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Igor Támara 2025-11-11 20:32:14 -05:00 • committed by CJ van den Berg
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content/docs/architecture/editor.smd
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@ -3,7 +3,7 @@
.date = @date("2025-10-19T00:00:00"),
.author = "Igor Támara",
.layout = "tutorial.shtml",
.draft = true,
.draft = false,
.custom = {
.githubedit = "docs/architecture/editor.smd",
.codepath = "src/tui/editor.zig",
@ -48,7 +48,7 @@ makes the link between both of them, signaling the part of the `Buffer`
that can be modified and manipulated as you see it. It scrolls on the
current visible portion [view](#view_concept) of the buffer, when
manipulated with the keyboard, the mouse can change the move the view
while the primary mouse is offscreen; when keystrokes arrive to the
while the primary mouse is off-screen; when keystrokes arrive to the
editor, the view focuses to the primary cursor to make it visible and
available to be used.
@ -69,7 +69,7 @@ Cursor is a [CurSel](#cursel_concept).
### Selection
A selection is represented by begin and end [cursors](#cursor_concept)
and offers basic functions that will consitute the changes needed with
and offers basic functions that will constitute the changes needed with
deletions, insert replacements handled by the[editor](#tui_editor)
services and [commands](/docs/architecture/command).
@ -104,10 +104,10 @@ buffer, knowing if the end or the beginning of the document have been
reached when interacting with a Cursor.
Cursors, Selections and Cursels don't know about the buffer, and they
need to receive a reference to them to have positions and also
sometimes receive metrics from the editor that help determine if a
cursor is about to exit boundaries of the buffer and have everything
"in place".
need to receive a reference to it in order to be aware of the
restrictions and usually receive `metrics` from the editor that help
determine if a cursor is about to exit the boundaries of the buffer
and be inside bounds.
[]($section.id("commands"))
## Editor Commands
@ -117,7 +117,8 @@ cursors and selections, moreover, there are various commands acting
over the set of cursors, selections, cursels or marks. Given said
this, we will be using functions as parameters in most of the
situations. Functional programming languages are popular in these
scenarios, to name a prominent one, Emacs and emacs lisp.
scenarios, to name a prominent one, Emacs and emacs lisp. Flow is
inspired on it and others.
If the buffer is not to be modified, we will be using the method
`buf_root` to get the root of the buffer to find and position the
@ -134,34 +135,130 @@ cursors, the same applies to selections, cursels and marks.
## Moving
For example, to move the cursors a page up, we can look at the command
`move_page_up`, which uses the method `with_cursors_and_view_const`
sending the function `move_cursor_page_up`.
`move_page_up`,
Looking inside `with_cursors_and_view_const`, it iterates over all the
cursors and invokes `with_cursor_and_view_const`, sending a cursor as
a parameter, that function, will invoke `move_cursor_page_up` whose
commitment is to use the method `move_page_up` from the cursor,
sending the view and the metrics of the editor.
>[]($block.attrs('line-numbers-js'))
>```zig
>pub fn move_page_up(self: *Self, _: Context) Result {
> try self.send_editor_jump_source();
> const root = try self.buf_root();
> try self.with_cursors_and_view_const(root, move_cursor_page_up, &self.view);
> self.clamp();
>}
>pub const move_page_up_meta: Meta = .{ .description = "Move cursor page up" };
>```
The family of `move` functions is big, look for the methods whose name
has the word move in them. with the command palette is possible to get
a glimpse of them.
which uses the method `with_cursors_and_view_const` sending the function
`move_cursor_page_up`.
Looking inside `with_cursors_and_view_const`
>[]($block.attrs('line-numbers-js'))
>```zig
>fn with_cursors_and_view_const(self: *Self, root: Buffer.Root, move: cursor_view_operator_const, view: *const View) error{Stop}!void {
> var someone_stopped = false;
> for (self.cursels.items) |*cursel_| if (cursel_.*) |*cursel|
> with_cursor_and_view_const(root, move, cursel, view, self.metrics) catch {
> someone_stopped = true;
> };
> self.collapse_cursors();
> return if (someone_stopped) error.Stop else {};
>}
>```
It iterates over all the cursors and invokes
`with_cursor_and_view_const`, sending the `move` function, a cursor,
remember that the function passed was `move_cursor_page_up` as seen
previously.
The commitment of `move_cursor_page_up` is to use the method
`move_page_up` from Cursor, sending editor `view` and `metrics`.
