gtsocial-umbx

resolve.go (8514B)

---

 //
 // Copyright (c) 2011-2019 Canonical Ltd
 //
 // 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 yaml
 
 import (
 	"encoding/base64"
 	"math"
 	"regexp"
 	"strconv"
 	"strings"
 	"time"
 )
 
 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, boolTag, []string{"true", "True", "TRUE"}},
 		{false, boolTag, []string{"false", "False", "FALSE"}},
 		{nil, nullTag, []string{"", "~", "null", "Null", "NULL"}},
 		{math.NaN(), floatTag, []string{".nan", ".NaN", ".NAN"}},
 		{math.Inf(+1), floatTag, []string{".inf", ".Inf", ".INF"}},
 		{math.Inf(+1), floatTag, []string{"+.inf", "+.Inf", "+.INF"}},
 		{math.Inf(-1), floatTag, []string{"-.inf", "-.Inf", "-.INF"}},
 		{"<<", mergeTag, []string{"<<"}},
 	}
 
 	m := resolveMap
 	for _, item := range resolveMapList {
 		for _, s := range item.l {
 			m[s] = resolveMapItem{item.v, item.tag}
 		}
 	}
 }
 
 const (
 	nullTag      = "!!null"
 	boolTag      = "!!bool"
 	strTag       = "!!str"
 	intTag       = "!!int"
 	floatTag     = "!!float"
 	timestampTag = "!!timestamp"
 	seqTag       = "!!seq"
 	mapTag       = "!!map"
 	binaryTag    = "!!binary"
 	mergeTag     = "!!merge"
 )
 
 var longTags = make(map[string]string)
 var shortTags = make(map[string]string)
 
 func init() {
 	for _, stag := range []string{nullTag, boolTag, strTag, intTag, floatTag, timestampTag, seqTag, mapTag, binaryTag, mergeTag} {
 		ltag := longTag(stag)
 		longTags[stag] = ltag
 		shortTags[ltag] = stag
 	}
 }
 
 const longTagPrefix = "tag:yaml.org,2002:"
 
 func shortTag(tag string) string {
 	if strings.HasPrefix(tag, longTagPrefix) {
 		if stag, ok := shortTags[tag]; ok {
 			return stag
 		}
 		return "!!" + tag[len(longTagPrefix):]
 	}
 	return tag
 }
 
 func longTag(tag string) string {
 	if strings.HasPrefix(tag, "!!") {
 		if ltag, ok := longTags[tag]; ok {
 			return ltag
 		}
 		return longTagPrefix + tag[2:]
 	}
 	return tag
 }
 
 func resolvableTag(tag string) bool {
 	switch tag {
 	case "", strTag, boolTag, intTag, floatTag, nullTag, timestampTag:
 		return true
 	}
 	return false
 }
 
 var yamlStyleFloat = regexp.MustCompile(`^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$`)
 
 func resolve(tag string, in string) (rtag string, out interface{}) {
 	tag = shortTag(tag)
 	if !resolvableTag(tag) {
 		return tag, in
 	}
 
 	defer func() {
 		switch tag {
 		case "", rtag, strTag, binaryTag:
 			return
 		case floatTag:
 			if rtag == intTag {
 				switch v := out.(type) {
 				case int64:
 					rtag = floatTag
 					out = float64(v)
 					return
 				case int:
 					rtag = floatTag
 					out = float64(v)
 					return
 				}
 			}
 		}
 		failf("cannot decode %s `%s` as a %s", shortTag(rtag), in, shortTag(tag))
 	}()
 
 	// Any data is accepted as a !!str or !!binary.
 	// Otherwise, the prefix is enough of a hint about what it might be.
 	hint := byte('N')
 	if in != "" {
 		hint = resolveTable[in[0]]
 	}
 	if hint != 0 && tag != strTag && tag != binaryTag {
 		// Handle things we can lookup in a map.
 		if item, ok := resolveMap[in]; ok {
 			return item.tag, item.value
 		}
 
 		// Base 60 floats are a bad idea, were dropped in YAML 1.2, and
 		// are purposefully unsupported here. They're still quoted on
 		// the way out for compatibility with other parser, though.
 
