Add cell paths

crates/nu-protocol/src/ast/cell_path.rs

@@ -0,0 +1,19 @@
+use super::Expression;
+use crate::Span;
+
+#[derive(Debug, Clone)]
+pub enum PathMember {
+    String { val: String, span: Span },
+    Int { val: usize, span: Span },
+}
+
+#[derive(Debug, Clone)]
+pub struct CellPath {
+    pub members: Vec<PathMember>,
+}
+
+#[derive(Debug, Clone)]
+pub struct FullCellPath {
+    pub head: Expression,
+    pub tail: Vec<PathMember>,
+}

crates/nu-protocol/src/ast/expr.rs

@@ -1,4 +1,4 @@
-use super::{Call, Expression, Operator, RangeOperator};
+use super::{Call, Expression, FullCellPath, Operator, RangeOperator};
 use crate::{BlockId, Signature, Span, VarId};
 
 #[derive(Debug, Clone)]
@@ -22,6 +22,7 @@ pub enum Expr {
     Table(Vec<Expression>, Vec<Vec<Expression>>),
     Keyword(Vec<u8>, Span, Box<Expression>),
     String(String), // FIXME: improve this in the future?
+    FullCellPath(Box<FullCellPath>),
     Signature(Box<Signature>),
     Garbage,
 }

crates/nu-protocol/src/ast/mod.rs

@@ -1,5 +1,6 @@
 mod block;
 mod call;
+mod cell_path;
 mod expr;
 mod expression;
 mod operator;
@@ -8,6 +9,7 @@ mod statement;
 
 pub use block::*;
 pub use call::*;
+pub use cell_path::*;
 pub use expr::*;
 pub use expression::*;
 pub use operator::*;