Add assignment

Author: orosmatthew

docs/grammar.md

@@ -5,6 +5,7 @@ $$
     \begin{cases}
         \text{exit}([\text{Expr}]); \\
         \text{let}\space\text{ident} = [\text{Expr}]; \\
+        \text{ident} = \text{[Expr]}; \\
         \text{if} ([\text{Expr}])[\text{Scope}]\text{[IfPred]}\\
         [\text{Scope}]
     \end{cases} \\

src/generation.hpp

@@ -188,6 +188,20 @@ class Generator {
                 gen.m_output << "    ;; /let\n";
             }
 
+            void operator()(const NodeStmtAssign* stmt_assign) const
+            {
+                const auto it = std::ranges::find_if(gen.m_vars, [&](const Var& var) {
+                    return var.name == stmt_assign->ident.value.value();
+                });
+                if (it == gen.m_vars.end()) {
+                    std::cerr << "Undeclared identifier: " << stmt_assign->ident.value.value() << std::endl;
+                    exit(EXIT_FAILURE);
+                }
+                gen.gen_expr(stmt_assign->expr);
+                gen.pop("rax");
+                gen.m_output << "    mov [rsp + " << (gen.m_stack_size - it->stack_loc - 1) * 8 << "], rax\n";
+            }
+
             void operator()(const NodeScope* scope) const
             {
                 gen.m_output << "    ;; scope\n";
@@ -204,13 +218,16 @@ class Generator {
                 gen.m_output << "    test rax, rax\n";
                 gen.m_output << "    jz " << label << "\n";
                 gen.gen_scope(stmt_if->scope);
-                gen.m_output << "    jmp " << label << "\n";
-                gen.m_output << label << ":\n";
                 if (stmt_if->pred.has_value()) {
                     const std::string end_label = gen.create_label();
+                    gen.m_output << "    jmp " << end_label << "\n";
+                    gen.m_output << label << ":\n";
                     gen.gen_if_pred(stmt_if->pred.value(), end_label);
                     gen.m_output << end_label << ":\n";
                 }
+                else {
+                    gen.m_output << label << ":\n";
+                }
                 gen.m_output << "    ;; /if\n";
             }
         };

src/parser.hpp

@@ -89,8 +89,13 @@ struct NodeStmtIf {
     std::optional<NodeIfPred*> pred;
 };
 
+struct NodeStmtAssign {
+    Token ident;
+    NodeExpr* expr {};
+};
+
 struct NodeStmt {
-    std::variant<NodeStmtExit*, NodeStmtLet*, NodeScope*, NodeStmtIf*> var;
+    std::variant<NodeStmtExit*, NodeStmtLet*, NodeScope*, NodeStmtIf*, NodeStmtAssign*> var;
 };
 
 struct NodeProg {
@@ -279,6 +284,22 @@ class Parser {
             stmt->var = stmt_let;
             return stmt;
         }
+        if (peek().has_value() && peek().value().type == TokenType::ident && peek(1).has_value()
+            && peek(1).value().type == TokenType::eq) {
+            const auto assign = m_allocator.alloc<NodeStmtAssign>();
+            assign->ident = consume();
+            consume();
+            if (const auto expr = parse_expr()) {
+                assign->expr = expr.value();
+            }
+            else {
+                std::cerr << "Expected expression" << std::endl;
+                exit(EXIT_FAILURE);
+            }
+            try_consume(TokenType::semi, "Expected `;`");
+            auto stmt = m_allocator.emplace<NodeStmt>(assign);
+            return stmt;
+        }
         if (peek().has_value() && peek().value().type == TokenType::open_curly) {
             if (auto scope = parse_scope()) {
                 auto stmt = m_allocator.emplace<NodeStmt>(scope.value());

test.hy

@@ -1,14 +1,16 @@
 let y = (10 - 2 * 3) / 2;
-let x = 1; // first
+let x = 7; // first
 // first
-if (1) {
-    exit(69);
-} elif (1) {
-    exit(68);
+if (0) {
+    x = 1;
+} elif (0) {
+    x = 2;
 } else {
-    exit(67);
+    x = 3;
 }
 
+exit(x);
+
 /*
 exit(4);
 */