Scale back the traits

crates/ra_syntax/src/ast.rs

@@ -11,10 +11,7 @@ pub mod make;
 use std::marker::PhantomData;
 
 use crate::{
-    syntax_node::{
+    syntax_node::{SyntaxNode, SyntaxNodeChildren, SyntaxToken},
-        NodeOrToken, SyntaxElement, SyntaxElementChildren, SyntaxNode, SyntaxNodeChildren,
-        SyntaxToken,
-    },
     SmolStr, SyntaxKind,
 };
 
@@ -33,24 +30,16 @@ pub use self::{
 /// conversion itself has zero runtime cost: ast and syntax nodes have exactly
 /// the same representation: a pointer to the tree root and a pointer to the
 /// node itself.
-pub trait AstNode: AstElement {
+pub trait AstNode {
     fn can_cast(kind: SyntaxKind) -> bool
     where
         Self: Sized;
 
-    fn cast_or_return(syntax: SyntaxNode) -> Result<Self, SyntaxNode>
-    where
-        Self: Sized;
-
     fn cast(syntax: SyntaxNode) -> Option<Self>
     where
-        Self: Sized,
+        Self: Sized;
-    {
-        <Self as AstNode>::cast_or_return(syntax).ok()
-    }
 
     fn syntax(&self) -> &SyntaxNode;
-    fn into_syntax(self) -> SyntaxNode;
 }
 
 #[test]
@@ -59,51 +48,22 @@ fn assert_ast_is_object_safe() {
 }
 
 /// Like `AstNode`, but wraps tokens rather than interior nodes.
-pub trait AstToken: AstElement {
+pub trait AstToken {
     fn can_cast(token: SyntaxKind) -> bool
     where
         Self: Sized;
 
-    fn cast_or_return(syntax: SyntaxToken) -> Result<Self, SyntaxToken>
-    where
-        Self: Sized;
-
     fn cast(syntax: SyntaxToken) -> Option<Self>
     where
-        Self: Sized,
+        Self: Sized;
-    {
-        <Self as AstToken>::cast_or_return(syntax).ok()
-    }
 
     fn syntax(&self) -> &SyntaxToken;
-    fn into_syntax(self) -> SyntaxToken;
 
     fn text(&self) -> &SmolStr {
         self.syntax().text()
     }
 }
 
-/// Like `AstNode`, but wraps either nodes or tokens rather than interior nodes.
-pub trait AstElement: std::fmt::Display {
-    fn can_cast_element(kind: SyntaxKind) -> bool
-    where
-        Self: Sized;
-
-    fn cast_or_return_element(syntax: SyntaxElement) -> Result<Self, SyntaxElement>
-    where
-        Self: Sized;
-
-    fn cast_element(syntax: SyntaxElement) -> Option<Self>
-    where
-        Self: Sized,
-    {
-        <Self as AstElement>::cast_or_return_element(syntax).ok()
-    }
-
-    fn syntax_element(&self) -> NodeOrToken<&SyntaxNode, &SyntaxToken>;
-    fn into_syntax_element(self) -> SyntaxElement;
-}
-
 /// An iterator over `SyntaxNode` children of a particular AST type.
 #[derive(Debug, Clone)]
 pub struct AstChildren<N> {
@@ -132,64 +92,6 @@ fn children<P: AstNode + ?Sized, C: AstNode>(parent: &P) -> AstChildren<C> {
     AstChildren::new(parent.syntax())
 }
 
-/// An iterator over `SyntaxToken` children of a particular AST type.
-#[derive(Debug, Clone)]
-pub struct AstChildTokens<N> {
-    inner: SyntaxElementChildren,
-    ph: PhantomData<N>,
-}
-
-impl<N> AstChildTokens<N> {
-    fn new(parent: &SyntaxNode) -> Self {
-        AstChildTokens { inner: parent.children_with_tokens(), ph: PhantomData }
-    }
-}
-
-impl<N: AstToken> Iterator for AstChildTokens<N> {
-    type Item = N;
-    fn next(&mut self) -> Option<N> {
-        self.inner.by_ref().filter_map(|x| x.into_token()).find_map(N::cast)
-    }
-}
-
-fn child_token_opt<P: AstNode + ?Sized, C: AstToken>(parent: &P) -> Option<C> {
-    child_tokens(parent).next()
-}
-
-fn child_tokens<P: AstNode + ?Sized, C: AstToken>(parent: &P) -> AstChildTokens<C> {
-    AstChildTokens::new(parent.syntax())
-}
-
-/// An iterator over `SyntaxNode` children of a particular AST type.
-#[derive(Debug, Clone)]
-pub struct AstChildElements<N> {
-    inner: SyntaxElementChildren,
-    ph: PhantomData<N>,
-}
-
-impl<N> AstChildElements<N> {
-    fn new(parent: &SyntaxNode) -> Self {
-        AstChildElements { inner: parent.children_with_tokens(), ph: PhantomData }
-    }
-}
-
-impl<N: AstElement> Iterator for AstChildElements<N> {
-    type Item = N;
-    fn next(&mut self) -> Option<N> {
-        self.inner.by_ref().find_map(N::cast_element)
-    }
-}
-
-#[allow(dead_code)]
-fn child_element_opt<P: AstNode + ?Sized, C: AstElement>(parent: &P) -> Option<C> {
-    child_elements(parent).next()
-}
-
-#[allow(dead_code)]
-fn child_elements<P: AstNode + ?Sized, C: AstElement>(parent: &P) -> AstChildElements<C> {
-    AstChildElements::new(parent.syntax())
-}
-
 #[test]
 fn test_doc_comment_none() {
     let file = SourceFile::parse(

