rawline

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A small, self-contained line editing library.

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rawline
=======

A small line editing library in C, intended to replace other "huge" libraries
such as libedit and readline. Written in less than 1000 lines of MPLv2 licensed
code.

### Features ###

* Single line editing
* History
* Completion

### Using rawline ###

Everything starts with a simple:
```
raw_t *raw_state = raw_new(<str>);

/* str is the string which raw_input() will return when
 * it recieves an abrubt return (ctrl-d, but not ctrl-c).
 * If str is NULL, then ctrl-d will act as a delete key. */

/* ... */

raw_free(raw_state);
```

`raw_state` is the state of a rawline instance. You can have as many instances you want. rawline will handle _all_ of
the memory management inside of `raw_state`. `raw_free` will free all of the memory associated to `raw_state`.

It is important to understand that any allocated pointers returned by rawline (e.g. `raw_hist_get()` or `raw_input()`) are
considered to be "part of" the `raw_state` structure, and shouldn't be touched. This means that you mustn't free it (which makes
life easier for you), but it also means that the value will probably change with the next call to a rawline function. If you
need the pointer for later use, `memcpy` (or `strcpy`) it to a safe location of your own.

### Options ###

By default, all options (except line editing) are **disabled** by default. The first argument and second argument are always
the `raw_state` pointer and a `bool` reflecting whether you are enabling (`1`) or disabling (`0`) the option. When disabling
an option, everything about that option is __lost__, including any buffers. This is noticable when working with history. Also,
if you are disabling an option, the other arguments are **ignored**.

#### History ####

To (en/dis)able line history:
```
raw_hist(raw_state, <(en/dis)able>, <size of history buffer>);

/* If the number of lines of history is less than 1,
 * raw_hist will return -1, and nothing will change. */
```

You can also serialise (convert to a string) the entire history, and use a serialised string to replace an existing history.

```
char *history = raw_hist_get(raw_state); /* get the history */
raw_hist_set(raw_state, history); /* set the history */
```

#### Completion ####

Tab-completion requires a callback function, to give rawline a search table, based on input. There is no requirement for you to do any form of searching. Rawline uses a prefix completion search spec (see below).

To (en/dis)able tab-completion:
```
raw_comp(raw_state, <(en/dis)able>, search_callback, <search_cleanup or NULL>);

/* If search_cleanup is not defined, rawline will not attempt to free the pointer returned
 * by search_callback(input). If search_callback is not give (i.e. NULL), raw_comp() will
 * return -1 and nothing will change. */
```

Here are some sample `search_callback()` and `search_cleanup()` function definitions:

```
char **search_callback(char *input) {
	/* `input` is the input string when the user pressed <tab> */

char **ret = NULL;

/* If the returned search table is empty (the first item is NULL or
	 * the table itself is NULL), the input will be unaffected and the
	 * terminal will beep. */

/* The search table *must* be terminated with a `NULL` pointer. This
	 * is used by rawline to find the end of the table (like '\0' terminators
	 * in C "strings" used to find the end by strlen(3) and others). */

/* ... */

return ret;
}

void search_cleanup(char **table) {
	/* This is the standard way to free (void **) */
	int i;
	for(i = 0; table[i] != NULL; i++)
		free(table[i])
	free(table);
}
```

##### Prefix completion? #####

Prefix completion is where the largest common "prefix" (starting from the input string) in a search table is matched, and no more. This is very similar to the technique bash uses. Here's some examples:

```
/* Assuming the following is the search table */
char **search_table = {
	"Hello, world!",
	"How many roads must a man walk down?",
	"How many streets must a man walk down?",
	"The only winning move is not to play."
	"This is a test",
	"This is a test of the emergency broadcast system.",
	NULL
};

/* <input-before-tab-completion> ==> <input-after-tab-completion>*/

"H"					==> "H" (beep)
"He"				==> "Hello, world!"

"Ho"				==> "How many "
"How many r"		==> "How many roads must a man walk down?"
"How many s"		==> "How many streets must a man walk down?"

"T"					==> "T" (beep)
"Th"				==> "Th" (beep)
"The only winn"		==> "The only winning move is not to play."
"This "				==> "This is a test"
"This is a test "	==> "This is a test of the emergency broadcast system."

/* Dummy matches aren't modified */

""					==> "" (beep)
"A strange game."	==> "A strange game." (beep)
```

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