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Add support for Nil *Table and provide Example
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@urban-wombat
urban-wombat committed Feb 21, 2020
1 parent 1df7a72 commit f38db84
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Showing 3 changed files with 291 additions and 37 deletions.
137 changes: 114 additions & 23 deletions gotables.go
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Original file line number Diff line number Diff line change
Expand Up @@ -376,6 +376,7 @@ func (tableSet *TableSet) TableCount() int {

// Add a table to a table set.
func (tableSet *TableSet) AppendTable(newTable *Table) error {

if tableSet == nil {
return fmt.Errorf("%s ERROR: tableSet.%s tableSet is <nil>", UtilFuncSource(), UtilFuncName())
}
Expand Down Expand Up @@ -450,6 +451,7 @@ type Table struct {
rows []tableRow
sortKeys []sortKey
structShape bool
isNilTable bool
}

type TableExported struct {
Expand All @@ -475,13 +477,40 @@ type tableRow []interface{}

// Note: Reimplement this as a slice of byte for each row and a master map and/or slice to track offset.

// Factory function to generate a *Table pointer.
/*
var myTable *gotables.Table
myTable, err = gotables.NewTable("My_Table")
if err != nil {
panic(err)
}
Factory function to create an empty *Table that is not yet ready to use.
The table is for use as zero value, a *Table that is a placeholder without being a Go nil.
To make it usable, give it a table name: table.SetTableName("MyTableName")
In its unusable NilTable state, table.IsValidTable() will return false.
var myTable *gotables.Table = gotables.NewNilTable()
Note: does not return an error. It cannot fail.
*/
func NewNilTable() *Table {
var newTable *Table = new(Table)

newTable.colNames = []string{}
newTable.colTypes = []string{}
newTable.colNamesMap = map[string]int{}
newTable.rows = []tableRow{}

newTable.isNilTable = true

return newTable
}

/*
Factory function to create an empty *Table
var myTable *gotables.Table
myTable, err = gotables.NewTable("My_Table")
if err != nil {
panic(err)
}
*/
func NewTable(tableName string) (*Table, error) {
var newTable *Table = NewNilTable()
Expand All @@ -506,23 +535,6 @@ func newNonZeroTable(tableName string) *Table {
return newTable
}

// Factory function to generate a nil *Table pointer.
/*
var myTable *gotables.Table = gotables.NewNilTable()
Note: Does not return an error. It cannot fail.
*/
func NewNilTable() *Table {
var newTable *Table = new(Table)

newTable.colNames = []string{}
newTable.colTypes = []string{}
newTable.colNamesMap = map[string]int{}
newTable.rows = []tableRow{}

return newTable
}

func newTableExported(tableName string) (*TableExported, error) {
var err error
var NewTableExported *TableExported = new(TableExported)
Expand Down Expand Up @@ -585,10 +597,15 @@ func (table *Table) appendRowOfNil() error {

// Note: Can append rows to an empty (no columns) table, and later append columns - but not for long!
func (table *Table) AppendRows(howMany int) error {

if table == nil {
return fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

var err error

if debugging {
Expand Down Expand Up @@ -622,10 +639,15 @@ func (table *Table) AppendRows(howMany int) error {
// All cells in the new added row will be set to their zero value, such as 0, "", or false.
// Note: Can append rows to an empty (no columns) table, and later append columns.
func (table *Table) AppendRow() error {

if table == nil {
return fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

var err error

if debugging {
Expand Down Expand Up @@ -1504,6 +1526,10 @@ func (table *Table) GetTableAsCSV(optionalSubstituteHeadingNames ...string) (str
return "", fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return "", fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

var buf *bytes.Buffer = new(bytes.Buffer)
csvWriter := csv.NewWriter(buf)
var record []string = make([]string, table.ColCount())
Expand Down Expand Up @@ -1593,6 +1619,10 @@ func (table *Table) AppendCol(colName string, colType string) error {
return fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if isValid, err := IsValidColName(colName); !isValid {
return err
}
Expand Down Expand Up @@ -1819,6 +1849,11 @@ func (table *Table) GetColInfoAsTable() (*Table, error) {
if table == nil {
return nil, fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return nil, fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

