From 4c6dd311a7cb125f226e39615ff93af956a3df24 Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Tue, 12 Oct 2021 22:14:20 +0200
Subject: [PATCH] Added Assignable support in parser / AST

---
 ablescript/src/ast.rs       | 14 ++++++++++-
 ablescript/src/interpret.rs | 11 ++++++---
 ablescript/src/parser.rs    | 49 +++++++++++++++++++++++++++++++------
 3 files changed, 63 insertions(+), 11 deletions(-)

diff --git a/ablescript/src/ast.rs b/ablescript/src/ast.rs
index 8e654ed..e11cb33 100644
--- a/ablescript/src/ast.rs
+++ b/ablescript/src/ast.rs
@@ -38,6 +38,18 @@ impl Hash for Ident {
     }
 }
 
+#[derive(Debug, PartialEq, Clone, Hash)]
+pub struct Assignable {
+    pub ident: Ident,
+    pub kind: AssignableKind,
+}
+
+#[derive(Debug, PartialEq, Clone, Hash)]
+pub enum AssignableKind {
+    Variable,
+    Cart { indices: Vec<Expr> },
+}
+
 #[derive(Debug, PartialEq, Clone, Hash)]
 pub struct Block {
     pub block: Vec<Stmt>,
@@ -80,7 +92,7 @@ pub enum StmtKind {
         init: Option<Expr>,
     },
     Assign {
-        ident: Ident,
+        assignable: Assignable,
         value: Expr,
     },
 
diff --git a/ablescript/src/interpret.rs b/ablescript/src/interpret.rs
index ab58a7e..f9b10e7 100644
--- a/ablescript/src/interpret.rs
+++ b/ablescript/src/interpret.rs
@@ -197,7 +197,11 @@ impl ExecEnv {
 
                 self.decl_var(&ident.ident, init);
             }
-            StmtKind::Functio { ident, params, body } => {
+            StmtKind::Functio {
+                ident,
+                params,
+                body,
+            } => {
                 self.decl_var(
                     &ident.ident,
                     Value::Functio(Functio::AbleFunctio {
@@ -240,9 +244,10 @@ impl ExecEnv {
                     HaltStatus::Hopback(_) => continue,
                 }
             },
-            StmtKind::Assign { ident, value } => {
+            StmtKind::Assign { assignable, value } => {
+                // TODO: Assigning to carts
                 let value = self.eval_expr(value)?;
-                self.get_var_mut(ident)?.value.replace(value);
+                self.get_var_mut(&assignable.ident)?.value.replace(value);
             }
             StmtKind::Break => {
                 return Ok(HaltStatus::Break(stmt.span.clone()));
diff --git a/ablescript/src/parser.rs b/ablescript/src/parser.rs
index f07039d..f01a9da 100644
--- a/ablescript/src/parser.rs
+++ b/ablescript/src/parser.rs
@@ -355,15 +355,25 @@ impl<'source> Parser<'source> {
 
                 // Variable Assignment
                 Token::Equal => {
-                    if let Some(Expr {
-                        kind: ExprKind::Variable(ident),
-                        span,
-                    }) = buf
-                    {
+                    let assignable = buf.take().and_then(|buf| match buf.kind {
+                        ExprKind::Variable(ident) => Some(Assignable {
+                            ident: Ident::new(ident, buf.span),
+                            kind: AssignableKind::Variable,
+                        }),
+                        ExprKind::Index { expr, index } => self.cart_assignable_flow(*expr, *index),
+                        _ => None,
+                    });
+
+                    if let Some(assignable) = assignable {
                         break StmtKind::Assign {
-                            ident: Ident::new(ident, span),
+                            assignable,
                             value: self.expr_flow(Token::Semicolon)?,
                         };
+                    } else {
+                        return Err(Error::new(
+                            ErrorKind::UnexpectedToken(Token::Equal),
+                            self.lexer.span(),
+                        ));
                     }
                 }
 
@@ -385,6 +395,27 @@ impl<'source> Parser<'source> {
         Ok(r)
     }
 
+    /// Parse Cart Assignable flow
+    fn cart_assignable_flow(&mut self, mut buf: Expr, index: Expr) -> Option<Assignable> {
+        let mut indices = vec![index];
+        let ident = loop {
+            match buf.kind {
+                ExprKind::Variable(ident) => break ident,
+                ExprKind::Index { expr, index } => {
+                    indices.push(*index);
+                    buf = *expr;
+                }
+                _ => return None,
+            }
+        };
+
+        indices.reverse();
+        Some(Assignable {
+            ident: Ident::new(ident, buf.span),
+            kind: AssignableKind::Cart { indices },
+        })
+    }
+
     /// Parse If flow
     ///
     /// Consists of condition and block, there is no else
@@ -431,7 +462,11 @@ impl<'source> Parser<'source> {
 
         let body = self.get_block()?;
 
-        Ok(StmtKind::Functio { ident, params, body })
+        Ok(StmtKind::Functio {
+            ident,
+            params,
+            body,
+        })
     }
 
     /// Parse BF function declaration