text-util: add text_range_intersect utility function

2 files changed, 8 insertions, 0 deletions

diff --git a/text-util.c b/text-util.c
index f198d81..4936d92 100644
--- a/text-util.c
+++ b/text-util.c
@@ -27,6 +27,12 @@ Filerange text_range_union(const Filerange *r1, const Filerange *r2) {
 	};
 }
 
+Filerange text_range_intersect(const Filerange *r1, const Filerange *r2) {
+	if (!text_range_overlap(r1, r2))
+		return text_range_empty();
+	return text_range_new(MAX(r1->start, r2->start), MIN(r1->end, r2->end));
+}
+
 Filerange text_range_new(size_t a, size_t b) {
 	return (Filerange) {
 		.start = MIN(a, b),
diff --git a/text-util.h b/text-util.h
index 86d3307..709e255 100644
--- a/text-util.h
+++ b/text-util.h
@@ -13,6 +13,8 @@ size_t text_range_size(const Filerange*);
 Filerange text_range_empty(void);
 /* merge two ranges into a new one which contains both of them */
 Filerange text_range_union(const Filerange*, const Filerange*);
+/* get intersection of two ranges */
+Filerange text_range_intersect(const Filerange*, const Filerange*);
 /* create new range [min(a,b), max(a,b)] */
 Filerange text_range_new(size_t a, size_t b);
 /* test whether two ranges are equal */