Desugar field access

src/desugar.rs

@@ -1,5 +1,6 @@
 mod basic;
 mod call;
 mod expr;
+mod field;
 mod lit;
 mod program;

src/desugar/expr.rs

@@ -9,8 +9,8 @@ impl Expr {
             }
 
             Self::Call(call) => call.desugar(),
+            Self::Field(field) => field.desugar(),
 
-            Self::Field(field) => (Self::Field(field), false), // TODO Implement
             Self::Var(var) => (Self::Var(var), false), // TODO Implement
             Self::TableConstr(constr) => (Self::TableConstr(constr), false), // TODO Implement
             Self::TableDestr(destr) => (Self::TableDestr(destr), false), // TODO Implement

src/desugar/field.rs

@@ -0,0 +1,133 @@
+use crate::ast::{
+    Call, Expr, Field, Lit, Separated, Space, TableConstr, TableConstrElem, TableLitElem,
+};
+use crate::builtin::Builtin;
+
+impl Field {
+    pub fn desugar(self) -> (Expr, bool) {
+        match self {
+            Self::Access {
+                expr,
+                s0,
+                s1,
+                index,
+                s2,
+                span,
+            } => {
+                let (expr, desugared) = expr.desugar();
+                if desugared {
+                    let new = Expr::Field(Self::Access {
+                        expr: Box::new(expr),
+                        s0,
+                        s1,
+                        index,
+                        s2,
+                        span,
+                    });
+                    return (new, true);
+                }
+
+                let (index, desugared) = index.desugar();
+                if desugared {
+                    let new = Expr::Field(Self::Access {
+                        expr: Box::new(expr),
+                        s0,
+                        s1,
+                        index: Box::new(index),
+                        s2,
+                        span,
+                    });
+                    return (new, true);
+                }
+
+                let elems = Separated::NonEmpty {
+                    first_elem: TableConstrElem::Lit(TableLitElem::Positional(Box::new(expr))),
+                    last_elems: vec![(
+                        (Space::empty(span), Space::empty(span)),
+                        TableConstrElem::Lit(TableLitElem::Positional(Box::new(index))),
+                    )],
+                    trailing: None,
+                    span,
+                };
+                let constr = TableConstr {
+                    s0: Space::empty(span),
+                    elems,
+                    s1: Space::empty(span),
+                    span,
+                };
+                let new = Expr::Call(Call::Constr {
+                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::Get, span))),
+                    s0: Space::empty(span),
+                    constr,
+                    span,
+                });
+                (new, true)
+            }
+
+            Self::Assign {
+                expr,
+                s0,
+                s1,
+                index,
+                s2,
+                s3,
+                s4,
+                value,
+                span,
+            } => {
+                let new = Expr::Field(Self::Assign {
+                    expr,
+                    s0,
+                    s1,
+                    index,
+                    s2,
+                    s3,
+                    s4,
+                    value,
+                    span,
+                });
+                (new, true) // TODO Implement
+            }
+
+            Self::AccessIdent {
+                expr,
+                s0,
+                s1,
+                ident,
+                span,
+            } => {
+                let new = Expr::Field(Self::AccessIdent {
+                    expr,
+                    s0,
+                    s1,
+                    ident,
+                    span,
+                });
+                (new, false) // TODO Implement
+            }
+
+            Self::AssignIdent {
+                expr,
+                s0,
+                s1,
+                ident,
+                s2,
+                s3,
+                value,
+                span,
+            } => {
+                let new = Expr::Field(Self::AssignIdent {
+                    expr,
+                    s0,
+                    s1,
+                    ident,
+                    s2,
+                    s3,
+                    value,
+                    span,
+                });
+                (new, false) // TODO Implement
+            }
+        }
+    }
+}