try Cow<'static, str> for Text nodes.

This mostly just applies to smart quotes, which are unlikely to benefit
hugely (small String optimisation?), but I'm interested in seeing how
far we can go with Cow; what if we can avoid allocations entirely in
some cases by referring to the input?

Author: kivikakk

README.md

@@ -202,7 +202,7 @@ fn replace_text(document: &str, orig_string: &str, replacement: &str) -> String
     for node in root.descendants() {
         if let NodeValue::Text(ref mut text) = node.data.borrow_mut().value {
             // If the node is a text node, perform the string replacement.
-            *text = text.replace(orig_string, replacement)
+            *text = text.to_mut().replace(orig_string, replacement).into()
         }
     }
 

examples/iterator_replace.rs

@@ -13,7 +13,7 @@ fn replace_text(document: &str, orig_string: &str, replacement: &str) -> String
     for node in root.descendants() {
         if let NodeValue::Text(ref mut text) = node.data.borrow_mut().value {
             // If the node is a text node, replace `orig_string` with `replacement`.
-            *text = text.replace(orig_string, replacement)
+            *text = text.to_mut().replace(orig_string, replacement).into()
         }
     }
 

examples/sample.rs

@@ -24,7 +24,7 @@ fn large() {
         for node in root.descendants() {
             if let NodeValue::Text(ref mut text) = node.data.borrow_mut().value {
                 // If the node is a text node, perform the string replacement.
-                *text = text.replace(orig_string, replacement)
+                *text = text.to_mut().replace(orig_string, replacement).into()
             }
         }
 

examples/update-readme.rs

@@ -74,7 +74,7 @@ fn main() -> Result<(), Box<dyn Error>> {
             }
             NodeValue::Text(ref mut t) => {
                 if in_msrv {
-                    std::mem::swap(t, &mut msrv.to_string());
+                    std::mem::swap(t, &mut msrv.to_string().into());
                 }
             }
             _ => {}

src/html.rs

@@ -354,8 +354,10 @@ pub fn format_document_with_formatter<'a, 'o, 'c: 'o, T>(
                 let new_cr = match child_rendering {
                     ChildRendering::Plain => {
                         match node.data.borrow().value {
-                            NodeValue::Text(ref literal)
-                            | NodeValue::Code(NodeCode { ref literal, .. })
+                            NodeValue::Text(ref literal) => {
+                                context.escape(literal)?;
+                            }
+                            NodeValue::Code(NodeCode { ref literal, .. })
                             | NodeValue::HtmlInline(ref literal) => {
                                 context.escape(literal)?;
                             }
@@ -1609,9 +1611,8 @@ pub fn collect_text<'a>(node: &'a AstNode<'a>) -> String {
 /// whitespace character.
 pub fn collect_text_append<'a>(node: &'a AstNode<'a>, output: &mut String) {
     match node.data.borrow().value {
-        NodeValue::Text(ref literal) | NodeValue::Code(NodeCode { ref literal, .. }) => {
-            output.push_str(literal)
-        }
+        NodeValue::Text(ref literal) => output.push_str(literal),
+        NodeValue::Code(NodeCode { ref literal, .. }) => output.push_str(literal),
         NodeValue::LineBreak | NodeValue::SoftBreak => output.push(' '),
         NodeValue::Math(NodeMath { ref literal, .. }) => output.push_str(literal),
         _ => {

src/lib.rs

@@ -30,7 +30,7 @@
 //!
 //! for node in root.descendants() {
 //!     if let NodeValue::Text(ref mut text) = node.data.borrow_mut().value {
-//!         *text = text.replace("pretty", "beautiful");
+//!         *text = text.to_mut().replace("pretty", "beautiful").into()
 //!     }
 //! }
 //!

src/nodes.rs

@@ -1,15 +1,15 @@
 //! The CommonMark AST.
 
-use crate::arena_tree::Node;
+use std::borrow::Cow;
 use std::cell::RefCell;
 use std::convert::TryFrom;
 
-#[cfg(feature = "shortcodes")]
-pub use crate::parser::shortcodes::NodeShortCode;
-
+use crate::arena_tree::Node;
 pub use crate::parser::alert::{AlertType, NodeAlert};
 pub use crate::parser::math::NodeMath;
 pub use crate::parser::multiline_block_quote::NodeMultilineBlockQuote;
+#[cfg(feature = "shortcodes")]
+pub use crate::parser::shortcodes::NodeShortCode;
 
 /// The core AST node enum.
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -112,7 +112,7 @@ pub enum NodeValue {
 
     /// **Inline**.  [Textual content](https://github.github.com/gfm/#textual-content).  All text
     /// in a document will be contained in a `Text` node.
-    Text(String),
+    Text(Cow<'static, str>),
 
     /// **Block**. [Task list item](https://github.github.com/gfm/#task-list-items-extension-).
     /// The value is the symbol that was used in the brackets to mark a task item as checked, or
@@ -474,7 +474,7 @@ impl NodeValue {
     /// Return a reference to the text of a `Text` inline, if this node is one.
     ///
     /// Convenience method.
-    pub fn text(&self) -> Option<&String> {
+    pub fn text(&self) -> Option<&Cow<'static, str>> {
         match *self {
             NodeValue::Text(ref t) => Some(t),
             _ => None,
@@ -484,7 +484,7 @@ impl NodeValue {
     /// Return a mutable reference to the text of a `Text` inline, if this node is one.
     ///
     /// Convenience method.
-    pub fn text_mut(&mut self) -> Option<&mut String> {
+    pub fn text_mut(&mut self) -> Option<&mut Cow<'static, str>> {
         match *self {
             NodeValue::Text(ref mut t) => Some(t),
             _ => None,

src/parser/autolink.rs

@@ -91,15 +91,15 @@ pub(crate) fn process_email_autolinks<'a>(
                     initial_end_col,
                 )
                     .into();
-                let after = make_inline(arena, NodeValue::Text(remain.to_string()), asp);
+                let after = make_inline(arena, NodeValue::Text(remain.into()), asp);
                 post.insert_after(after);
 
                 let after_ast = &mut after.data.borrow_mut();
                 process_email_autolinks(
                     arena,
                     after,
                     match after_ast.value {
-                        NodeValue::Text(ref mut t) => t,
+                        NodeValue::Text(ref mut t) => t.to_mut(),
                         _ => unreachable!(),
                     },
                     relaxed_autolinks,
@@ -209,7 +209,7 @@ fn email_match<'a>(
 
     inl.append(make_inline(
         arena,
-        NodeValue::Text(text.to_string()),
+        NodeValue::Text(text.to_string().into()),
         (0, 1, 0, 1).into(),
     ));
     Some((inl, rewind, rewind + link_end))
@@ -270,7 +270,7 @@ pub fn www_match<'a>(
 
     inl.append(make_inline(
         subject.arena,
-        NodeValue::Text(subject.input[i..link_end + i].into()),
+        NodeValue::Text(subject.input[i..link_end + i].to_string().into()),
         (0, 1, 0, 1).into(),
     ));
     Some((inl, 0, link_end))
@@ -436,7 +436,7 @@ pub fn url_match<'a>(
 
     inl.append(make_inline(
         subject.arena,
-        NodeValue::Text(url.to_string()),
+        NodeValue::Text(url.to_string().into()),
         (0, 1, 0, 1).into(),
     ));
     Some((inl, rewind, rewind + link_end))