automatically declare default namespaces unless overriden

1 files changed, 49 insertions, 13 deletions

diff --git a/src/writer.rs b/src/writer.rs
index e319fdc..8b45869 100644
--- a/src/writer.rs
+++ b/src/writer.rs
@@ -93,20 +93,38 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
     }
 
     pub async fn write_empty(&mut self, element: &Element) -> Result<()> {
-        let namespace_declarations_stack: Vec<_> = self
+        let mut namespace_declarations_stack: Vec<_> = self
             .namespace_declarations
             .iter()
             .flatten()
-            .chain(&element.namespace_declarations)
+            .chain(&element.namespace_declaration_overrides)
             .collect();
 
+        let mut namespace_declarations = element.namespace_declaration_overrides.clone();
+
+        let default_namespace_declaration;
         let prefix;
         if let Some(namespace) = &element.name.namespace {
-            let name_namespace_declaration = namespace_declarations_stack
+            if let Some(name_namespace_declaration) = namespace_declarations_stack
                 .iter()
                 .rfind(|namespace_declaration| namespace_declaration.namespace == *namespace)
-                .ok_or(Error::UndeclaredNamespace(namespace.clone()))?;
-            prefix = name_namespace_declaration.prefix.as_ref();
+            {
+                prefix = name_namespace_declaration.prefix.as_ref();
+            } else {
+                default_namespace_declaration = NamespaceDeclaration {
+                    prefix: None,
+                    namespace: namespace.clone(),
+                };
+                if namespace_declarations.insert(default_namespace_declaration.clone()) {
+                    namespace_declarations_stack.push(&default_namespace_declaration);
+                    prefix = None
+                } else {
+                    return Err(Error::DuplicateNameSpaceDeclaration(NamespaceDeclaration {
+                        prefix: None,
+                        namespace: namespace.clone(),
+                    }));
+                }
+            }
         } else {
             prefix = None
         }
@@ -125,7 +143,7 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
 
         let mut attributes = Vec::new();
 
-        for namespace_declaration in &element.namespace_declarations {
+        for namespace_declaration in namespace_declarations.iter() {
             let ns_name = namespace_declaration
                 .prefix
                 .as_ref()
@@ -180,20 +198,38 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
     }
 
     pub async fn write_element_start(&mut self, element: &Element) -> Result<()> {
-        let namespace_declarations_stack: Vec<_> = self
+        let mut namespace_declarations_stack: Vec<_> = self
             .namespace_declarations
             .iter()
             .flatten()
-            .chain(&element.namespace_declarations)
+            .chain(&element.namespace_declaration_overrides)
             .collect();
 
+        let mut namespace_declarations = element.namespace_declaration_overrides.clone();
+
+        let default_namespace_declaration;
         let prefix;
         if let Some(namespace) = &element.name.namespace {
-            let name_namespace_declaration = namespace_declarations_stack
+            if let Some(name_namespace_declaration) = namespace_declarations_stack
                 .iter()
                 .rfind(|namespace_declaration| namespace_declaration.namespace == *namespace)
-                .ok_or(Error::UndeclaredNamespace(namespace.clone()))?;
-            prefix = name_namespace_declaration.prefix.as_ref();
+            {
+                prefix = name_namespace_declaration.prefix.as_ref();
+            } else {
+                default_namespace_declaration = NamespaceDeclaration {
+                    prefix: None,
+                    namespace: namespace.clone(),
+                };
+                if namespace_declarations.insert(default_namespace_declaration.clone()) {
+                    namespace_declarations_stack.push(&default_namespace_declaration);
+                    prefix = None
+                } else {
+                    return Err(Error::DuplicateNameSpaceDeclaration(NamespaceDeclaration {
+                        prefix: None,
+                        namespace: namespace.clone(),
+                    }));
+                }
+            }
         } else {
             prefix = None
         }
@@ -212,7 +248,7 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
 
         let mut attributes = Vec::new();
 
-        for namespace_declaration in &element.namespace_declarations {
+        for namespace_declaration in namespace_declarations.iter() {
             let ns_name = namespace_declaration
                 .prefix
                 .as_ref()
@@ -265,7 +301,7 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
 
         self.depth.push(element.name.clone());
         self.namespace_declarations
-            .push(element.namespace_declarations.clone());
+            .push(namespace_declarations.clone());
         Ok(())
     }