| Scanner Skeleton | |
note
description: "General lexical analyzers"
library: "Gobo Eiffel Lexical Library"
copyright: "Copyright (c) 2001, Eric Bezault and others"
license: "MIT License"
deferred class YY_SCANNER
create
make
-- Create a new scanner with
-- standard input as input file.
make_with_file (a_file: FILE)
-- Create a new scanner with
-- a_file as input file.
require
a_file_not_void: a_file /= Void
a_file_open_read: a_file.is_open_read
make_with_buffer (a_buffer: like input_buffer)
-- Create a new scanner with
-- a_buffer as input buffer.
require
a_buffer_not_void: a_buffer /= Void
ensure
input_buffer_set: input_buffer = a_buffer
feature -- Initialization
reset
-- Reset scanner before scanning next input source.
-- (This routine can be called in wrap before scanning
-- another input buffer.)
feature -- Access
last_token: INTEGER
-- Code of last token read
-- (0 means that the end-of-input has been reached,
-- non-positive values mean that an error occurred
-- (see header-comment of scanning_error.))
text: STRING
-- Text of last token read
-- (Create a new string at each call.)
ensure
text_not_void: Result /= Void
correct_count: Result.count = text_count
text_item (i: INTEGER): CHARACTER
-- i-th character of last token read
require
i_large_enough: i >= 1
i_small_enough: i <= text_count
ensure
definition: Result = text.item (i)
text_substring (s, e: INTEGER): STRING
-- Substring of last token read
-- (Create a new string at each call.)
-- (For efficiency reason, this function can bypass the
-- call to text and create the substring directly from
-- the input buffer.)
require
meaningful_start: 1 <= s
meaningful_interval: s <= e + 1
meaningful_end: e <= text_count
ensure
text_substring_not_void: Result /= Void
text_substring_empty: (s > e) implies Result.empty
definition: s <= e implies Result.is_equal (text.substring (s, e))
start_condition: INTEGER
-- Start condition
feature -- Measurement
text_count: INTEGER
-- Length of last token read
ensure
positive_count: Result >= 0
line: INTEGER
-- Line number of last token read when
-- '%option line' has been specified
ensure
line_positive: Result >= 1
column: INTEGER
-- Column number of last token read when
-- '%option line' has been specified
ensure
column_positive: Result >= 1
position: INTEGER
-- Position of last token read (i.e. number of
-- characters from the start of the input source)
-- when '%option position' has been specified
ensure
position_positive: Result >= 1
feature -- Status report
end_of_file: BOOLEAN
-- Has the end of input buffer been reached?
-- This means that last_token has been set
-- to 0 indicating "all done".
scanning_error: BOOLEAN
-- Has an error occurred during scanning?
-- This can occur when too many reject are called (and hence
-- nothing can be matched anymore) or when the option "nodefault"
-- (or option -s) has been specified but the default rule is
-- matched nevertheless.
valid_start_condition (sc: INTEGER): BOOLEAN
-- Is sc a valid start condition?
feature -- Setting
set_last_token (a_token: INTEGER)
-- Set last_token to a_token.
ensure
last_token_set: last_token = a_token
set_start_condition (a_start_condition: INTEGER)
-- Set start_condition to a_start_condition.
require
valid_start_condition: valid_start_condition (a_start_condition)
ensure
start_condition_set: start_condition = a_start_condition
feature -- Scanning
scan
-- Scan input_buffer until end of file is found.
ensure
end_of_file: not scanning_error implies end_of_file
read_token
-- Read a token from input_buffer.
-- Make result available in last_token.
feature -- Element change
append_text_to_string (a_string: STRING)
-- Append text at end of a_string.
-- (For efficiency reason, this feature can bypass the
-- call to text and directly copy the characters from
-- the input buffer.)
require
a_string_not_void: a_string /= Void
append_text_substring_to_string (s, e: INTEGER; a_string: STRING)
-- Append text_substring at end of a_string.
