Parser Skeleton

note

    description: "General parsers"
    library: "Gobo Eiffel Parse Library"
    copyright: "Copyright (c) 1999-2005, Eric Bezault and others"
    license: "MIT License"

deferred class YY_PARSER [G]

create

    make
            -- Create a new parser.

feature -- Parsing

    parse
            -- Parse input stream.
            -- Set syntax_error to True if
            -- parsing has not been successful.

feature -- Status report

    syntax_error: BOOLEAN
            -- Has last parsing been unsuccesful?

    is_suspended: BOOLEAN
            -- Has parsing been suspended?
            -- The next call to parse will resume parsing in the state
            -- where the parser was when it was suspended. Note that a call
            -- to abort or accept will force parse to parse from scratch.

feature -- Access

    error_count: INTEGER
            -- Number of errors detected during last parsing
            -- (error_count can be non-zero even though
            -- syntax_error is false. This can happen when
            -- error recovery occurred.)
        ensure
            error_count_non_negative: Result >= 0

feature -- Basic operations

    accept
            -- Stop parsing successfully.
        ensure
            accepted: not syntax_error

    abort
            -- Abort parsing.
            -- Do not print error message.
        ensure
            aborted: syntax_error

    clear_all
            -- Clear temporary objects so that they can be collected
            -- by the garbage collector. (This routine is called by
            -- parse before exiting. It can be redefined in descendants.)

feature {YY_PARSER_ACTION} -- Basic operations

    suspend
            -- Suspend parsing.
            -- The next call to parse will resume parsing in the state
            -- where the parser was when it was suspended. Note that a call
            -- to abort or accept will force parse to parse from scratch.
        ensure
            suspended: is_suspended

    raise_error
            -- Raise a syntax error.
            -- Report error using the error action %error associated
            -- with current parsing state or report_error by default,
            -- and perform normal error recovery if possible.

    recover
            -- Recover immediately after a parse error.

    report_error (a_message: STRING)
            -- Print error message.
            -- (This routine is called by default by parse when it
            -- detects a syntax error and there is no error action
            -- %error available. It can be redefined in descendants.)
        require
            a_message_not_void: a_message /= Void

    clear_token
            -- Clear the previous lookahead token.
            -- Used in error-recovery rule actions.

feature {YY_PARSER_ACTION} -- Status report

    is_recovering: BOOLEAN
            -- Is current parser recovering from a syntax error?

feature {YY_PARSER_ACTION} -- Scanning

    read_token
            -- Read a token from input stream.
            -- Make result available in last_token.
            -- (This routine is called by parse when it needs a
            -- new token from the input stream.)

    last_token: INTEGER
            -- Last token read

    last_value: G
            -- Semantic value of last token read

end

Copyright © 1999-2005, Eric Bezault and others mailto:ericb@gobosoft.com http://www.gobosoft.com Last Updated: 29 October 2005