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*                                   parser                                    *
* recursive decent expression parser for turbo-pascal, Loewy Ron, 1991.       *
* parser.doc, Last Update :                  Jun. 14, 1991.                   *
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Introduction
------------

  Parser is a recursive decent expression parser unit for Turbo-Pascal, this
 unit includes the 5 basic math. operators (+ - * / ^), and some basic
 mathematical functions (sin, exp, cos, ln, log10, log2, abs, arctan, sqr,
 sqrt, tan, cotan, arcsin, arccos) and 2 constants (pi, e). Parser can be
 used to receive formula input from the user, and perform the neccessary
 calculations during program runtime. Parser supports 10 general purpose
 variables (v0, v1, .., v9) that can be set (using the = operator) and used
 in formulas by the user.

Operation
---------

  Simply use parser unit in your program using the USES clause, when ever you
 want to parse a string formula do :
        macro := stringFormula; { stringFormula is where you've got the formula }
        myResult := getExpr(validity);
        if (validity = false) then
                tellError { the formula has an error at the errAt byte }
        else
                tellResult(myResult);

  Please notice - the source code is provided, so you will probably find it
 easy to understand that example after you will look into the code.

Contact
-------

  You can contact me on what-ever you want to at my address at :

          Loewy Ron,                            Loewy Ron
          9 Haneveem st.            Or          20 Smolanskin st.
          Herzeliya, 46465,                     Haifa, 34366,
          Israel.                               Israel.