fixed x, added checks, enhanced doc

README.md

@@ -136,6 +136,31 @@ sub stack of before.
 Every operation which  modifies the stack can be  reversed by entering
 the <kbd>u</kbd> command. There's only one level of undo and no redo.
 
+## Functions
+
+You can define functions anytime directly on the cli or in a file called
+`~/.rpnc`. A function has a name (which must not collide with existing
+functions and commands) and a body of commands.
+
+Example:
+
+    f res2vcc 1.22 R1 R2 + R2 / 1 + *
+
+Which calculates:
+
+    (((R1 + R2) / R2) + 1) * 1.22 = ??
+    
+To use it later, just enter the variables into the stack followed by the
+function name:
+
+    470
+    220
+    res2vcc
+
+You  can  also  put  the   function  definition  in  the  config  file
+`~/.rpnc`. Empty lines and lines beginning with `#` will be ignored.
+
+
 ## Using STDIN via a PIPE
 
 If the commandline  includes any operator, commands will  be read from
@@ -150,18 +175,22 @@ Examples:
     
 Both commands will print 4 to STDOUT.
 
+
 ## Complete list of all supported commands:
 
-* <kbd>c</kbd>    clear stack
+### Stack Management
+
 * <kbd>s</kbd>    show the stack
-* <kbd>d</kbd>    toggle debugging (current setting: 0)
+* <kbd>ss</kbd>    show the whole stack
-* <kbd>r</kbd>    reverse the stack
+* <kbd>sc</kbd>    clear stack
-* <kbd>R</kbd>    rotate the stack
+* <kbd>scx</kbd>   clear last stack element
-* <kbd>(</kbd>    enter collect mode
+* <kbd>sr</kbd>    reverse the stack
-* <kbd>)</kbd>    leave collect mode
+* <kbd>srt</kbd>    rotate the stack
-* <kbd>u</kbd>    undo last operation
+
-* <kbd>q</kbd>    finish (<kbd>C-d</kbd> works as well)
+## Configuration
-* <kbd>?</kbd>    print help
+
+* <kbd>td</kbd>    toggle debugging (-d)
+* <kbd>ts</kbd>    toggle display of the stack (-n)
 
 ## Supported mathematical operators:
 
@@ -171,10 +200,47 @@ Both commands will print 4 to STDOUT.
 * <kbd>*</kbd>     multiply
 * <kbd>^</kbd>     expotentiate
 * <kbd>%</kbd>     percent
+* <kbd>%+</kbd>     add percent
+* <kbd>%-</kbd>     substract percent
+* <kbd>%d</kbd>     percentual difference
 * <kbd>&</kbd>     bitwise AND
 * <kbd>|</kbd>     bitwise OR
 * <kbd>x</kbd>     bitwise XOR
-* <kbd>V</kbd>     pull root (2nd if stack==1)
+* <kbd>m</kbd>     median
+* <kbd>a</kbd>     average
+* <kbd>v</kbd>     pull root (2nd if stack==1)
+* <kbd>(</kbd>    enter collect mode
+* <kbd>)</kbd>    leave collect mode
+
+## Register Commands
+
+* <kbd>r</kbd>    put element into register
+* <kbd>rc</kbd>   clear register
+* <kbd>rcx</kbd>  clear last register element
+
+## Various Commands
+
+* <kbd>u</kbd>    undo last operation
+* <kbd>q</kbd>    finish (<kbd>C-d</kbd> works as well)
+* <kbd>h</kbd>    show history of past operations
+* <kbd>?</kbd>    print help
+
+## Converters
+
+* <kbd>tl</kbd> gallons to liters
+* <kbd>tk</kbd> miles to kilometers
+* <kbd>tm</kbd> yards to meters
+* <kbd>tc</kbd> inches to centimeters
+* <kbd>tkb</kbd> bytes to kilobytes
+* <kbd>tmb</kbd> bytes to megabytes
+* <kbd>tgb</kbd> bytes to gigabytes
+* <kbd>ttb</kbd> bytes to terabytes
+
+## Function Comands
+
+* <kbd>f NAME CODE</kbd>  define a functions (see ab above)
+* <kbd>fs</kbd>   show list of defined functions
+
 
 ## Copyleft
 

rpnc

@@ -106,6 +106,7 @@ my %func    = (
                    return 0;
                  }
                },
+
                '%d' => sub {
                  # percentual difference
                  if (scalar @_ == 2) {
@@ -118,6 +119,7 @@ my %func    = (
                    return 0;
                  }
                },
+
                '%+' => sub {
                  # Y + (X $ of Y)
                  if (scalar @_ == 2) {
@@ -130,6 +132,7 @@ my %func    = (
                    return 0;
                  }
                },
+
                '%-' => sub {
                  # Y - (X $ of Y)
                  if (scalar @_ == 2) {
@@ -142,6 +145,7 @@ my %func    = (
                    return 0;
                  }
                },
+
                'v' => sub {
                  if (scalar @_ == 2) {
                    my ($a, $b) = @_;
@@ -152,11 +156,13 @@ my %func    = (
                    return "$a ** (1 / 2)";
                  }
                },
+
                'pr' => sub {
                  # parallel resistance, maybe add ~/.rpncrc support
                  # where to add such custom functions...
                  return "1 / (" . join(' + ', map { "1 / $_"} @_) . ")";
                },
+
                'm' => sub {
                  # median
                  if (scalar @_ >= 2) {
@@ -175,10 +181,12 @@ my %func    = (
                    undo(); return 0;
                  }
                },
+
                'a' => sub {
                  # average
                  return "(" . join(' + ', @_) . ") / " . scalar @_;
                },
+
                # converters:
                # gallons to liters
                'tl' => sub { return $_[-1] * 3.785 },
@@ -193,6 +201,9 @@ my %func    = (
                'tmb' => sub { return $_[-1] / 1000 / 1000},
                'tgb' => sub { return $_[-1] / 1000 / 1000 / 1000 },
                'ttb' => sub { return $_[-1] / 1000 / 1000 / 1000 / 1000 },
+
+               # alias
+               'x' => sub { return join "^", @_ },
               );
 
 # math constants, always upper case letters, usable via eval{}
@@ -540,6 +551,21 @@ sub defun {
   my $code = shift;
   my ($op, $name, @tokens) = split /\s\s*/, $code;
 
+  if ($name !~ /^[a-zA-Z0-9_]+$/) {
+    print "invalid function name (a-z0-9_)!\n";
+    return;
+  }
+
+  if (grep {$name eq $_} keys %commands) {
+    print "reserved function name (command)!\n";
+    return;
+  }
+
+  if (grep {$name eq $_} keys %func) {
+    print "reserved function name (function)!\n";
+    return;
+  }
+
   $custom{$name} = "@tokens";
 
   $func{$name} = sub {
@@ -549,13 +575,14 @@ sub defun {
     # replace N1..NN with actual args
     my @body;
     foreach my $item (@tokens) {
-      if ($item =~ /^N(\d+)$/) {
+      if ($item =~ /^([A-Z])(\d+)$/) {
-        my $i = $1;
+        my $letter = $1;
+        my $i = $2;
         if ($i <= $max) {
           push @body, $args[$i-1];
         }
         else {
-          print "undefined variable N$i!\n";
+          print "undefined variable ${letter}${i}!\n";
           push @body, 0;
         }
       }