Make RenderDisplayStrings return the column positions

Not used by anything yet, but we'll need it later in this branch.

pkg/gui/context/list_renderer.go

@@ -23,7 +23,7 @@ func (self *ListRenderer) renderLines(startIdx int, endIdx int) string {
 	if self.getColumnAlignments != nil {
 		columnAlignments = self.getColumnAlignments()
 	}
-	lines := utils.RenderDisplayStrings(
+	lines, _ := utils.RenderDisplayStrings(
 		self.getDisplayStrings(startIdx, utils.Min(endIdx, self.list.Len())),
 		columnAlignments)
 	return strings.Join(lines, "\n")

pkg/gui/presentation/commits_test.go

@@ -422,7 +422,7 @@ func TestGetCommitListDisplayStrings(t *testing.T) {
 					s.showYouAreHereLabel,
 				)
 
-				renderedLines := utils.RenderDisplayStrings(result, nil)
+				renderedLines, _ := utils.RenderDisplayStrings(result, nil)
 				renderedResult := strings.Join(renderedLines, "\n")
 				t.Logf("\n%s", renderedResult)
 

pkg/utils/formatting.go

@@ -37,10 +37,14 @@ func WithPadding(str string, padding int, alignment Alignment) string {
 
 // defaults to left-aligning each column. If you want to set the alignment of
 // each column, pass in a slice of Alignment values.
-func RenderDisplayStrings(displayStringsArr [][]string, columnAlignments []Alignment) []string {
+// returns a list of strings that should be joined with "\n", and an array of
+// the column positions
+func RenderDisplayStrings(displayStringsArr [][]string, columnAlignments []Alignment) ([]string, []int) {
 	displayStringsArr, columnAlignments = excludeBlankColumns(displayStringsArr, columnAlignments)
 	padWidths := getPadWidths(displayStringsArr)
 	columnConfigs := make([]ColumnConfig, len(padWidths))
+	columnPositions := make([]int, len(padWidths)+1)
+	columnPositions[0] = 0
 	for i, padWidth := range padWidths {
 		// gracefully handle when columnAlignments is shorter than padWidths
 		alignment := AlignLeft
@@ -52,8 +56,9 @@ func RenderDisplayStrings(displayStringsArr [][]string, columnAlignments []Align
 			Width:     padWidth,
 			Alignment: alignment,
 		}
+		columnPositions[i+1] = columnPositions[i] + padWidth + 1
 	}
-	return getPaddedDisplayStrings(displayStringsArr, columnConfigs)
+	return getPaddedDisplayStrings(displayStringsArr, columnConfigs), columnPositions
 }
 
 // NOTE: this mutates the input slice for the sake of performance

pkg/utils/formatting_test.go

@@ -160,69 +160,82 @@ func TestRenderDisplayStrings(t *testing.T) {
 	type scenario struct {
 		input                   [][]string
 		columnAlignments        []Alignment
-		expected         string
+		expectedOutput          string
+		expectedColumnPositions []int
 	}
 
 	tests := []scenario{
 		{
 			input:                   [][]string{{""}, {""}},
 			columnAlignments:        nil,
-			expected:         "",
+			expectedOutput:          "",
+			expectedColumnPositions: []int{0},
 		},
 		{
 			input:                   [][]string{{"a"}, {""}},
 			columnAlignments:        nil,
-			expected:         "a\n",
+			expectedOutput:          "a\n",
+			expectedColumnPositions: []int{0},
 		},
 		{
 			input:                   [][]string{{"a"}, {"b"}},
 			columnAlignments:        nil,
-			expected:         "a\nb",
+			expectedOutput:          "a\nb",
+			expectedColumnPositions: []int{0},
 		},
 		{
 			input:                   [][]string{{"a", "b"}, {"c", "d"}},
 			columnAlignments:        nil,
-			expected:         "a b\nc d",
+			expectedOutput:          "a b\nc d",
+			expectedColumnPositions: []int{0, 2},
 		},
 		{
 			input:                   [][]string{{"a", "", "c"}, {"d", "", "f"}},
 			columnAlignments:        nil,
-			expected:         "a c\nd f",
+			expectedOutput:          "a c\nd f",
+			expectedColumnPositions: []int{0, 2},
 		},
 		{
 			input:                   [][]string{{"a", "", "c", ""}, {"d", "", "f", ""}},
 			columnAlignments:        nil,
-			expected:         "a c\nd f",
+			expectedOutput:          "a c\nd f",
+			expectedColumnPositions: []int{0, 2},
 		},
 		{
 			input:                   [][]string{{"abc", "", "d", ""}, {"e", "", "f", ""}},
 			columnAlignments:        nil,
-			expected:         "abc d\ne   f",
+			expectedOutput:          "abc d\ne   f",
+			expectedColumnPositions: []int{0, 4},
 		},
 		{
 			input:                   [][]string{{"abc", "", "d", ""}, {"e", "", "f", ""}},
 			columnAlignments:        []Alignment{AlignLeft, AlignLeft}, // same as nil (default)
-			expected:         "abc d\ne   f",
+			expectedOutput:          "abc d\ne   f",
+			expectedColumnPositions: []int{0, 4},
 		},
 		{
 			input:                   [][]string{{"abc", "", "d", ""}, {"e", "", "f", ""}},
 			columnAlignments:        []Alignment{AlignRight, AlignLeft},
-			expected:         "abc d\n  e f",
+			expectedOutput:          "abc d\n  e f",
+			expectedColumnPositions: []int{0, 4},
 		},
 		{
 			input:                   [][]string{{"a", "", "bcd", "efg", "h"}, {"i", "", "j", "k", "l"}},
 			columnAlignments:        []Alignment{AlignLeft, AlignLeft, AlignRight, AlignLeft},
-			expected:         "a bcd efg h\ni   j k   l",
+			expectedOutput:          "a bcd efg h\ni   j k   l",
+			expectedColumnPositions: []int{0, 2, 6, 10},
 		},
 		{
 			input:                   [][]string{{"abc", "", "d", ""}, {"e", "", "f", ""}},
 			columnAlignments:        []Alignment{AlignRight}, // gracefully defaults unspecified columns to left-align
-			expected:         "abc d\n  e f",
+			expectedOutput:          "abc d\n  e f",
+			expectedColumnPositions: []int{0, 4},
 		},
 	}
 
 	for _, test := range tests {
-		output := RenderDisplayStrings(test.input, test.columnAlignments)
+		output, columnPositions := RenderDisplayStrings(test.input, test.columnAlignments)
-		assert.EqualValues(t, test.expected, strings.Join(output, "\n"))
+		assert.EqualValues(t, test.expectedOutput, strings.Join(output, "\n"))
+		assert.EqualValues(t, test.expectedColumnPositions, columnPositions)
 	}
 }