Calculator function

[Peter Stephenson <pws@xxxxxxx>]

I keep meaning to add this.  Maybe someone has a better one somewhere?

Index: Doc/Zsh/contrib.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/contrib.yo,v
retrieving revision 1.12
diff -u -r1.12 contrib.yo
--- Doc/Zsh/contrib.yo	2001/07/20 13:04:51	1.12
+++ Doc/Zsh/contrib.yo	2001/07/27 10:57:27
@@ -786,6 +786,42 @@
 ifzman(above)\
 ifnzman((noderef(Utilities))).
 )
+findex(zcalc)
+item(tt(zcalc) [ var(expression) ... ])(
+A reasonably powerful calculator based on zsh's arithmetic evaluation
+facility.  The syntax is similar to that of formulae in most programming
+languages; see
+ifzman(the section `Arithmetic Evaluation' in zmanref(zshmisc))\
+ifnzman(noderef(Arithmetic Evaluation)) for details.  The mathematical
+library tt(zsh/mathfunc) will be loaded if it is available; see
+ifzman(the section `The zsh/mathfunc Module' in zmanref(zshmodules))\
+ifnzman(noderef(The zsh/mathfunc Module)).  The mathematical functions
+correspond to the raw system libraries, so trigonometric functions are
+evaluated using radians, and so on.
+
+Each line typed is evaluated as an expression.  The prompt shows a number,
+which corresponds to a positional parameter where the result of that
+calculation is stored.  For example, the result of the calculation on the
+line preceeded by `tt(4> )' is available as tt($4).  Full command line
+editing, including the history of previous calculations, is available.
+To exit, enter a blank line or type `tt(q)' on its own.
+
+If arguments are given to tt(zcalc) on start up, they are used to prime the
+first few positional parameters.  A visual indication of this is given when
+the calculator starts.
+
+The constants tt(PI) (3.14159...) and tt(E) (2.71828...) are provided.
+Parameter assignment is possible, but note that all parameters will be put
+into the global namespace.
+
+An extra facility is provided for changing the default output base.  Use,
+for example, `tt([#16])' to display hexadecimal output preceeded by an
+indication of the base, or `tt([##16])' just to display the raw number in
+the given base.  Bases themselves are always specified in decimal.
+`tt([#])' restores the normal output format.
+
+See the comments in the function for a few extra tips.
+)
 findex(zed)
 item(tt(zed) [ tt(-f) ] var(name))(
 This function uses the ZLE editor to edit a file or function.  It rebinds
Index: Functions/Misc/zcalc
===================================================================
RCS file: zcalc
diff -N zcalc
--- /dev/null	Thu May 24 22:33:05 2001
+++ zcalc	Fri Jul 27 03:57:27 2001
@@ -0,0 +1,142 @@
+#!/usr/local/bin/zsh -i
+#
+# Zsh calculator.  Understands most ordinary arithmetic expressions.
+# Line editing and history are available. A blank line or `q' quits.
+#
+# Runs as a script or a function.  If used as a function, the history
+# is remembered for reuse in a later call (and also currently in the
+# shell's own history).  There are various problems using this as a
+# script, so a function is recommended.
+#
+# The prompt shows a number for the current line.  The corresponding
+# result can be referred to with $<line-no>, e.g.
+#   1> 32 + 10
+#   42
+#   2> $1 ** 2
+#   1764
+# The set of remembered numbers is primed with anything given on the
+# command line.  For example,
+#   zcalc '2 * 16'
+#   1> 32                     # printed by function
+#   2> $1 + 2                 # typed by user
+#   34
+#   3> 
+# Here, 32 is stored as $1.  This works in the obvious way for any
+# number of arguments.
+#
+# If the mathfunc library is available, probably understands most system
+# mathematical functions.  The left parenthesis must be adjacent to the
+# end of the function name, to distinguish from shell parameters
+# (translation: to prevent the maintainers from having to write proper
+# lookahead parsing).  For example,
+#   1> sqrt(2)
+#   1.4142135623730951
+# is right, but `sqrt (2)' will give you an error.
+#
+# You can do things with parameters like
+#   1> pi = 4.0 * atan(1)
+# too.  These go into global parameters, so be careful.  You can declare
+# local variables, however:
+#   1> local pi
+# but note this can't appear on the same line as a calculation.  Don't
+# use the variables listed in the `local' and `integer' lines below
+# (translation: I can't be bothered to provide a sandbox).
+#
+# Some constants are already available: (case sensitive as always):
+#   PI     pi, i.e. 3.1415926545897931
+#   E      e, i.e. 2.7182818284590455
+#
+# You can also change the output base.
+#   1> [#16]
+#   1>
+# Changes the default output to hexadecimal with numbers preceded by `16#'.
+# Note the line isn't remembered.
+#   2> [##16]
+#   2>
+# Change the default output base to hexadecimal with no prefix.
+#   3> [#]
+# Reset the default output base.
+#
+# This is based on the builtin feature that you can change the output base
+# of a given expression.  For example,
+#   1> [##16]  32 + 20 / 2
+#   2A
+#   2> 
+# prints the result of the calculation in hexadecimal.
+#
+# You can't change the default input base, but the shell allows any small
+# integer as a base:
+#   1> 2#1111
+#   15
+#   2> [##13] 13#6 * 13#9
+#   42
+# and the standard C-like notation with a leading 0x for hexadecimal is
+# also understood.  However, leading 0 for octal is not understood --- it's
+# too confusing in a calculator.  Use 8#777 etc.
+#
+#
+# To do:
+# - separate zcalc history from shell history using arrays --- or allow
+#   zsh to switch internally to and from array-based history.
+# - allow setting number of decimal places for display, scientific notation, 
+#   etc.
+
+emulate -L zsh
+setopt extendedglob
+
+local line latest base defbase match mbegin mend
+integer num
+
+zmodload -i zsh/mathfunc 2>/dev/null
+
+# Supply some constants.
+float PI E
+(( PI = 4 * atan(1), E = exp(1) ))
+
+for (( num = 1; num <= $#; num++ )); do
+  # Make sure all arguments have been evaluated.
+  # The `$' before the second argv forces string rather than numeric
+  # substitution.
+  (( argv[$num] = $argv[$num] ))
+  print "$num> $argv[$num]"
+done
+
+while vared -chp "$num> " line; do
+  [[ -z $line ]] && break
+  # special cases
+  # Set default base if `[#16]' or `[##16]' etc. on its own.
+  # Unset it if `[#]' or `[##]'.
+  if [[ $line = (#b)[[:blank:]]#('[#'(\#|)(<->|)']')[[:blank:]]#(*) ]]; then
+    if [[ -z $match[4] ]]; then
+      if [[ -z $match[3] ]]; then
+	defbase=
+      else
+	defbase=$match[1]
+      fi
+      print -s -- $line
+      line=
+      continue
+    else
+      base=
+    fi
+  else
+    base=$defbase
+  fi
+  # Exit if `q' on its own.
+  [[ $line = [[:blank:]]#q[[:blank:]]# ]] && return 0
+
+  print -s -- $line
+  if [[ $line = [[:blank:]]#local([[:blank:]]##*|) ]]; then
+    eval $line
+  else
+    # Latest value is stored as a string, because it might be floating
+    # point or integer --- we don't know till after the evaluation, and
+    # arrays always store scalars anyway.
+    eval "latest=\$(( $base $line ))"
+    argv[num++]=$latest
+    print -- $latest
+  fi
+  line=
+done
+
+return 0

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR Ltd., Unit 300, Science Park, Milton Road,
Cambridge, CB4 0XL, UK                          Tel: +44 (0)1223 392070


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