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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "utf8stringfieldsearcherbase.h"
#include <vespa/vsm/common/charbuffer.h>
namespace vsm {
using SharedOffsetBuffer = std::shared_ptr<std::vector<size_t> >;
/**
* This class does substring searches the same way as UTF8SubStringFieldSearcher.
* While matching the query term(s) against the field reference it builds a modified
* buffer based on the field reference where the only difference is that unit separators
* are inserted before and after a match. These extra unit separators make it possible
* to highlight a substring match when later generating snippets.
**/
class UTF8SubstringSnippetModifier : public UTF8StringFieldSearcherBase
{
private:
CharBuffer::SP _modified; // buffer to write the modified field value
SharedOffsetBuffer _offsets; // for each character in _buf we have an offset into the utf8 buffer (field reference)
const char * _readPtr; // buffer to read from (field reference)
char _unitSep; // the unit separator character to use
size_t matchTerm(const FieldRef & f, search::streaming::QueryTerm & qt) override;
size_t matchTerms(const FieldRef & f, size_t shortestTerm) override;
/**
* Copies n bytes from the field reference to the modified buffer and updates the read pointer.
* Separator characters from the field reference can be skipped.
* This is to avoid that a match is splitted by separator characters from the original field reference.
*
* @param n the number of bytes to copy.
* @param skipSep whether we should skip separator characters from the field reference.
**/
void copyToModified(size_t n, bool skipSep = false);
/**
* Copies from the field reference to the modified buffer and inserts unit separators for a match
* starting at mbegin (in the field reference) and ending at mend (in the field reference).
* A unit separator is inserted before and after the match.
*
* @param mbegin the beginning of the match.
* @param mend the end of the match.
**/
void insertSeparators(const char * mbegin, const char * mend);
public:
using SP = std::shared_ptr<UTF8SubstringSnippetModifier>;
std::unique_ptr<FieldSearcher> duplicate() const override;
explicit UTF8SubstringSnippetModifier(FieldIdT fId);
~UTF8SubstringSnippetModifier() override;
/**
* Creates a new instance.
*
* @param fId the field id to operate on.
* @param modBuf the shared buffer used to store the modified field value.
* @param offBuf the shared buffer used to store the offsets into the field reference.
**/
UTF8SubstringSnippetModifier(FieldIdT fId, const CharBuffer::SP & modBuf, const SharedOffsetBuffer & offBuf);
const CharBuffer & getModifiedBuf() const { return *_modified; }
const search::streaming::QueryTermList & getQueryTerms() const { return _qtl; }
};
}
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