fix: memory issues in syntax root

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

src/02_syntax/root.zig

@@ -3,21 +3,71 @@ const lexic = @import("lexic");
 const expression = @import("./expression.zig");
 const variable = @import("./variable.zig");
 const types = @import("./types.zig");
+const statement = @import("./statement.zig");
 
 const Token = lexic.Token;
 const TokenType = lexic.TokenType;
 const ParseError = types.ParseError;
+const TokenStream = types.TokenStream;
 
-const Statement = union(enum) {
+pub const Module = struct {
-    VariableBinding: u8,
+    statements: std.ArrayList(*statement.Statement),
+    alloc: std.mem.Allocator,
 
-    fn parse(tokens: *const std.ArrayList(Token), pos: usize) ParseError!@This() {
+    pub fn init(target: *@This(), tokens: *const TokenStream, pos: usize, allocator: std.mem.Allocator) ParseError!void {
-        _ = tokens;
+        var arrl = std.ArrayList(*statement.Statement).init(allocator);
-        _ = pos;
+        errdefer arrl.deinit();
-        return ParseError.Error;
+
+        const input_len = tokens.items.len;
+        var current_pos = pos;
+
+        // 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?
+            var stmt = try allocator.create(statement.Statement);
+            errdefer allocator.destroy(stmt);
+            const next_pos = try stmt.init(tokens, current_pos, allocator);
+            current_pos = next_pos;
+
+            arrl.append(stmt) catch {
+                return ParseError.Error;
+            };
+        }
+
+        target.* = .{
+            // FIXME: is this copying the whole arraylist? should use a pointer?
+            .statements = arrl,
+            .alloc = allocator,
+        };
+    }
+
+    pub fn deinit(self: @This()) void {
+        // FIXME: should deinit all elements inside the arraylist no? otherwise
+        // they will leak no?
+        for (self.statements.items) |stmt| {
+            stmt.deinit();
+            self.alloc.destroy(stmt);
+        }
+        self.statements.deinit();
     }
 };
 
 test {
     std.testing.refAllDecls(@This());
 }
+
+test "should parse a single statement" {
+    const input = "var my_variable = 322";
+    const tokens = try lexic.tokenize(input, std.testing.allocator);
+    defer tokens.deinit();
+
+    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

@@ -11,14 +11,16 @@ const ParseError = types.ParseError;
 pub const Statement = union(enum) {
     VariableBinding: *variable.VariableBinding,
 
-    fn init(target: *Statement, tokens: *const TokenStream, pos: usize, allocator: std.mem.Allocator) ParseError!void {
+    /// 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 parse_failed = false;
-        vardef.init(tokens, pos, allocator) catch |err| switch (err) {
+        const vardef_end = vardef.init(tokens, pos, allocator) catch |err| switch (err) {
-            error.Unmatched => {
+            error.Unmatched => blk: {
                 parse_failed = true;
+                break :blk 0;
             },
             else => {
                 return err;
@@ -29,14 +31,14 @@ pub const Statement = union(enum) {
             target.* = .{
                 .VariableBinding = &vardef,
             };
-            return;
+            return vardef_end;
         }
 
         // fail
         return ParseError.Unmatched;
     }
 
-    fn deinit(self: @This()) void {
+    pub fn deinit(self: @This()) void {
         switch (self) {
             .VariableBinding => |v| v.deinit(),
         }
@@ -49,7 +51,7 @@ test "should parse a variable declaration statement" {
     defer tokens.deinit();
 
     var statement: Statement = undefined;
-    try statement.init(&tokens, 0, std.testing.allocator);
+    _ = try statement.init(&tokens, 0, std.testing.allocator);
     defer statement.deinit();
 
     switch (statement) {
@@ -65,7 +67,7 @@ test "should fail on other constructs" {
     defer tokens.deinit();
 
     var statement: Statement = undefined;
-    statement.init(&tokens, 0, std.testing.allocator) catch |e| switch (e) {
+    _ = statement.init(&tokens, 0, std.testing.allocator) catch |e| switch (e) {
         error.Unmatched => {
             return;
         },

src/02_syntax/variable.zig

@@ -11,11 +11,11 @@ pub const VariableBinding = struct {
     is_mutable: bool,
     datatype: ?*lexic.Token,
     identifier: *lexic.Token,
-    expression: *expression.Expression,
+    expression: *const expression.Expression,
     alloc: std.mem.Allocator,
 
