Huge refactorig for consistent col/row numbering (#356)

* Huge refactorig for consistent col/row numbering

Started from simply changing ToALphaString()/TitleToNumber() logic and related fixes.
But have to go deeper, do fixes, after do related fixes and again and again.

Major improvements:

1. Tests made stronger again (But still be weak).
2. "Empty" returns for incorrect input replaces with panic.
3. Check for correct col/row/cell naming & addressing by default.
4. Removed huge amount of duplicated code.
5. Removed ToALphaString(), TitleToNumber() and it helpers functions at all,
and replaced with SplitCellName(), JoinCellName(), ColumnNameToNumber(), ColumnNumberToName(), CellNameToCoordinates(), CoordinatesToCellName().
6. Minor fixes for internal variable naming for code readability (ex. col, row for input params, colIdx, rowIdx for slice indexes etc).

* Formatting fixes

1 files changed, 38 insertions, 10 deletions

diff --git a/chart_test.go b/chart_test.go
index f3d7bdf..1dfc468 100644
--- a/chart_test.go
+++ b/chart_test.go
@@ -9,19 +9,46 @@ import (
 )
 
 func TestChartSize(t *testing.T) {
+	xlsx := NewFile()
+	sheet1 := xlsx.GetSheetName(1)
 
-	var buffer bytes.Buffer
+	categories := map[string]string{
+		"A2": "Small",
+		"A3": "Normal",
+		"A4": "Large",
+		"B1": "Apple",
+		"C1": "Orange",
+		"D1": "Pear",
+	}
+	for cell, v := range categories {
+		xlsx.SetCellValue(sheet1, cell, v)
+	}
 
-	categories := map[string]string{"A2": "Small", "A3": "Normal", "A4": "Large", "B1": "Apple", "C1": "Orange", "D1": "Pear"}
-	values := map[string]int{"B2": 2, "C2": 3, "D2": 3, "B3": 5, "C3": 2, "D3": 4, "B4": 6, "C4": 7, "D4": 8}
-	xlsx := NewFile()
-	for k, v := range categories {
-		xlsx.SetCellValue("Sheet1", k, v)
+	values := map[string]int{
+		"B2": 2,
+		"C2": 3,
+		"D2": 3,
+		"B3": 5,
+		"C3": 2,
+		"D3": 4,
+		"B4": 6,
+		"C4": 7,
+		"D4": 8,
 	}
-	for k, v := range values {
-		xlsx.SetCellValue("Sheet1", k, v)
+	for cell, v := range values {
+		xlsx.SetCellValue(sheet1, cell, v)
 	}
-	xlsx.AddChart("Sheet1", "E4", `{"type":"col3DClustered","dimension":{"width":640, "height":480},"series":[{"name":"Sheet1!$A$2","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$2:$D$2"},{"name":"Sheet1!$A$3","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$3:$D$3"},{"name":"Sheet1!$A$4","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$4:$D$4"}],"title":{"name":"Fruit 3D Clustered Column Chart"}}`)
+
+	xlsx.AddChart("Sheet1", "E4", `{"type":"col3DClustered","dimension":{"width":640, "height":480},`+
+		`"series":[{"name":"Sheet1!$A$2","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$2:$D$2"},`+
+		`{"name":"Sheet1!$A$3","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$3:$D$3"},`+
+		`{"name":"Sheet1!$A$4","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$4:$D$4"}],`+
+		`"title":{"name":"Fruit 3D Clustered Column Chart"}}`)
+
+	var (
+		buffer bytes.Buffer
+	)
+
 	// Save xlsx file by the given path.
 	err := xlsx.Write(&buffer)
 	if !assert.NoError(t, err) {
@@ -51,7 +78,8 @@ func TestChartSize(t *testing.T) {
 		t.FailNow()
 	}
 
-	err = xml.Unmarshal([]byte("<decodeTwoCellAnchor>"+workdir.TwoCellAnchor[0].Content+"</decodeTwoCellAnchor>"), &anchor)
+	err = xml.Unmarshal([]byte("<decodeTwoCellAnchor>"+
+		workdir.TwoCellAnchor[0].Content+"</decodeTwoCellAnchor>"), &anchor)
 	if !assert.NoError(t, err) {
 		t.FailNow()
 	}