terminal: clean up some code and comments

This commit is contained in:
Qwerasd
2024-03-26 10:19:23 -06:00
parent 2274b8a912
commit 492e147e26
2 changed files with 34 additions and 36 deletions

View File

@ -1988,8 +1988,12 @@ fn destroyPageExt(
}
/// Fast-path function to erase exactly 1 row. Erasing means that the row
/// is completely removed, not just cleared. All rows below the removed row
/// will be moved up by 1 to account for this.
/// is completely REMOVED, not just cleared. All rows following the removed
/// row will be shifted up by 1 to fill the empty space.
///
/// Unlike eraseRows, eraseRow does not change the size of any pages. The
/// caller is responsible for adjusting the row count of the final page if
/// that behavior is required.
pub fn eraseRow(
self: *PageList,
pt: point.Point,
@ -2029,7 +2033,7 @@ pub fn eraseRow(
// 1 | 2 2 2
// 2 | 3 3 3
// 3 <' 0 <. 4 4
// --- --- | --- ---
// --- --- | --- --- <- page boundary
// 4 4 -' 4 -. 5
// 5 5 5 | 6
// 6 6 6 | 7
@ -2057,35 +2061,34 @@ pub fn eraseRow(
}
}
// The final row needs to be cleared in case we re-use it.
// Clear the final row which was rotated from the top of the page.
page.data.clearCells(&rows[page.data.size.rows - 1], 0, page.data.size.cols);
// We don't trim off the final row if we erased active, since one of
// our invariants is that we always have full active space.
if (pt != .active) {
page.data.size.rows -= 1;
}
}
/// A special-case of eraseRow that shifts only a bounded number of following
/// A variant of eraseRow that shifts only a bounded number of following
/// rows up, filling the space they leave behind with blank rows.
///
/// `limit` is exclusive of the erased row. A limit of 1 will erase the target
/// row and shift the row below in to its position, leaving a blank row below.
///
/// This function has a lot of repeated code in it because it is a hot path.
pub fn eraseRowBounded(
self: *PageList,
pt: point.Point,
limit: usize,
) !void {
// This function has a lot of repeated code in it because it is a hot path.
//
// To get a better idea of what's happening, read eraseRow first for more
// in-depth explanatory comments. To avoid repetition, the only comments for
// this function are for where it differs from eraseRow.
const pn = self.pin(pt).?;
var page = pn.page;
var rows = page.data.rows.ptr(page.data.memory.ptr);
// Special case where we'll reach the limit in the same page as the erased
// row, so we don't have to handle cloning rows between pages.
// If the row limit is less than the remaining rows before the end of the
// page, then we clear the row, rotate it to the end of the boundary limit
// and update our pins.
if (page.data.size.rows - pn.y > limit) {
page.data.clearCells(&rows[pn.y], 0, page.data.size.cols);
fastmem.rotateOnce(Row, rows[pn.y..][0..limit + 1]);
@ -2100,14 +2103,14 @@ pub fn eraseRowBounded(
return;
}
var shifted: usize = 0;
fastmem.rotateOnce(Row, rows[pn.y..page.data.size.rows]);
shifted += page.data.size.rows - pn.y;
// We need to keep track of how many rows we've shifted so that we can
// determine at what point we need to do a partial shift on subsequent
// pages.
var shifted: usize = page.data.size.rows - pn.y;
// We adjust the tracked pins in this page, moving up any that were below
// the removed row.
// Update tracked pins.
{
var pin_it = self.tracked_pins.keyIterator();
while (pin_it.next()) |p_ptr| {
@ -2124,6 +2127,11 @@ pub fn eraseRowBounded(
page = next;
rows = next_rows;
// We check to see if this page contains enough rows to satisfy the
// specified limit, accounting for rows we've already shifted in prior
// pages.
//
// The logic here is very similar to the one before the loop.
const shifted_limit = limit - shifted;
if (page.data.size.rows > shifted_limit) {
page.data.clearCells(&rows[0], 0, page.data.size.cols);
@ -2147,11 +2155,10 @@ pub fn eraseRowBounded(
fastmem.rotateOnce(Row, rows[0..page.data.size.rows]);
// Account for the rows shifted in this page.
shifted += page.data.size.rows;
// Our tracked pins for this page need to be updated.
// If the pin is in row 0 that means the corresponding row has
// been moved to the previous page. Otherwise, move it up by 1.
// Update tracked pins.
var pin_it = self.tracked_pins.keyIterator();
while (pin_it.next()) |p_ptr| {
const p = p_ptr.*;

View File

@ -1103,19 +1103,10 @@ pub fn index(self: *Terminal) !void {
self.screen.cursorAbsolute(cursor_x, cursor_y);
}
if (self.scrolling_region.bottom < self.rows) {
try self.screen.pages.eraseRowBounded(
.{ .active = .{ .y = self.scrolling_region.top } },
self.scrolling_region.bottom - self.scrolling_region.top
);
} else {
// If we have no bottom margin we don't need to worry about
// potentially damaging rows below the scrolling region,
// and eraseRow is cheaper than eraseRowBounded.
try self.screen.pages.eraseRow(
.{ .active = .{ .y = self.scrolling_region.top } },
);
}
try self.screen.pages.eraseRowBounded(
.{ .active = .{ .y = self.scrolling_region.top } },
self.scrolling_region.bottom - self.scrolling_region.top
);
// The operations above can prune our cursor style so we need to
// update. This should never fail because the above can only FREE