Arithmetic expression evaluation in numeric input fields.

The sign designing program I use at work lets us enter arithmetic expressions in the numeric entry fields. For example, if the letter height field shows 2.345, and I want it to be doubled, I don't have to calculate the value elsewhere and enter it manually, I just add "*2" following the 2.345 and tab or press enter and the value changes to 2.345*2.

I'd like to see this, and I'd want the fields to be a little wider. My friend suggested this awhile back: /13/13/38801/1.html

Interesting idea. It'd be nice for novice builders... though from what I have seen, many of the more experienced builders have tools that change prim properties via a HUD, thus meaning the builder can change prims with HUD clicks and doesn't have to mess with numbers in boxes.

I created a Jira issue on this topic back in May of 2007, https://jira.secondlife.com/browse/VWR-675, "Ability to do simple math in numeric edit fields"

A comment by Aimee Trescothick appeared there November 12th reporting


Congratulations and thanks to Aimee Trescothick.

Perhaps it's time to vote for this Jira issue .

Good news from Aimee Trescothick
http://jira.secondlife.com/browse/VWR-675


Outstanding!

More votes would be nice.

Off the top of my head:

list DIGITS = [
  "0", "1", "2", "3", "4",
  "5", "6", "7", "8", "9"
];

list digits(string s)
{
  string token = llGetSubString(s, 0, 1);
  s = llGetSubString(s, 1, -1);
  while(token == " ")
  {
    token = llGetSubString(s, 0, 1);
    s = llGetSubString(s, 1, -1);
  }

  string result = "";
  while(llListFindList(DIGITS, [token]) != -1)
  {
    result += token;
    token = llGetSubString(s, 0, 1);
    s = llGetSubString(s, 1, -1);
  }

  while(token == " ")
  {
    token = llGetSubString(s, 0, 1);
    s = llGetSubString(s, 1, -1);
  }

  return [result, token, string];
}

list term(string s)
{
    list l = digits(s);
    string value = llList2String(l, 0);
    string token = llList2String(l, 1);
    string = llList2String(l, 2);

    if(token == ".") {
      l = digits(s);
      value = value + "." + llList2String(l, 0);
      token = llList2String(l, 1);
      string = llList2String(l, 2);
    }

    return [ (float)value, token, string ];
}


list prod(string s)
{
    list l = term(s);
    float value = llList2Float(l, 0);
    string token = llList2String(l, 1);
    string = llList2String(l, 2);
    while(token == "*" || token == "/") {
      l = term(s);
      if(token == "*") value *= llList2Float(l,0);
      else value /= llList2Float(l, 0);
      token = llList2String(l, 1);
      string = llList2String(l,2);
    }
    return [value, token, string];
}

list sum(string s)
{
    list l = prod(s);
    float value = llList2Float(l, 0);
    string token = llList2String(l, 1);
    string = llList2String(l, 2);
    while(token == "+" || token == "-") {
      l = prod(s);
      if(token == "+") value += llList2Float(l,0);
      else value -= llList2Float(l, 0);
      token = llList2String(l, 1);
      string = llList2String(l,2);
    }
    return [value, token, string];
}

float eval (string expr)
{
  list l = sum(expr);
  return llList2Float(l, 0);
}

No warranty intended or implied, it probably doesn't even compile, but I've desk-checked it and if it doesn't compile a scripter of average ability should be able to get it to work.

There's a viewer patch already written.

If that's an LSL script it's not real applicable to the topic.

Expression evaluation for builders has been implemented in the Imprudence viewer.

Here's the url on the topic at the Imprudence wiki: http://imprudenceviewer.org/wiki/Build_Math_Expressions .

It's a fair bit more advanced that what I was hoping for. It has variables and constants added in. I just moved something by typing "+5" at the end of the current postion and it added 5 to the current position and moved the object there.

Far out!

This was implemented by Aimee Trescothick . Thanks for the work, Aimee.

I hope this or something similar makes it into the regular SL viewer; I know builders will love it once they see it.

The Imprudence web site is at http://imprudenceviewer.org/ . There are Windows and Linux versions with the expression evalualtor and also with a number of interesting changes in the interface. Might as well give it a try.