feat(parser): add impl statement.

crates/fuse-ast/src/ast.rs

@@ -423,7 +423,7 @@ pub enum ConstructionField {
 pub struct ImplStatement {
     pub span: Span,
     pub target: TypeAnnotation,
-    pub r#trait: Option<()>,
+    pub r#trait: Option<TypeAnnotation>,
     pub methods: Vec<ImplMethod>,
 }
 

crates/fuse-parser/src/parsers/binding.rs

@@ -33,7 +33,15 @@ impl<'a> Parser<'a> {
         }
 
         let identifier = self.parse_binding_identifier();
-        Ok(self.ast.binding_identifier_pattern(identifier, None, false))
+        let type_annotation = if self.consume_if(TokenKind::Colon).is_some() {
+            Some(self.parse_type_annotation()?)
+        } else {
+            None
+        };
+
+        Ok(self
+            .ast
+            .binding_identifier_pattern(identifier, type_annotation, false))
     }
 
     pub(crate) fn parse_binding_identifier(&mut self) -> BindingIdentifier {

crates/fuse-parser/src/parsers/statements.rs

@@ -91,12 +91,18 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_impl_statement(&mut self) -> ParserResult<Statement> {
-        debug_assert!(self.at(TokenKind::Trait));
+        debug_assert!(self.at(TokenKind::Impl));
         let start = self.start_span();
         // Consume the struct keyword.
         self.consume();
 
-        let target = self.parse_type_annotation()?;
+        let (target, r#trait) = {
+            let first_type = self.parse_type_annotation()?;
+            match self.consume_if(TokenKind::For) {
+                Some(_) => (self.parse_type_annotation()?, Some(first_type)),
+                None => (first_type, None),
+            }
+        };
         let mut methods: Vec<ImplMethod> = Vec::new();
         while !self.at(TokenKind::End) {
             let modifier = self.try_parse_visibility_modifier();
@@ -108,7 +114,7 @@ impl<'a> Parser<'a> {
         Ok(self.ast.impl_statement(ImplStatement {
             span: self.end_span(start),
             target,
-            r#trait: None,
+            r#trait,
             methods,
         }))
     }

crates/fuse-parser/tests/cases/pass/impl-statement-01/ast.snap

@@ -0,0 +1,33 @@
+---
+source: crates/fuse-parser/tests/cases/mod.rs
+description: "impl Test\nend\n"
+expression: parsed.chunk
+input_file: crates/fuse-parser/tests/cases/pass/impl-statement-01/case.fuse
+---
+Some(Chunk(
+  span: Span(
+    start: 0,
+    end: 14,
+  ),
+  body: Block(
+    statements: [
+      ImplStatement(ImplStatement(
+        span: Span(
+          start: 0,
+          end: 13,
+        ),
+        target: TypeAnnotation(
+          identifier: Identifier(
+            span: Span(
+              start: 5,
+              end: 9,
+            ),
+            name: Atom("Test"),
+          ),
+        ),
+        trait: None,
+        methods: [],
+      )),
+    ],
+  ),
+))

crates/fuse-parser/tests/cases/pass/impl-statement-01/case.fuse

@@ -0,0 +1,2 @@
+impl Test
+end

crates/fuse-parser/tests/cases/pass/impl-statement-01/tokens.snap

@@ -0,0 +1,65 @@
+---
+source: crates/fuse-parser/tests/cases/mod.rs
+description: "impl Test\nend\n"
+expression: tokens
+input_file: crates/fuse-parser/tests/cases/pass/impl-statement-01/case.fuse
+---
+[
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 0,
+        end: 4,
+      ),
+      kind: Impl,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 4,
+          end: 5,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 5,
+        end: 9,
+      ),
+      kind: Identifier,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 9,
+          end: 10,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 10,
+        end: 13,
+      ),
+      kind: End,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 13,
+          end: 14,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+]

crates/fuse-parser/tests/cases/pass/impl-statement-02/ast.snap

@@ -0,0 +1,41 @@
+---
+source: crates/fuse-parser/tests/cases/mod.rs
+description: "impl Trait for Test\nend\n"
+expression: parsed.chunk
+input_file: crates/fuse-parser/tests/cases/pass/impl-statement-02/case.fuse
+---
+Some(Chunk(
+  span: Span(
+    start: 0,
+    end: 24,
+  ),
+  body: Block(
+    statements: [
+      ImplStatement(ImplStatement(
+        span: Span(
+          start: 0,
+          end: 23,
+        ),
+        target: TypeAnnotation(
+          identifier: Identifier(
+            span: Span(
+              start: 15,
+              end: 19,
+            ),
+            name: Atom("Test"),
+          ),
+        ),
+        trait: Some(TypeAnnotation(
+          identifier: Identifier(
+            span: Span(
+              start: 5,
+              end: 10,
+            ),
+            name: Atom("Trait"),
+          ),
+        )),
+        methods: [],
+      )),
+    ],
+  ),
+))

crates/fuse-parser/tests/cases/pass/impl-statement-02/case.fuse

@@ -0,0 +1,2 @@
+impl Trait for Test
+end

crates/fuse-parser/tests/cases/pass/impl-statement-02/tokens.snap

@@ -0,0 +1,103 @@
+---
+source: crates/fuse-parser/tests/cases/mod.rs
+description: "impl Trait for Test\nend\n"
+expression: tokens
+input_file: crates/fuse-parser/tests/cases/pass/impl-statement-02/case.fuse
+---
+[
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 0,
+        end: 4,
+      ),
+      kind: Impl,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 4,
+          end: 5,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 5,
+        end: 10,
+      ),
+      kind: Identifier,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 10,
+          end: 11,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 11,
+        end: 14,
+      ),
+      kind: For,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 14,
+          end: 15,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 15,
+        end: 19,
+      ),
+      kind: Identifier,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 19,
+          end: 20,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+  TokenReference(
+    token: Token(
+      span: Span(
+        start: 20,
+        end: 23,
+      ),
+      kind: End,
+    ),
+    leading_trivia: [],
+    trailing_trivia: [
+      Token(
+        span: Span(
+          start: 23,
+          end: 24,
+        ),
+        kind: Whitespace,
+      ),
+    ],
+  ),
+]