Parsing/RPN calculator algorithm: Difference between revisions

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@@ Line 3,276: / Line 3,276: @@
 =={{header|Perl}}==
-<lang Perl>
+<lang perl>use strict;
+use warnings;
-# RPN calculator
+use feature 'say';
-#
-# Nigel Galloway April 2nd., 2012
+my $number   = '[+-]?(?:\.\d+|\d+(?:\.\d*)?)';
-#
-$WSb = '(?:^|\s+)';
+my $operator = '[-+*/^]';
-$WSa = '(?:\s+|$)';
+my @tests = ('3 4 2 * 1 5 - 2 3 ^ ^ / +');
-$num = '([+-/]?(?:\.\d+|\d+(?:\.\d*)?))';
-$op = '([-+*/^])';
-sub myE {
+for (@tests) {
+    while (
-  my $a = '('.$1.')'.$3.'('.$2.')';
+        s/ \s* ((?<left>$number))     # 1st operand
-  $a =~ s/\^/**/;
+           \s+ ((?<right>$number))    # 2nd operand
-  return eval($a);
+           \s+ ((?<op>$operator))     # operator
+           (?:\s+|$)                  # more to parse, or done?
+         /
+           ' '.evaluate().' '         # substitute results of evaluation
+         /ex
+    ) {}
+    say;
 }
-while (<>)  {
+sub evaluate {
-  while (s/$WSb$num\s+$num\s+$op$WSa/' '.myE().' '/e)  {}
+  (my $a = "($+{left})$+{op}($+{right})") =~ s/\^/**/;
-  print ($_, "\n");
+  say $a;
-}
+  eval $a;
-</lang>
+}</lang>
-Produces:
+{{out}}
-<pre>
+<pre>(4)*(2)
->rpnC.pl
+(1)-(5)
-4 2 * 1 5 - 2 3 ^ ^ / +
+(2)**(3)
-.0001220703125
+(-4)**(8)
-</pre>
+(8)/(65536)
+(3)+(0.0001220703125)
+.0001220703125</pre>
 =={{header|Perl 6}}==