-    /// Parses a variable binding
+    /// Parses a variable binding and returns the position of the next token
-    pub fn init(target: *VariableBinding, tokens: *const TokenStream, pos: usize, allocator: std.mem.Allocator) ParseError!void {
+    pub fn init(target: *VariableBinding, tokens: *const TokenStream, pos: usize, allocator: std.mem.Allocator) ParseError!usize {
         std.debug.assert(pos < tokens.items.len);
 
         // try to parse a var keyword
@@ -42,9 +42,8 @@ pub const VariableBinding = struct {
 
         // parse expression
         if (pos + 3 >= tokens.items.len) return ParseError.Error;
-        var exp = try allocator.create(expression.Expression);
+
-        errdefer allocator.destroy(exp);
+        const exp = expression.Expression.init(tokens, pos + 3) catch {
-        exp.init(tokens, pos + 3) catch {
             return ParseError.Error;
         };
 
@@ -53,13 +52,15 @@ 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.alloc.destroy(self.expression);
+        _ = self;
     }
 };
 
@@ -69,7 +70,7 @@ test "should parse a minimal var" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    try binding.init(&tokens, 0, std.testing.allocator);
+    _ = try binding.init(&tokens, 0, std.testing.allocator);
     defer binding.deinit();
 
     try std.testing.expectEqual(true, binding.is_mutable);
@@ -81,7 +82,7 @@ test "should fail is it doesnt start with var" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    binding.init(&tokens, 0, std.testing.allocator) catch |err| {
+    _ = binding.init(&tokens, 0, std.testing.allocator) catch |err| {
         try std.testing.expectEqual(ParseError.Unmatched, err);
         return;
     };
@@ -95,7 +96,7 @@ test "should fail if the idenfier is missing" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    binding.init(&tokens, 0, std.testing.allocator) catch |err| {
+    _ = binding.init(&tokens, 0, std.testing.allocator) catch |err| {
         try std.testing.expectEqual(ParseError.Error, err);
         return;
     };
@@ -109,7 +110,7 @@ test "should fail if there is not an identifier after var" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    binding.init(&tokens, 0, std.testing.allocator) catch |err| {
+    _ = binding.init(&tokens, 0, std.testing.allocator) catch |err| {
         try std.testing.expectEqual(ParseError.Error, err);
         return;
     };
@@ -123,7 +124,7 @@ test "should fail if the equal sign is missing" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    binding.init(&tokens, 0, std.testing.allocator) catch |err| {
+    _ = binding.init(&tokens, 0, std.testing.allocator) catch |err| {
         try std.testing.expectEqual(ParseError.Error, err);
         return;
     };
@@ -137,7 +138,7 @@ test "should fail if the equal sign is not found" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    binding.init(&tokens, 0, std.testing.allocator) catch |err| {
+    _ = binding.init(&tokens, 0, std.testing.allocator) catch |err| {
         try std.testing.expectEqual(ParseError.Error, err);
         return;
     };
@@ -151,7 +152,7 @@ test "should fail if the expression parsing fails" {
     defer tokens.deinit();
 
     var binding: VariableBinding = undefined;
-    binding.init(&tokens, 0, std.testing.allocator) catch |err| {
+    _ = binding.init(&tokens, 0, std.testing.allocator) catch |err| {
         try std.testing.expectEqual(ParseError.Error, err);
         return;
     };