exduckdb

#include "duckdb/common/operator/comparison_operators.hpp"
#include "duckdb/common/vector_operations/vector_operations.hpp"
#include "duckdb/execution/merge_join.hpp"
#include "duckdb/parser/expression/comparison_expression.hpp"

namespace duckdb {

template <class T, class OP>
static idx_t MergeJoinSimpleGreaterThan(ScalarMergeInfo &l, ChunkMergeInfo &r) {
	auto ldata = (T *)l.order.vdata.data;
	auto &lorder = l.order.order;
	l.pos = l.order.count;
	for (idx_t chunk_idx = 0; chunk_idx < r.order_info.size(); chunk_idx++) {
		// we only care about the SMALLEST value in each of the RHS
		// because we want to figure out if they are greater than [or equal] to ANY value
		// get the smallest value from the RHS
		auto &rorder = r.order_info[chunk_idx];
		auto rdata = (T *)rorder.vdata.data;
		auto min_r_value = rdata[rorder.vdata.sel->get_index(rorder.order.get_index(0))];
		// now we start from the current lpos value and check if we found a new value that is [>= OR >] the min RHS
		// value
		while (true) {
			auto lidx = lorder.get_index(l.pos - 1);
			auto dlidx = l.order.vdata.sel->get_index(lidx);
			if (OP::Operation(ldata[dlidx], min_r_value)) {
				// found a match for lpos, set it in the found_match vector
				r.found_match[lidx] = true;
				l.pos--;
				if (l.pos == 0) {
					// early out: we exhausted the entire LHS and they all match
					return 0;
				}
			} else {
				// we found no match: any subsequent value from the LHS we scan now will be smaller and thus also not
				// match move to the next RHS chunk
				break;
			}
		}
	}
	return 0;
}
template <class T>
idx_t MergeJoinSimple::GreaterThan::Operation(ScalarMergeInfo &l, ChunkMergeInfo &r) {
	return MergeJoinSimpleGreaterThan<T, duckdb::GreaterThan>(l, r);
}

template <class T>
idx_t MergeJoinSimple::GreaterThanEquals::Operation(ScalarMergeInfo &l, ChunkMergeInfo &r) {
	return MergeJoinSimpleGreaterThan<T, duckdb::GreaterThanEquals>(l, r);
}

template <class T, class OP>
static idx_t MergeJoinSimpleLessThan(ScalarMergeInfo &l, ChunkMergeInfo &r) {
	auto ldata = (T *)l.order.vdata.data;
	auto &lorder = l.order.order;
	l.pos = 0;
	for (idx_t chunk_idx = 0; chunk_idx < r.order_info.size(); chunk_idx++) {
		// we only care about the BIGGEST value in each of the RHS
		// because we want to figure out if they are less than [or equal] to ANY value
		// get the biggest value from the RHS
		auto &rorder = r.order_info[chunk_idx];
		auto rdata = (T *)rorder.vdata.data;
		auto max_r_value = rdata[rorder.vdata.sel->get_index(rorder.order.get_index(rorder.count - 1))];
		// now we start from the current lpos value and check if we found a new value that is [<= OR <] the max RHS
		// value
		while (true) {
			auto lidx = lorder.get_index(l.pos);
			auto dlidx = l.order.vdata.sel->get_index(lidx);
			if (OP::Operation(ldata[dlidx], max_r_value)) {
				// found a match for lpos, set it in the found_match vector
				r.found_match[lidx] = true;
				l.pos++;
				if (l.pos == l.order.count) {
					// early out: we exhausted the entire LHS and they all match
					return 0;
				}
			} else {
				// we found no match: any subsequent value from the LHS we scan now will be bigger and thus also not
				// match move to the next RHS chunk
				break;
			}
		}
	}
	return 0;
}

template <class T>
idx_t MergeJoinSimple::LessThan::Operation(ScalarMergeInfo &l, ChunkMergeInfo &r) {
	return MergeJoinSimpleLessThan<T, duckdb::LessThan>(l, r);
}

template <class T>
idx_t MergeJoinSimple::LessThanEquals::Operation(ScalarMergeInfo &l, ChunkMergeInfo &r) {
	return MergeJoinSimpleLessThan<T, duckdb::LessThanEquals>(l, r);
}

INSTANTIATE_MERGEJOIN_TEMPLATES(MergeJoinSimple, LessThan, ScalarMergeInfo, ChunkMergeInfo)
INSTANTIATE_MERGEJOIN_TEMPLATES(MergeJoinSimple, LessThanEquals, ScalarMergeInfo, ChunkMergeInfo)
INSTANTIATE_MERGEJOIN_TEMPLATES(MergeJoinSimple, GreaterThan, ScalarMergeInfo, ChunkMergeInfo)
INSTANTIATE_MERGEJOIN_TEMPLATES(MergeJoinSimple, GreaterThanEquals, ScalarMergeInfo, ChunkMergeInfo)

} // namespace duckdb