# Minimum Profit Data Model

     Angel Ortega <angel@triptico.com>

This document describes all the MPSL data structures that build the Minimum Profit Text Editor, with examples showing how to change or update its behaviour.

## Documents

Each open document is a hash, containing all the information about it, including its text, position, name and the list of changes. A new document is created by calling mp.`new()` or mp.`open()`. The keys stored in each document are the following:

name | The name of the document (<unnamed> for unnamed documents).
syntax | The optional syntax highlight definition that applies to it (a value in the `mp.syntax` hash, may be NULL or undefined).
txt | The state of the document (see below).
undo | A list of different values of `txt`. Every time the user changes a document (inserting or deleting text, etc.), the previous value of `txt` is pushed here. Every time the 'undo' action is executed, the last value is popped from here and stored in the `txt` key and the `redo` list.
redo | A list of values popped from the `undo` key.

The `txt` component contains the current state of the document:

lines | The array of lines that form the document (the document itself).
y | The Y position (line, from 0 to size(txt.lines) - 1).
x | The X position (column, from 0 to size(txt.lines[txt.y]) - 1).
mod | A modifier flag. If it's nonzero, the document has unsaved changes.
vx | The first column (from 0) that is visible on screen.
vy | The first line (from 0) that is visible on screen.

## The document list

The list of open documents in stored in the `mp.docs` array. The subscript to the active one (the one returned by mp.`active()`) is stored in the `mp.active_i` variable. Setting this value effectively changes the active document (obviously, in the 0 .. size(mp.`docs()`) - 1 range).

## Configuration data

The configuration is stored in the `mp.config` hash. Information about this structure can be found in the included document Minimum Profit Configuration Directives.

## Colors

Colors are defined in the `mp.colors` hash. The keys contain the name of the color in a syntax highlighting context (i.e. `comments` for the text inside source code comments, `quotes` for the text inside quotes, and so on), and the values are hashes containing the definition for that color in the different driver types. For now, only `gui` and `text` drivers exist, with another special key, `flags`, for special effects.

The color keys are:

cursor | The color of the cursor.
selection | The color of the selected block.
comments | Text inside programming language comments.
quotes | Text between quotes.
matching | The color of the matching brace (if the cursor is over one).
word1 | 1st definition for special words (i.e. tokens).
word2 | 2nd definiton for special words (i.e. variables).
tag | Color for tags (symbol names).
spell | Color for mis-spelled words (if spelling is on).
search | Color for the last matched string in searches.
normal | Text outside any other context, or the base color if no syntax highlight is selected.

For each key, the value is a hash containing the following keys:

text | a two element array containing the color names for background and foreground. These strings match the colors in Curses terminal modes and must be one of `black`, `red`, `green`, `yellow`, `blue`, `magenta`, `cyan` and `white`. Another special value, `default`, skips setting a color.
gui | A two element array containing the RGB color for background and foreground. It's handy to set this values as hexadecimal numbers, having 0x000000 for black and 0xffffff for white.
flags | This is an optional array containing keywords for special effects in colors. Acceptable values are `reverse`, `bright` and `underline` (not all drivers accept all these keywords).

## Syntax Highlighting

The syntax highlight definitions are stored in the `mp.syntax` hash. Each key is the name of the syntax highlight (for example, `html`), and they value is the definition hash. This definition set can be assigned to a document `syntax` key and will be immediately applied.

The keys in the definition hash are:

id | The same as the key, as `perl` or `html`.
name | A human-consuming name, that will be shown in the status line (for example, "C / C++" or "Shell script").
filenames | An array of regular expressions to be applied to the document name for syntax detection.
help | An array of system commands to be executed when the help system is invoked by pressing `f1` over a word in a document. It must contain a %s as a placeholder of the word (for example, "man %s" or "perldoc -f %s").
defs | An array of definitions.
detect | An optional subroutine that accepts a document as the only argument and that must return a boolean value. This subroutine will be called when auto-detecting the syntax highlight.

The syntax highlight definitions is a list containing color names (keys to the `mp.colors` hash) and an array. The array can contain single strings of regular expressions (matching string will have the color set), or an array of two regular expressions (setting the start and the end of the block to be coloured).

This is a snippet for the `comments` definition in the C language syntax highlight. The first definition is a two array of regular expressions, matching the start (/) and the end (/) of a C style comment; all text between these marks will be coloured as a comment. The following one, a single string, is a regular expression that matches from two slashes to the end of the line:

    	/* more code above... */
    	'comments',	[
    		[ '|/\|', '|\/|' ],	/* C style */
    		'|//.$|m',		/ C++ style */
    	]

See the `mp_syntax.mpsl` for details and examples.

## Keycodes

Keycodes are defined in the `mp.keycodes` hash. Each key contain the name of the keycode, as `ctrl-f` or `f3`. The value can be an executable value (that will be directly executed with the current document as only argument), a string containing the name of an action (that must be a key to the `mp.actions` hash), or another hash, that will contain itself keycodes as keys and executable values or action names as values (this mechanism can be nested ad infinitum), to implement keystroke chains in the Emacs style.

Examples:

    	/* bind ctrl-f to the 'seek' action */
    	mp.keycodes['ctrl-f'] = 'seek';

    	/* bind F5 to an anonymous subroutine */
    	mp.keycodes['f5'] = sub (d) {
    		mp.insert(d, "<form action = 'post'></form>");
    	};

    	/* bind Ctrl-x Ctrl-f to 'open', and
    	   Ctrl-x Ctrl-s to 'save' */
    	mp.keycodes['ctrl-x'] = {
    		'ctrl-f'	=> 'open',
    		'ctrl-s'	=> 'save'
    	};

## Actions

Actions are defined in the `mp.actions` hash. Each key contain the name of the action, as `seek` or `move_up`. Each value contain an executable value that accepts a document as the only argument.

    	mp.actions['sync'] = sub (d) {
    		/* save all modified documents */
    		foreach (local d, grep(sub (e) { e.txt.mod; }, mp.docs))
    			mp.actions.save(d);
    	};

### Action descriptions

Action descriptions are strings stored in the `mp.actdesc` hash. Each key contain the name of the action and each value the translatable string for human consuming and will be used in the menu.

Examples:

    	mp.actdesc['seek']	= LL("Search text...");
    	mp.actdesc['seek_next']	= LL("Search next");
    	mp.actdesc['sync']	= LL("Save modified texts");

## The menu

The menu is stored in the `mp.menu` structure. The menu is an array of dropdown menu definitions. Each dropdown menu is a two-element array containing a string for the label (File, Edit, etc.) and another array of action names (keys to `mp.actions`). See the `mp_core.mpsl` source file where it's defined.

## Message notification

If a non-obstrusive message must be notified to the user, the `mp.message` can be set and the message will be shown in the status line until a specified time is reached. This structure is a hash containing:

string | The string to be shown in the status line.
timeout | The time when the string will stop being showed.

Example:

    	/* show a message for 4 seconds */
    	mp.message = {
    		'string'	=> "Unknown keystroke",
    		'timeout'	=> time() + 4
    	};

## The clipboard

The clipboard is stored in the `mp.clipboard` array, and it's a simple array of lines. Each copy and paste operation manipulates this.

Angel Ortega <angel@triptico.com>