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csv.go
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csv.go
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package csv
import (
"encoding/csv"
"fmt"
"io"
"strings"
"sync"
"github.com/qri-io/dataset/dsio/replacecr"
"go.starlark.net/starlark"
"go.starlark.net/starlarkstruct"
)
// ModuleName defines the expected name for this Module when used
// in starlark's load() function, eg: load('csv.star', 'csv')
const ModuleName = "encoding/csv.star"
var (
once sync.Once
csvModule starlark.StringDict
)
// LoadModule loads the base64 module.
// It is concurrency-safe and idempotent.
func LoadModule() (starlark.StringDict, error) {
once.Do(func() {
csvModule = starlark.StringDict{
"csv": starlarkstruct.FromStringDict(starlarkstruct.Default, starlark.StringDict{
"read_all": starlark.NewBuiltin("read_all", ReadAll),
}),
}
})
return csvModule, nil
}
// Module joins http tools to a dataset, allowing dataset
// to follow along with http requests
type Module struct {
}
// Struct returns this module's methods as a starlark Struct
func (m *Module) Struct() *starlarkstruct.Struct {
return starlarkstruct.FromStringDict(starlarkstruct.Default, m.StringDict())
}
// StringDict returns all module methods in a starlark.StringDict
func (m *Module) StringDict() starlark.StringDict {
return starlark.StringDict{
"read_all": starlark.NewBuiltin("read_all", ReadAll),
}
}
// ReadAll gets all values from a csv source
func ReadAll(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
var (
r io.Reader
source starlark.Value
lazyQuotes, trimLeadingSpace starlark.Bool
skip = starlark.MakeInt(0)
fieldsPerRecord = starlark.MakeInt(0)
_comma, _comment starlark.String
)
err := starlark.UnpackArgs("read_all", args, kwargs,
"source", &source,
"comma?", &_comma,
"comment", &_comment,
"lazy_quotes", &lazyQuotes,
"trim_leading_space", &trimLeadingSpace,
"fields_per_record", &fieldsPerRecord,
"skip", &skip)
if err != nil {
return nil, err
}
switch source.Type() {
case "string":
str := string(source.(starlark.String))
r = strings.NewReader(str)
}
csvr := csv.NewReader(replacecr.Reader(r))
csvr.LazyQuotes = bool(lazyQuotes)
csvr.TrimLeadingSpace = bool(trimLeadingSpace)
comma := string(_comma)
if comma == "" {
comma = ","
} else if len(comma) != 1 {
return starlark.None, fmt.Errorf("expected comma param to be a single-character string")
}
csvr.Comma = []rune(comma)[0]
comment := string(_comment)
if comment != "" && len(comment) != 1 {
return starlark.None, fmt.Errorf("expected comment param to be a single-character string")
} else if comment != "" {
csvr.Comment = []rune(comment)[0]
}
if fpr, ok := fieldsPerRecord.Int64(); ok && fpr != 0 {
csvr.FieldsPerRecord = int(fpr)
}
if s, ok := skip.Int64(); ok {
for i := 0; i < int(s); i++ {
csvr.Read()
}
}
strs, err := csvr.ReadAll()
if err != nil {
return starlark.None, err
}
vals := make([]starlark.Value, len(strs))
for i, rowStr := range strs {
row := make([]starlark.Value, len(rowStr))
for j, cell := range rowStr {
row[j] = starlark.String(cell)
}
vals[i] = starlark.NewList(row)
}
return starlark.NewList(vals), nil
}