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philpennockphilpennock
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Implement sort-by-column feature
The `Table` interface gains `SortByNamedColumn()` and `SortByColumnNumber()` which sort the table rows in-place. err = tb.SortByNamedColumn("Some Header", tabular.SORT_ASC) Introduce the `SortInter` interface which a value stored in a Cell can implement; a method `SortInt64() int64` will let objects define their sort order. See the `sort_test.go` sorting by position-in-greek-alphabet for an example. Fixed nested `*Cell` inside `Cell` to propagate rendering values. Fixed that table `columnNames` field was never populated. We populate it afresh on every `AddHeader` call.
1 parent a5a8ded commit 99d6ff2

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6 files changed

+444
-5
lines changed

6 files changed

+444
-5
lines changed

‎atable.go

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
// Copyright © 2016,2018 Pennock Tech, LLC.
1+
// Copyright © 2016,2018,2025 Pennock Tech, LLC.
22
// All rights reserved, except as granted under license.
33
// Licensed per file LICENSE.txt
44

@@ -143,11 +143,15 @@ func (t *ATable) Headers() []Cell {
143143
func (t *ATable) AddHeaders(items ...interface{}) Table {
144144
t.resizeColumnsAtLeast(len(items))
145145
hr := NewRowWithCapacity(len(items))
146+
columnNames := make(map[string]int, len(items))
146147
hr.ErrorContainer = t.ErrorContainer
147148
for i := range items {
148-
hr.Add(NewCell(items[i]))
149+
cell := NewCell(items[i])
150+
hr.Add(cell)
151+
columnNames[cell.String()] = i
149152
}
150153
t.headerRow = hr
154+
t.columnNames = columnNames
151155

152156
invokePropertyCallbacks(t.tableRowAdditionCallbacks, CB_AT_ADD, hr, t.ErrorContainer)
153157
for i := range hr.cells {

‎cell.go

Lines changed: 106 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,12 @@
1-
// Copyright © 2016,2018 Pennock Tech, LLC.
1+
// Copyright © 2016,2018,2025 Pennock Tech, LLC.
22
// All rights reserved, except as granted under license.
33
// Licensed per file LICENSE.txt
44

55
package tabular // import "go.pennock.tech/tabular"
66

77
import (
88
"fmt"
9+
"reflect"
910
"strings"
1011

1112
"go.pennock.tech/tabular/length"
@@ -69,6 +70,12 @@ func (c *Cell) Update() {
6970
c.height = o.height
7071
c.empty = o.empty
7172
return
73+
case *Cell:
74+
c.str = o.str
75+
c.width = o.width
76+
c.height = o.height
77+
c.empty = o.empty
78+
return
7279

7380
// After this point, MUST set .str
7481
case string:
@@ -189,3 +196,101 @@ func (c *Cell) Empty() bool {
189196
}
190197
return c.empty
191198
}
199+
200+
// LessThan returns true if the value of this cell is less than the value of
201+
// the other cell. The determination of "less" is euphemistically heuristic.
202+
func (c *Cell) LessThan(d *Cell) bool {
203+
var (
204+
g, h, t *Cell
205+
u Cell
206+
ok bool
207+
cv, dv reflect.Value
208+
tt, sortIntType reflect.Type
209+
as string
210+
af float64
211+
aOkay bool
212+
)
213+
214+
g, ok = c, true
215+
for ok {
216+
if t, ok = g.raw.(*Cell); ok {
217+
g = t
218+
} else if u, ok = g.raw.(Cell); ok {
219+
g = &u
220+
}
221+
}
222+
cv = reflect.ValueOf(g.raw)
223+
224+
h, ok = d, true
225+
for ok {
226+
if t, ok = h.raw.(*Cell); ok {
227+
h = t
228+
} else if u, ok = h.raw.(Cell); ok {
229+
h = &u
230+
}
231+
}
232+
dv = reflect.ValueOf(h.raw)
233+
234+
// Do not try to convert to uint, because positive floats convert and lose precision.
235+
// Similarly for int.
236+
// Leave _conversions_ for the float. But "can" is the underlying type.
237+
// We want to use SortInter as our _first_ choice, including when defined on types for which the underlying type is an int
238+
239+
sortIntType = reflect.TypeOf((*SortInter)(nil)).Elem()
240+
241+
if cv.Type().Implements(sortIntType) {
242+
if dv.Type().Implements(sortIntType) {
243+
return cv.Interface().(SortInter).SortInt64() < dv.Interface().(SortInter).SortInt64()
244+
} else if dv.CanInt() {
245+
return cv.Interface().(SortInter).SortInt64() < dv.Int()
246+
}
247+
} else if dv.Type().Implements(sortIntType) {
248+
if cv.CanInt() {
249+
return cv.Int() < dv.Interface().(SortInter).SortInt64()
250+
}
251+
}
252+
253+
if cv.CanFloat() && dv.CanFloat() {
254+
return cv.Float() < dv.Float()
255+
}
256+
if cv.CanUint() && dv.CanUint() {
257+
return cv.Uint() < dv.Uint()
258+
}
259+
if cv.CanInt() {
260+
if dv.CanFloat() {
261+
return float64(cv.Int()) < dv.Float()
262+
} else if dv.CanInt() {
263+
return cv.Int() < dv.Int()
264+
}
265+
} else if cv.CanFloat() && dv.CanInt() {
266+
return cv.Float() < float64(dv.Int())
267+
}
268+
269+
tt = reflect.TypeOf(af)
270+
if cv.CanConvert(tt) && dv.CanConvert(tt) {
271+
return cv.Convert(tt).Float() < dv.Convert(tt).Float()
272+
}
273+
274+
aOkay = false
275+
if x, ok := g.raw.(string); ok {
276+
as = x
277+
aOkay = true
278+
} else if x, ok := g.raw.(Stringer); ok {
279+
as = x.String()
280+
aOkay = true
281+
} else if x, ok := g.raw.(GoStringer); ok {
282+
as = x.GoString()
283+
aOkay = true
284+
}
285+
if aOkay {
286+
if x, ok := h.raw.(string); ok {
287+
return as < x
288+
} else if x, ok := h.raw.(Stringer); ok {
289+
return as < x.String()
290+
} else if x, ok := h.raw.(GoStringer); ok {
291+
return as < x.GoString()
292+
}
293+
}
294+
295+
return false
296+
}

