NAME

       erl_parse - The Erlang Parser

DESCRIPTION

       This  module  is  the  basic Erlang parser which converts tokens into the abstract form of
       either forms (i.e., top-level constructs), expressions, or terms. The Abstract  Format  is
       described  in the ERTS User's Guide. Note that a token list must end with the dot token in
       order to be acceptable to the parse functions (see erl_scan(3erl)).

DATA TYPES

       abstract_clause() = term()

              Parse tree for Erlang clause.

       abstract_expr() = term()

              Parse tree for Erlang expression.

       abstract_form() = term()

              Parse tree for Erlang form.

       error_description() = term()

       error_info() = {erl_scan:line(), module(), error_description()}

       token() = erl_scan:token()

EXPORTS

       parse_form(Tokens) -> {ok, AbsForm} | {error, ErrorInfo}

              Types:

                 Tokens = [token()]
                 AbsForm = abstract_form()
                 ErrorInfo = error_info()

              This function parses Tokens as if it were a form. It returns:

                {ok, AbsForm}:
                  The parsing was successful. AbsForm is the abstract form of the parsed form.

                {error, ErrorInfo}:
                  An error occurred.

       parse_exprs(Tokens) -> {ok, ExprList} | {error, ErrorInfo}

              Types:

                 Tokens = [token()]
                 ExprList = [abstract_expr()]
                 ErrorInfo = error_info()

              This function parses Tokens as if it were a list of expressions. It returns:

                {ok, ExprList}:
                  The parsing was successful. ExprList is a list of the  abstract  forms  of  the
                  parsed expressions.

                {error, ErrorInfo}:
                  An error occurred.

       parse_term(Tokens) -> {ok, Term} | {error, ErrorInfo}

              Types:

                 Tokens = [token()]
                 Term = term()
                 ErrorInfo = error_info()

              This function parses Tokens as if it were a term. It returns:

                {ok, Term}:
                  The  parsing was successful. Term is the Erlang term corresponding to the token
                  list.

                {error, ErrorInfo}:
                  An error occurred.

       format_error(ErrorDescriptor) -> Chars

              Types:

                 ErrorDescriptor = error_description()
                 Chars = [char() | Chars]

              Uses an ErrorDescriptor and returns  a  string  which  describes  the  error.  This
              function is usually called implicitly when an ErrorInfo structure is processed (see
              below).

       tokens(AbsTerm) -> Tokens

       tokens(AbsTerm, MoreTokens) -> Tokens

              Types:

                 AbsTerm = abstract_expr()
                 MoreTokens = Tokens = [token()]

              This function generates a list of tokens representing the abstract form AbsTerm  of
              an expression. Optionally, it appends MoreTokens.

       normalise(AbsTerm) -> Data

              Types:

                 AbsTerm = abstract_expr()
                 Data = term()

              Converts  the  abstract  form  AbsTerm  of  a  term into a conventional Erlang data
              structure (i.e., the term itself). This is the inverse of abstract/1.

       abstract(Data) -> AbsTerm

              Types:

                 Data = term()
                 AbsTerm = abstract_expr()

              Converts the Erlang data structure Data into an abstract form of type AbsTerm. This
              is the inverse of normalise/1.

              erl_parse:abstract(T) is equivalent to erl_parse:abstract(T, 0).

       abstract(Data, Options) -> AbsTerm

              Types:

                 Data = term()
                 Options = Line | [Option]
                 Option = {line, Line} | {encoding, Encoding}
                 Encoding = latin1 | unicode | utf8
                 Line = erl_scan:line()
                 AbsTerm = abstract_expr()

              Converts the Erlang data structure Data into an abstract form of type AbsTerm.

              The  Line  option  is  the  line that will be assigned to each node of the abstract
              form.

              The Encoding option is used for selecting which integer lists will be considered as
              strings. The default is to use the encoding returned by epp:default_encoding/0

ERROR INFORMATION

       The  ErrorInfo  mentioned above is the standard ErrorInfo structure which is returned from
       all IO modules. It has the format:

           {ErrorLine, Module, ErrorDescriptor}

       A string which describes the error is obtained with the following call:

           Module:format_error(ErrorDescriptor)

SEE ALSO

       io(3erl), erl_scan(3erl), ERTS User's Guide