fix: memory issues

src/02_syntax/expression.zig

@@ -10,7 +10,7 @@ pub const Expression = union(enum) {
     /// Attempts to parse an expression from a token stream.
     ///
     /// Receives a pointer to the memory for initialization
-    pub fn init(tokens: *const std.ArrayList(Token), pos: usize) error{Unmatched}!Expression {
+    pub fn init(self: *@This(), tokens: *const std.ArrayList(Token), pos: usize) error{Unmatched}!void {
         std.debug.assert(pos < tokens.items.len);
 
         const t = tokens.items[pos];
@@ -18,7 +18,7 @@ pub const Expression = union(enum) {
             return error.Unmatched;
         }
 
-        return .{
+        self.* = .{
             .number = &t,
         };
     }
@@ -29,7 +29,8 @@ test "should parse expression" {
     const tokens = try lexic.tokenize(input, std.testing.allocator);
     defer tokens.deinit();
 
-    const expr = try Expression.init(&tokens, 0);
+    var expr: Expression = undefined;
+    try expr.init(&tokens, 0);
     try std.testing.expectEqualDeep("322", expr.number.value);
     try std.testing.expectEqualDeep(TokenType.Int, expr.number.token_type);
 }
@@ -39,7 +40,8 @@ test "should fail on non expression" {
     const tokens = try lexic.tokenize(input, std.testing.allocator);
     defer tokens.deinit();
 
-    const expr = Expression.init(&tokens, 0) catch |err| {
+    var expr: Expression = undefined;
+    expr.init(&tokens, 0) catch |err| {
         try std.testing.expectEqual(ParseError.Unmatched, err);
         return;
     };

src/02_syntax/root.zig

@@ -23,8 +23,6 @@ pub const Module = struct {
 
         // parse many statements
         while (current_pos < input_len) {
-            std.debug.print("running on pos {d} \n", .{current_pos});
-
             // FIXME: if a statement was added to the array list,
             // and then one of these fails,
             // will all previous statements leak memory?
@@ -34,6 +32,7 @@ pub const Module = struct {
             current_pos = next_pos;
 
             arrl.append(stmt) catch {
+                // TODO: free stmt if this fails
                 return ParseError.Error;
             };
         }
@@ -68,6 +67,5 @@ test "should parse a single statement" {
     var module: Module = undefined;
     _ = try module.init(&tokens, 0, std.testing.allocator);
 
-    std.debug.print("len: {d} \n", .{module.statements.items.len});
     defer module.deinit();
 }

src/02_syntax/statement.zig

@@ -8,14 +8,21 @@ const variable = @import("./variable.zig");
 const TokenStream = types.TokenStream;
 const ParseError = types.ParseError;
 
-pub const Statement = union(enum) {
-    VariableBinding: *variable.VariableBinding,
+pub const Statement = struct {
+    alloc: std.mem.Allocator,
+    value: union(enum) {
+        variableBinding: *variable.VariableBinding,
+    },
 
     /// Parses a Statement and return the position of the next token
     pub fn init(target: *Statement, tokens: *const TokenStream, pos: usize, allocator: std.mem.Allocator) ParseError!usize {
         // try to parse a variable definition
 
-        var vardef: variable.VariableBinding = undefined;
+        var vardef = allocator.create(variable.VariableBinding) catch {
+            return ParseError.OutOfMemory;
+        };
+        errdefer allocator.destroy(vardef);
+
         var parse_failed = false;
         const vardef_end = vardef.init(tokens, pos, allocator) catch |err| switch (err) {
             error.Unmatched => blk: {
@@ -29,7 +36,8 @@ pub const Statement = union(enum) {
         if (!parse_failed) {
             // return the parsed variable definition
             target.* = .{
-                .VariableBinding = &vardef,
+                .alloc = allocator,
+                .value = .{ .variableBinding = vardef },
             };
             return vardef_end;
         }
@@ -39,8 +47,11 @@ pub const Statement = union(enum) {
     }
 
     pub fn deinit(self: @This()) void {
-        switch (self) {
-            .VariableBinding => |v| v.deinit(),
+        switch (self.value) {
+            .variableBinding => |v| {
+                v.deinit();
+                self.alloc.destroy(v);
+            },
         }
     }
 };
@@ -54,8 +65,8 @@ test "should parse a variable declaration statement" {
     _ = try statement.init(&tokens, 0, std.testing.allocator);
     defer statement.deinit();
 
-    switch (statement) {
-        .VariableBinding => |v| {
+    switch (statement.value) {
+        .variableBinding => |v| {
             try std.testing.expectEqual(true, v.is_mutable);
         },
     }

src/02_syntax/variable.zig

@@ -11,7 +11,7 @@ pub const VariableBinding = struct {
     is_mutable: bool,
     datatype: ?*lexic.Token,
     identifier: *lexic.Token,
-    expression: *const expression.Expression,
+    expression: *expression.Expression,
     alloc: std.mem.Allocator,
 
     /// Parses a variable binding and returns the position of the next token
@@ -43,7 +43,12 @@ pub const VariableBinding = struct {
         // parse expression
         if (pos + 3 >= tokens.items.len) return ParseError.Error;
 
-        const exp = expression.Expression.init(tokens, pos + 3) catch {
+        // TODO: allocate on the stack
+        const exp = allocator.create(expression.Expression) catch {
+            return ParseError.OutOfMemory;
+        };
+        errdefer allocator.destroy(exp);
+        exp.init(tokens, pos + 3) catch {
             return ParseError.Error;
         };
 
@@ -52,15 +57,15 @@ pub const VariableBinding = struct {
             .is_mutable = true,
             .datatype = null,
             .identifier = identifier,
-            .expression = &exp,
+            .expression = exp,
             .alloc = allocator,
         };
         // TODO: when expression parses more than one token this will break.
         return pos + 4;
     }
 
-    pub fn deinit(self: *VariableBinding) void {
-        _ = self;
+    pub fn deinit(self: @This()) void {
+        self.alloc.destroy(self.expression);
     }
 };
 
@@ -74,6 +79,14 @@ test "should parse a minimal var" {
     defer binding.deinit();
 
     try std.testing.expectEqual(true, binding.is_mutable);
+    try std.testing.expect(binding.datatype == null);
+    try std.testing.expectEqualDeep("my_variable", binding.identifier.value);
+    const expr = binding.expression;
+    switch (expr.*) {
+        .number => |n| {
+            try std.testing.expectEqualDeep("322", n.value);
+        },
+    }
 }
 
 test "should fail is it doesnt start with var" {