NAME

       erl_format - Create and match Erlang terms.

DESCRIPTION

       This  module  contains  two  routines: one general function for creating Erlang terms and one for pattern
       matching Erlang terms.

EXPORTS

       ETERM *erl_format(FormatStr, ...)

              Types:

                 char *FormatStr;

              A general function for creating Erlang terms using a format specifier and a corresponding  set  of
              arguments, much in the way printf() works.

              FormatStr is a format specification string. The valid format specifiers are as follows:

                * ~i - Integer

                * ~f - Floating point

                * ~a - Atom

                * ~s - String

                * ~w - Arbitrary Erlang term

              For  each format specifier included in FormatStr, there must be a corresponding argument following
              FormatStr. An Erlang term is built according to FormatStr with values and Erlang terms substituted
              from the corresponding arguments, and according to the individual format specifiers. For example:

              erl_format("[{name,~a},{age,~i},{data,~w}]",
                         "madonna",
                         21,
                         erl_format("[{adr,~s,~i}]","E-street",42));

              This    creates    an    (ETERM    *)    structure    corresponding    to    the    Erlang    term
              [{name,madonna},{age,21},{data,[{adr,"E-street",42}]}]

              The function returns an Erlang term, or NULL if FormatStr does not describe a valid Erlang term.

       int erl_match(Pattern, Term)

              Types:

                 ETERM *Pattern,*Term;

              This function is used to perform pattern matching similar to that done  in  Erlang.  For  matching
              rules and more examples, see section  Pattern Matching in the Erlang Reference Manual.

                * Pattern is an Erlang term, possibly containing unbound variables.

                * Term is an Erlang term that we wish to match against Pattern.

              Term  and  Pattern  are  compared  and any unbound variables in Pattern are bound to corresponding
              values in Term.

              If Term and Pattern can be matched, the function returns a non-zero value and  binds  any  unbound
              variables in Pattern. If Term and Pattern do not match, 0 is returned. For example:

              ETERM *term, *pattern, *pattern2;
              term1    = erl_format("{14,21}");
              term2    = erl_format("{19,19}");
              pattern1 = erl_format("{A,B}");
              pattern2 = erl_format("{F,F}");
              if (erl_match(pattern1, term1)) {
                /* match succeeds:
                 * A gets bound to 14,
                 * B gets bound to 21
                 */
                ...
              }
              if (erl_match(pattern2, term1)) {
                /* match fails because F cannot be
                 * bound to two separate values, 14 and 21
                 */
                ...
              }
              if (erl_match(pattern2, term2)) {
                /* match succeeds and F gets bound to 19 */
                ...
              }

              erl_var_content() can be used to retrieve the content of any variables bound as a result of a call
              to erl_match().