add support for has_attribute, has_attribute_ns

CHANGELOG.md

@@ -3,10 +3,11 @@
 ## [0.3.1] (in development)
 
 * Added: Thanks to @lepapareil, @hurlenko and @ballsteve for contributing installation docs for Windows and MacOS.
+* Added: `Node` and `RoNode` now have `has_property` (alias `has_attribute`) and `has_property_ns` (alias `has_attribute_ns`) to check attribute presence without allocating the value.
 
 ## [0.3.0] 2021-27-05
 
-* Change `Parser::parse_file/string_with_encoding` to `Parser::parse_file/string_with_options`. 
+* Change `Parser::parse_file/string_with_encoding` to `Parser::parse_file/string_with_options`.
 
 * Introduce `ParserOptions` which encapsulates the forced encoding setting together with libxml2s HTML and XML parser options.
 

src/readonly/tree.rs

@@ -303,6 +303,29 @@ impl RoNode {
     self.get_properties()
   }
 
+  /// Check if a property has been defined, without allocating its value
+  pub fn has_property(self, name: &str) -> bool {
+    let c_name = CString::new(name).unwrap();
+    let value_ptr = unsafe { xmlHasProp(self.0, c_name.as_bytes().as_ptr()) };
+    !value_ptr.is_null()
+  }
+  /// Check if property `name` in namespace `ns` exists
+  pub fn has_property_ns(self, name: &str, ns: &str) -> bool {
+    let c_name = CString::new(name).unwrap();
+    let c_ns = CString::new(ns).unwrap();
+    let value_ptr =
+      unsafe { xmlHasNsProp(self.0, c_name.as_bytes().as_ptr(), c_ns.as_bytes().as_ptr()) };
+    !value_ptr.is_null()
+  }
+  /// Alias for has_property
+  pub fn has_attribute(self, name: &str) -> bool {
+    self.has_property(name)
+  }
+  /// Alias for has_property_ns
+  pub fn has_attribute_ns(self, name: &str, ns: &str) -> bool {
+    self.has_property_ns(name, ns)
+  }
+
   /// Gets the active namespace associated of this node
   pub fn get_namespace(self) -> Option<Namespace> {
     let ns_ptr = xmlNodeNs(self.0);

src/tree/node.rs

@@ -460,6 +460,29 @@ impl Node {
     }
   }
 
+  /// Check if a property has been defined, without allocating its value
+  pub fn has_property(&self, name: &str) -> bool {
+    let c_name = CString::new(name).unwrap();
+    let value_ptr = unsafe { xmlHasProp(self.node_ptr(), c_name.as_bytes().as_ptr()) };
+    !value_ptr.is_null()
+  }
+  /// Check if property `name` in namespace `ns` exists
+  pub fn has_property_ns(&self, name: &str, ns: &str) -> bool {
+    let c_name = CString::new(name).unwrap();
+    let c_ns = CString::new(ns).unwrap();
+    let value_ptr =
+      unsafe { xmlHasNsProp(self.node_ptr(), c_name.as_bytes().as_ptr(), c_ns.as_bytes().as_ptr()) };
+    !value_ptr.is_null()
+  }
+  /// Alias for has_property
+  pub fn has_attribute(&self, name: &str) -> bool {
+    self.has_property(name)
+  }
+  /// Alias for has_property_ns
+  pub fn has_attribute_ns(&self, name: &str, ns: &str) -> bool {
+    self.has_property_ns(name, ns)
+  }
+
   /// Sets the value of property `name` to `value`
   pub fn set_property(&mut self, name: &str, value: &str) -> Result<(), Box<dyn Error + Send + Sync>> {
     let c_name = CString::new(name).unwrap();

tests/tree_tests.rs

@@ -83,6 +83,8 @@ fn node_attributes_accessor() {
   assert_eq!(attributes.len(), 1);
   assert_eq!(attributes.get("attribute"), Some(&"value".to_string()));
 
+  // Has
+  assert_eq!(child.has_attribute("attribute"), true);
   // Get
   assert_eq!(child.get_attribute("attribute"), Some("value".to_string()));
   // Get as node
@@ -101,6 +103,7 @@ fn node_attributes_accessor() {
   // Remove
   assert!(child.remove_attribute("attribute").is_ok());
   assert_eq!(child.get_attribute("attribute"), None);
+  assert_eq!(child.has_attribute("attribute"), false);
   // Recount
   let attributes = child.get_attributes();
   assert_eq!(attributes.len(), 0);
@@ -239,10 +242,14 @@ fn can_manage_attributes() {
   let value = "examplevalue";
   let pre_value = hello_element.get_attribute(key);
   assert_eq!(pre_value, None);
+  let pre_prop_check = hello_element.has_property(key);
+  assert_eq!(pre_prop_check, false);
   let pre_prop_value = hello_element.get_property(key);
   assert_eq!(pre_prop_value, None);
 
   assert!(hello_element.set_attribute(key, value).is_ok());
+  let new_check = hello_element.has_attribute(key);
+  assert_eq!(new_check, true);
   let new_value = hello_element.get_attribute(key);
   assert_eq!(new_value, Some(value.to_owned()));
 }