103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
package stdlib
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import (
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"encoding/csv"
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"fmt"
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"io"
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"strings"
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"github.com/zclconf/go-cty/cty"
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"github.com/zclconf/go-cty/cty/function"
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)
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var CSVDecodeFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "str",
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Type: cty.String,
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},
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},
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Type: func(args []cty.Value) (cty.Type, error) {
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str := args[0]
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if !str.IsKnown() {
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return cty.DynamicPseudoType, nil
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}
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r := strings.NewReader(str.AsString())
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cr := csv.NewReader(r)
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headers, err := cr.Read()
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if err == io.EOF {
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return cty.DynamicPseudoType, fmt.Errorf("missing header line")
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}
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if err != nil {
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return cty.DynamicPseudoType, csvError(err)
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}
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atys := make(map[string]cty.Type, len(headers))
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for _, name := range headers {
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if _, exists := atys[name]; exists {
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return cty.DynamicPseudoType, fmt.Errorf("duplicate column name %q", name)
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}
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atys[name] = cty.String
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}
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return cty.List(cty.Object(atys)), nil
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},
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Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
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ety := retType.ElementType()
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atys := ety.AttributeTypes()
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str := args[0]
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r := strings.NewReader(str.AsString())
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cr := csv.NewReader(r)
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cr.FieldsPerRecord = len(atys)
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// Read the header row first, since that'll tell us which indices
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// map to which attribute names.
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headers, err := cr.Read()
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if err != nil {
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return cty.DynamicVal, err
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}
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var rows []cty.Value
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for {
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cols, err := cr.Read()
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if err == io.EOF {
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break
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}
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if err != nil {
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return cty.DynamicVal, csvError(err)
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}
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vals := make(map[string]cty.Value, len(cols))
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for i, str := range cols {
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name := headers[i]
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vals[name] = cty.StringVal(str)
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}
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rows = append(rows, cty.ObjectVal(vals))
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}
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if len(rows) == 0 {
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return cty.ListValEmpty(ety), nil
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}
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return cty.ListVal(rows), nil
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},
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})
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// CSVDecode parses the given CSV (RFC 4180) string and, if it is valid,
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// returns a list of objects representing the rows.
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//
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// The result is always a list of some object type. The first row of the
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// input is used to determine the object attributes, and subsequent rows
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// determine the values of those attributes.
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func CSVDecode(str cty.Value) (cty.Value, error) {
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return CSVDecodeFunc.Call([]cty.Value{str})
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}
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func csvError(err error) error {
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switch err := err.(type) {
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case *csv.ParseError:
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return fmt.Errorf("CSV parse error on line %d: %w", err.Line, err.Err)
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default:
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return err
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}
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}
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