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recorder.go
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recorder.go
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package core
import (
"bytes"
"context"
"fmt"
"io"
"strings"
"mvdan.cc/sh/v3/interp"
"mvdan.cc/sh/v3/syntax"
)
type Recorder struct {
Stdout io.Writer
Stderr io.Writer
Transcript bytes.Buffer
needsBlank bool
runner *interp.Runner
stdout *lineBufferingWriter
stderr *lineBufferingWriter
}
func (rec *Recorder) Init() error {
var err error
rec.stdout = &lineBufferingWriter{
W: &prefixingWriter{
Prefix: "1 ",
W: &rec.Transcript,
},
}
rec.stderr = &lineBufferingWriter{
W: &prefixingWriter{
Prefix: "2 ",
W: &rec.Transcript,
},
}
rec.runner, err = interp.New(
interp.StdIO(nil,
io.MultiWriter(rec.stdout, orDiscard(rec.Stdout)),
io.MultiWriter(rec.stderr, orDiscard(rec.Stderr)),
))
return err
}
func orDiscard(w io.Writer) io.Writer {
if w == nil {
return io.Discard
}
return w
}
func (rec *Recorder) flush() error {
if err := rec.stdout.Flush(); err != nil {
return err
}
if err := rec.stderr.Flush(); err != nil {
return err
}
return nil
}
type CommandResult struct {
Output []byte
ExitCode int
}
func (rec *Recorder) RunCommand(ctx context.Context, command string) (*CommandResult, error) {
stmt, err := parseStmt(command)
if err != nil {
return nil, fmt.Errorf("parsing: %w", err)
}
// Record command. Include a preceeding blank line for all but the first command.
beforeCommandMark := rec.Transcript.Len()
if rec.needsBlank {
fmt.Fprintln(&rec.Transcript)
rec.needsBlank = false
}
fmt.Fprintf(&rec.Transcript, "$ %s\n", command)
afterCommandMark := rec.Transcript.Len()
// Execute command and record output.
runErr := rec.runner.Run(ctx, stmt)
if err := rec.flush(); err != nil {
return nil, err
}
var res CommandResult
res.Output = rec.Transcript.Bytes()[afterCommandMark:rec.Transcript.Len()]
// Record exit code.
if status, ok := interp.IsExitStatus(runErr); ok {
res.ExitCode = int(status)
fmt.Fprintf(&rec.Transcript, "? %d\n", status)
rec.needsBlank = true
runErr = nil
}
// Assume final command is simply "exit", so exclude it from transcript.
// TODO: Validate this assumption.
if rec.runner.Exited() {
rec.Transcript.Truncate(beforeCommandMark)
}
if runErr != nil {
return nil, runErr
}
return &res, nil
}
func (rec *Recorder) RecordComment(text string) {
fmt.Fprintln(&rec.Transcript, text)
rec.needsBlank = false
}
func (rec *Recorder) Exited() bool {
return rec.runner.Exited()
}
func parseStmt(s string) (syntax.Node, error) {
r := strings.NewReader(s)
f, err := syntax.NewParser().Parse(r, "")
if err != nil {
return nil, err
}
if err == nil && len(f.Stmts) != 1 {
return nil, fmt.Errorf("expected exactly one statement, got %d", len(f.Stmts))
}
return f.Stmts[0], nil
}