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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package lowmemjson
import (
"errors"
"io"
)
type runeTypeScanner interface {
// The returned error is a *ReadError, a *SyntaxError, or nil.
// An EOF condition is represented as one of:
//
// end of value but not file: (_, >0, RuneTypeEOF, nil)
// end of both value and file: (_, 0, RuneTypeEOF, nil)
// end of file in middle of value: (_, 0, RuneTypeError, &DecodeSyntaxError{Offset: offset: Err: io.ErrUnexepctedEOF})
// end of file at start of value: (_, 0, RuneTypeError, &DecodeSyntaxError{Offset: offset: Err: io.EOF})
ReadRuneType() (rune, int, RuneType, error)
// The returned error is a *DecodeReadError, a *DecodeSyntaxError, io.EOF, or nil.
ReadRune() (rune, int, error)
UnreadRune() error
Reset()
InputOffset() int64
}
// runeTypeScannerImpl /////////////////////////////////////////////////////////////////////////////
type runeTypeScannerImpl struct {
inner io.RuneScanner
initialized bool
parser Parser
offset int64
repeat bool
stuck bool
rRune rune
rRuneOK bool
rSize int
rType RuneType
rErr error
}
var _ runeTypeScanner = (*runeTypeScannerImpl)(nil)
func (sc *runeTypeScannerImpl) Reset() {
sc.parser.Reset()
unread := sc.stuck && sc.rType == RuneTypeEOF && sc.rRuneOK
sc.stuck = false
sc.repeat = false
if unread {
// re-figure the rType and rErr
var err error
sc.rType, err = sc.parser.HandleRune(sc.rRune)
if err != nil {
sc.rErr = &DecodeSyntaxError{
Offset: sc.offset,
Err: err,
}
} else {
sc.rErr = nil
}
// tell it to use that rType and rErr
_ = sc.UnreadRune() // we set it up to always succeed
}
}
func (sc *runeTypeScannerImpl) ReadRuneType() (rune, int, RuneType, error) {
switch {
case sc.stuck:
// do nothing
case sc.repeat:
_, _, _ = sc.inner.ReadRune()
default:
var err error
sc.rRune, sc.rSize, err = sc.inner.ReadRune()
sc.offset += int64(sc.rSize)
sc.rRuneOK = err == nil
switch err {
case nil:
sc.rType, err = sc.parser.HandleRune(sc.rRune)
if err != nil {
sc.rErr = &DecodeSyntaxError{
Offset: sc.offset,
Err: err,
}
} else {
sc.rErr = nil
}
case io.EOF:
sc.rType, err = sc.parser.HandleEOF()
if err != nil {
sc.rErr = &DecodeSyntaxError{
Offset: sc.offset,
Err: err,
}
} else {
sc.rErr = nil
}
default:
sc.rType = 0
sc.rErr = &DecodeReadError{
Offset: sc.offset,
Err: err,
}
}
}
sc.initialized = true
sc.repeat = false
sc.stuck = sc.rType == RuneTypeEOF || sc.rType == RuneTypeError
return sc.rRune, sc.rSize, sc.rType, sc.rErr
}
func (sc *runeTypeScannerImpl) ReadRune() (rune, int, error) {
r, s, t, e := sc.ReadRuneType()
switch t {
case RuneTypeEOF:
return 0, 0, io.EOF
case RuneTypeError:
return 0, 0, e
default:
return r, s, nil
}
}
// UnreadRune undoes a call to .ReadRune() or .ReadRuneType().
//
// If the last call to .ReadRune() or .ReadRuneType() has already been
// unread, or if that call returned a rune with size 0, then
// ErrInvalidUnreadRune is returned. Otherwise, nil is returned.
func (sc *runeTypeScannerImpl) UnreadRune() error {
if !sc.initialized || sc.repeat || sc.rSize == 0 {
return ErrInvalidUnreadRune
}
sc.repeat = true
_ = sc.inner.UnreadRune()
return nil
}
func (sc *runeTypeScannerImpl) InputOffset() int64 {
ret := sc.offset
if sc.repeat {
ret -= int64(sc.rSize)
}
return ret
}
// noWSRuneTypeScanner /////////////////////////////////////////////////////////////////////////////
type noWSRuneTypeScanner struct {
inner runeTypeScanner
}
var _ runeTypeScanner = (*noWSRuneTypeScanner)(nil)
func (sc *noWSRuneTypeScanner) ReadRuneType() (rune, int, RuneType, error) {
again:
r, s, t, e := sc.inner.ReadRuneType()
if t == RuneTypeSpace {
goto again
}
return r, s, t, e
}
func (sc *noWSRuneTypeScanner) ReadRune() (rune, int, error) {
r, s, t, e := sc.ReadRuneType()
switch t {
case RuneTypeEOF:
return 0, 0, io.EOF
case RuneTypeError:
return 0, 0, e
default:
return r, s, nil
}
}
func (sc *noWSRuneTypeScanner) UnreadRune() error { return sc.inner.UnreadRune() }
func (sc *noWSRuneTypeScanner) Reset() { sc.inner.Reset() }
func (sc *noWSRuneTypeScanner) InputOffset() int64 { return sc.inner.InputOffset() }
// elemRuneTypeScanner /////////////////////////////////////////////////////////////////////////////
type elemRuneTypeScanner struct {
inner runeTypeScanner
parser Parser
repeat bool
stuck bool
rType RuneType
rErr error
}
var _ runeTypeScanner = (*elemRuneTypeScanner)(nil)
func (sc *elemRuneTypeScanner) ReadRuneType() (rune, int, RuneType, error) {
// Read it, run it through the parent's parser.
r, s, t, e := sc.inner.ReadRuneType()
// Run it through our child parser.
if s > 0 || errors.Is(e, io.ErrUnexpectedEOF) {
if sc.repeat || sc.stuck {
sc.repeat = false
} else {
var err error
if s > 0 {
sc.rType, err = sc.parser.HandleRune(r)
} else {
sc.rType, err = sc.parser.HandleEOF()
}
if err != nil {
sc.rErr = &DecodeSyntaxError{
Offset: sc.inner.InputOffset(),
Err: err,
}
} else {
sc.rErr = nil
}
}
sc.stuck = sc.rType == RuneTypeEOF || sc.rType == RuneTypeError
t, e = sc.rType, sc.rErr
}
// Check if we need to truncate the result.
if t == RuneTypeEOF {
if s > 0 {
_ = sc.inner.UnreadRune()
}
return 0, 0, RuneTypeEOF, nil
}
return r, s, t, e
}
func (sc *elemRuneTypeScanner) ReadRune() (rune, int, error) {
r, s, t, e := sc.ReadRuneType()
switch t {
case RuneTypeEOF:
return 0, 0, io.EOF
case RuneTypeError:
return 0, 0, e
default:
return r, s, nil
}
}
func (sc *elemRuneTypeScanner) UnreadRune() error {
ret := sc.inner.UnreadRune()
sc.repeat = true
return ret
}
func (sc *elemRuneTypeScanner) InputOffset() int64 { return sc.inner.InputOffset() }
func (sc *elemRuneTypeScanner) Reset() {}
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