334 lines
6.9 KiB
Go
334 lines
6.9 KiB
Go
// A modified version of Go's JSON implementation.
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// Copyright 2010, 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package json
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import (
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"bytes"
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"encoding/base64"
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"errors"
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"math"
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"strconv"
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"unicode/utf8"
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"github.com/d5/tengo/v2"
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)
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// safeSet holds the value true if the ASCII character with the given array
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// position can be represented inside a JSON string without any further
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// escaping.
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//
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// All values are true except for the ASCII control characters (0-31), the
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// double quote ("), and the backslash character ("\").
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var safeSet = [utf8.RuneSelf]bool{
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' ': true,
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'!': true,
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'"': false,
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'#': true,
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'$': true,
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'%': true,
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'&': true,
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'\'': true,
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'(': true,
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')': true,
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'*': true,
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'+': true,
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',': true,
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'-': true,
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'.': true,
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'/': true,
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'0': true,
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'1': true,
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'2': true,
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'3': true,
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'4': true,
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'5': true,
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'6': true,
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'7': true,
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'8': true,
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'9': true,
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':': true,
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';': true,
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'<': true,
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'=': true,
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'>': true,
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'?': true,
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'@': true,
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'A': true,
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'B': true,
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'C': true,
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'D': true,
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'E': true,
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'F': true,
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'G': true,
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'H': true,
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'I': true,
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'J': true,
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'K': true,
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'L': true,
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'M': true,
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'N': true,
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'O': true,
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'P': true,
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'Q': true,
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'R': true,
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'S': true,
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'T': true,
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'U': true,
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'V': true,
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'W': true,
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'X': true,
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'Y': true,
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'Z': true,
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'[': true,
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'\\': false,
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']': true,
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'^': true,
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'_': true,
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'`': true,
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'a': true,
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'b': true,
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'c': true,
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'd': true,
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'e': true,
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'f': true,
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'g': true,
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'h': true,
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'i': true,
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'j': true,
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'k': true,
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'l': true,
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'm': true,
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'n': true,
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'o': true,
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'p': true,
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'q': true,
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'r': true,
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's': true,
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't': true,
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'u': true,
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'v': true,
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'w': true,
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'x': true,
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'y': true,
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'z': true,
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'{': true,
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'|': true,
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'}': true,
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'~': true,
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'\u007f': true,
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}
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var hex = "0123456789abcdef"
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// Encode returns the JSON encoding of the object.
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func Encode(o tengo.Object) ([]byte, error) {
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var b []byte
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switch o := o.(type) {
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case *tengo.Array:
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b = append(b, '[')
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len1 := len(o.Value) - 1
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for idx, elem := range o.Value {
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eb, err := Encode(elem)
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if err != nil {
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return nil, err
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}
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b = append(b, eb...)
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if idx < len1 {
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b = append(b, ',')
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}
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}
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b = append(b, ']')
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case *tengo.ImmutableArray:
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b = append(b, '[')
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len1 := len(o.Value) - 1
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for idx, elem := range o.Value {
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eb, err := Encode(elem)
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if err != nil {
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return nil, err
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}
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b = append(b, eb...)
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if idx < len1 {
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b = append(b, ',')
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}
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}
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b = append(b, ']')
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case *tengo.Map:
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b = append(b, '{')
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len1 := len(o.Value) - 1
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idx := 0
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for key, value := range o.Value {
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b = encodeString(b, key)
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b = append(b, ':')
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eb, err := Encode(value)
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if err != nil {
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return nil, err
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}
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b = append(b, eb...)
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if idx < len1 {
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b = append(b, ',')
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}
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idx++
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}
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b = append(b, '}')
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case *tengo.ImmutableMap:
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b = append(b, '{')
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len1 := len(o.Value) - 1
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idx := 0
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for key, value := range o.Value {
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b = encodeString(b, key)
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b = append(b, ':')
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eb, err := Encode(value)
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if err != nil {
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return nil, err
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}
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b = append(b, eb...)
