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perf: index occupied cells when filling table gaps #364

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52 changes: 46 additions & 6 deletions src/layout-manager.js
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,10 @@ const { ColSpanCell, RowSpanCell } = Cell;
return yConflict && xConflict;
}

function conflictExists(rows, x, y) {
function conflictExists(rows, x, y, occupied) {
if (occupied) {
return occupied[y][x] === 1;
}
let i_max = Math.min(rows.length - 1, y);
let cell = { x: x, y: y };
for (let i = 0; i <= i_max; i++) {
Expand All @@ -78,9 +81,9 @@ const { ColSpanCell, RowSpanCell } = Cell;
return false;
}

function allBlank(rows, y, xMin, xMax) {
function allBlank(rows, y, xMin, xMax, occupied) {
for (let x = xMin; x < xMax; x++) {
if (conflictExists(rows, x, y)) {
if (conflictExists(rows, x, y, occupied)) {
return false;
}
}
Expand Down Expand Up @@ -124,21 +127,57 @@ const { ColSpanCell, RowSpanCell } = Cell;
row.splice(x, 0, cell);
}

function markOccupied(occupied, cell) {
if (occupied) {
let yMax = Math.min(occupied.length, cell.y + (cell.rowSpan || 1));
for (let y = cell.y; y < yMax; y++) {
occupied[y].fill(1, cell.x, cell.x + (cell.colSpan || 1));
}
}
}

function indexOccupiedCells(table, width) {
// Preserve the existing conflict checks for malformed coordinates or spans.
if (
width === 0 ||
!Number.isInteger(width) ||
!table.every((row, y) =>
row.every(
(cell) =>
cell.y === y &&
Number.isInteger(cell.x) &&
cell.x >= 0 &&
Number.isInteger(cell.rowSpan || 1) &&
(cell.rowSpan || 1) > 0 &&
Number.isInteger(cell.colSpan || 1) &&
(cell.colSpan || 1) > 0
)
)
) {
return null;
}

let occupied = table.map(() => Buffer.alloc(width));
table.forEach((row) => row.forEach((cell) => markOccupied(occupied, cell)));
return occupied;
}

function fillInTable(table) {
let h_max = maxHeight(table);
let w_max = maxWidth(table);
let occupied = indexOccupiedCells(table, w_max);
debug(`Max rows: ${h_max}; Max cols: ${w_max}`);
for (let y = 0; y < h_max; y++) {
for (let x = 0; x < w_max; x++) {
if (!conflictExists(table, x, y)) {
if (!conflictExists(table, x, y, occupied)) {
let opts = { x: x, y: y, colSpan: 1, rowSpan: 1 };
x++;
while (x < w_max && !conflictExists(table, x, y)) {
while (x < w_max && !conflictExists(table, x, y, occupied)) {
opts.colSpan++;
x++;
}
let y2 = y + 1;
while (y2 < h_max && allBlank(table, y2, opts.x, opts.x + opts.colSpan)) {
while (y2 < h_max && allBlank(table, y2, opts.x, opts.x + opts.colSpan, occupied)) {
opts.rowSpan++;
y2++;
}
Expand All @@ -147,6 +186,7 @@ const { ColSpanCell, RowSpanCell } = Cell;
cell.y = opts.y;
warn(`Missing cell at ${cell.y}-${cell.x}.`);
insertCell(cell, table[y]);
markOccupied(occupied, cell);
}
}
}
Expand Down
104 changes: 104 additions & 0 deletions test/table-layout-test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,110 @@ describe('tableLayout', function () {
return cell;
}

it('does not repeatedly inspect preceding rows when checking occupied cells', function () {
let spanReads = 0;
let cells = Array.from({ length: 50 }, (_, y) =>
Array.from({ length: 5 }, (_, x) => {
let cell = mc('value', y, x);
Object.defineProperty(cell, 'rowSpan', {
get() {
spanReads++;
return 1;
},
});
return cell;
})
);

fillInTable(cells);

// Bound work by the number of cells, rather than by machine-dependent timings.
expect(spanReads).toBeLessThanOrEqual(50 * 5 * 10);
expect(cells.every((row) => row.length === 5)).toBe(true);
});

it('preserves gap rectangles and warning order around staggered spans', function () {
const debug = require('../src/debug');
let cells = [
[mc({ content: 'a', rowSpan: 3 }, 0, 0), mc({ content: 'b', colSpan: 2 }, 0, 3)],
[mc({ content: 'c', rowSpan: 2 }, 1, 2)],
[],
[mc('d', 3, 1)],
];

debug.reset();
debug.setDebugLevel(1);
try {
fillInTable(cells);

expect(
cells.map((row) => row.map((cell) => [cell.x, cell.y, cell.colSpan, cell.rowSpan, cell.content]))
).toEqual([
[
[0, 0, 1, 3, 'a'],
[1, 0, 2, 1, ''],
[3, 0, 2, 1, 'b'],
],
[
[1, 1, 1, 2, ''],
[2, 1, 1, 2, 'c'],
[3, 1, 2, 3, ''],
],
[],
[
[0, 3, 1, 1, ''],
[1, 3, 1, 1, 'd'],
[2, 3, 1, 1, ''],
],
]);
expect(debug.debugMessages()).toEqual([
'Missing cell at 0-1.',
'Missing cell at 1-1.',
'Missing cell at 1-3.',
'Missing cell at 3-0.',
'Missing cell at 3-2.',
]);
} finally {
debug.setDebugLevel(0);
debug.reset();
}
});

it('preserves the existing fractional-span conflict behavior', function () {
let cells = [[mc({ content: 'a', rowSpan: 1.5 }, 0, 0)], [mc('b', 1, 1)]];

fillInTable(cells);

expect(cells.map((row) => row.map((cell) => [cell.x, cell.y, cell.content]))).toEqual([
[
[0, 0, 'a'],
[1, 0, ''],
],
[
[0, 1, ''],
[1, 1, 'b'],
],
]);
expect(cells[0][0].rowSpan).toBe(1.5);
});

it('only checks existing rows when a span extends below the table', function () {
let cells = [[mc({ content: 'a', rowSpan: 4 }, 0, 0)], [], []];

fillInTable(cells);

expect(cells.map((row) => row.length)).toEqual([1, 0, 0]);
expect(cells[0][0].rowSpan).toBe(4);
});

it('leaves an empty table unchanged', function () {
let cells = [[], []];

fillInTable(cells);

expect(cells).toEqual([[], []]);
});

it('will blank out individual cells', function () {
let cells = [[mc('a', 0, 1)], [mc('b', 1, 0)]];
fillInTable(cells);
Expand Down