Implement dirname for form submit and directionality for element

components/script/dom/htmlinputelement.rs

@@ -75,6 +75,7 @@ use std::ptr::NonNull;
 use style::attr::AttrValue;
 use style::element_state::ElementState;
 use style::str::{split_commas, str_join};
+use unicode_bidi::{bidi_class, BidiClass};
 
 const DEFAULT_SUBMIT_VALUE: &'static str = "Submit";
 const DEFAULT_RESET_VALUE: &'static str = "Reset";
@@ -327,6 +328,41 @@ impl HTMLInputElement {
         )
     }
 
+    pub fn directionality(&self, element_direction: &str) -> String {
+        match self.input_type() {
+            InputType::Tel => return "ltr".to_owned(),
+            InputType::Text | InputType::Search | InputType::Url | InputType::Email => {
+                if element_direction == "auto" {
+                    let value: String = self.Value().to_string();
+                    return HTMLInputElement::auto_directionality(&value);
+                }
+            },
+            _ => {},
+        }
+
+        return "ltr".to_owned();
+    }
+
+    pub fn auto_directionality(value: &str) -> String {
+        if HTMLInputElement::first_strong_character_is_rtl(value) {
+            "rtl".to_owned()
+        } else {
+            "ltr".to_owned()
+        }
+    }
+
+    fn first_strong_character_is_rtl(value: &str) -> bool {
+        for ch in value.chars() {
+            return match bidi_class(ch) {
+                BidiClass::L => false,
+                BidiClass::AL => true,
+                BidiClass::R => true,
+                _ => continue,
+            };
+        }
+        false
+    }
+
     // https://html.spec.whatwg.org/multipage/#dom-input-value
     // https://html.spec.whatwg.org/multipage/#concept-input-apply
     fn value_mode(&self) -> ValueMode {