2 files changed, 134 insertions, 7 deletions

diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index cb0aee422..44de4af89 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -1,6 +1,8 @@
 //! Various extension methods to ast Nodes, which are hard to code-generate.
 //! Extensions for various expressions live in a sibling `expr_extensions` module.
 
+use itertools::Itertools;
+
 use crate::{
     ast::{self, child_opt, children, AstNode, AttrInput, SyntaxNode},
     SmolStr, SyntaxElement,
@@ -35,6 +37,12 @@ fn text_of_first_token(node: &SyntaxNode) -> &SmolStr {
     node.green().children().next().and_then(|it| it.into_token()).unwrap().text()
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AttrKind {
+    Inner,
+    Outer,
+}
+
 impl ast::Attr {
     pub fn as_simple_atom(&self) -> Option<SmolStr> {
         match self.input() {
@@ -69,6 +77,18 @@ impl ast::Attr {
             _ => None,
         }
     }
+
+    pub fn kind(&self) -> AttrKind {
+        let first_token = self.syntax().first_token();
+        let first_token_kind = first_token.as_ref().map(SyntaxToken::kind);
+        let second_token_kind =
+            first_token.and_then(|token| token.next_token()).as_ref().map(SyntaxToken::kind);
+
+        match (first_token_kind, second_token_kind) {
+            (Some(SyntaxKind::POUND), Some(SyntaxKind::EXCL)) => AttrKind::Inner,
+            _ => AttrKind::Outer,
+        }
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -293,6 +313,40 @@ impl ast::BindPat {
     }
 }
 
+pub struct SlicePatComponents {
+    pub prefix: Vec<ast::Pat>,
+    pub slice: Option<ast::Pat>,
+    pub suffix: Vec<ast::Pat>,
+}
+
+impl ast::SlicePat {
+    pub fn components(&self) -> SlicePatComponents {
+        let mut args = self.args().peekable();
+        let prefix = args
+            .peeking_take_while(|p| match p {
+                ast::Pat::DotDotPat(_) => false,
+                ast::Pat::BindPat(bp) => match bp.pat() {
+                    Some(ast::Pat::DotDotPat(_)) => false,
+                    _ => true,
+                },
+                ast::Pat::RefPat(rp) => match rp.pat() {
+                    Some(ast::Pat::DotDotPat(_)) => false,
+                    Some(ast::Pat::BindPat(bp)) => match bp.pat() {
+                        Some(ast::Pat::DotDotPat(_)) => false,
+                        _ => true,
+                    },
+                    _ => true,
+                },
+                _ => true,
+            })
+            .collect();
+        let slice = args.next();
+        let suffix = args.collect();
+
+        SlicePatComponents { prefix, slice, suffix }
+    }
+}
+
 impl ast::PointerType {
     pub fn is_mut(&self) -> bool {
         self.syntax().children_with_tokens().any(|n| n.kind() == T![mut])
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 435135f92..8eb240801 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -1759,8 +1759,8 @@ impl AstNode for MatchArm {
 }
 impl ast::AttrsOwner for MatchArm {}
 impl MatchArm {
-    pub fn pats(&self) -> AstChildren<Pat> {
-        AstChildren::new(&self.syntax)
+    pub fn pat(&self) -> Option<Pat> {
+        AstChildren::new(&self.syntax).next()
     }
     pub fn guard(&self) -> Option<MatchGuard> {
         AstChildren::new(&self.syntax).next()
@@ -1887,6 +1887,60 @@ impl RecordField {
     }
 }
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct OrPat {
+    pub(crate) syntax: SyntaxNode,
+}
+impl AstNode for OrPat {
+    fn can_cast(kind: SyntaxKind) -> bool {
+        match kind {
+            OR_PAT => true,
+            _ => false,
+        }
+    }
+    fn cast(syntax: SyntaxNode) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode {
+        &self.syntax
+    }
+}
+impl OrPat {
+    pub fn pats(&self) -> AstChildren<Pat> {
+        AstChildren::new(&self.syntax)
+    }
+}
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ParenPat {
+    pub(crate) syntax: SyntaxNode,
+}
+impl AstNode for ParenPat {
+    fn can_cast(kind: SyntaxKind) -> bool {
+        match kind {
+            PAREN_PAT => true,
+            _ => false,
+        }
+    }
+    fn cast(syntax: SyntaxNode) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode {
+        &self.syntax
+    }
+}
+impl ParenPat {
+    pub fn pat(&self) -> Option<Pat> {
+        AstChildren::new(&self.syntax).next()
+    }
+}
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct RefPat {
     pub(crate) syntax: SyntaxNode,
 }
@@ -2063,7 +2117,11 @@ impl AstNode for SlicePat {
         &self.syntax
     }
 }
-impl SlicePat {}
+impl SlicePat {
+    pub fn args(&self) -> AstChildren<Pat> {
+        AstChildren::new(&self.syntax)
+    }
+}
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct RangePat {
     pub(crate) syntax: SyntaxNode,
@@ -3900,6 +3958,8 @@ impl AstNode for Expr {
 }
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Pat {
+    OrPat(OrPat),
+    ParenPat(ParenPat),
     RefPat(RefPat),
     BoxPat(BoxPat),
     BindPat(BindPat),
@@ -3913,6 +3973,16 @@ pub enum Pat {
     RangePat(RangePat),
     LiteralPat(LiteralPat),
 }
+impl From<OrPat> for Pat {
+    fn from(node: OrPat) -> Pat {
+        Pat::OrPat(node)
+    }
+}
+impl From<ParenPat> for Pat {
+    fn from(node: ParenPat) -> Pat {
+        Pat::ParenPat(node)
+    }
+}
 impl From<RefPat> for Pat {
     fn from(node: RefPat) -> Pat {
         Pat::RefPat(node)
@@ -3976,15 +4046,16 @@ impl From<LiteralPat> for Pat {
 impl AstNode for Pat {
     fn can_cast(kind: SyntaxKind) -> bool {
         match kind {
-            REF_PAT | BOX_PAT | BIND_PAT | PLACEHOLDER_PAT | DOT_DOT_PAT | PATH_PAT
-            | RECORD_PAT | TUPLE_STRUCT_PAT | TUPLE_PAT | SLICE_PAT | RANGE_PAT | LITERAL_PAT => {
-                true
-            }
+            OR_PAT | PAREN_PAT | REF_PAT | BOX_PAT | BIND_PAT | PLACEHOLDER_PAT | DOT_DOT_PAT
+            | PATH_PAT | RECORD_PAT | TUPLE_STRUCT_PAT | TUPLE_PAT | SLICE_PAT | RANGE_PAT
+            | LITERAL_PAT => true,
             _ => false,
         }
     }
     fn cast(syntax: SyntaxNode) -> Option<Self> {
         let res = match syntax.kind() {
+            OR_PAT => Pat::OrPat(OrPat { syntax }),
+            PAREN_PAT => Pat::ParenPat(ParenPat { syntax }),
             REF_PAT => Pat::RefPat(RefPat { syntax }),
             BOX_PAT => Pat::BoxPat(BoxPat { syntax }),
             BIND_PAT => Pat::BindPat(BindPat { syntax }),
@@ -4003,6 +4074,8 @@ impl AstNode for Pat {
     }
     fn syntax(&self) -> &SyntaxNode {
         match self {
+            Pat::OrPat(it) => &it.syntax,
+            Pat::ParenPat(it) => &it.syntax,
             Pat::RefPat(it) => &it.syntax,
             Pat::BoxPat(it) => &it.syntax,
             Pat::BindPat(it) => &it.syntax,