xapian: Add docstring to mset-snippet.

* xapian/xapian.scm (mset-snippet): Add docstring.

1 files changed, 31 insertions, 0 deletions

diff --git a/xapian/xapian.scm b/xapian/xapian.scm
index 75924ae..f13365e 100644
--- a/xapian/xapian.scm
+++ b/xapian/xapian.scm
@@ -204,6 +204,37 @@ on the database object."
                        (background-model? #t) (exhaustive? #t)
                        (empty-without-match? #t)
                        (cjk-ngram? #t))
+  "Generate a snippet from @var{text}. @var{mset} is the xapian
+@code{MSet} object representing a list of search results.
+
+@var{length} is the number of bytes of @var{text} to aim to select.
+
+The same stemmer used to build the query should be specified as
+@var{stemmer}.
+
+@var{highlight-start} and @var{highlight-end} are inserted
+respectively before and after the highlit terms.
+
+If the chosen snippet seems to start or end mid-sentence, then
+@var{omit} is prepended or appended to indicate this.
+
+If @var{background-model?} is @code{#true}, the relevance of non-query
+terms are modelled to prefer snippets containing a more interesting
+background.
+
+If @var{exhaustive?} is @code{#true}, exhaustively evaluate candidate
+snippets. Else, snippet generation will stop once a @emph{good enough}
+snippet has been found.
+
+If @var{empty-without-match?} is @code{#true}, return the empty string
+if not a single term was found in @var{text}. Else, return a substring
+of text without any highlit terms.
+
+If @var{cjk-ngram?} is @code{#true}, enable generation of n-grams from
+CJK text.
+
+See @code{MSet::snippet} in @file{xapian/mset.h} of the xapian source
+for more details."
   (MSet-snippet mset text length stemmer
                 (bitwise-ior (get-flag MSet-SNIPPET-BACKGROUND-MODEL background-model?)
                              (get-flag MSet-SNIPPET-EXHAUSTIVE exhaustive?)