1package yaml
2
3import (
4	"encoding/base64"
5	"math"
6	"regexp"
7	"strconv"
8	"strings"
9	"unicode/utf8"
10)
11
12type resolveMapItem struct {
13	value interface{}
14	tag   string
15}
16
17var resolveTable = make([]byte, 256)
18var resolveMap = make(map[string]resolveMapItem)
19
20func init() {
21	t := resolveTable
22	t[int('+')] = 'S' // Sign
23	t[int('-')] = 'S'
24	for _, c := range "0123456789" {
25		t[int(c)] = 'D' // Digit
26	}
27	for _, c := range "yYnNtTfFoO~" {
28		t[int(c)] = 'M' // In map
29	}
30	t[int('.')] = '.' // Float (potentially in map)
31
32	var resolveMapList = []struct {
33		v   interface{}
34		tag string
35		l   []string
36	}{
37		{true, yaml_BOOL_TAG, []string{"y", "Y", "yes", "Yes", "YES"}},
38		{true, yaml_BOOL_TAG, []string{"true", "True", "TRUE"}},
39		{true, yaml_BOOL_TAG, []string{"on", "On", "ON"}},
40		{false, yaml_BOOL_TAG, []string{"n", "N", "no", "No", "NO"}},
41		{false, yaml_BOOL_TAG, []string{"false", "False", "FALSE"}},
42		{false, yaml_BOOL_TAG, []string{"off", "Off", "OFF"}},
43		{nil, yaml_NULL_TAG, []string{"", "~", "null", "Null", "NULL"}},
44		{math.NaN(), yaml_FLOAT_TAG, []string{".nan", ".NaN", ".NAN"}},
45		{math.Inf(+1), yaml_FLOAT_TAG, []string{".inf", ".Inf", ".INF"}},
46		{math.Inf(+1), yaml_FLOAT_TAG, []string{"+.inf", "+.Inf", "+.INF"}},
47		{math.Inf(-1), yaml_FLOAT_TAG, []string{"-.inf", "-.Inf", "-.INF"}},
48		{"<<", yaml_MERGE_TAG, []string{"<<"}},
49	}
50
51	m := resolveMap
52	for _, item := range resolveMapList {
53		for _, s := range item.l {
54			m[s] = resolveMapItem{item.v, item.tag}
55		}
56	}
57}
58
59const longTagPrefix = "tag:yaml.org,2002:"
60
61func shortTag(tag string) string {
62	// TODO This can easily be made faster and produce less garbage.
63	if strings.HasPrefix(tag, longTagPrefix) {
64		return "!!" + tag[len(longTagPrefix):]
65	}
66	return tag
67}
68
69func longTag(tag string) string {
70	if strings.HasPrefix(tag, "!!") {
71		return longTagPrefix + tag[2:]
72	}
73	return tag
74}
75
76func resolvableTag(tag string) bool {
77	switch tag {
78	case "", yaml_STR_TAG, yaml_BOOL_TAG, yaml_INT_TAG, yaml_FLOAT_TAG, yaml_NULL_TAG:
79		return true
80	}
81	return false
82}
83
84var yamlStyleFloat = regexp.MustCompile(`^[-+]?[0-9]*\.?[0-9]+([eE][-+][0-9]+)?$`)
85
86func resolve(tag string, in string) (rtag string, out interface{}) {
87	if !resolvableTag(tag) {
88		return tag, in
89	}
90
91	defer func() {
92		switch tag {
93		case "", rtag, yaml_STR_TAG, yaml_BINARY_TAG:
94			return
95		}
96		failf("cannot decode %s `%s` as a %s", shortTag(rtag), in, shortTag(tag))
97	}()
98
99	// Any data is accepted as a !!str or !!binary.
100	// Otherwise, the prefix is enough of a hint about what it might be.
101	hint := byte('N')
102	if in != "" {
103		hint = resolveTable[in[0]]
104	}
105	if hint != 0 && tag != yaml_STR_TAG && tag != yaml_BINARY_TAG {
106		// Handle things we can lookup in a map.
107		if item, ok := resolveMap[in]; ok {
108			return item.tag, item.value
109		}
110
111		// Base 60 floats are a bad idea, were dropped in YAML 1.2, and
112		// are purposefully unsupported here. They're still quoted on
113		// the way out for compatibility with other parser, though.
114
115		switch hint {
116		case 'M':
117			// We've already checked the map above.
118
119		case '.':
120			// Not in the map, so maybe a normal float.
121			floatv, err := strconv.ParseFloat(in, 64)
122			if err == nil {
123				return yaml_FLOAT_TAG, floatv
124			}
125
126		case 'D', 'S':
127			// Int, float, or timestamp.
128			plain := strings.Replace(in, "_", "", -1)
129			intv, err := strconv.ParseInt(plain, 0, 64)
130			if err == nil {
131				if intv == int64(int(intv)) {
132					return yaml_INT_TAG, int(intv)
133				} else {
134					return yaml_INT_TAG, intv
135				}
136			}
137			uintv, err := strconv.ParseUint(plain, 0, 64)
138			if err == nil {
139				return yaml_INT_TAG, uintv
140			}
141			if yamlStyleFloat.MatchString(plain) {
142				floatv, err := strconv.ParseFloat(plain, 64)
143				if err == nil {
144					return yaml_FLOAT_TAG, floatv
145				}
146			}
147			if strings.HasPrefix(plain, "0b") {
148				intv, err := strconv.ParseInt(plain[2:], 2, 64)
149				if err == nil {
150					if intv == int64(int(intv)) {
151						return yaml_INT_TAG, int(intv)
152					} else {
153						return yaml_INT_TAG, intv
154					}
155				}
156				uintv, err := strconv.ParseUint(plain[2:], 2, 64)
157				if err == nil {
158					return yaml_INT_TAG, uintv
159				}
160			} else if strings.HasPrefix(plain, "-0b") {
161				intv, err := strconv.ParseInt(plain[3:], 2, 64)
162				if err == nil {
163					if intv == int64(int(intv)) {
164						return yaml_INT_TAG, -int(intv)
165					} else {
166						return yaml_INT_TAG, -intv
167					}
168				}
169			}
170			// XXX Handle timestamps here.
171
172		default:
173			panic("resolveTable item not yet handled: " + string(rune(hint)) + " (with " + in + ")")
174		}
175	}
176	if tag == yaml_BINARY_TAG {
177		return yaml_BINARY_TAG, in
178	}
179	if utf8.ValidString(in) {
180		return yaml_STR_TAG, in
181	}
182	return yaml_BINARY_TAG, encodeBase64(in)
183}
184
185// encodeBase64 encodes s as base64 that is broken up into multiple lines
186// as appropriate for the resulting length.
187func encodeBase64(s string) string {
188	const lineLen = 70
189	encLen := base64.StdEncoding.EncodedLen(len(s))
190	lines := encLen/lineLen + 1
191	buf := make([]byte, encLen*2+lines)
192	in := buf[0:encLen]
193	out := buf[encLen:]
194	base64.StdEncoding.Encode(in, []byte(s))
195	k := 0
196	for i := 0; i < len(in); i += lineLen {
197		j := i + lineLen
198		if j > len(in) {
199			j = len(in)
200		}
201		k += copy(out[k:], in[i:j])
202		if lines > 1 {
203			out[k] = '\n'
204			k++
205		}
206	}
207	return string(out[:k])
208}
209