351 lines
8.7 KiB
Go
351 lines
8.7 KiB
Go
// Copyright 2015 go-swagger maintainers
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package runtime
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import (
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"bytes"
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"context"
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"encoding"
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"encoding/csv"
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"errors"
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"fmt"
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"io"
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"reflect"
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"golang.org/x/sync/errgroup"
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)
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// CSVConsumer creates a new CSV consumer.
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//
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// The consumer consumes CSV records from a provided reader into the data passed by reference.
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//
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// CSVOpts options may be specified to alter the default CSV behavior on the reader and the writer side (e.g. separator, skip header, ...).
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// The defaults are those of the standard library's csv.Reader and csv.Writer.
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//
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// Supported output underlying types and interfaces, prioritized in this order:
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// - *csv.Writer
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// - CSVWriter (writer options are ignored)
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// - io.Writer (as raw bytes)
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// - io.ReaderFrom (as raw bytes)
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// - encoding.BinaryUnmarshaler (as raw bytes)
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// - *[][]string (as a collection of records)
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// - *[]byte (as raw bytes)
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// - *string (a raw bytes)
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//
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// The consumer prioritizes situations where buffering the input is not required.
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func CSVConsumer(opts ...CSVOpt) Consumer {
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o := csvOptsWithDefaults(opts)
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return ConsumerFunc(func(reader io.Reader, data interface{}) error {
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if reader == nil {
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return errors.New("CSVConsumer requires a reader")
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}
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if data == nil {
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return errors.New("nil destination for CSVConsumer")
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}
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csvReader := csv.NewReader(reader)
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o.applyToReader(csvReader)
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closer := defaultCloser
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if o.closeStream {
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if cl, isReaderCloser := reader.(io.Closer); isReaderCloser {
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closer = cl.Close
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}
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}
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defer func() {
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_ = closer()
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}()
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switch destination := data.(type) {
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case *csv.Writer:
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csvWriter := destination
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o.applyToWriter(csvWriter)
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return pipeCSV(csvWriter, csvReader, o)
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case CSVWriter:
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csvWriter := destination
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// no writer options available
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return pipeCSV(csvWriter, csvReader, o)
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case io.Writer:
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csvWriter := csv.NewWriter(destination)
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o.applyToWriter(csvWriter)
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return pipeCSV(csvWriter, csvReader, o)
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case io.ReaderFrom:
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var buf bytes.Buffer
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csvWriter := csv.NewWriter(&buf)
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o.applyToWriter(csvWriter)
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if err := bufferedCSV(csvWriter, csvReader, o); err != nil {
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return err
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}
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_, err := destination.ReadFrom(&buf)
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return err
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case encoding.BinaryUnmarshaler:
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var buf bytes.Buffer
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csvWriter := csv.NewWriter(&buf)
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o.applyToWriter(csvWriter)
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if err := bufferedCSV(csvWriter, csvReader, o); err != nil {
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return err
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}
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return destination.UnmarshalBinary(buf.Bytes())
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default:
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// support *[][]string, *[]byte, *string
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if ptr := reflect.TypeOf(data); ptr.Kind() != reflect.Ptr {
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return errors.New("destination must be a pointer")
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}
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v := reflect.Indirect(reflect.ValueOf(data))
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t := v.Type()
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switch {
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case t.Kind() == reflect.Slice && t.Elem().Kind() == reflect.Slice && t.Elem().Elem().Kind() == reflect.String:
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csvWriter := &csvRecordsWriter{}
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// writer options are ignored
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if err := pipeCSV(csvWriter, csvReader, o); err != nil {
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return err
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}
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v.Grow(len(csvWriter.records))
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v.SetCap(len(csvWriter.records)) // in case Grow was unnessary, trim down the capacity
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v.SetLen(len(csvWriter.records))
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reflect.Copy(v, reflect.ValueOf(csvWriter.records))
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return nil
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case t.Kind() == reflect.Slice && t.Elem().Kind() == reflect.Uint8:
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var buf bytes.Buffer
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csvWriter := csv.NewWriter(&buf)
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o.applyToWriter(csvWriter)
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if err := bufferedCSV(csvWriter, csvReader, o); err != nil {
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return err
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}
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v.SetBytes(buf.Bytes())
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return nil
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case t.Kind() == reflect.String:
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var buf bytes.Buffer
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csvWriter := csv.NewWriter(&buf)
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o.applyToWriter(csvWriter)
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if err := bufferedCSV(csvWriter, csvReader, o); err != nil {
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return err
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}
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v.SetString(buf.String())
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return nil
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default:
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return fmt.Errorf("%v (%T) is not supported by the CSVConsumer, %s",
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data, data, "can be resolved by supporting CSVWriter/Writer/BinaryUnmarshaler interface",
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)
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}
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}
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})
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}
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// CSVProducer creates a new CSV producer.
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//
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// The producer takes input data then writes as CSV to an output writer (essentially as a pipe).
