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path: root/vendor/github.com/robertkrimen/otto/value_string.go
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package otto

import (
    "fmt"
    "math"
    "regexp"
    "strconv"
    "unicode/utf16"
)

var matchLeading0Exponent = regexp.MustCompile(`([eE][\+\-])0+([1-9])`) // 1e-07 => 1e-7

// FIXME
// https://code.google.com/p/v8/source/browse/branches/bleeding_edge/src/conversions.cc?spec=svn18082&r=18082
func floatToString(value float64, bitsize int) string {
    // TODO Fit to ECMA-262 9.8.1 specification
    if math.IsNaN(value) {
        return "NaN"
    } else if math.IsInf(value, 0) {
        if math.Signbit(value) {
            return "-Infinity"
        }
        return "Infinity"
    }
    exponent := math.Log10(math.Abs(value))
    if exponent >= 21 || exponent < -6 {
        return matchLeading0Exponent.ReplaceAllString(strconv.FormatFloat(value, 'g', -1, bitsize), "$1$2")
    }
    return strconv.FormatFloat(value, 'f', -1, bitsize)
}

func numberToStringRadix(value Value, radix int) string {
    float := value.float64()
    if math.IsNaN(float) {
        return "NaN"
    } else if math.IsInf(float, 1) {
        return "Infinity"
    } else if math.IsInf(float, -1) {
        return "-Infinity"
    }
    // FIXME This is very broken
    // Need to do proper radix conversion for floats, ...
    // This truncates large floats (so bad).
    return strconv.FormatInt(int64(float), radix)
}

func (value Value) string() string {
    if value.kind == valueString {
        switch value := value.value.(type) {
        case string:
            return value
        case []uint16:
            return string(utf16.Decode(value))
        }
    }
    if value.IsUndefined() {
        return "undefined"
    }
    if value.IsNull() {
        return "null"
    }
    switch value := value.value.(type) {
    case bool:
        return strconv.FormatBool(value)
    case int:
        return strconv.FormatInt(int64(value), 10)
    case int8:
        return strconv.FormatInt(int64(value), 10)
    case int16:
        return strconv.FormatInt(int64(value), 10)
    case int32:
        return strconv.FormatInt(int64(value), 10)
    case int64:
        return strconv.FormatInt(value, 10)
    case uint:
        return strconv.FormatUint(uint64(value), 10)
    case uint8:
        return strconv.FormatUint(uint64(value), 10)
    case uint16:
        return strconv.FormatUint(uint64(value), 10)
    case uint32:
        return strconv.FormatUint(uint64(value), 10)
    case uint64:
        return strconv.FormatUint(value, 10)
    case float32:
        if value == 0 {
            return "0" // Take care not to return -0
        }
        return floatToString(float64(value), 32)
    case float64:
        if value == 0 {
            return "0" // Take care not to return -0
        }
        return floatToString(value, 64)
    case []uint16:
        return string(utf16.Decode(value))
    case string:
        return value
    case *_object:
        return value.DefaultValue(defaultValueHintString).string()
    }
    panic(fmt.Errorf("%v.string( %T)", value.value, value.value))
}