var err error
var colsTable *Table

Expand Down Expand Up @@ -1883,6 +1918,10 @@ func (table *Table) GetColInfoAsSlices() ([]string, []string, error) {
return nil, nil, fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return nil, nil, fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

var colNames []string = []string{}
var colTypes []string = []string{}

Expand Down Expand Up @@ -2003,10 +2042,16 @@ func (table *Table) RowCount() int {
Like its non-MustGet alternative but panics on error.
*/
func (table *Table) GetValMustGet(colName string, rowIndex int) (val interface{}) {
if table.isNilTable {
err := fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
panic(err)
}

val, err := table.GetVal(colName, rowIndex)
if err != nil {
panic(err)
}

return val
}

Expand All @@ -2019,6 +2064,10 @@ func (table *Table) GetVal(colName string, rowIndex int) (interface{}, error) {
return nil, fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return nil, fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if printCaller {
UtilPrintCaller()
}
Expand Down Expand Up @@ -2054,6 +2103,16 @@ func (table *Table) GetVal(colName string, rowIndex int) (interface{}, error) {
Like its non-MustGet alternative but panics on error.
*/
func (table *Table) GetValByColIndexMustGet(colIndex int, rowIndex int) (val interface{}) {
if table == nil {
err := fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
panic(err)
}

if table.isNilTable {
err := fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
panic(err)
}

val, err := table.GetValByColIndex(colIndex, rowIndex)
if err != nil {
panic(err)
Expand All @@ -2067,6 +2126,10 @@ func (table *Table) GetValByColIndex(colIndex int, rowIndex int) (interface{}, e
return nil, fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return nil, fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if printCaller {
UtilPrintCaller()
}
Expand Down Expand Up @@ -2259,6 +2322,8 @@ func (table *Table) SetName(tableName string) error {

table.tableName = tableName

table.isNilTable = false

return nil
}

Expand Down Expand Up @@ -2559,6 +2624,10 @@ func (table *Table) GetValAsStringByColIndex(colIndex int, rowIndex int) (string
return "", fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return "", fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if printCaller {
UtilPrintCaller()
}
Expand Down Expand Up @@ -2677,6 +2746,10 @@ func (table *Table) GetValAsString(colName string, rowIndex int) (string, error)
return "", fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return "", fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if printCaller {
UtilPrintCaller()
}
Expand Down Expand Up @@ -2744,6 +2817,10 @@ func (table *Table) GetColValsAsStrings(colName string) ([]string, error) {
return nil, fmt.Errorf("%s ERROR: table.%s: table is <nil>", UtilFuncSource(), UtilFuncName())
}

if table.isNilTable {
return nil, fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

rowCount := table.RowCount()
sVals := make([]string, rowCount)
for rowIndex := 0; rowIndex < rowCount; rowIndex++ {
Expand Down Expand Up @@ -3014,13 +3091,19 @@ func (table1 *Table) Equals(table2 *Table) (bool, error) {
Column order is ignored. Identical duplicate columns are ignored.
*/
func (table *Table) AppendColsFromTable(fromTable *Table) error {

if table == nil {
return fmt.Errorf("%s ERROR: table.%s(fromTable): table is <nil>", UtilFuncSource(), UtilFuncName())
}

if fromTable == nil {
return fmt.Errorf("fromTable.table.%s: table is <nil>", UtilFuncName())
}

if table.isNilTable {
return fmt.Errorf("table.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

var err error

colsTable, err := fromTable.GetColInfoAsTable()
Expand Down Expand Up @@ -3073,6 +3156,14 @@ func (toTable *Table) AppendRowsFromTable(fromTable *Table, firstRow int, lastRo
return fmt.Errorf("fromTable.table.%s: table is <nil>", UtilFuncName())
}

if toTable.isNilTable {
return fmt.Errorf("toTable.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if fromTable.isNilTable {
return fmt.Errorf("fromTable.%s: table is an unnamed NilTable. Call table.SetName() to un-Nil it", UtilFuncName())
}

if debugging {
_, err = toTable.IsValidTable()
if err != nil {
Expand Down
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