xtask/src/codegen/gen_syntax.rs

@@ -97,11 +97,13 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
         let name = format_ident!("{}", to_pascal_case(kind_str));
         quote! {
             #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-            pub struct #name(SyntaxToken);
+            pub struct #name {
+                pub(crate) syntax: SyntaxToken,
+            }
 
             impl std::fmt::Display for #name {
                 fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-                    std::fmt::Display::fmt(self.syntax(), f)
+                    std::fmt::Display::fmt(&self.syntax, f)
                 }
             }
 
@@ -112,29 +114,10 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
                         _ => false,
                     }
                 }
-                fn cast_or_return(syntax: SyntaxToken) -> Result<Self, SyntaxToken> {
+                fn cast(syntax: SyntaxToken) -> Option<Self> {
-                    if Self::can_cast(syntax.kind()) { Ok(Self(syntax)) } else { Err(syntax) }
+                    if Self::can_cast(syntax.kind()) { Some(Self { syntax }) } else { None }
-                }
-                fn syntax(&self) -> &SyntaxToken { &self.0 }
-                fn into_syntax(self) -> SyntaxToken { self.0 }
-            }
-
-            impl AstElement for #name {
-                fn can_cast_element(kind: SyntaxKind) -> bool {
-                    match kind {
-                        #kind => true,
-                        _ => false,
-                    }
-                }
-                fn cast_or_return_element(syntax: SyntaxElement) -> Result<Self, SyntaxElement> {
-                    if Self::can_cast_element(syntax.kind()) { Ok(Self(syntax.into_token().unwrap())) } else { Err(syntax) }
-                }
-                fn syntax_element(&self) -> NodeOrToken<&SyntaxNode, &SyntaxToken> {
-                    NodeOrToken::Token(&self.0)
-                }
-                fn into_syntax_element(self) -> SyntaxElement {
-                    NodeOrToken::Token(self.0)
                 }
+                fn syntax(&self) -> &SyntaxToken { &self.syntax }
             }
         }
     });
@@ -156,28 +139,21 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
                 FieldSrc::Optional(ty) | FieldSrc::Many(ty) => ty,
                 FieldSrc::Shorthand => name,
             };
-            let element_kinds = &element_kinds_map.get(*ty).unwrap_or_else(|| panic!("type not found: {}", *ty));
+
-            let iter = if !element_kinds.has_tokens {
-                format_ident!("AstChildren")
-            } else if !element_kinds.has_nodes {
-                format_ident!("AstChildTokens")
-            } else {
-                format_ident!("AstChildElements")
-            };
             let ty = format_ident!("{}", ty);
 
             match field {
                 FieldSrc::Many(_) => {
                     quote! {
-                        pub fn #method_name(&self) -> #iter<#ty> {
+                        pub fn #method_name(&self) -> AstChildren<#ty> {
-                            #iter::new(&self.syntax)
+                            AstChildren::new(&self.syntax)
                         }
                     }
                 }
                 FieldSrc::Optional(_) | FieldSrc::Shorthand => {
                     quote! {
                         pub fn #method_name(&self) -> Option<#ty> {
-                            #iter::new(&self.syntax).next()
+                            AstChildren::new(&self.syntax).next()
                         }
                     }
                 }
@@ -203,29 +179,10 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
                         _ => false,
                     }
                 }
-                fn cast_or_return(syntax: SyntaxNode) -> Result<Self, SyntaxNode> {
+                fn cast(syntax: SyntaxNode) -> Option<Self> {
-                    if Self::can_cast(syntax.kind()) { Ok(Self { syntax }) } else { Err(syntax) }
+                    if Self::can_cast(syntax.kind()) { Some(Self { syntax }) } else { None }
                 }
                 fn syntax(&self) -> &SyntaxNode { &self.syntax }
-                fn into_syntax(self) -> SyntaxNode { self.syntax }
-            }
-
-            impl AstElement for #name {
-                fn can_cast_element(kind: SyntaxKind) -> bool {
-                    match kind {
-                        #kind => true,
-                        _ => false,
-                    }
-                }
-                fn cast_or_return_element(syntax: SyntaxElement) -> Result<Self, SyntaxElement> {
-                    if Self::can_cast_element(syntax.kind()) { Ok(Self { syntax: syntax.into_node().unwrap() }) } else { Err(syntax) }
-                }
-                fn syntax_element(&self) -> NodeOrToken<&SyntaxNode, &SyntaxToken> {
-                    NodeOrToken::Node(&self.syntax)
-                }
-                fn into_syntax_element(self) -> SyntaxElement {
-                    NodeOrToken::Node(self.syntax)
-                }
             }
 
