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erl_parse(3erl) Erlang Module Definition erl_parse(3erl)

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() = {Tag :: atom(), Line :: erl_scan:line()}

 

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.
 

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
stdlib 1.18.1 Ericsson AB