feat: Group

The main use case here is `VisitMut`; we might want to replace one element with multiple.

src/element.rs

@@ -1,7 +1,7 @@
 use alloc::{borrow::Cow, string::ToString, vec::Vec};
 use core::fmt::{Debug, Write};
 
-use crate::{Audio, Break, Emphasis, Mark, Meta, SayAs, Serialize, SerializeOptions, Text, Voice, XmlWriter, util};
+use crate::{Audio, Break, Emphasis, Mark, Meta, SayAs, Serialize, SerializeOptions, Text, Voice, XmlWriter, group::Group, util};
 
 macro_rules! el {
 	(
@@ -52,6 +52,7 @@ el! {
 		Emphasis(Emphasis<'s>),
 		Mark(Mark<'s>),
 		SayAs(SayAs<'s>),
+		Group(Group<'s>),
 		FlavorMSTTS(crate::mstts::Element<'s>),
 		Custom(CustomElement<'s>)
 		// Lang(LangElement),

src/group.rs

@@ -0,0 +1,74 @@
+use core::{
+	fmt::Write,
+	ops::{Add, AddAssign}
+};
+
+use crate::{Element, Serialize, SerializeOptions, XmlWriter};
+
+#[derive(Clone, Default, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct Group<'s> {
+	pub(crate) children: Vec<Element<'s>>
+}
+
+impl<'s> Group<'s> {
+	pub fn new<S: Into<Element<'s>>, I: IntoIterator<Item = S>>(elements: I) -> Self {
+		Self {
+			children: elements.into_iter().map(|f| f.into()).collect()
+		}
+	}
+
+	pub fn children(&self) -> &[Element<'s>] {
+		&self.children
+	}
+
+	pub fn children_mut(&mut self) -> &mut Vec<Element<'s>> {
+		&mut self.children
+	}
+
+	pub fn push(&mut self, element: impl Into<Element<'s>>) {
+		self.children.push(element.into());
+	}
+
+	pub fn extend<S: Into<Element<'s>>, I: IntoIterator<Item = S>>(&mut self, elements: I) {
+		self.children.extend(elements.into_iter().map(|f| f.into()));
+	}
+
+	pub fn to_owned(&self) -> Group<'static> {
+		self.clone().into_owned()
+	}
+
+	pub fn into_owned(self) -> Group<'static> {
+		Group {
+			children: self.children.into_iter().map(Element::into_owned).collect()
+		}
+	}
+}
+
+impl<'s> Serialize for Group<'s> {
+	fn serialize_xml<W: Write>(&self, writer: &mut XmlWriter<W>, options: &SerializeOptions) -> crate::Result<()> {
+		for child in &self.children {
+			child.serialize_xml(writer, options)?;
+		}
+		Ok(())
+	}
+}
+
+impl<'s, 's2: 's, T: Into<Element<'s2>>> Add<T> for Group<'s> {
+	type Output = Group<'s>;
+
+	fn add(mut self, rhs: T) -> Self::Output {
+		self.push(rhs.into());
+		self
+	}
+}
+
+impl<'s, 's2: 's, T: Into<Element<'s2>>> AddAssign<T> for Group<'s> {
+	fn add_assign(&mut self, rhs: T) {
+		self.push(rhs.into());
+	}
+}
+
+pub fn group<'s, S: Into<Element<'s>>, I: IntoIterator<Item = S>>(elements: I) -> Group<'s> {
+	Group::new(elements)
+}

src/lib.rs

@@ -41,6 +41,7 @@ mod r#break;
 mod element;
 mod emphasis;
 mod error;
+mod group;
 mod mark;
 pub mod mstts;
 mod say_as;
@@ -59,6 +60,7 @@ pub use self::{
 	element::{CustomElement, Element, IntoElement},
 	emphasis::{Emphasis, EmphasisLevel, emphasis},
 	error::{Error, Result},
+	group::{Group, group},
 	mark::{Mark, mark},
 	say_as::{DateFormat, SayAs, SpeechFormat, say_as},
 	speak::{Speak, speak},

src/say_as.rs

@@ -1,4 +1,4 @@
-use alloc::borrow::Cow;
+use alloc::{borrow::Cow, boxed::Box};
 use core::fmt::Write;
 
 use crate::{Flavor, Serialize, SerializeOptions, XmlWriter};
@@ -124,7 +124,7 @@ impl<'s> SayAs<'s> {
 
 	pub fn into_owned(self) -> SayAs<'static> {
 		SayAs {
-			format: self.format.to_owned(),
+			format: self.format.clone(),
 			text: match self.text {
 				Cow::Borrowed(b) => Cow::Owned(b.to_string()),
 				Cow::Owned(b) => Cow::Owned(b)

src/visit.rs

@@ -141,7 +141,12 @@ pub fn visit_element<'s, V: Visit<'s> + ?Sized>(v: &mut V, node: &'s Element) {
 		Element::Mark(node) => visit_mark(v, node),
 		Element::SayAs(node) => visit_say_as(v, node),
 		Element::FlavorMSTTS(node) => visit_mstts_element(v, node),
-		Element::Custom(node) => visit_custom(v, node)
+		Element::Custom(node) => visit_custom(v, node),
+		Element::Group(node) => {
+			for child in node.children() {
+				visit_element(v, child);
+			}
+		}
 	}
 }
 

src/visit_mut.rs

@@ -107,7 +107,12 @@ pub fn visit_element_mut<'s, V: VisitMut<'s> + ?Sized>(v: &mut V, node: &'s mut
 		Element::Mark(node) => visit_mark_mut(v, node),
 		Element::SayAs(node) => visit_say_as_mut(v, node),
 		Element::FlavorMSTTS(node) => visit_mstts_element_mut(v, node),
-		Element::Custom(node) => visit_custom_mut(v, node)
+		Element::Custom(node) => visit_custom_mut(v, node),
+		Element::Group(node) => {
+			for child in node.children_mut() {
+				visit_element_mut(v, child);
+			}
+		}
 	}
 }