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1 | // Licensed to the Apache Software Foundation (ASF) under one |
2 | // or more contributor license agreements. See the NOTICE file | |
3 | // distributed with this work for additional information | |
4 | // regarding copyright ownership. The ASF licenses this file | |
5 | // to you under the Apache License, Version 2.0 (the | |
6 | // "License"); you may not use this file except in compliance | |
7 | // with the License. You may obtain a copy of the License at | |
8 | // | |
9 | // http://www.apache.org/licenses/LICENSE-2.0 | |
10 | // | |
11 | // Unless required by applicable law or agreed to in writing, software | |
12 | // distributed under the License is distributed on an "AS IS" BASIS, | |
13 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
14 | // See the License for the specific language governing permissions and | |
15 | // limitations under the License. | |
16 | ||
17 | package arrow | |
18 | ||
19 | import ( | |
20 | "fmt" | |
21 | "sort" | |
22 | "strings" | |
23 | ) | |
24 | ||
25 | type Metadata struct { | |
26 | keys []string | |
27 | values []string | |
28 | } | |
29 | ||
30 | func NewMetadata(keys, values []string) Metadata { | |
31 | if len(keys) != len(values) { | |
32 | panic("arrow: len mismatch") | |
33 | } | |
34 | ||
35 | n := len(keys) | |
36 | if n == 0 { | |
37 | return Metadata{} | |
38 | } | |
39 | ||
40 | md := Metadata{ | |
41 | keys: make([]string, n), | |
42 | values: make([]string, n), | |
43 | } | |
44 | copy(md.keys, keys) | |
45 | copy(md.values, values) | |
46 | return md | |
47 | } | |
48 | ||
49 | func MetadataFrom(kv map[string]string) Metadata { | |
50 | md := Metadata{ | |
51 | keys: make([]string, 0, len(kv)), | |
52 | values: make([]string, 0, len(kv)), | |
53 | } | |
54 | for k := range kv { | |
55 | md.keys = append(md.keys, k) | |
56 | } | |
57 | sort.Strings(md.keys) | |
58 | for _, k := range md.keys { | |
59 | md.values = append(md.values, kv[k]) | |
60 | } | |
61 | return md | |
62 | } | |
63 | ||
64 | func (md Metadata) Len() int { return len(md.keys) } | |
65 | func (md Metadata) Keys() []string { return md.keys } | |
66 | func (md Metadata) Values() []string { return md.values } | |
67 | ||
68 | func (md Metadata) String() string { | |
69 | o := new(strings.Builder) | |
70 | fmt.Fprintf(o, "[") | |
71 | for i := range md.keys { | |
72 | if i > 0 { | |
73 | fmt.Fprintf(o, ", ") | |
74 | } | |
75 | fmt.Fprintf(o, "%q: %q", md.keys[i], md.values[i]) | |
76 | } | |
77 | fmt.Fprintf(o, "]") | |
78 | return o.String() | |
79 | } | |
80 | ||
81 | // FindKey returns the index of the key-value pair with the provided key name, | |
82 | // or -1 if such a key does not exist. | |
83 | func (md Metadata) FindKey(k string) int { | |
84 | for i, v := range md.keys { | |
85 | if v == k { | |
86 | return i | |
87 | } | |
88 | } | |
89 | return -1 | |
90 | } | |
91 | ||
92 | func (md Metadata) clone() Metadata { | |
93 | if len(md.keys) == 0 { | |
94 | return Metadata{} | |
95 | } | |
96 | ||
97 | o := Metadata{ | |
98 | keys: make([]string, len(md.keys)), | |
99 | values: make([]string, len(md.values)), | |
100 | } | |
101 | copy(o.keys, md.keys) | |
102 | copy(o.values, md.values) | |
103 | ||
104 | return o | |
105 | } | |
106 | ||
107 | func (md Metadata) sortedIndices() []int { | |
108 | idxes := make([]int, len(md.keys)) | |
109 | for i := range idxes { | |
110 | idxes[i] = i | |
111 | } | |
112 | ||
113 | sort.Slice(idxes, func(i, j int) bool { | |
114 | return md.keys[idxes[i]] < md.keys[idxes[j]] | |
115 | }) | |
116 | return idxes | |
117 | } | |
118 | ||
119 | func (md Metadata) Equal(rhs Metadata) bool { | |
120 | if md.Len() != rhs.Len() { | |
121 | return false | |
122 | } | |
123 | ||
124 | idxes := md.sortedIndices() | |
