105 lines
1.9 KiB
Go
105 lines
1.9 KiB
Go
package cmdlang
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import (
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"bufio"
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"context"
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"errors"
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"io"
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"os"
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"strings"
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)
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func echoBuiltin(ctx context.Context, args invocationArgs) (object, error) {
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if len(args.args) == 0 {
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return asStream(""), nil
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}
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var line strings.Builder
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for _, arg := range args.args {
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line.WriteString(arg)
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}
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return asStream(line.String()), nil
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}
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func toUpperBuiltin(ctx context.Context, args invocationArgs) (object, error) {
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// Handle args
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return mapFilterStream{
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in: args.inStream,
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mapFn: func(x object) (object, bool) {
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s, ok := x.(string)
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if !ok {
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return nil, false
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}
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return strings.ToUpper(s), true
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},
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}, nil
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}
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func catBuiltin(ctx context.Context, args invocationArgs) (object, error) {
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if err := args.expectArgn(1); err != nil {
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return nil, err
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}
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return &fileLinesStream{filename: args.args[0]}, nil
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}
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type fileLinesStream struct {
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filename string
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f *os.File
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scnr *bufio.Scanner
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}
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func (f *fileLinesStream) next() (object, error) {
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var err error
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// We open the file on the first pull. That way, an unconsumed stream won't result in a FD leak
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if f.f == nil {
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f.f, err = os.Open(f.filename)
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if err != nil {
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return nil, err
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}
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f.scnr = bufio.NewScanner(f.f)
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}
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if f.scnr.Scan() {
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return f.scnr.Text(), nil
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}
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if f.scnr.Err() == nil {
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return nil, io.EOF
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}
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return nil, f.scnr.Err()
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}
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func (f *fileLinesStream) close() error {
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if f.f != nil {
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return f.f.Close()
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}
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return nil
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}
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func errorTestBuiltin(ctx context.Context, args invocationArgs) (object, error) {
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return &timeBombStream{args.inStream, 2}, nil
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}
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type timeBombStream struct {
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in stream
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x int
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}
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func (ms *timeBombStream) next() (object, error) {
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if ms.x > 0 {
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ms.x--
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return ms.in.next()
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}
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return nil, errors.New("BOOM")
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}
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func (ms *timeBombStream) close() error {
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closable, ok := ms.in.(closableStream)
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if ok {
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return closable.close()
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}
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return nil
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}
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