Merge pull request #31 from Lilit0x/functions/right

RIGHT String Function: #13

crates/gitql-ast/src/function.rs

@@ -32,6 +32,7 @@ lazy_static! {
         map.insert("replace", text_replace);
         map.insert("substring", text_substring);
         map.insert("stuff", text_stuff);
+        map.insert("right", text_right);
 
         // Date functions
         map.insert("current_date", date_current_date);
@@ -157,6 +158,13 @@ lazy_static! {
                 result: DataType::Text,
             },
         );
+        map.insert(
+            "right",
+            Prototype {
+                parameters: vec![DataType::Text, DataType::Number],
+                result: DataType::Text
+             },
+        );
 
         // Date functions
         map.insert(
@@ -284,7 +292,7 @@ fn text_replace(inputs: Vec<Value>) -> Value {
     result.push_str(&text.get(end..text.len()).unwrap());
 
     return Value::Text(result);
-  }
+}
 
 fn text_substring(inputs: Vec<Value>) -> Value {
     let text = inputs[0].as_text();
@@ -323,6 +331,21 @@ fn text_stuff(inputs: Vec<Value>) -> Value {
     return Value::Text(text.into_iter().collect());
 }
 
+fn text_right(inputs: Vec<Value>) -> Value {
+    let text = inputs[0].as_text();
+    if text.is_empty() {
+        return Value::Text("".to_string());
+    }
+
+    let number_of_chars = inputs[1].as_number() as usize;
+    if number_of_chars > text.len() {
+        return Value::Text(text);
+    }
+
+    let text = text.as_str();
+
+    return Value::Text(text[text.len() - number_of_chars..text.len()].to_string());
+}
 
 // Date functions
 

docs/function/functions.md

@@ -21,7 +21,7 @@ note that all functions names are case-insensitive.
 | REPLACE    | Text, Text, Text | Text  | Replaces all occurrences of a substring within a string, with a new substring. |
 | SUBSTRING  | Text, Number, Number | Text | Extracts some characters from a string.                       |
 | STUFF      | Text, Number, Number, Text | Deletes a part of a string and then inserts another part into the string, starting at a specified position. |
-
+| RIGHT      | Text, Number | Text   | Extracts a number of characters from a string (starting from right).|
 ### String functions samples
 
 ```sql
@@ -38,6 +38,7 @@ SELECT CHAR(345) AS code
 SELECT REPLACE("ABC ABC ABC", "a", "c") as replacedText
 SELECT name, SUBSTRING(name, 1, 5) AS extract FROM commits
 SELECT STUFF("GQL tutorial!", 13, 1, " is fun!")
+SELECT RIGHT("AmrDeveloper", 3) AS extract
 ```
 
 ### Date functions