125 | rhsIdxes := rhs.sortedIndices() | |
126 | for i := range idxes { | |
127 | j := idxes[i] | |
128 | k := rhsIdxes[i] | |
129 | if md.keys[j] != rhs.keys[k] || md.values[j] != rhs.values[k] { | |
130 | return false | |
131 | } | |
132 | } | |
133 | return true | |
134 | } | |
135 | ||
136 | // Schema is a sequence of Field values, describing the columns of a table or | |
137 | // a record batch. | |
138 | type Schema struct { | |
139 | fields []Field | |
140 | index map[string][]int | |
141 | meta Metadata | |
142 | } | |
143 | ||
144 | // NewSchema returns a new Schema value from the slice of fields and metadata. | |
145 | // | |
146 | // NewSchema panics if there is a field with an invalid DataType. | |
147 | func NewSchema(fields []Field, metadata *Metadata) *Schema { | |
148 | sc := &Schema{ | |
149 | fields: make([]Field, 0, len(fields)), | |
150 | index: make(map[string][]int, len(fields)), | |
151 | } | |
152 | if metadata != nil { | |
153 | sc.meta = metadata.clone() | |
154 | } | |
155 | for i, field := range fields { | |
156 | if field.Type == nil { | |
157 | panic("arrow: field with nil DataType") | |
158 | } | |
159 | sc.fields = append(sc.fields, field) | |
160 | sc.index[field.Name] = append(sc.index[field.Name], i) | |
161 | } | |
162 | return sc | |
163 | } | |
164 | ||
165 | func (sc *Schema) Metadata() Metadata { return sc.meta } | |
166 | func (sc *Schema) Fields() []Field { return sc.fields } | |
167 | func (sc *Schema) Field(i int) Field { return sc.fields[i] } | |
168 | ||
169 | func (sc *Schema) FieldsByName(n string) ([]Field, bool) { | |
170 | indices, ok := sc.index[n] | |
171 | if !ok { | |
172 | return nil, ok | |
173 | } | |
174 | fields := make([]Field, 0, len(indices)) | |
175 | for _, v := range indices { | |
176 | fields = append(fields, sc.fields[v]) | |
177 | } | |
178 | return fields, ok | |
179 | } | |
180 | ||
181 | // FieldIndices returns the indices of the named field or nil. | |
182 | func (sc *Schema) FieldIndices(n string) []int { | |
183 | return sc.index[n] | |
184 | } | |
185 | ||
186 | func (sc *Schema) HasField(n string) bool { return len(sc.FieldIndices(n)) > 0 } | |
187 | func (sc *Schema) HasMetadata() bool { return len(sc.meta.keys) > 0 } | |
188 | ||
189 | // Equal returns whether two schema are equal. | |
190 | // Equal does not compare the metadata. | |
191 | func (sc *Schema) Equal(o *Schema) bool { | |
192 | switch { | |
193 | case sc == o: | |
194 | return true | |
195 | case sc == nil || o == nil: | |
196 | return false | |
197 | case len(sc.fields) != len(o.fields): | |
198 | return false | |
199 | } | |
200 | ||
201 | for i := range sc.fields { | |
202 | if !sc.fields[i].Equal(o.fields[i]) { | |
203 | return false | |
204 | } | |
205 | } | |
206 | return true | |
207 | } | |
208 | ||
209 | func (s *Schema) String() string { | |
210 | o := new(strings.Builder) | |
211 | fmt.Fprintf(o, "schema:\n fields: %d\n", len(s.Fields())) | |
212 | for i, f := range s.Fields() { | |
213 | if i > 0 { | |
214 | o.WriteString("\n") | |
215 | } | |
216 | fmt.Fprintf(o, " - %v", f) | |
217 | } | |
218 | if meta := s.Metadata(); meta.Len() > 0 { | |
219 | fmt.Fprintf(o, "\n metadata: %v", meta) | |
220 | } | |
221 | return o.String() | |
222 | } | |
223 | ||
224 | func (s *Schema) Fingerprint() string { | |
225 | if s == nil { | |
226 | return "" | |
227 | } | |
228 | ||
229 | var b strings.Builder | |
230 | b.WriteString("S{") | |
231 | for _, f := range s.Fields() { | |
232 | fieldFingerprint := f.Fingerprint() | |
233 | if fieldFingerprint == "" { | |
234 | return "" | |
235 | } | |
236 | ||
237 | b.WriteString(fieldFingerprint) | |
238 | b.WriteByte(';') | |
239 | } | |
240 | // endianness | |
241 | b.WriteByte('}') | |
242 | return b.String() | |
243 | } |