-- (For efficiency reason, this feature can bypass
-- the call to text_substring and directly copy
-- the characters from the input buffer.)
require
a_string_not_void: a_string /= Void
s_large_enough: 1 <= s
valid_interval: s <= e + 1
e_small_enough: e <= text_count
terminate
-- Terminate scanner and set last_token
-- to 0 indicating "all done".
wrap: BOOLEAN
-- Should current scanner terminate when end of file is reached?
-- This function can be redefined to switch to another input
-- buffer (but don't forget to update start_condition).
-- (Default: True.)
more
-- Tell scanner to append the next matched token
-- to current value of text instead of
-- replacing it.
less (n: INTEGER)
-- Return all but the first n matched
-- characters back to input_buffer.
require
n_large_enough: n >= 0
n_small_enough: n <= text_count
ensure
text_count_set: text_count = n
unread_character (c: CHARACTER)
-- Put c back to input_buffer. This will alter both
-- text and the content of input_buffer.
read_character
-- Read a character from input_buffer.
-- Make result available in last_character.
last_character: CHARACTER
-- Last character read by read_character
feature -- Input
input_buffer: YY_BUFFER
-- Input buffer
set_input_buffer (a_buffer: like input_buffer)
-- Set input_buffer to a_buffer.
require
a_buffer_not_void: a_buffer /= Void
ensure
input_buffer_set: input_buffer = a_buffer
flush_input_buffer
-- Flush input_buffer. input_buffer will be automatically
-- refilled unless end of file has been found.
ensure
flushed: input_buffer.count = 0
new_file_buffer (a_file: FILE): YY_FILE_BUFFER
-- New input buffer for a_file
require
a_file_not_void: a_file /= Void
a_file_open_read: a_file.is_open_read
ensure
new_buffer_not_void: Result /= Void
new_string_buffer (a_string: STRING): YY_BUFFER
-- New input buffer for a_string
require
a_string_not_void: a_string /= Void
ensure
new_buffer_not_void: Result /= Void
Empty_buffer: YY_BUFFER
-- Empty input buffer
ensure
empty_buffer_not_void: Result /= Void
feature -- Output
output (a_text: like text)
-- Output a_text.
-- (Note: this routine can be redefined in descendant
-- classes. Default: print a_text to standard output.)
require
a_text_not_void: a_text /= Void
echo
-- Output text using feature output.
feature -- Action
pre_action
-- Action executed before every semantic action
-- when '%option pre-action' has been specified.
-- (Note: this routine can be redefined in descendant
-- classes. Default: do nothing.)
post_action
-- Action executed after every semantic action
-- when '%option post-action' has been specified.
-- (Note: this routine can be redefined in descendant
-- classes. Default: do nothing.)
pre_eof_action
-- Action executed before every end-of-file semantic action
-- (i.e. <<EOF>>) when '%option pre-eof-action' has been specified.
-- (Note: this routine can be redefined in descendant classes.
-- Default: do nothing.)
post_eof_action
-- Action executed after every end-of-file semantic action
-- (i.e. <<EOF>>) when '%option post-eof-action' has been specified.
-- (Note: this routine can be redefined in descendant classes.
-- Default: do nothing.)
default_action
-- Action executed when default rule is matched.
-- (Note: this routine can be redefined in descendant classes.
-- Default: print last character read to standard output.)
feature -- Error handling
fatal_error (a_message: STRING)
-- A fatal error occurred.
-- Print a_message.
require
a_message_not_void: a_message /= Void
feature -- Debugging
print_last_token
-- Print to standard error debug information
-- about the last token read. Can be redefined
-- in descendant classes to print more information.
-- (Called at the end of read_token when compiled
-- with 'debug ("GELEX")' enabled).
invariant
input_buffer_not_void: input_buffer /= Void
valid_start_condition: valid_start_condition (start_condition)
end
|
Copyright © 2001-2005, Eric
Bezault and others mailto:ericb@gobosoft.com http://www.gobosoft.com Last Updated: 16 February 2005 |
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