add: a new method String::rev() (#866)

* add: a new method String::reverse() * rename String::reverse() -> String::rev() --------- Co-authored-by: Yorkin <[email protected]>
moonbitlang · Aug 19, 2024 · 0bccc94 · 0bccc94
1 parent 71de79a
commit 0bccc94
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diff --git a/string/string.mbt b/string/string.mbt
@@ -441,3 +441,14 @@ pub fn to_upper(self : String) -> String {
   }
   buf.to_string()
 }
+
+/// Reverse string
+pub fn rev(self : String) -> String {
+  // TODO: deal with non-ascii characters
+  let mut result : String = ""
+  let len = self.length()
+  for i = len - 1; i >= 0; i = i - 1 {
+    result = result + self[i].to_string()
+  }
+  result
+}
diff --git a/string/string.mbti b/string/string.mbti
@@ -16,6 +16,7 @@ impl String {
   last_index_of(String, String, ~from : Int = ..) -> Int
   replace(String, ~old : String, ~new : String) -> String
   replace_all(String, ~old : String, ~new : String) -> String
+  rev(String) -> String
   split(String, String) -> Iter[String]
   starts_with(String, String) -> Bool
   substring(String, ~start : Int = .., ~end : Int = ..) -> String

diff --git a/string/string_test.mbt b/string/string_test.mbt
@@ -348,6 +348,12 @@ test "replace_all" {
   )
 }
 
+test "reverse" {
+  inspect!("hello".rev(), content="olleh")
+  inspect!("Nothing".rev(), content="gnihtoN")
+  inspect!("< >".rev(), content="> <")
+}
+
 test "to_lower" {
   inspect!("ABCXYZ".to_lower(), content="abcxyz")
   inspect!("aBcXyZ".to_lower(), content="abcxyz")