‎sort.go

Lines changed: 82 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,82 @@
1+
// Copyright © 2025 Pennock Tech, LLC.
2+
// All rights reserved, except as granted under license.
3+
// Licensed per file LICENSE.txt
4+
5+
package tabular // import "go.pennock.tech/tabular"
6+
7+
import (
8+
"errors"
9+
"sort"
10+
"strconv"
11+
)
12+
13+
type ErrorNoSuchColumn string
14+
15+
func (e ErrorNoSuchColumn) Error() string { return "no such column " + strconv.Quote(string(e)) }
16+
17+
type ErrorColumnOutOfRange int
18+
19+
func (e ErrorColumnOutOfRange) Error() string {
20+
return "column " + strconv.Itoa(int(e)) + " out of range"
21+
}
22+
23+
var ErrNoColumnHeaders = errors.New("no headers have defined columns")
24+
25+
type SortOrder int
26+
27+
const (
28+
SORT_ASC SortOrder = iota + 1
29+
SORT_DESC
30+
)
31+
32+
func (so SortOrder) String() string {
33+
switch so {
34+
case SORT_ASC:
35+
return "ascending"
36+
case SORT_DESC:
37+
return "descending"
38+
default:
39+
panic("unhandled sort order for String")
40+
}
41+
}
42+
43+
// SortByNamedColumn performs an in-place row-sort.
44+
func (t *ATable) SortByNamedColumn(name string, order SortOrder) error {
45+
if t.columnNames == nil {
46+
return ErrNoColumnHeaders
47+
}
48+
columnNumber, ok := t.columnNames[name]
49+
if !ok {
50+
return ErrorNoSuchColumn(name)
51+
}
52+
return t.SortByColumnNumber(columnNumber, order)
53+
}
54+
55+
type tableSorter struct {
56+
tb *ATable
57+
column int
58+
order SortOrder
59+
}
60+
61+
func (t tableSorter) Len() int { return t.tb.NRows() }
62+
func (t tableSorter) Swap(i, j int) {
63+
t.tb.rows[i], t.tb.rows[j] = t.tb.rows[j], t.tb.rows[i]
64+
}
65+
func (t tableSorter) Less(i, j int) bool {
66+
if t.order == SORT_ASC {
67+
return t.tb.rows[i].cells[t.column].LessThan(&t.tb.rows[j].cells[t.column])
68+
} else if t.order == SORT_DESC {
69+
return t.tb.rows[j].cells[t.column].LessThan(&t.tb.rows[i].cells[t.column])
70+
} else {
71+
panic("unhandled order in tableSorter.Less")
72+
}
73+
}
74+
75+
func (t *ATable) SortByColumnNumber(sortCol int, order SortOrder) error {
76+
if sortCol < 0 || sortCol >= t.nColumns {
77+
return ErrorColumnOutOfRange(sortCol)
78+
}
79+
ts := tableSorter{t, sortCol, order}
80+
sort.Sort(ts)
81+
return nil
82+
}

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