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// Copyright (C) 2017-2018 Luke Shumaker <lukeshu@lukeshu.com>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package libfastimport
import (
"bufio"
"io"
"os"
"git.lukeshu.com/go/libfastimport/textproto"
)
type UnsupportedCommand string
func (e UnsupportedCommand) Error() string {
return "Unsupported command: " + string(e)
}
// A Frontend is something that produces a fast-import stream; the
// Frontend object provides methods for reading from it. A program
// that writes to a Frontend would itself be a backend.
//
// You may think of a "Frontend" object as a "Reader" object, though
// it was not given that name because the RespondGetMark,
// RespondCatBlob, and RespondLs methods actually write information;
// it isn't a read-only object.
type Frontend struct {
fastImport *parser
catBlobWrite *textproto.CatBlobWriter
catBlobFlush *bufio.Writer
onErr func(error) error
}
// NewFrontend creates a new Frontend object that reads from the given
// io.Reader.
//
// Optionally, you may also provide an io.Writer that responses to
// "cat-blob", "get-mark", and "ls" commands can be written to.
//
// Optionally, you may also provide an onErr function that can bue
// used to handle or transform errors when they are encountered.
func NewFrontend(fastImport io.Reader, catBlob io.Writer, onErr func(error) error) *Frontend {
ret := &Frontend{}
ret.fastImport = newParser(textproto.NewFIReader(fastImport))
if catBlob == nil {
catBlob = os.Stdout
}
ret.catBlobFlush = bufio.NewWriter(catBlob)
ret.catBlobWrite = textproto.NewCatBlobWriter(ret.catBlobFlush)
if onErr == nil {
onErr = func(e error) error { return e }
}
ret.onErr = onErr
return ret
}
// ReadCmd reads a command from the Frontend.
func (f *Frontend) ReadCmd() (Cmd, error) {
cmd, err := f.fastImport.ReadCmd()
if err != nil {
err = f.onErr(err)
}
return cmd, err
}
// RespondGetMark sends to the Frontend a response to a "get-mark"
// command.
//
// It is an error (panic) to call RespondGetMark if NewFrontend did
// not have a cat-blob writer passed to it.
func (f *Frontend) RespondGetMark(sha1 string) error {
err := f.catBlobWrite.WriteLine(sha1)
if err != nil {
return err
}
return f.catBlobFlush.Flush()
}
// RespondCatBlob sends to the Frontend a response to a "cat-blob"
// command.
//
// It is an error (panic) to call RespondCatBlob if NewFrontend did
// not have a cat-blob writer passed to it.
func (f *Frontend) RespondCatBlob(sha1 string, data string) error {
err := f.catBlobWrite.WriteBlob(sha1, data)
if err != nil {
return err
}
return f.catBlobFlush.Flush()
}
// RespondLs sends to the Frontend a response to a "ls" command.
//
// It is an error (panic) to call RespondLs if NewFrontend did not
// have a cat-blob writer passed to it.
func (f *Frontend) RespondLs(mode Mode, dataref string, path Path) error {
var err error
if mode == 0 {
err = f.catBlobWrite.WriteLine("missing", path)
} else {
var t string
switch mode {
case ModeDir:
t = "tree"
case ModeGit:
t = "commit"
default:
t = "blob"
}
err = f.catBlobWrite.WriteLine(mode, t, dataref+"\t"+PathEscape(path))
}
if err != nil {
return err
}
return f.catBlobFlush.Flush()
}
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