mirror of
https://github.com/JetSetIlly/Gopher2600.git
synced 2024-05-20 13:48:02 -04:00
91 lines
2.2 KiB
Go
91 lines
2.2 KiB
Go
// This file is part of Gopher2600.
|
|
//
|
|
// Gopher2600 is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// Gopher2600 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 General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with Gopher2600. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
package test
|
|
|
|
import (
|
|
"fmt"
|
|
"strings"
|
|
)
|
|
|
|
// RingWriter is an implementation of io.Writer that will keep the buffer to a
|
|
// predefined size, keeping the most recent writes and dropping the earlier
|
|
// writes as appropriate.
|
|
type RingWriter struct {
|
|
buffer []byte
|
|
size int
|
|
cursor int
|
|
wrapped bool
|
|
}
|
|
|
|
// NewRingWriter is the preferred method of initialisation for the CappedWriter
|
|
// type.
|
|
func NewRingWriter(size int) (*RingWriter, error) {
|
|
if size <= 0 {
|
|
return nil, fmt.Errorf("invalid size for RingWriter (%d)", size)
|
|
}
|
|
return &RingWriter{
|
|
size: size,
|
|
buffer: make([]byte, size),
|
|
}, nil
|
|
}
|
|
|
|
func (r *RingWriter) String() string {
|
|
var s strings.Builder
|
|
|
|
if r.wrapped {
|
|
s.WriteString(string(r.buffer[r.cursor:]))
|
|
s.WriteString(string(r.buffer[:r.cursor]))
|
|
} else {
|
|
s.WriteString(string(r.buffer[:r.cursor]))
|
|
}
|
|
|
|
return s.String()
|
|
}
|
|
|
|
// Reset empties the ring writer's buffer
|
|
func (r *RingWriter) Reset() {
|
|
r.cursor = 0
|
|
r.wrapped = false
|
|
}
|
|
|
|
// Write implements io.Writer
|
|
func (r *RingWriter) Write(p []byte) (n int, err error) {
|
|
l := len(p)
|
|
|
|
// new text is larger than ring so simply reset the ring and continue as
|
|
// normal
|
|
if l > r.size {
|
|
r.cursor = 0
|
|
r.wrapped = false
|
|
}
|
|
|
|
// copy p to buffer, accounting for any wrapping as required
|
|
l = r.size - r.cursor
|
|
copy(r.buffer[r.cursor:], p)
|
|
if len(p) >= l {
|
|
r.wrapped = true
|
|
copy(r.buffer, p[l:])
|
|
}
|
|
|
|
// adjust cursor
|
|
r.cursor = ((r.cursor + len(p)) % r.size)
|
|
|
|
if len(p) > r.size {
|
|
return r.size, nil
|
|
}
|
|
return len(p), nil
|
|
}
|