INTERFACE FmtLexSupport;

Arithmetic for Modula-3, see doc for details

Abstract: Support for FmtLex type modules

IMPORT Rd, Thread;
IMPORT Lex AS L;

TYPE
  Precedence = {Sum              (* a-b is considered as a+b*(-1) *)
                , Product        (* a/b is considered as a*b^(-1) *)
                , Power          (* this refers to parentheses of the
                                    basis, the exponent can always live
                                    without parentheses*)
               };

PROCEDURE Parenthesize (t: TEXT; inner, outer: Precedence; ): TEXT;

t contains a mathematical expression, formatted in TeX; The main operation of the expression in t is of type 'inner' and we want to used it within a operation of type 'outer'. Returns t enclosed in parentheses if necessary and t unmodified if parentheses are not required.

PROCEDURE AssertChar (rd: Rd.T; sep: CHAR; )
  RAISES {L.Error, Rd.Failure, Thread.Alerted};

Assert that the next non-space character is the separator 'sep' otherwise raise the Error.

PROCEDURE CheckChar (rd: Rd.T; sep: CHAR; ): BOOLEAN
  RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted};

Check that the next non-space character is the separator 'sep' and return TRUE in that case.

END FmtLexSupport.