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Merge pull request #290 from noborus/add-row-number-column
Add row number column
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| package trdsql | ||
|
|
||
| import ( | ||
| "strconv" | ||
| ) | ||
|
|
||
| // rowNumberReader is a wrapper around a Reader that transforms. | ||
| type rowNumberReader struct { | ||
| reader Reader | ||
| originRow []any | ||
| lineCount int | ||
| } | ||
|
|
||
| // newRowNumberReader creates a new TransformReader. | ||
| func newRowNumberReader(r Reader) *rowNumberReader { | ||
| columnNum := 1 | ||
| names, err := r.Names() | ||
| if err == nil { | ||
| columnNum = len(names) | ||
| } | ||
| originRow := make([]any, columnNum) | ||
| return &rowNumberReader{ | ||
| reader: r, | ||
| originRow: originRow, | ||
| lineCount: 0, | ||
| } | ||
| } | ||
|
|
||
| // Names returns column names with an additional row number column. | ||
| func (r *rowNumberReader) Names() ([]string, error) { | ||
| number := "num" | ||
| names, err := r.reader.Names() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| for i := 0; i < len(names)+1; i++ { | ||
| orig := number | ||
| for _, name := range names { | ||
| if number == name { | ||
| number = orig + strconv.Itoa(i) | ||
| i++ | ||
| continue | ||
| } | ||
| } | ||
| } | ||
|
|
||
| return append([]string{number}, names...), nil | ||
| } | ||
|
|
||
| // Types returns column types with an additional row number column. | ||
| func (r *rowNumberReader) Types() ([]string, error) { | ||
| types, err := r.reader.Types() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return append([]string{"int"}, types...), nil | ||
| } | ||
|
|
||
| // PreReadRow returns pre-read rows with an additional row number column. | ||
| func (r *rowNumberReader) PreReadRow() [][]any { | ||
| preReadRows := r.reader.PreReadRow() | ||
| for i := range preReadRows { | ||
| preReadRows[i] = append([]any{r.lineCount + i + 1}, preReadRows[i]...) | ||
| } | ||
| r.lineCount += len(preReadRows) | ||
| return preReadRows | ||
| } | ||
|
|
||
| // ReadRow reads the rest of the row with an additional row number column. | ||
| func (r *rowNumberReader) ReadRow(row []any) ([]any, error) { | ||
| var err error | ||
| r.lineCount++ | ||
| r.originRow, err = r.reader.ReadRow(r.originRow) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| if len(r.originRow) == 0 { | ||
| return nil, nil | ||
| } | ||
|
|
||
| return append([]any{r.lineCount}, r.originRow...), nil | ||
| } |
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