standard: Add `Text.search_last`.

[nit.git] / lib / standard / string_search.nit

diff --git a/lib/standard/string_search.nit b/lib/standard/string_search.nit
index 5aeac25..c718c96 100644 (file)
--- a/lib/standard/string_search.nit
+++ b/lib/standard/string_search.nit
@@ -334,6 +334,30 @@ redef class Text
        #     assert "I say hello to the world!".search_from("hello",7)       == null
        fun search_from(p: Pattern, from: Int): nullable Match do return p.search_in(self, from)
 
+       # Search the last occurence of the text `t`.
+       #
+       #     assert "bob".search_last("b").from == 2
+       fun search_last(t: Text): nullable Match do
+               return search_last_up_to(t, length)
+       end
+
+       # Search the last occurence of the text `t` before `up_to`.
+       #
+       #     assert "bobbob".search_last_up_to("b", 3).from == 2
+       #     assert "bobbob".search_last_up_to("b", 6).from == 5
+       #     assert "bobbob".search_last_up_to("b", 0) == null
+       fun search_last_up_to(t: Text, up_to: Int): nullable Match do
+               var i = up_to - t.length
+
+               while i >= 0 do
+                       if substring(i, t.length) == t then
+                               return new Match(self.to_s, i, t.length)
+                       end
+                       i -= 1
+               end
+               return null
+       end
+
        # Search all occurrences of p into self.
        #
        #     var a = new Array[Int]