github.com/goshafaq/sonic@v0.0.0-20231026082336-871835fb94c6/internal/decoder/decoder.go

/*
 * Copyright 2021 ByteDance Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package decoder

import (
	"encoding/json"
	"reflect"
	"runtime"
	"unsafe"

	"github.com/goshafaq/sonic/internal/native"
	"github.com/goshafaq/sonic/internal/native/types"
	"github.com/goshafaq/sonic/internal/rt"
	"github.com/goshafaq/sonic/option"
	"github.com/goshafaq/sonic/utf8"
)

const (
	_F_use_int64       = 0
	_F_disable_urc     = 2
	_F_disable_unknown = 3
	_F_copy_string     = 4

	_F_use_number      = types.B_USE_NUMBER
	_F_validate_string = types.B_VALIDATE_STRING
	_F_allow_control   = types.B_ALLOW_CONTROL
)

type Options uint64

const (
	OptionUseInt64         Options = 1 << _F_use_int64
	OptionUseNumber        Options = 1 << _F_use_number
	OptionUseUnicodeErrors Options = 1 << _F_disable_urc
	OptionDisableUnknown   Options = 1 << _F_disable_unknown
	OptionCopyString       Options = 1 << _F_copy_string
	OptionValidateString   Options = 1 << _F_validate_string
)

func (self *Decoder) SetOptions(opts Options) {
	if (opts&OptionUseNumber != 0) && (opts&OptionUseInt64 != 0) {
		panic("can't set OptionUseInt64 and OptionUseNumber both!")
	}
	self.f = uint64(opts)
}

// Decoder is the decoder context object
type Decoder struct {
	i int
	f uint64
	s string
}

// NewDecoder creates a new decoder instance.
func NewDecoder(s string) *Decoder {
	return &Decoder{s: s}
}

// Pos returns the current decoding position.
func (self *Decoder) Pos() int {
	return self.i
}

func (self *Decoder) Reset(s string) {
	self.s = s
	self.i = 0
	// self.f = 0
}

func (self *Decoder) CheckTrailings() error {
	pos := self.i
	buf := self.s
	/* skip all the trailing spaces */
	if pos != len(buf) {
		for pos < len(buf) && (types.SPACE_MASK&(1<<buf[pos])) != 0 {
			pos++
		}
	}

	/* then it must be at EOF */
	if pos == len(buf) {
		return nil
	}

	/* junk after JSON value */
	return SyntaxError{
		Src:  buf,
		Pos:  pos,
		Code: types.ERR_INVALID_CHAR,
	}
}

// Decode parses the JSON-encoded data from current position and stores the result
// in the value pointed to by val.
func (self *Decoder) Decode(val interface{}) error {
	/* validate json if needed */
	if (self.f&(1<<_F_validate_string)) != 0 && !utf8.ValidateString(self.s) {
		dbuf := utf8.CorrectWith(nil, rt.Str2Mem(self.s), "\ufffd")
		self.s = rt.Mem2Str(dbuf)
	}

	vv := rt.UnpackEface(val)
	vp := vv.Value

	/* check for nil type */
	if vv.Type == nil {
		return &json.InvalidUnmarshalError{}
	}

	/* must be a non-nil pointer */
	if vp == nil || vv.Type.Kind() != reflect.Ptr {
		return &json.InvalidUnmarshalError{Type: vv.Type.Pack()}
	}

	etp := rt.PtrElem(vv.Type)

	/* check the defined pointer type for issue 379 */
	if vv.Type.IsNamed() {
		newp := vp
		etp = vv.Type
		vp = unsafe.Pointer(&newp)
	}

	/* create a new stack, and call the decoder */
	sb := newStack()
	nb, err := decodeTypedPointer(self.s, self.i, etp, vp, sb, self.f)
	/* return the stack back */
	self.i = nb
	freeStack(sb)

	/* avoid GC ahead */
	runtime.KeepAlive(vv)
	return err
}

// UseInt64 indicates the Decoder to unmarshal an integer into an interface{} as an
// int64 instead of as a float64.
func (self *Decoder) UseInt64() {
	self.f |= 1 << _F_use_int64
	self.f &^= 1 << _F_use_number
}

// UseNumber indicates the Decoder to unmarshal a number into an interface{} as a
// json.Number instead of as a float64.
func (self *Decoder) UseNumber() {
	self.f &^= 1 << _F_use_int64
	self.f |= 1 << _F_use_number
}

// UseUnicodeErrors indicates the Decoder to return an error when encounter invalid
// UTF-8 escape sequences.
func (self *Decoder) UseUnicodeErrors() {
	self.f |= 1 << _F_disable_urc
}

// DisallowUnknownFields indicates the Decoder to return an error when the destination
// is a struct and the input contains object keys which do not match any
// non-ignored, exported fields in the destination.
func (self *Decoder) DisallowUnknownFields() {
	self.f |= 1 << _F_disable_unknown
}

// CopyString indicates the Decoder to decode string values by copying instead of referring.
func (self *Decoder) CopyString() {
	self.f |= 1 << _F_copy_string
}

// ValidateString causes the Decoder to validate string values when decoding string value
// in JSON. Validation is that, returning error when unescaped control chars(0x00-0x1f) or
// invalid UTF-8 chars in the string value of JSON.
func (self *Decoder) ValidateString() {
	self.f |= 1 << _F_validate_string
}

// Pretouch compiles vt ahead-of-time to avoid JIT compilation on-the-fly, in
// order to reduce the first-hit latency.
//
// Opts are the compile options, for example, "option.WithCompileRecursiveDepth" is
// a compile option to set the depth of recursive compile for the nested struct type.
func Pretouch(vt reflect.Type, opts ...option.CompileOption) error {
	cfg := option.DefaultCompileOptions()
	for _, opt := range opts {
		opt(&cfg)
	}
	return pretouchRec(map[reflect.Type]bool{vt: true}, cfg)
}

func pretouchType(_vt reflect.Type, opts option.CompileOptions) (map[reflect.Type]bool, error) {
	/* compile function */
	compiler := newCompiler().apply(opts)
	decoder := func(vt *rt.GoType, _ ...interface{}) (interface{}, error) {
		if pp, err := compiler.compile(_vt); err != nil {
			return nil, err
		} else {
			as := newAssembler(pp)
			as.name = _vt.String()
			return as.Load(), nil
		}
	}

	/* find or compile */
	vt := rt.UnpackType(_vt)
	if val := programCache.Get(vt); val != nil {
		return nil, nil
	} else if _, err := programCache.Compute(vt, decoder); err == nil {
		return compiler.rec, nil
	} else {
		return nil, err
	}
}

func pretouchRec(vtm map[reflect.Type]bool, opts option.CompileOptions) error {
	if opts.RecursiveDepth < 0 || len(vtm) == 0 {
		return nil
	}
	next := make(map[reflect.Type]bool)
	for vt := range vtm {
		sub, err := pretouchType(vt, opts)
		if err != nil {
			return err
		}
		for svt := range sub {
			next[svt] = true
		}
	}
	opts.RecursiveDepth -= 1
	return pretouchRec(next, opts)
}

// Skip skips only one json value, and returns first non-blank character position and its ending position if it is valid.
// Otherwise, returns negative error code using start and invalid character position using end
func Skip(data []byte) (start int, end int) {
	s := rt.Mem2Str(data)
	p := 0
	m := types.NewStateMachine()
	ret := native.SkipOne(&s, &p, m, uint64(0))
	types.FreeStateMachine(m)
	return ret, p
}