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- // Copyright 2019 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- package json
- import (
- "bytes"
- "fmt"
- "strconv"
- )
- // Kind represents a token kind expressible in the JSON format.
- type Kind uint16
- const (
- Invalid Kind = (1 << iota) / 2
- EOF
- Null
- Bool
- Number
- String
- Name
- ObjectOpen
- ObjectClose
- ArrayOpen
- ArrayClose
- // comma is only for parsing in between tokens and
- // does not need to be exported.
- comma
- )
- func (k Kind) String() string {
- switch k {
- case EOF:
- return "eof"
- case Null:
- return "null"
- case Bool:
- return "bool"
- case Number:
- return "number"
- case String:
- return "string"
- case ObjectOpen:
- return "{"
- case ObjectClose:
- return "}"
- case Name:
- return "name"
- case ArrayOpen:
- return "["
- case ArrayClose:
- return "]"
- case comma:
- return ","
- }
- return "<invalid>"
- }
- // Token provides a parsed token kind and value.
- //
- // Values are provided by the difference accessor methods. The accessor methods
- // Name, Bool, and ParsedString will panic if called on the wrong kind. There
- // are different accessor methods for the Number kind for converting to the
- // appropriate Go numeric type and those methods have the ok return value.
- type Token struct {
- // Token kind.
- kind Kind
- // pos provides the position of the token in the original input.
- pos int
- // raw bytes of the serialized token.
- // This is a subslice into the original input.
- raw []byte
- // boo is parsed boolean value.
- boo bool
- // str is parsed string value.
- str string
- }
- // Kind returns the token kind.
- func (t Token) Kind() Kind {
- return t.kind
- }
- // RawString returns the read value in string.
- func (t Token) RawString() string {
- return string(t.raw)
- }
- // Pos returns the token position from the input.
- func (t Token) Pos() int {
- return t.pos
- }
- // Name returns the object name if token is Name, else it panics.
- func (t Token) Name() string {
- if t.kind == Name {
- return t.str
- }
- panic(fmt.Sprintf("Token is not a Name: %v", t.RawString()))
- }
- // Bool returns the bool value if token kind is Bool, else it panics.
- func (t Token) Bool() bool {
- if t.kind == Bool {
- return t.boo
- }
- panic(fmt.Sprintf("Token is not a Bool: %v", t.RawString()))
- }
- // ParsedString returns the string value for a JSON string token or the read
- // value in string if token is not a string.
- func (t Token) ParsedString() string {
- if t.kind == String {
- return t.str
- }
- panic(fmt.Sprintf("Token is not a String: %v", t.RawString()))
- }
- // Float returns the floating-point number if token kind is Number.
- //
- // The floating-point precision is specified by the bitSize parameter: 32 for
- // float32 or 64 for float64. If bitSize=32, the result still has type float64,
- // but it will be convertible to float32 without changing its value. It will
- // return false if the number exceeds the floating point limits for given
- // bitSize.
- func (t Token) Float(bitSize int) (float64, bool) {
- if t.kind != Number {
- return 0, false
- }
- f, err := strconv.ParseFloat(t.RawString(), bitSize)
- if err != nil {
- return 0, false
- }
- return f, true
- }
- // Int returns the signed integer number if token is Number.
- //
- // The given bitSize specifies the integer type that the result must fit into.
- // It returns false if the number is not an integer value or if the result
- // exceeds the limits for given bitSize.
- func (t Token) Int(bitSize int) (int64, bool) {
- s, ok := t.getIntStr()
- if !ok {
- return 0, false
- }
- n, err := strconv.ParseInt(s, 10, bitSize)
- if err != nil {
- return 0, false
- }
- return n, true
- }
- // Uint returns the signed integer number if token is Number.
- //
- // The given bitSize specifies the unsigned integer type that the result must
- // fit into. It returns false if the number is not an unsigned integer value
- // or if the result exceeds the limits for given bitSize.
- func (t Token) Uint(bitSize int) (uint64, bool) {
- s, ok := t.getIntStr()
- if !ok {
- return 0, false
- }
- n, err := strconv.ParseUint(s, 10, bitSize)
- if err != nil {
- return 0, false
- }
- return n, true
- }
- func (t Token) getIntStr() (string, bool) {
- if t.kind != Number {
- return "", false
- }
- parts, ok := parseNumberParts(t.raw)
- if !ok {
- return "", false
- }
- return normalizeToIntString(parts)
- }
- // TokenEquals returns true if given Tokens are equal, else false.
- func TokenEquals(x, y Token) bool {
- return x.kind == y.kind &&
- x.pos == y.pos &&
- bytes.Equal(x.raw, y.raw) &&
- x.boo == y.boo &&
- x.str == y.str
- }
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