/*
StrExpr2 - Calculates a binary numerical expression in a string and returns the result as a number. One of the elements can be itself a binary expression, in which case it must be set in parentheses. Requires the UDO StrExpr1

DESCRIPTION
Calculates a binary numerical expression in a string and returns the result as a number. One of the elements can be itself a binary expression, in which case it must be set in parentheses. No spaces are allowed. Supported math operations are +, -, *, /, ^, and %. A simple number string or a simple expression (like in StrExpr1) is also accepted and converted to a number.
Requires the UDO StrExpr1.

SYNTAX
iNum StrExpr2 Str

INITIALIZATION
Str - Input string with a binary math expression. One of the elements can be itself a binary expression, in which case it must be set in parentheses. No spaces are allowed. Supported math operations are +, -, *, /, ^, and %. A simple number string or a simple expression (like in StrExpr1) is also accepted and converted to a number.
iNum - result of the binary operation as number

CREDITS
joachim heintz 2012
*/

  opcode StrExpr2, i, S
Sin       xin
ilen      strlen    Sin
;if a parenthesis can be found
iparenth  strindex  Sin, "("
if iparenth > -1 then
  ;if in first half and no '-' preceeds
  if iparenth == 0 then
    ;then first element ends in ")"
iprend    strindex   Sin, ")"
S1        strsub     Sin, 1, iprend
    ;convert this element into a number
i1        StrExpr1   S1
    ;append the rest and convert again
S2        strsub     Sin, iprend+2 
Sep       strsub     Sin, iprend+1, iprend+2
Scoll     sprintf    "%f%s%s", i1, Sep, S2
ires      StrExpr1   Scoll
  ;if in first half and '-' preceeds
  elseif iparenth == 1 then
    ;then first element ends in ")"
iprend    strindex   Sin, ")"
S1        strsub     Sin, 2, iprend
    ;convert this element into a number
i1        StrExpr1   S1
i1        =          -i1
    ;append the rest and convert again
S2        strsub     Sin, iprend+2 
Sep       strsub     Sin, iprend+1, iprend+2
Scoll     sprintf    "%f%s%s", i1, Sep, S2
ires      StrExpr1   Scoll
  ;if the parenthesis is in the second half
  else
    ;isolate first element and the conjunction
S1        strsub     Sin, 0, iparenth-1
Sep       strsub     Sin, iparenth-1, iparenth
    ;convert the second element
S2        strsub     Sin, iparenth+1, ilen-1
i2        StrExpr1   S2
      ;if subtraction and i2 negative, convert to addition
isepminus strcmp     Sep, "-"
      if i2 < 0 && isepminus == 0 then
i2        =          -i2
Sep       =          "+"
      endif
    ;convert the whole
Scoll     sprintf    "%s%s%f", S1, Sep, i2
ires      StrExpr1   Scoll
  endif
;if no parenthesis, simply convert
else	
ires      StrExpr1   Sin
endif
          xout       ires
  endop