filter: add fulltext filtering code

Add code that indexes all words of a dive and provides searching
for words.

A query is represented by the FullTextQuery class, which can be
initialized by assigning a string to it. It is basically a list
of words.

The result of a search is stored in the FullTextResult class,
which is a list of dives.

The actual indexing and searching is implemented in the FullText
class. However, this class is not exported because the interface
is partially accessible to C. Notably, the reloading of the
fulltext index is done from the C core.

Currently, the indexing and searching is totally unoptimized.
In a ~4000 dives test-log searches typically took single-digit
ms times. There is ample room for optimization (e.g. when
searching for multiple words, chose the words with few dives
first and when down to a few dives, check them individually).

The words of each dive are tokenized and uppercased and
cached with the dive. A pointer to these words is stashed
in the dive structure.

For now, compile only on desktop.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 2 insertions, 0 deletions

diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt
index 24df1854b..d3f1401f1 100644
--- a/core/CMakeLists.txt
+++ b/core/CMakeLists.txt
@@ -88,6 +88,8 @@ set(SUBSURFACE_CORE_LIB_SRCS
 	file.h
 	format.cpp
 	format.h
+	fulltext.cpp
+	fulltext.h
 	gas.c
 	gas.h
 	gas-model.c