Field access

5 files changed, 56 insertions, 27 deletions

diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 4a616b58..d9651cce 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -215,6 +215,7 @@ impl Eval for Expr {
             Self::Array(v) => v.eval(ctx, scp).map(Value::Array),
             Self::Dict(v) => v.eval(ctx, scp).map(Value::Dict),
             Self::Group(v) => v.eval(ctx, scp),
+            Self::FieldAccess(v) => v.eval(ctx, scp),
             Self::FuncCall(v) => v.eval(ctx, scp),
             Self::MethodCall(v) => v.eval(ctx, scp),
             Self::Closure(v) => v.eval(ctx, scp),
@@ -434,6 +435,23 @@ impl BinaryExpr {
     }
 }
 
+impl Eval for FieldAccess {
+    type Output = Value;
+
+    fn eval(&self, ctx: &mut Context, scp: &mut Scopes) -> EvalResult<Self::Output> {
+        let object = self.object().eval(ctx, scp)?;
+        Ok(match object {
+            Value::Dict(dict) => dict.get(self.field().take()).at(self.span())?.clone(),
+
+            v => bail!(
+                self.object().span(),
+                "cannot access field on {}",
+                v.type_name()
+            ),
+        })
+    }
+}
+
 impl Eval for FuncCall {
     type Output = Value;
 
@@ -442,14 +460,8 @@ impl Eval for FuncCall {
         let args = self.args().eval(ctx, scp)?;
 
         Ok(match callee {
-            Value::Array(array) => {
-                array.get(args.into_index()?).map(Value::clone).at(self.span())?
-            }
-
-            Value::Dict(dict) => {
-                dict.get(args.into_key()?).map(Value::clone).at(self.span())?
-            }
-
+            Value::Array(array) => array.get(args.into_index()?).at(self.span())?.clone(),
+            Value::Dict(dict) => dict.get(args.into_key()?).at(self.span())?.clone(),
             Value::Func(func) => {
                 let point = || Tracepoint::Call(func.name().map(ToString::to_string));
                 func.call(ctx, args).trace(point, self.span())?
diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index be947170..c387de0c 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -368,10 +368,9 @@ fn expr_prec(p: &mut Parser, atomic: bool, min_prec: usize) -> ParseResult {
     };
 
     loop {
-        // Exclamation mark, parenthesis or bracket means this is a function
-        // call.
+        // Parenthesis or bracket means this is a function call.
         if let Some(NodeKind::LeftParen | NodeKind::LeftBracket) = p.peek_direct() {
-            func_call(p, marker)?;
+            marker.perform(p, NodeKind::FuncCall, |p| args(p, true, true))?;
             continue;
         }
 
@@ -379,8 +378,14 @@ fn expr_prec(p: &mut Parser, atomic: bool, min_prec: usize) -> ParseResult {
             break;
         }
 
-        if p.at(&NodeKind::Dot) {
-            method_call(p, marker)?;
+        // Method call or field access.
+        if p.eat_if(&NodeKind::Dot) {
+            ident(p)?;
+            if let Some(NodeKind::LeftParen | NodeKind::LeftBracket) = p.peek_direct() {
+                marker.perform(p, NodeKind::MethodCall, |p| args(p, true, true))?;
+            } else {
+                marker.end(p, NodeKind::FieldAccess);
+            }
             continue;
         }
 
