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use std::io;
use crate::common::BinarySerializable;
use crate::directory::FileSlice;
use crate::positions::PositionReader;
use crate::postings::TermInfo;
use crate::postings::{BlockSegmentPostings, SegmentPostings};
use crate::schema::IndexRecordOption;
use crate::schema::Term;
use crate::termdict::TermDictionary;
pub struct InvertedIndexReader {
termdict: TermDictionary,
postings_file_slice: FileSlice,
positions_file_slice: FileSlice,
positions_idx_file_slice: FileSlice,
record_option: IndexRecordOption,
total_num_tokens: u64,
}
impl InvertedIndexReader {
#[cfg_attr(feature = "cargo-clippy", allow(clippy::needless_pass_by_value))]
pub(crate) fn new(
termdict: TermDictionary,
postings_file_slice: FileSlice,
positions_file_slice: FileSlice,
positions_idx_file_slice: FileSlice,
record_option: IndexRecordOption,
) -> io::Result<InvertedIndexReader> {
let (total_num_tokens_slice, postings_body) = postings_file_slice.split(8);
let total_num_tokens = u64::deserialize(&mut total_num_tokens_slice.read_bytes()?)?;
Ok(InvertedIndexReader {
termdict,
postings_file_slice: postings_body,
positions_file_slice,
positions_idx_file_slice,
record_option,
total_num_tokens,
})
}
pub fn empty(record_option: IndexRecordOption) -> InvertedIndexReader {
InvertedIndexReader {
termdict: TermDictionary::empty(),
postings_file_slice: FileSlice::empty(),
positions_file_slice: FileSlice::empty(),
positions_idx_file_slice: FileSlice::empty(),
record_option,
total_num_tokens: 0u64,
}
}
pub fn get_term_info(&self, term: &Term) -> io::Result<Option<TermInfo>> {
self.termdict.get(term.value_bytes())
}
pub fn terms(&self) -> &TermDictionary {
&self.termdict
}
pub fn reset_block_postings_from_terminfo(
&self,
term_info: &TermInfo,
block_postings: &mut BlockSegmentPostings,
) -> io::Result<()> {
let start_offset = term_info.postings_start_offset as usize;
let stop_offset = term_info.postings_stop_offset as usize;
let postings_slice = self.postings_file_slice.slice(start_offset, stop_offset);
block_postings.reset(term_info.doc_freq, postings_slice.read_bytes()?);
Ok(())
}
pub fn read_block_postings(
&self,
term: &Term,
option: IndexRecordOption,
) -> io::Result<Option<BlockSegmentPostings>> {
self.get_term_info(term)?
.map(move |term_info| self.read_block_postings_from_terminfo(&term_info, option))
.transpose()
}
pub fn read_block_postings_from_terminfo(
&self,
term_info: &TermInfo,
requested_option: IndexRecordOption,
) -> io::Result<BlockSegmentPostings> {
let postings_data = self.postings_file_slice.slice(
term_info.postings_start_offset as usize,
term_info.postings_stop_offset as usize,
);
BlockSegmentPostings::open(
term_info.doc_freq,
postings_data,
self.record_option,
requested_option,
)
}
pub fn read_postings_from_terminfo(
&self,
term_info: &TermInfo,
option: IndexRecordOption,
) -> io::Result<SegmentPostings> {
let block_postings = self.read_block_postings_from_terminfo(term_info, option)?;
let position_stream = {
if option.has_positions() {
let position_reader = self.positions_file_slice.clone();
let skip_reader = self.positions_idx_file_slice.clone();
let position_reader =
PositionReader::new(position_reader, skip_reader, term_info.positions_idx)?;
Some(position_reader)
} else {
None
}
};
Ok(SegmentPostings::from_block_postings(
block_postings,
position_stream,
))
}
pub fn total_num_tokens(&self) -> u64 {
self.total_num_tokens
}
pub fn read_postings(
&self,
term: &Term,
option: IndexRecordOption,
) -> io::Result<Option<SegmentPostings>> {
self.get_term_info(term)?
.map(move |term_info| self.read_postings_from_terminfo(&term_info, option))
.transpose()
}
pub(crate) fn read_postings_no_deletes(
&self,
term: &Term,
option: IndexRecordOption,
) -> io::Result<Option<SegmentPostings>> {
self.get_term_info(term)?
.map(|term_info| self.read_postings_from_terminfo(&term_info, option))
.transpose()
}
pub fn doc_freq(&self, term: &Term) -> io::Result<u32> {
Ok(self
.get_term_info(term)?
.map(|term_info| term_info.doc_freq)
.unwrap_or(0u32))
}
}