Disambiguate expressions in rsx by requiring curlies

packages/rsx/src/node.rs

@@ -6,7 +6,8 @@ use syn::{
     braced,
     parse::{Parse, ParseStream},
     spanned::Spanned,
-    token, Expr, ExprIf, LitStr, Pat, Result,
+    token::{self, Brace},
+    Expr, ExprIf, LitStr, Pat, Result,
 };
 
 /*
@@ -15,14 +16,14 @@ Parse
 -> Component {}
 -> component()
 -> "text {with_args}"
--> (0..10).map(|f| rsx!("asd")),  // <--- notice the comma - must be a complete expr
+-> {(0..10).map(|f| rsx!("asd"))}  // <--- notice the curly braces
 */
 #[derive(PartialEq, Eq, Clone, Debug, Hash)]
 pub enum BodyNode {
     Element(Element),
     Component(Component),
     ForLoop(ForLoop),
-    IfChain(ExprIf),
+    IfChain(IfChain),
     Text(IfmtInput),
     RawExpr(Expr),
 }
@@ -112,7 +113,27 @@ impl Parse for BodyNode {
             return Ok(BodyNode::IfChain(stream.parse()?));
         }
 
-        Ok(BodyNode::RawExpr(stream.parse::<Expr>()?))
+        // Match statements are special but have no special arm syntax
+        // we could allow arm syntax if we wanted
+        //
+        // ```
+        // match {
+        //  val => div {}
+        //  other_val => div {}
+        // }
+        // ```
+        if stream.peek(Token![match]) {
+            return Ok(BodyNode::RawExpr(stream.parse::<Expr>()?));
+        }
+
+        if stream.peek(token::Brace) {
+            return Ok(BodyNode::RawExpr(stream.parse::<Expr>()?));
+        }
+
+        Err(syn::Error::new(
+            stream.span(),
+            "Expected a valid body node.\nExpressions must be wrapped in curly braces.",
+        ))
     }
 }
 
@@ -151,71 +172,52 @@ impl ToTokens for BodyNode {
                 })
             }
             BodyNode::IfChain(chain) => {
-                if is_if_chain_terminated(chain) {
-                    tokens.append_all(quote! {
-                        {
-                            let ___nodes = (#chain).into_dyn_node(__cx);
-                            ___nodes
-                        }
-                    });
-                } else {
-                    let ExprIf {
+                let mut body = TokenStream2::new();
+                let mut terminated = false;
+
+                let mut elif = Some(chain);
+
+                while let Some(chain) = elif {
+                    let IfChain {
+                        if_token,
                         cond,
                         then_branch,
+                        else_if_branch,
                         else_branch,
-                        ..
                     } = chain;
 
-                    let mut body = TokenStream2::new();
+                    let mut renderer: TemplateRenderer = TemplateRenderer {
+                        roots: then_branch,
+                        location: None,
+                    };
 
-                    body.append_all(quote! {
-                        if #cond {
-                            Some(#then_branch)
-                        }
-                    });
+                    body.append_all(quote! { #if_token #cond { Some({#renderer}) } });
 
-                    let mut elif = else_branch;
-
-                    while let Some((_, ref branch)) = elif {
-                        match branch.as_ref() {
-                            Expr::If(ref eelif) => {
-                                let ExprIf {
-                                    cond,
-                                    then_branch,
-                                    else_branch,
-                                    ..
-                                } = eelif;
-
-                                body.append_all(quote! {
-                                    else if #cond {
-                                        Some(#then_branch)
-                                    }
-                                });
-
-                                elif = else_branch;
-                            }
-                            _ => {
-                                body.append_all(quote! {
-                                    else {
-                                        #branch
-                                    }
-                                });
-                                break;
-                            }
-                        }
+                    if let Some(next) = else_if_branch {
+                        body.append_all(quote! { else });
+                        elif = Some(next);
+                    } else if let Some(else_branch) = else_branch {
+                        renderer.roots = else_branch;
+                        body.append_all(quote! { else { Some({#renderer}) } });
+                        terminated = true;
+                        break;
+                    } else {
+                        elif = None;
                     }
+                }
 
+                if !terminated {
                     body.append_all(quote! {
                         else { None }
                     });
-
-                    tokens.append_all(quote! {
-                        {
-                            let ___nodes = (#body).into_dyn_node(__cx);
-                            ___nodes
-                        }
-                    });
                 }
+
+                tokens.append_all(quote! {
+                    {
+                        let ___nodes = (#body).into_dyn_node(__cx);
+                        ___nodes
+                    }
+                });
             }
         }
     }
@@ -240,26 +242,73 @@ impl Parse for ForLoop {
         let in_token: Token![in] = input.parse()?;
         let expr: Expr = input.call(Expr::parse_without_eager_brace)?;
 
-        let content;
-        let brace_token = braced!(content in input);
-
-        let mut children = vec![];
-
-        while !content.is_empty() {
-            children.push(content.parse()?);
-        }
+        let (brace_token, body) = parse_buffer_as_braced_children(input)?;
 
         Ok(Self {
             for_token,
             pat,
             in_token,
-            body: children,
-            expr: Box::new(expr),
+            body,
             brace_token,
+            expr: Box::new(expr),
         })
     }
 }
 
+#[derive(PartialEq, Eq, Clone, Debug, Hash)]
+pub struct IfChain {
+    pub if_token: Token![if],
+    pub cond: Box<Expr>,
+    pub then_branch: Vec<BodyNode>,
+    pub else_if_branch: Option<Box<IfChain>>,
+    pub else_branch: Option<Vec<BodyNode>>,
+}
+
+impl Parse for IfChain {
+    fn parse(input: ParseStream) -> Result<Self> {
+        let if_token: Token![if] = input.parse()?;
+
+        // stolen from ExprIf
+        let cond = Box::new(input.call(Expr::parse_without_eager_brace)?);
+
+        let (_, then_branch) = parse_buffer_as_braced_children(input)?;
+
+        let mut else_branch = None;
+        let mut else_if_branch = None;
+
+        // if the next token is `else`, set the else branch as the next if chain
+        if input.peek(Token![else]) {
+            input.parse::<Token![else]>()?;
+            if input.peek(Token![if]) {
+                else_if_branch = Some(Box::new(input.parse::<IfChain>()?));
+            } else {
+                let (_, else_branch_nodes) = parse_buffer_as_braced_children(input)?;
+                else_branch = Some(else_branch_nodes);
+            }
+        }
+
+        Ok(Self {
+            cond,
+            if_token,
+            then_branch,
+            else_if_branch,
+            else_branch,
+        })
+    }
+}
+
+fn parse_buffer_as_braced_children(
+    input: &syn::parse::ParseBuffer<'_>,
+) -> Result<(Brace, Vec<BodyNode>)> {
+    let content;
+    let brace_token = braced!(content in input);
+    let mut then_branch = vec![];
+    while !content.is_empty() {
+        then_branch.push(content.parse()?);
+    }
+    Ok((brace_token, then_branch))
+}
+
 pub(crate) fn is_if_chain_terminated(chain: &ExprIf) -> bool {
     let mut current = chain;
     loop {