```zig
fn move_cursor_page_up(root: Buffer.Root, cursor: *Cursor, view: *const View, metrics: Buffer.Metrics) !void {
cursor.move_page_up(root, view, metrics);
}
```
The `move` functions set is numerous, look for the methods whose name
have the word `move` in them. with the command palette is possible to get
a glimpse of the available functions present(ctrl+f2).
[]($section.id("selecting"))
## Selections
There are naming conventions for the functions that help understanding
what each one is doing, there has been taken great deal of care to
maintain consistency that needs to be followed to make it easier to
continue extending on functionalities.
Function naming conventions help understand the purpose of each one,
there has been taken great deal of care to maintain consistency, it's
unlikely that there is need for new functions, in case of need, add
it following what is already present.
Look at the following set of functions, all of them act on cursors,
cursels and selections, in singular and plural, and some of them
receive arguments, the repeat functions act many times over the set of
the group that they are intended to do so. The parameters and
following the calls from one to another will let you navigate and get
the hang of their usage.
Follows an example of a functionality that receives a repetition
parameter, the `select_up` command, which given a number, takes all
the current cursors and selections and select lines above them the
number of times specified.
```zig
pub fn select_up(self: *Self, ctx: Context) Result {
const root = try self.buf_root();
try self.with_selections_const_repeat(root, move_cursor_up, ctx);
self.clamp();
}
pub const select_up_meta: Meta = .{ .description = "Select up", .arguments = &.{.integer} };
```
It's meta is guiding about the integer argument that the command can
make use of. Invokes `with_selections_const_repeat` passing the
function `move_cursor_up` as parameter and also the context, which
actually holds the integer parameter holding the repetition information.
>[]($block.attrs('line-numbers-js'))
>```zig
>pub fn with_selections_const_repeat(self: *Self, root: Buffer.Root, move: cursor_operator_const, ctx: Context) error{Stop}!void {
> var someone_stopped = false;
> var repeat: usize = 1;
> _ = ctx.args.match(.{tp.extract(&repeat)}) catch false;
> while (repeat > 0) : (repeat -= 1) {
> for (self.cursels.items) |*cursel_| if (cursel_.*) |*cursel|
> with_selection_const(root, move, cursel, self.metrics) catch {
> someone_stopped = true;
> };
> self.collapse_cursors();
> if (someone_stopped) break;
> }
> return if (someone_stopped) error.Stop else {};
>}
>```
Factor repetition is taken from the context in line XX, being used in
the `while`, then for each repetition, the set of cursels is iterated,
cursels hold cursors and selections, applying `with_selection_const`
function, passing `root`(the buffer), `move_cursor_up` function, cursel
and metrics as parameters. Note that after the function is applied to
each cursel, self.collapse_cursors() is invoked, given that it's
possible that some cursors in the operation have overlapped. With each
cursel operation there is also a tracking of possible fails, continuing
gracefully, one of such fails can be happening because come cursels
might have been reaching the beginning of the buffer and there might be
other cursels that have not yet reached the beginning of the file.
```zig
pub fn with_selection_const(root: Buffer.Root, move: cursor_operator_const, cursel: *CurSel, metrics: Buffer.Metrics) error{Stop}!void {
const sel = try cursel.enable_selection(root, metrics);
try move(root, &sel.end, metrics);
cursel.cursor = sel.end;
cursel.check_selection(root, metrics);
}
```
If there are cursels that are not yet selections, their respective
selections are activated with `cursel.enable_selection`, finally
`move_cursor_up` (`move`s value is a pointer to the `move_cursor_up`)
is applied, passing the end marker of the selection; with its new
value, the cursor is positioned and finally a sanity check on cursel is
applied with its method `check_selection`.
Flow allows navigating the code with `goto_definition` and `references`
commands to deepen the understanding and following the different calls.
[]($section.id("modifying"))
## Modifying the buffer
@ -170,37 +267,105 @@ The `select` family of functions is bigger than the set of `move`
functions, in contrast, the `cut`, `delete`, `insert`, `paste` looks
smaller, and this is accomplished making composition of functions.
Usually when modifying something, first there is a process to locate
the cursor, cursel o selection in the proper place and then applying
the modification.
the cursor, cursel or selection in the proper place and then applying
the modification. There are cases when there is need to locate and
act right away.
[Discord](https://discord.com/invite/4wvteUPphx) and
[Github issues](https://github.com/neurocyte/flow/issues) are the main
channels to do so.
## Helper function
When creating commands and services for the editor, sometimes is handy
where are the cursels. It's possible to use `log_cursel`:
When additions, changes and removal of buffer contents, editor offers
the method `buf_for_update`; we will look first to the method
`to_upper_cursel`, which by default in Flow, takes a CurSel, if it has
no selection, the word that it is stepped on, if any, is selected and
gets uppercased.
