Feature: select rows programatically (#84)

* Add Row.Selected function

This would allow to select rows programatically. See #79 for
additional information.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Add test for selecting rows programatically

This will fail, as the current implementation doesn't really work,
however, this is useful to drive the right implementation.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Compute selected rows only when needed

Previously the selected rows were cached in the model whenever the
toggle mark key event was received. Moving that computation instead to
the Model.SelectedRows function fixes this by only computing these
rows when needed.

I've also identified some optimizations that will be addressed in
upcoming commits.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Add benchmark for Model.SelectedRows

This will be useful for future optimizations.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Reduce allocations when computing selected rows

By allocating the returned slice with an initial capacity but length 0
we reduce the number of allocations by roughly 80%. I've run the
benchmark using the following command:

    go test ./table/ -bench=BenchmarkSelectedRows -benchtime=100000x -count=10

I've run the benchmark with the previous commit and with this one, and
these are the results using benchstat for comparison:

name             old time/op    new time/op    delta
SelectedRows-12    18.3µs ± 1%    17.0µs ± 1%   -7.26%  (p=0.000 n=8+10)

name             old alloc/op   new alloc/op   delta
SelectedRows-12    84.2kB ± 0%    81.9kB ± 0%   -2.70%  (p=0.002 n=8+10)

name             old allocs/op  new allocs/op  delta
SelectedRows-12      11.0 ± 0%       2.0 ± 0%  -81.82%  (p=0.000 n=10+10)

As you can see there's also some small improvement in the overall
performance of the call.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Remove unnecessary field in Model

Given that the selected rows are now computed on the fly this field
isn't needed anymore.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Update table/row.go

Co-authored-by: Brandon Fulljames <bfullj@gmail.com>

* Refactor Model.SelectedRows tests

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Add newline before return

…and make the linter happy.

Signed-off-by: Leandro López (inkel) <inkel.ar@gmail.com>

* Revert "Reduce allocations when computing selected rows"

This reverts commit 396041d.

Co-authored-by: Brandon Fulljames <bfullj@gmail.com>

table/model.go

@@ -24,7 +24,6 @@ type Model struct {
 	focused        bool
 	keyMap         KeyMap
 	selectableRows bool
-	selectedRows   []Row
 	rowCursorIndex int
 
 	// Styles

table/options.go

@@ -32,7 +32,6 @@ func (m Model) HeaderStyle(style lipgloss.Style) Model {
 // WithRows sets the rows to show as data in the table.
 func (m Model) WithRows(rows []Row) Model {
 	m.rows = rows
-	m.selectedRows = nil
 
 	if m.pageSize != 0 {
 		maxPage := m.MaxPages()
@@ -92,7 +91,15 @@ func (m Model) HighlightedRow() Row {
 
 // SelectedRows returns all rows that have been set as selected by the user.
 func (m Model) SelectedRows() []Row {
-	return m.selectedRows
+	selectedRows := []Row{}
+
+	for _, row := range m.GetVisibleRows() {
+		if row.selected {
+			selectedRows = append(selectedRows, row)
+		}
+	}
+
+	return selectedRows
 }
 
 // HighlightStyle sets a custom style to use when the row is being highlighted

table/options_test.go

@@ -137,3 +137,90 @@ func TestPageOptions(t *testing.T) {
 	assert.Greater(t, len(model.renderFooter(10)), 10)
 	assert.Contains(t, model.renderFooter(10), "6/6")
 }
+
+func TestSelectRowsProgramatically(t *testing.T) {
+	const col = "id"
+
+	tests := map[string]struct {
+		rows        []Row
+		selectedIds []int
+	}{
+		"no rows selected": {
+			[]Row{
+				NewRow(RowData{col: 1}),
+				NewRow(RowData{col: 2}),
+				NewRow(RowData{col: 3}),
+			},
+			[]int{},
+		},
+
+		"all rows selected": {
+			[]Row{
+				NewRow(RowData{col: 1}).Selected(true),
+				NewRow(RowData{col: 2}).Selected(true),
+				NewRow(RowData{col: 3}).Selected(true),
+			},
+			[]int{1, 2, 3},
+		},
+
+		"first row selected": {
+			[]Row{
+				NewRow(RowData{col: 1}).Selected(true),
+				NewRow(RowData{col: 2}),
+				NewRow(RowData{col: 3}),
+			},
+			[]int{1},
+		},
+
+		"last row selected": {
+			[]Row{
+				NewRow(RowData{col: 1}),
+				NewRow(RowData{col: 2}),
+				NewRow(RowData{col: 3}).Selected(true),
+			},
+			[]int{3},
+		},
+	}
+
+	model := New([]Column{
+		NewColumn(col, col, 1),
+	})
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			sel := model.WithRows(tt.rows).SelectedRows()
+
+			assert.Equal(t, len(tt.selectedIds), len(sel))
+			for i, id := range tt.selectedIds {
+				assert.Equal(t, id, sel[i].Data[col], "expecting row %d to have same %s column value", i)
+			}
+		})
+	}
+}
+
+func BenchmarkSelectedRows(b *testing.B) {
+	const N = 1000
+
+	b.ReportAllocs()
+
+	rows := make([]Row, 0, N)
+	for i := 0; i < N; i++ {
+		rows = append(rows, NewRow(RowData{"row": i}).Selected(i%2 == 0))
+	}
+
+	model := New([]Column{
+		NewColumn("row", "Row", 4),
+	}).WithRows(rows)
+
+	var sel []Row
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		sel = model.SelectedRows()
+	}
+
+	Rows = sel
+}
+
+var Rows []Row

table/row.go

@@ -171,3 +171,10 @@ func (m Model) renderRow(rowIndex int, last bool) string {
 
 	return lipgloss.JoinHorizontal(lipgloss.Bottom, columnStrings...)
 }
+
+// Selected sets whether the row is selected or not.
+func (r Row) Selected(selected bool) Row {
+	r.selected = selected
+
+	return r
+}

table/update.go

@@ -36,14 +36,6 @@ func (m *Model) toggleSelect() {
 	rows[m.rowCursorIndex].selected = !rows[m.rowCursorIndex].selected
 
 	m.rows = rows
-
-	m.selectedRows = []Row{}
-
-	for _, row := range m.GetVisibleRows() {
-		if row.selected {
-			m.selectedRows = append(m.selectedRows, row)
-		}
-	}
 }
 
 func (m Model) updateFilterTextInput(msg tea.Msg) (Model, tea.Cmd) {