@spec and_intersect([posting_list()]) :: scored_list()

Computes the AND intersection of multiple posting lists.

Uses a two-pointer merge algorithm for each pair of lists.

Example

iex> BooleanEngine.and_intersect([
...>   [{"a", 1, 0}, {"b", 1, 1}, {"c", 1, 2}],
...>   [{"b", 1, 0}, {"c", 1, 1}, {"d", 1, 2}]
...> ])
[{"b", 1}, {"c", 3}]

@spec intersect_scored([scored_list()]) :: scored_list()

Computes the AND intersection of multiple scored posting lists ({post_id, tf} pairs sorted by post_id).

Uses a two-pointer merge algorithm for each pair of lists, summing the scores of matching posts.

Example

iex> BooleanEngine.intersect_scored([
...>   [{"a", 2}, {"b", 1}, {"c", 3}],
...>   [{"b", 4}, {"c", 1}, {"d", 2}]
...> ])
[{"b", 5}, {"c", 4}]

@spec not_difference(posting_list(), posting_list()) :: [
  {String.t(), non_neg_integer()}
]

Computes the difference: posts in include that are NOT in exclude.

Example

iex> BooleanEngine.not_difference(
...>   [{"a", 1, 0}, {"b", 1, 1}, {"c", 1, 2}],
...>   [{"b", 1, 0}]
...> )
[{"a", 1}, {"c", 1}]

@spec or_union([posting_list()]) :: scored_list()

Computes the OR union of multiple posting lists.

Example

iex> BooleanEngine.or_union([
...>   [{"a", 1, 0}, {"b", 1, 1}],
...>   [{"b", 1, 0}, {"c", 1, 1}]
...> ])
[{"a", 1}, {"b", 1}, {"c", 1}]

@spec union_scored([scored_list()]) :: scored_list()

Computes the OR union of multiple scored posting lists ({post_id, tf} pairs). Scores of posts appearing in several lists are summed. The result is sorted by post_id.

Example

iex> BooleanEngine.union_scored([
...>   [{"a", 1}, {"b", 2}],
...>   [{"b", 4}, {"c", 1}]
...> ])
[{"a", 1}, {"b", 6}, {"c", 1}]