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if idx < len1 {
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b = append(b, ',')
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}
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idx++
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}
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b = append(b, '}')
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case *tengo.Bool:
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if o.IsFalsy() {
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b = strconv.AppendBool(b, false)
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} else {
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b = strconv.AppendBool(b, true)
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}
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case *tengo.Bytes:
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b = append(b, '"')
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encodedLen := base64.StdEncoding.EncodedLen(len(o.Value))
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dst := make([]byte, encodedLen)
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base64.StdEncoding.Encode(dst, o.Value)
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b = append(b, dst...)
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b = append(b, '"')
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case *tengo.Char:
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b = strconv.AppendInt(b, int64(o.Value), 10)
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case *tengo.Float:
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var y []byte
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f := o.Value
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if math.IsInf(f, 0) || math.IsNaN(f) {
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return nil, errors.New("unsupported float value")
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}
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// Convert as if by ES6 number to string conversion.
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// This matches most other JSON generators.
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abs := math.Abs(f)
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fmt := byte('f')
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if abs != 0 {
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if abs < 1e-6 || abs >= 1e21 {
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fmt = 'e'
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}
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}
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y = strconv.AppendFloat(y, f, fmt, -1, 64)
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if fmt == 'e' {
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// clean up e-09 to e-9
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n := len(y)
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if n >= 4 && y[n-4] == 'e' && y[n-3] == '-' && y[n-2] == '0' {
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y[n-2] = y[n-1]
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y = y[:n-1]
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}
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}
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b = append(b, y...)
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case *tengo.Int:
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b = strconv.AppendInt(b, o.Value, 10)
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case *tengo.String:
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// string encoding bug is fixed with newly introduced function
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// encodeString(). See: https://github.com/d5/tengo/issues/268
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b = encodeString(b, o.Value)
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case *tengo.Time:
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y, err := o.Value.MarshalJSON()
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if err != nil {
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return nil, err
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}
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b = append(b, y...)
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case *tengo.Undefined:
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b = append(b, "null"...)
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default:
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// unknown type: ignore
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}
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return b, nil
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}
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// encodeString encodes given string as JSON string according to
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// https://www.json.org/img/string.png
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// Implementation is inspired by https://github.com/json-iterator/go
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// See encodeStringSlowPath() for more information.
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func encodeString(b []byte, val string) []byte {
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valLen := len(val)
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buf := bytes.NewBuffer(b)
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buf.WriteByte('"')
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// write string, the fast path, without utf8 and escape support
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i := 0
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for ; i < valLen; i++ {
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c := val[i]
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if c > 31 && c != '"' && c != '\\' {
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buf.WriteByte(c)
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} else {
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break
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}
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}
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if i == valLen {
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buf.WriteByte('"')
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return buf.Bytes()
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}
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encodeStringSlowPath(buf, i, val, valLen)
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buf.WriteByte('"')
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return buf.Bytes()
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}
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// encodeStringSlowPath is ported from Go 1.14.2 encoding/json package.
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// U+2028 U+2029 JSONP security holes can be fixed with addition call to
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// json.html_escape() thus it is removed from the implementation below.
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// Note: Invalid runes are not checked as they are checked in original
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// implementation.
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func encodeStringSlowPath(buf *bytes.Buffer, i int, val string, valLen int) {
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start := i
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for i < valLen {
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if b := val[i]; b < utf8.RuneSelf {
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if safeSet[b] {
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i++
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continue
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}
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if start < i {
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buf.WriteString(val[start:i])
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}
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buf.WriteByte('\\')
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switch b {
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case '\\', '"':
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buf.WriteByte(b)
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case '\n':
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buf.WriteByte('n')
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case '\r':
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buf.WriteByte('r')
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case '\t':
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buf.WriteByte('t')
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default:
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// This encodes bytes < 0x20 except for \t, \n and \r.
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// If escapeHTML is set, it also escapes <, >, and &
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// because they can lead to security holes when
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// user-controlled strings are rendered into JSON
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// and served to some browsers.
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buf.WriteString(`u00`)
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buf.WriteByte(hex[b>>4])
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buf.WriteByte(hex[b&0xF])
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}
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i++
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start = i
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continue
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}
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i++
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continue
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}
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if start < valLen {
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buf.WriteString(val[start:])
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}
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}
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