resolve.go
3.28 KB
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package yaml
import (
"math"
"strconv"
"strings"
)
// TODO: merge, timestamps, base 60 floats, omap.
type resolveMapItem struct {
value interface{}
tag string
}
var resolveTable = make([]byte, 256)
var resolveMap = make(map[string]resolveMapItem)
func init() {
t := resolveTable
t[int('+')] = 'S' // Sign
t[int('-')] = 'S'
for _, c := range "0123456789" {
t[int(c)] = 'D' // Digit
}
for _, c := range "yYnNtTfFoO~" {
t[int(c)] = 'M' // In map
}
t[int('.')] = '.' // Float (potentially in map)
var resolveMapList = []struct {
v interface{}
tag string
l []string
}{
{true, "!!bool", []string{"y", "Y", "yes", "Yes", "YES"}},
{true, "!!bool", []string{"true", "True", "TRUE"}},
{true, "!!bool", []string{"on", "On", "ON"}},
{false, "!!bool", []string{"n", "N", "no", "No", "NO"}},
{false, "!!bool", []string{"false", "False", "FALSE"}},
{false, "!!bool", []string{"off", "Off", "OFF"}},
{nil, "!!null", []string{"~", "null", "Null", "NULL"}},
{math.NaN(), "!!float", []string{".nan", ".NaN", ".NAN"}},
{math.Inf(+1), "!!float", []string{".inf", ".Inf", ".INF"}},
{math.Inf(+1), "!!float", []string{"+.inf", "+.Inf", "+.INF"}},
{math.Inf(-1), "!!float", []string{"-.inf", "-.Inf", "-.INF"}},
{"<<", "!!merge", []string{"<<"}},
}
m := resolveMap
for _, item := range resolveMapList {
for _, s := range item.l {
m[s] = resolveMapItem{item.v, item.tag}
}
}
}
const longTagPrefix = "tag:yaml.org,2002:"
func shortTag(tag string) string {
if strings.HasPrefix(tag, longTagPrefix) {
return "!!" + tag[len(longTagPrefix):]
}
return tag
}
func resolvableTag(tag string) bool {
switch tag {
case "", "!!str", "!!bool", "!!int", "!!float", "!!null":
return true
}
return false
}
func resolve(tag string, in string) (rtag string, out interface{}) {
tag = shortTag(tag)
if !resolvableTag(tag) {
return tag, in
}
defer func() {
if tag != "" && tag != rtag {
panic("Can't decode " + rtag + " '" + in + "' as a " + tag)
}
}()
if in == "" {
return "!!null", nil
}
c := resolveTable[in[0]]
if c == 0 {
// It's a string for sure. Nothing to do.
return "!!str", in
}
// Handle things we can lookup in a map.
if item, ok := resolveMap[in]; ok {
return item.tag, item.value
}
switch c {
case 'M':
// We've already checked the map above.
case '.':
// Not in the map, so maybe a normal float.
floatv, err := strconv.ParseFloat(in, 64)
if err == nil {
return "!!float", floatv
}
// XXX Handle base 60 floats here (WTF!)
case 'D', 'S':
// Int, float, or timestamp.
plain := strings.Replace(in, "_", "", -1)
intv, err := strconv.ParseInt(plain, 0, 64)
if err == nil {
if intv == int64(int(intv)) {
return "!!int", int(intv)
} else {
return "!!int", intv
}
}
floatv, err := strconv.ParseFloat(plain, 64)
if err == nil {
return "!!float", floatv
}
if strings.HasPrefix(plain, "0b") {
intv, err := strconv.ParseInt(plain[2:], 2, 64)
if err == nil {
return "!!int", int(intv)
}
} else if strings.HasPrefix(plain, "-0b") {
intv, err := strconv.ParseInt(plain[3:], 2, 64)
if err == nil {
return "!!int", -int(intv)
}
}
// XXX Handle timestamps here.
default:
panic("resolveTable item not yet handled: " +
string([]byte{c}) + " (with " + in + ")")
}
return "!!str", in
}