diff options
Diffstat (limited to 'vcs-svn/line_buffer.txt')
| -rw-r--r-- | vcs-svn/line_buffer.txt | 49 |
1 files changed, 34 insertions, 15 deletions
diff --git a/vcs-svn/line_buffer.txt b/vcs-svn/line_buffer.txt index 8906fb1..8e139eb 100644 --- a/vcs-svn/line_buffer.txt +++ b/vcs-svn/line_buffer.txt @@ -14,22 +14,46 @@ Calling sequence The calling program: + - initializes a `struct line_buffer` to LINE_BUFFER_INIT - specifies a file to read with `buffer_init` - - processes input with `buffer_read_line`, `buffer_read_string`, - `buffer_skip_bytes`, and `buffer_copy_bytes` + - processes input with `buffer_read_line`, `buffer_skip_bytes`, + and `buffer_copy_bytes` - closes the file with `buffer_deinit`, perhaps to start over and read another file. -Before exiting, the caller can use `buffer_reset` to deallocate -resources for the benefit of profiling tools. +When finished, the caller can use `buffer_reset` to deallocate +resources. + +Using temporary files +--------------------- + +Temporary files provide a place to store data that should not outlive +the calling program. A program + + - initializes a `struct line_buffer` to LINE_BUFFER_INIT + - requests a temporary file with `buffer_tmpfile_init` + - acquires an output handle by calling `buffer_tmpfile_rewind` + - uses standard I/O functions like `fprintf` and `fwrite` to fill + the temporary file + - declares writing is over with `buffer_tmpfile_prepare_to_read` + - can re-read what was written with `buffer_read_line`, + `buffer_copy_bytes`, and so on + - can reuse the temporary file by calling `buffer_tmpfile_rewind` + again + - removes the temporary file with `buffer_deinit`, perhaps to + reuse the line_buffer for some other file. + +When finished, the calling program can use `buffer_reset` to deallocate +resources. Functions --------- -`buffer_init`:: - Open the named file for input. If filename is NULL, - start reading from stdin. On failure, returns -1 (with - errno indicating the nature of the failure). +`buffer_init`, `buffer_fdinit`:: + Open the named file or file descriptor for input. + buffer_init(buf, NULL) prepares to read from stdin. + On failure, returns -1 (with errno indicating the nature + of the failure). `buffer_deinit`:: Stop reading from the current file (closing it unless @@ -40,19 +64,14 @@ Functions Read a line and strip off the trailing newline. On failure or end of file, returns NULL. -`buffer_read_string`:: - Read `len` characters of input or up to the end of the - file, whichever comes first. Returns NULL on error. - Returns whatever characters were read (possibly "") - for end of file. - `buffer_copy_bytes`:: Read `len` bytes of input and dump them to the standard output stream. Returns early for error or end of file. `buffer_skip_bytes`:: Discards `len` bytes from the input stream (stopping early - if necessary because of an error or eof). + if necessary because of an error or eof). Return value is + the number of bytes successfully read. `buffer_reset`:: Deallocates non-static buffers. |