             #(#traits)*
@@ -238,71 +195,16 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
 
     let enums = grammar.enums.iter().map(|en| {
         let variants = en.variants.iter().map(|var| format_ident!("{}", var)).collect::<Vec<_>>();
-        let element_kinds = &element_kinds_map[&en.name.to_string()];
         let name = format_ident!("{}", en.name);
-        let kinds = en.variants
+        let kinds = variants
             .iter()
-            .map(|name| {
+            .map(|name| format_ident!("{}", to_upper_snake_case(&name.to_string())))
-                element_kinds_map[*name].kinds.iter().collect::<Vec<_>>()
-            })
             .collect::<Vec<_>>();
         let traits = en.traits.iter().map(|trait_name| {
             let trait_name = format_ident!("{}", trait_name);
             quote!(impl ast::#trait_name for #name {})
         });
 
-        let all_kinds = &element_kinds.kinds;
-
-        let specific_ast_trait = if element_kinds.has_nodes != element_kinds.has_tokens {
-            let (ast_trait, syntax_type) = if element_kinds.has_tokens {
-                (
-                    quote!(AstToken),
-                    quote!(SyntaxToken),
-                )
-            } else {
-                (
-                    quote!(AstNode),
-                    quote!(SyntaxNode),
-                )
-            };
-
-            quote! {
-                impl #ast_trait for #name {
-                    fn can_cast(kind: SyntaxKind) -> bool {
-                        match kind {
-                            #(#all_kinds)|* => true,
-                            _ => false,
-                        }
-                    }
-                    #[allow(unreachable_patterns)]
-                    fn cast_or_return(syntax: #syntax_type) -> Result<Self, #syntax_type> {
-                        match syntax.kind() {
-                            #(
-                            #(#kinds)|* => #variants::cast_or_return(syntax).map(|x| #name::#variants(x)),
-                            )*
-                            _ => Err(syntax),
-                        }
-                    }
-                    fn syntax(&self) -> &#syntax_type {
-                        match self {
-                            #(
-                            #name::#variants(it) => it.syntax(),
-                            )*
-                        }
-                    }
-                    fn into_syntax(self) -> #syntax_type {
-                        match self {
-                            #(
-                            #name::#variants(it) => it.into_syntax(),
-                            )*
-                        }
-                    }
-                }
-            }
-        } else {
-            Default::default()
-        };
-
         quote! {
             #[derive(Debug, Clone, PartialEq, Eq, Hash)]
             pub enum #name {
@@ -319,48 +221,34 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
 
             impl std::fmt::Display for #name {
                 fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-                    match self {
+                    std::fmt::Display::fmt(self.syntax(), f)
-                        #(
-                        #name::#variants(it) => std::fmt::Display::fmt(it, f),
-                        )*
-                    }
                 }
             }
 
-            #specific_ast_trait
+            impl AstNode for #name {
-
+                fn can_cast(kind: SyntaxKind) -> bool {
-            impl AstElement for #name {
-                fn can_cast_element(kind: SyntaxKind) -> bool {
                     match kind {
-                        #(#all_kinds)|* => true,
+                        #(#kinds)|* => true,
                         _ => false,
                     }
                 }
-                #[allow(unreachable_patterns)]
+                fn cast(syntax: SyntaxNode) -> Option<Self> {
-                fn cast_or_return_element(syntax: SyntaxElement) -> Result<Self, SyntaxElement> {
+                    let res = match syntax.kind() {
-                    match syntax.kind() {
                         #(
-                        #(#kinds)|* => #variants::cast_or_return_element(syntax).map(|x| #name::#variants(x)),
+                        #kinds => #name::#variants(#variants { syntax }),
                         )*
-                        _ => Err(syntax),
+                        _ => return None,
+                    };
+                    Some(res)
                 }
-                }
+                fn syntax(&self) -> &SyntaxNode {
-                fn syntax_element(&self) -> NodeOrToken<&SyntaxNode, &SyntaxToken> {
                     match self {
                         #(
-                        #name::#variants(it) => it.syntax_element(),
+                        #name::#variants(it) => &it.syntax,
-                        )*
-                    }
-                }
-                fn into_syntax_element(self) -> SyntaxElement {
-                    match self {
-                        #(
-                        #name::#variants(it) => it.into_syntax_element(),
                         )*
                     }
                 }
             }
-
             #(#traits)*
         }
     });
@@ -380,7 +268,7 @@ fn generate_ast(kinds: KindsSrc<'_>, grammar: AstSrc<'_>) -> Result<String> {
         #[allow(unused_imports)]
         use crate::{
             SyntaxNode, SyntaxToken, SyntaxElement, NodeOrToken, SyntaxKind::{self, *},
-            ast::{self, AstNode, AstToken, AstElement, AstChildren, AstChildTokens, AstChildElements},
+            ast::{self, AstNode, AstToken, AstChildren},
         };
 
         #(#tokens)*