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//
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// Supported input underlying types and interfaces, prioritized in this order:
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// - *csv.Reader
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// - CSVReader (reader options are ignored)
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// - io.Reader
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// - io.WriterTo
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// - encoding.BinaryMarshaler
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// - [][]string
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// - []byte
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// - string
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//
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// The producer prioritizes situations where buffering the input is not required.
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func CSVProducer(opts ...CSVOpt) Producer {
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o := csvOptsWithDefaults(opts)
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return ProducerFunc(func(writer io.Writer, data interface{}) error {
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if writer == nil {
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return errors.New("CSVProducer requires a writer")
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}
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if data == nil {
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return errors.New("nil data for CSVProducer")
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}
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csvWriter := csv.NewWriter(writer)
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o.applyToWriter(csvWriter)
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closer := defaultCloser
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if o.closeStream {
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if cl, isWriterCloser := writer.(io.Closer); isWriterCloser {
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closer = cl.Close
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}
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}
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defer func() {
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_ = closer()
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}()
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if rc, isDataCloser := data.(io.ReadCloser); isDataCloser {
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defer rc.Close()
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}
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switch origin := data.(type) {
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case *csv.Reader:
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csvReader := origin
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o.applyToReader(csvReader)
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return pipeCSV(csvWriter, csvReader, o)
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case CSVReader:
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csvReader := origin
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// no reader options available
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return pipeCSV(csvWriter, csvReader, o)
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case io.Reader:
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csvReader := csv.NewReader(origin)
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o.applyToReader(csvReader)
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return pipeCSV(csvWriter, csvReader, o)
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case io.WriterTo:
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// async piping of the writes performed by WriteTo
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r, w := io.Pipe()
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csvReader := csv.NewReader(r)
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o.applyToReader(csvReader)
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pipe, _ := errgroup.WithContext(context.Background())
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pipe.Go(func() error {
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_, err := origin.WriteTo(w)
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_ = w.Close()
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return err
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})
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pipe.Go(func() error {
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defer func() {
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_ = r.Close()
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}()
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return pipeCSV(csvWriter, csvReader, o)
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})
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return pipe.Wait()
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case encoding.BinaryMarshaler:
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buf, err := origin.MarshalBinary()
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if err != nil {
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return err
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}
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rdr := bytes.NewBuffer(buf)
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csvReader := csv.NewReader(rdr)
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return bufferedCSV(csvWriter, csvReader, o)
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default:
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// support [][]string, []byte, string (or pointers to those)
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v := reflect.Indirect(reflect.ValueOf(data))
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t := v.Type()
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switch {
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case t.Kind() == reflect.Slice && t.Elem().Kind() == reflect.Slice && t.Elem().Elem().Kind() == reflect.String:
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csvReader := &csvRecordsWriter{
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records: make([][]string, v.Len()),
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}
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reflect.Copy(reflect.ValueOf(csvReader.records), v)
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return pipeCSV(csvWriter, csvReader, o)
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case t.Kind() == reflect.Slice && t.Elem().Kind() == reflect.Uint8:
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buf := bytes.NewBuffer(v.Bytes())
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csvReader := csv.NewReader(buf)
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o.applyToReader(csvReader)
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return bufferedCSV(csvWriter, csvReader, o)
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case t.Kind() == reflect.String:
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buf := bytes.NewBufferString(v.String())
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csvReader := csv.NewReader(buf)
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o.applyToReader(csvReader)
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return bufferedCSV(csvWriter, csvReader, o)
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default:
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return fmt.Errorf("%v (%T) is not supported by the CSVProducer, %s",
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data, data, "can be resolved by supporting CSVReader/Reader/BinaryMarshaler interface",
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)
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}
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}
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})
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}
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// pipeCSV copies CSV records from a CSV reader to a CSV writer
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func pipeCSV(csvWriter CSVWriter, csvReader CSVReader, opts csvOpts) error {
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for ; opts.skippedLines > 0; opts.skippedLines-- {
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_, err := csvReader.Read()
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if err != nil {
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if errors.Is(err, io.EOF) {
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return nil
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}
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return err
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}
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}
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for {
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record, err := csvReader.Read()
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if err != nil {
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if errors.Is(err, io.EOF) {
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break
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}
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return err
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}
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if err := csvWriter.Write(record); err != nil {
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return err
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}
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}
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csvWriter.Flush()
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return csvWriter.Error()
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}
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// bufferedCSV copies CSV records from a CSV reader to a CSV writer,
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// by first reading all records then writing them at once.
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func bufferedCSV(csvWriter *csv.Writer, csvReader *csv.Reader, opts csvOpts) error {
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for ; opts.skippedLines > 0; opts.skippedLines-- {
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_, err := csvReader.Read()
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if err != nil {
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if errors.Is(err, io.EOF) {
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return nil
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}
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return err
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}
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}
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records, err := csvReader.ReadAll()
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if err != nil {
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return err
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}
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return csvWriter.WriteAll(records)
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}
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