Deserialize a block from bytes. Returns `None` if malformed.
(buf: &[u8])
| 150 | |
| 151 | /// Deserialize a block from bytes. Returns `None` if malformed. |
| 152 | pub fn from_bytes(buf: &[u8]) -> Option<Self> { |
| 153 | let mut pos = 0; |
| 154 | |
| 155 | // Doc count. |
| 156 | if buf.len() < 2 { |
| 157 | return None; |
| 158 | } |
| 159 | let doc_count = u16::from_le_bytes([buf[pos], buf[pos + 1]]) as usize; |
| 160 | pos += 2; |
| 161 | |
| 162 | if doc_count == 0 { |
| 163 | return Some(Self { |
| 164 | doc_ids: Vec::new(), |
| 165 | term_freqs: Vec::new(), |
| 166 | fieldnorms: Vec::new(), |
| 167 | positions: Vec::new(), |
| 168 | }); |
| 169 | } |
| 170 | |
| 171 | // Packed doc ID deltas. |
| 172 | if pos + 4 > buf.len() { |
| 173 | return None; |
| 174 | } |
| 175 | let ids_len = |
| 176 | u32::from_le_bytes([buf[pos], buf[pos + 1], buf[pos + 2], buf[pos + 3]]) as usize; |
| 177 | pos += 4; |
| 178 | if pos + ids_len > buf.len() { |
| 179 | return None; |
| 180 | } |
| 181 | let packed_deltas = &buf[pos..pos + ids_len]; |
| 182 | let deltas = bitpack::unpack(packed_deltas); |
| 183 | let raw_ids = delta::decode(&deltas); |
| 184 | let doc_ids: Vec<Surrogate> = raw_ids.into_iter().map(Surrogate).collect(); |
| 185 | pos += ids_len; |
| 186 | |
| 187 | // Packed term frequencies. |
| 188 | if pos + 4 > buf.len() { |
| 189 | return None; |
| 190 | } |
| 191 | let freqs_len = |
| 192 | u32::from_le_bytes([buf[pos], buf[pos + 1], buf[pos + 2], buf[pos + 3]]) as usize; |
| 193 | pos += 4; |
| 194 | if pos + freqs_len > buf.len() { |
| 195 | return None; |
| 196 | } |
| 197 | let term_freqs = bitpack::unpack(&buf[pos..pos + freqs_len]); |
| 198 | pos += freqs_len; |
| 199 | |
| 200 | // Fieldnorms. |
| 201 | if pos + doc_count > buf.len() { |
| 202 | return None; |
| 203 | } |
| 204 | let fieldnorms = buf[pos..pos + doc_count].to_vec(); |
| 205 | pos += doc_count; |
| 206 | |
| 207 | // Position data. |
| 208 | let mut positions = Vec::with_capacity(doc_count); |
| 209 | for _ in 0..doc_count { |