'app-plug-in 'menu Calculator ###################################################################### # \$Id: calc.bas,v 1.5 2005/05/11 23:30:14 zeeb90au Exp \$ # calc.bas Copyright (c) Chris Warren-Smith April 2005 # Demonstration for html user interfaces # # Version 1.0 # # This program is distributed under the terms of the GPL v2.0 or later # Download the GNU Public License (GPL) from www.gnu.org # ###################################################################### func compute(byref operator, lval, rval) local result = 0 if (operator = "+") then result = lval + rval elseif (operator = "-") then result = lval - rval elseif (operator = "/") then result = lval / rval elseif (operator = "*") then result = lval * rval elseif (lval > 0) then result = lval else result = rval fi compute = result end # evaluate the expression string func eval(byref expr) local strl,num,pt,result,operator,inner,endb,i,j,nbracket strl = len(expr) num = 0 pt = 0 result = 0 operator = "" for i = 0 to strl if (i < strl) ch = mid(expr, i+1, 1) else # end of last operand eval = compute(operator, result, num) exit func fi if ch = "." then pt = 1 elseif isnumber(ch) then if pt > 0 then num = num + (ch/(10^pt)) pt++ else num = num*10+ch fi else # non number if ch = "(" then # find the matching ) if (len(operator) = 0) then #short form notation eg 3(1+1) operator = "*" if (result = 0) then result = num else result = compute(operator, result, num) fi else # complete the previous expression result = compute(operator, result, num) fi nbracket = 1 endb = 0 i++ for j = i to strl-1 ch = mid(expr, j+1, 1) if ch = "(" then nbracket++ elseif ch = ")" then nbracket-- if nbracket = 0 then endb = j exit for fi fi next j if (endb = 0) then eval = "ERR" exit func endif inner = mid(expr, i+1, endb-i) if len(operator) = 0 then result = eval(inner) else num = eval(inner) result = compute(operator, result, num) fi i = endb if (i+1 = strl) then # nothing more to process eval = result exit func fi # scan for next operator operator = "" elseif ch = ")" then eval = result exit func else # operator character if (len(operator) = 0) then # first operand result = num else # resolve the current expression result = compute(operator, result, num) endif operator = ch fi # scan for next number num = 0 pt = 0 fi next i eval = result end sub main # install the application help file env("APP-HELP=calc_help.html") cls # display the user interface if not already displayed # the form-active field is a hidden form variable if env("form-active") != "true" then chdir env("BAS_HOME") html "file:calc.html" exit sub fi if len(command) = 0 then exit sub fi # process button clicks - the command variable takes the # value of the onclick argument if command = "CE" then env("out=0") exit sub fi curval= env("out") if instr(curval, "=") > 0 then exit sub fi out = "" if command = "BS" then if len(curval) > 1 then out = left(curval, len(curval)-1) else out = "0" fi elseif command = "mc" then elseif command = "mr" then elseif command = "ms" then elseif command = "m+" then elseif command = "dot" then if len(curval) > 0 && right(curval,1) != "." then out = curval+"." fi elseif command = "=" then out = curval+command+eval(curval) else # numeric input if (curval = "0") then curval = "" fi out = curval+command fi env("out="+out) end main