $_;
}

sub display {
  local($v) = @_;
  print "$v\n";
}