 		switch hint {
 		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 floatTag, floatv
 			}
 
 		case 'D', 'S':
 			// Int, float, or timestamp.
 			// Only try values as a timestamp if the value is unquoted or there's an explicit
 			// !!timestamp tag.
 			if tag == "" || tag == timestampTag {
 				t, ok := parseTimestamp(in)
 				if ok {
 					return timestampTag, t
 				}
 			}
 
 			plain := strings.Replace(in, "_", "", -1)
 			intv, err := strconv.ParseInt(plain, 0, 64)
 			if err == nil {
 				if intv == int64(int(intv)) {
 					return intTag, int(intv)
 				} else {
 					return intTag, intv
 				}
 			}
 			uintv, err := strconv.ParseUint(plain, 0, 64)
 			if err == nil {
 				return intTag, uintv
 			}
 			if yamlStyleFloat.MatchString(plain) {
 				floatv, err := strconv.ParseFloat(plain, 64)
 				if err == nil {
 					return floatTag, floatv
 				}
 			}
 			if strings.HasPrefix(plain, "0b") {
 				intv, err := strconv.ParseInt(plain[2:], 2, 64)
 				if err == nil {
 					if intv == int64(int(intv)) {
 						return intTag, int(intv)
 					} else {
 						return intTag, intv
 					}
 				}
 				uintv, err := strconv.ParseUint(plain[2:], 2, 64)
 				if err == nil {
 					return intTag, uintv
 				}
 			} else if strings.HasPrefix(plain, "-0b") {
 				intv, err := strconv.ParseInt("-"+plain[3:], 2, 64)
 				if err == nil {
 					if true || intv == int64(int(intv)) {
 						return intTag, int(intv)
 					} else {
 						return intTag, intv
 					}
 				}
 			}
 			// Octals as introduced in version 1.2 of the spec.
 			// Octals from the 1.1 spec, spelled as 0777, are still
 			// decoded by default in v3 as well for compatibility.
 			// May be dropped in v4 depending on how usage evolves.
 			if strings.HasPrefix(plain, "0o") {
 				intv, err := strconv.ParseInt(plain[2:], 8, 64)
 				if err == nil {
 					if intv == int64(int(intv)) {
 						return intTag, int(intv)
 					} else {
 						return intTag, intv
 					}
 				}
 				uintv, err := strconv.ParseUint(plain[2:], 8, 64)
 				if err == nil {
 					return intTag, uintv
 				}
 			} else if strings.HasPrefix(plain, "-0o") {
 				intv, err := strconv.ParseInt("-"+plain[3:], 8, 64)
 				if err == nil {
 					if true || intv == int64(int(intv)) {
 						return intTag, int(intv)
 					} else {
 						return intTag, intv
 					}
 				}
 			}
 		default:
 			panic("internal error: missing handler for resolver table: " + string(rune(hint)) + " (with " + in + ")")
 		}
 	}
 	return strTag, in
 }
 
 // encodeBase64 encodes s as base64 that is broken up into multiple lines
 // as appropriate for the resulting length.
 func encodeBase64(s string) string {
 	const lineLen = 70
 	encLen := base64.StdEncoding.EncodedLen(len(s))
 	lines := encLen/lineLen + 1
 	buf := make([]byte, encLen*2+lines)
 	in := buf[0:encLen]
 	out := buf[encLen:]
 	base64.StdEncoding.Encode(in, []byte(s))
 	k := 0
 	for i := 0; i < len(in); i += lineLen {
 		j := i + lineLen
 		if j > len(in) {
 			j = len(in)
 		}
 		k += copy(out[k:], in[i:j])
 		if lines > 1 {
 			out[k] = '\n'
 			k++
 		}
 	}
 	return string(out[:k])
 }
 
 // This is a subset of the formats allowed by the regular expression
 // defined at http://yaml.org/type/timestamp.html.
 var allowedTimestampFormats = []string{
 	"2006-1-2T15:4:5.999999999Z07:00", // RCF3339Nano with short date fields.
 	"2006-1-2t15:4:5.999999999Z07:00", // RFC3339Nano with short date fields and lower-case "t".
 	"2006-1-2 15:4:5.999999999",       // space separated with no time zone
 	"2006-1-2",                        // date only
 	// Notable exception: time.Parse cannot handle: "2001-12-14 21:59:43.10 -5"
 	// from the set of examples.
 }
 
 // parseTimestamp parses s as a timestamp string and
 // returns the timestamp and reports whether it succeeded.
 // Timestamp formats are defined at http://yaml.org/type/timestamp.html
 func parseTimestamp(s string) (time.Time, bool) {
 	// TODO write code to check all the formats supported by
 	// http://yaml.org/type/timestamp.html instead of using time.Parse.
 
 	// Quick check: all date formats start with YYYY-.
 	i := 0
 	for ; i < len(s); i++ {
 		if c := s[i]; c < '0' || c > '9' {
 			break
 		}
 	}
 	if i != 4 || i == len(s) || s[i] != '-' {
 		return time.Time{}, false
 	}
 	for _, format := range allowedTimestampFormats {
 		if t, err := time.Parse(format, s); err == nil {
 			return t, true
 		}
 	}
 	return time.Time{}, false
 }