>[]($block.attrs('line-numbers-js'))
>```zig
>pub fn log_cursel(self: *Self, cursel: CurSel) void {
> if (cursel.selection) |sel| {
> self.logger.print("[{}:{}.{}] {}:{}.{} - {}:{}.{}", .{
> cursel.cursor.row, cursel.cursor.col, cursel.cursor.target,
> sel.begin.row, sel.begin.col, sel.begin.target,
> sel.end.row, sel.end.col, sel.end.target,
> });
> } else {
> self.logger.print("[{}:{}.{}] no selection", .{
> cursel.cursor.row,
> cursel.cursor.col,
> cursel.cursor.target
> });
> }
>fn to_upper_cursel(self: *Self, root_: Buffer.Root, cursel: *CurSel, allocator: Allocator) error{Stop}!Buffer.Root {
> var root = root_;
> const saved = cursel.*;
> const sel = if (cursel.selection) |*sel| sel else ret: {
> var sel = cursel.enable_selection(root, self.metrics) catch return error.Stop;
> move_cursor_word_begin(root, &sel.begin, self.metrics) catch return error.Stop;
> move_cursor_word_end(root, &sel.end, self.metrics) catch return error.Stop;
> break :ret sel;
> };
> var sfa = std.heap.stackFallback(4096, self.allocator);
> const sfa_allocator = sfa.get();
> const cut_text = copy_selection(root, sel.*, sfa_allocator, self.metrics) catch return error.Stop;
> defer sfa_allocator.free(cut_text);
> const ucased = Buffer.unicode.get_letter_casing().toUpperStr(sfa_allocator, cut_text) catch return error.Stop;
> defer sfa_allocator.free(ucased);
> root = try self.delete_selection(root, cursel, allocator);
> root = self.insert(root, cursel, ucased, allocator) catch return error.Stop;
> cursel.* = saved;
> return root;
>}
>```
Lines through 4 to 9 implement the selection description sketched
previously, selecting the word if no selection was present to apply
uppercasing.
And to reflect the changes in the buffer from lines 10 to 19:
1. copy contents,
1. uppercase
1. remove the selection,
1. and add the uppercased in the position where the cut was made.
making sure the cursel is positioned in the expected place.
1. A `buffer`(`root`) is received, modified and finally returned.
As we saw, the method `to_upper_cursel` acts on a cursel, used by the
`to_upper` command, which acts on all the present cursels, getting the
buffer with the method `buf_for_update` to make modifications on it.
```zig
pub fn to_upper(self: *Self, _: Context) Result {
const b = try self.buf_for_update();
const root = try self.with_cursels_mut_once(b.root, to_upper_cursel, b.allocator);
try self.update_buf(root);
self.clamp();
}
pub const to_upper_meta: Meta = .{ .description = "Convert selection or word to upper case" };
```
via `with_cursels_mut_once` receives a buffer that will be modified
and returns one with modifications, updating what is presented with
the method `update_buf` and an allocator. The previously described
`to_upper_cursel` is sent
>[]($block.attrs('line-numbers-js'))
>```zig
> fn with_cursels_mut_once(self: *Self, root_: Buffer.Root, move: cursel_operator_mut, allocator: Allocator) error{Stop}!Buffer.Root {
> var root = root_;
> var someone_stopped = false;
> for (self.cursels.items) |*cursel_| if (cursel_.*) |*cursel| {
> root = self.with_cursel_mut(root, move, cursel, allocator) catch ret: {
> someone_stopped = true;
> break :ret root;
> };
> };
> self.collapse_cursors();
> return if (someone_stopped) error.Stop else root;
> }
>```
Worth to note that the modified `root` is being passed to the function
`with_cursel_mut` on each iteration over the cursels along with the
allocator and as described previously in selection functions, tracking
if there is some fail an error is popped up, whilst everything was
successful, the modified `root` is returned. Now time to see the
method `with_cursel_mut` that receives the pointer to `to_upper_cursel`
along with root, cursel and allocator.
```zig
fn with_cursel_mut(self: *Self, root: Buffer.Root, op: cursel_operator_mut, cursel: *CurSel, allocator: Allocator) error{Stop}!Buffer.Root {
return op(self, root, cursel, allocator);
}
```
As seen, the only task for `with_cursel_mut` is providing the required
elements to let `to_upper_cursel` do what was described previously.
[]($section.id("next"))
## Next steps