add before and before last.

README.md

@@ -28,8 +28,8 @@ psql
 - [x] after
 - [] afterLast
 - [x] ascii
-- [] before
+- [x] before
-- [] beforeLast
+- [x] beforeLast
 - [] between
 - [x] camel 
 - [x] contains

src/modules/before.rs

@@ -1,4 +1,54 @@
-// fn str_before<'a>(input: &'a str, search: &str) -> &'a str {
+use pgrx::prelude::*;
-// }
+
-// fn str_beforeLast<'a>(input: &'a str, search: &str) -> &'a str {
+#[pg_extern]
-// }
+pub fn str_before<'a>(input: &'a str, search: &str) -> &'a str {
+    local::str_before(input, search)
+}
+
+#[pg_extern]
+pub fn str_before_last<'a>(input: &'a str, search: &str) -> &'a str {
+    local::str_before_last(input, search)
+}
+
+mod local {
+    pub fn str_before<'a>(input: &'a str, search: &str) -> &'a str {
+        if search.is_empty() {
+            return input;
+        }
+        match input.find(search) {
+            Some(index) => &input[..index],
+            None => input,
+        }
+    }
+
+    pub fn str_before_last<'a>(input: &'a str, search: &str) -> &'a str {
+        match input.rfind(search) {
+            Some(index) => &input[..index],
+            None => input,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_str_before() {
+        assert_eq!(local::str_before("Hello, world!", "world"), "Hello, ");
+        assert_eq!(local::str_before("Hello, world!", "xyz"), "Hello, world!");
+        assert_eq!(local::str_before("", "world"), "");
+        assert_eq!(local::str_before("Hello, world!", ""), "Hello, world!");
+    }
+
+    #[test]
+    fn test_str_before_last() {
+        assert_eq!(local::str_before_last("Hello, world!", "o"), "Hello, w");
+        assert_eq!(
+            local::str_before_last("Hello, world!", "xyz"),
+            "Hello, world!"
+        );
+        assert_eq!(local::str_before_last("", "world"), "");
+        assert_eq!(local::str_before_last("Hello, world!", ""), "Hello, world!");
+    }
+}