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File Reading Primitives
int file_read(char *file, int transl)
The file_read( ) primitive reads the named file into the
current buffer, replacing the text that was there. It returns an
error code if an error occurred, or
0 if the read was successful.
transl parameter specifies the line translation to be done on
the file. The buffer's translation-type variable will be set
to its value. If
transl is FILETYPE_AUTO, Epsilon will
examine the file as it's read and set translation-type to an
appropriate translation type.
int new_file_read(char *name, int transl,
struct file_info *f_info,
int start, int max,
?int lowstart, int highstart)
The new_file_read( ) primitive reads a file like
file_read( ) but provides more options. The
parameter is a pointer to a structure, which Epsilon fills in with
information on the file's write date, file type, and so forth. The
structure has the same format as the check_file( ) primitive
uses (see File Properties). If the
parameter is null, Epsilon doesn't get such information.
When Epsilon reads the file, it starts at offset
start and reads
max characters. You can use this to read only part of a
big file. If
max are negative, they are
(individually) ignored: Epsilon starts at the beginning, or reads the
whole file, respectively. The
start parameter refers to the
file before Epsilon strips <Return>'s, while
max counts the
characters after stripping.
highstart are nonzero, Epsilon combines
them to make a 64-bit number and uses that as the initial offset
start, so that portions of very large files may be
read, even when the whole file is too large for Epsilon.
int do_file_read(char *s, int transl) /* files.e */
buffer char _read_aborted;
int read_file(char *file, int transl) /* files.e */
int find_remote_file(char *file, int transl)
update_readonly_warning(struct file_info *p)
Instead of calling the above primitives directly, extensions
typically call one of several subroutines, all defined in files.e,
that do things beyond simply reading in the file. Each takes the
same two parameters as file_read( ), and returns either
an error code.
The do_file_read( ) subroutine records the file's date and
time, so Epsilon can later warn the user that a file's been modified
on disk, if necessary. If the user aborted reading the file,
do_file_read( ) sets the
_read_aborted variable to
1; it uses the value
2 if an error occurred reading the file.
Epsilon then warns the user if he tries to save the partial file.
This subroutine also handles reading URLs by calling the
find_remote_file( ) subroutine, and character set
translations such as OEM translations (see Character Encoding Conversions) by calling file_convert_read( ).
The read_file( ) subroutine calls do_file_read( ), then
displays either an error message, if a read error occurred, or the
message "New file." It also handles calling
do_readonly_warning( ) when it detects a read-only file, or
update_readonly_warning( ) otherwise. (The latter can turn
off a buffer's read-only attribute, if the file is no longer
int find_in_other_buf(char *file, int transl) /* files.e */
call_mode(char *file) /* files.e */
The find_in_other_buf( ) subroutine makes up a unique buffer
name for the file, based on its name, and then calls
read_file( ). It then goes into the appropriate mode for the
file, based on the file's extension, by calling the
call_mode( ) subroutine. (See Language Modes.)
int find_it(char *fname, int transl) /* files.e */
int std_find_it(char *fname) /* files.e */
int ask_find_it(char *fname) /* files.e */
int get_default_translation_type(char *fname) /* files.e */
int look_file(char *fname) /* buffer.e */
The find_it( ) subroutine first looks in all existing buffers
for the named file, just as the find-file command would. If
it finds the file, it simply switches to that buffer. (It also
checks the copy of the file on disk, and warns the user if it's been
modified.) If the file isn't already in a buffer, it calls
find_in_other_buf( ), and returns
0 or its error code.
The find_it( ) subroutine uses the look_file( ) subroutine
to search through existing buffers for the file.
While find_it( ) requires you to pass the appropriate translation
type, the std_find_it( ) and ask_find_it( )
subroutines supply this themselves. The std_find_it( )
subroutine always uses the default translation type for a file with
the given name. The ask_find_it( ) subroutine usually does the
same, but if the calling command was invoked with a numeric prefix
argument, it prompts the user for the translation rules. The
get_default_translation_type( ) subroutine returns the
default translation type for a given file name.
The look_file( ) subroutine, defined in buffer.e, returns
if no buffer has the file. Otherwise, it returns
1 and switches
to the buffer by setting bufnum.
int do_find(char *file, int transl) /* files.e */
Finally, the do_find( ) subroutine is at the top of this tree
of file-reading functions. It checks to see if its "file name"
parameter is a directory. If it is (or if it's a file pattern with
wildcard characters), it calls dired_one( ) to run dired on the
pattern. If it's a normal file, do_find( ) calls find_it( ).
int err_file_read(char *file, int transl) /* files.e */
Use the err_file_read( ) subroutine when you want to read a
file that must exist, but you don't want all the extras that
higher-level functions provide: checking file dates, choosing a
buffer, setting up for read-only files, and so forth. It calls
file_read( ) to read the file into the current buffer, and
displays an error message if the file couldn't be read for any
reason. It returns the error code, or
0 if there were no errors.
By default, primitives that read and write files
respond to the user pressing the abort key by asking whether they
should abort the input/output operation. An EEL program can select a
different behavior by using
save_var to set the primitive variable
abort_file_io. The default setting,
the user whether to abort the operation. If he says no, the operation
continues. If he says yes, the primitive returns an error code,
EREADABORT for reading primitives or
for writing primitives. The setting ABORT_ERROR omits asking
the user; it immediately returns an error code if the user aborts.
The setting ABORT_IGNORE tells Epsilon to ignore the abort key
and continue. The setting ABORT_JUMP makes pressing the abort
key abort the current function by calling the check_abort( )
primitive, again without prompting first. (See Control Flow.)
Primitives and EEL Subroutines ||
File Writing Primitives|
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