@@ -715,20 +720,6 @@ fn content_block(p: &mut Parser) {
     });
 }
 
-/// Parse a function call.
-fn func_call(p: &mut Parser, callee: Marker) -> ParseResult {
-    callee.perform(p, NodeKind::FuncCall, |p| args(p, true, true))
-}
-
-/// Parse a method call.
-fn method_call(p: &mut Parser, marker: Marker) -> ParseResult {
-    marker.perform(p, NodeKind::MethodCall, |p| {
-        p.eat_assert(&NodeKind::Dot);
-        ident(p)?;
-        args(p, true, true)
-    })
-}
-
 /// Parse the arguments to a function call.
 fn args(p: &mut Parser, direct: bool, brackets: bool) -> ParseResult {
     match if direct { p.peek_direct() } else { p.peek() } {
diff --git a/src/syntax/ast.rs b/src/syntax/ast.rs
index 60856691..8af359bf 100644
--- a/src/syntax/ast.rs
+++ b/src/syntax/ast.rs
@@ -237,6 +237,8 @@ pub enum Expr {
     Unary(UnaryExpr),
     /// A binary operation: `a + b`.
     Binary(BinaryExpr),
+    /// A field access: `properties.age`.
+    FieldAccess(FieldAccess),
     /// An invocation of a function: `f(x, y)`.
     FuncCall(FuncCall),
     /// An invocation of a method: `array.push(v)`.
@@ -280,6 +282,7 @@ impl TypedNode for Expr {
             NodeKind::DictExpr => node.cast().map(Self::Dict),
             NodeKind::UnaryExpr => node.cast().map(Self::Unary),
             NodeKind::BinaryExpr => node.cast().map(Self::Binary),
+            NodeKind::FieldAccess => node.cast().map(Self::FieldAccess),
             NodeKind::FuncCall => node.cast().map(Self::FuncCall),
             NodeKind::MethodCall => node.cast().map(Self::MethodCall),
             NodeKind::ClosureExpr => node.cast().map(Self::Closure),
@@ -310,6 +313,7 @@ impl TypedNode for Expr {
             Self::Group(v) => v.as_red(),
             Self::Unary(v) => v.as_red(),
             Self::Binary(v) => v.as_red(),
+            Self::FieldAccess(v) => v.as_red(),
             Self::FuncCall(v) => v.as_red(),
             Self::MethodCall(v) => v.as_red(),
             Self::Closure(v) => v.as_red(),
@@ -790,6 +794,23 @@ pub enum Associativity {
 }
 
 node! {
+    /// A field access: `properties.age`.
+    FieldAccess: FieldAccess
+}
+
+impl FieldAccess {
+    /// The object with the field.
+    pub fn object(&self) -> Expr {
+        self.0.cast_first_child().expect("field access is missing object")
+    }
+
+    /// The name of the field.
+    pub fn field(&self) -> Ident {
+        self.0.cast_last_child().expect("field access call is missing name")
+    }
+}
+
+node! {
     /// An invocation of a function: `f(x, y)`.
     FuncCall: FuncCall
 }
diff --git a/src/syntax/highlight.rs b/src/syntax/highlight.rs
index 004ff957..10dfce69 100644
--- a/src/syntax/highlight.rs
+++ b/src/syntax/highlight.rs
@@ -209,6 +209,7 @@ impl Category {
             NodeKind::Named => None,
             NodeKind::UnaryExpr => None,
             NodeKind::BinaryExpr => None,
+            NodeKind::FieldAccess => None,
             NodeKind::FuncCall => None,
             NodeKind::MethodCall => None,
             NodeKind::CallArgs => None,
diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index d18b6a3d..71646cb2 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -653,6 +653,8 @@ pub enum NodeKind {
     UnaryExpr,
     /// A binary operation: `a + b`.
     BinaryExpr,
+    /// A field access: `properties.age`.
+    FieldAccess,
     /// An invocation of a function: `f(x, y)`.
     FuncCall,
     /// An invocation of a method: `array.push(v)`.
@@ -898,6 +900,7 @@ impl NodeKind {
             Self::Named => "named argument",
             Self::UnaryExpr => "unary expression",
             Self::BinaryExpr => "binary expression",
+            Self::FieldAccess => "field access",
             Self::FuncCall => "function call",
             Self::MethodCall => "method call",
             Self::CallArgs => "call arguments",
@@ -1021,6 +1024,7 @@ impl Hash for NodeKind {
             Self::Named => {}
             Self::UnaryExpr => {}
             Self::BinaryExpr => {}
+            Self::FieldAccess => {}
             Self::FuncCall => {}
             Self::MethodCall => {}
             Self::CallArgs => {}