From c8439a069354cb526e02a76f52e978738ad8871c Mon Sep 17 00:00:00 2001
From: Baitinq <manuelpalenzuelamerino@gmail.com>
Date: Thu, 15 May 2025 18:42:37 +0200
Subject: Feature: Add support for null pointers

---
 grammar.ebnf      |  2 +-
 src/codegen.zig   | 13 +++++++++++++
 src/parser.zig    |  6 +++++-
 src/tokenizer.zig |  2 ++
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/grammar.ebnf b/grammar.ebnf
index ec61e90..70c0641 100644
--- a/grammar.ebnf
+++ b/grammar.ebnf
@@ -28,7 +28,7 @@ MultiplicativeExpression ::= UnaryExpression (("*" | "/" | "%") UnaryExpression)
 
 UnaryExpression ::= ("!" | "-" | "*") UnaryExpression | PrimaryExpression
 
-PrimaryExpression ::= NUMBER | BOOLEAN | CHAR | STRING | IDENTIFIER | FunctionCallStatement | FunctionDefinition | LPAREN Expression RPAREN
+PrimaryExpression ::= NULL | NUMBER | BOOLEAN | CHAR | STRING | IDENTIFIER | FunctionCallStatement | FunctionDefinition | LPAREN Expression RPAREN
 
 FunctionDefinition ::= LPAREN FunctionParameters? RPAREN ARROW IDENTIFIER LBRACE Statement* ReturnStatement SEMICOLON RBRACE
 
diff --git a/src/codegen.zig b/src/codegen.zig
index 5733d5f..05cb877 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -426,6 +426,19 @@ pub const CodeGen = struct {
                 return try self.generate_function_call_statement(@ptrCast(fn_call));
             },
             .PRIMARY_EXPRESSION => |primary_expression| switch (primary_expression) {
+                .NULL => {
+                    return try self.generate_literal(llvm.LLVMConstNull(llvm.LLVMPointerType(llvm.LLVMInt8Type(), 0)), name, expression, try self.create_node(.{
+                        .TYPE = .{
+                            .POINTER_TYPE = .{
+                                .type = try self.create_node(.{
+                                    .TYPE = .{ .SIMPLE_TYPE = .{
+                                        .name = "i8",
+                                    } },
+                                }),
+                            },
+                        },
+                    }));
+                },
                 .NUMBER => |n| {
                     return try self.generate_literal(llvm.LLVMConstInt(llvm.LLVMInt64Type(), @intCast(n.value), 0), name, expression, try self.create_node(.{
                         .TYPE = .{
diff --git a/src/parser.zig b/src/parser.zig
index 7e1b695..ce1e4cb 100644
--- a/src/parser.zig
+++ b/src/parser.zig
@@ -61,6 +61,7 @@ pub const Node = union(enum) {
         BOOLEAN: struct {
             value: bool,
         },
+        NULL: void,
         CHAR: struct {
             value: u8,
         },
@@ -525,7 +526,7 @@ pub const Parser = struct {
         } });
     }
 
-    // PrimaryExpression ::= NUMBER | BOOLEAN | CHAR | STRING | IDENTIFIER | FunctionCallStatement | FunctionDefinition | LPAREN Expression RPAREN
+    // PrimaryExpression ::= NULL | NUMBER | BOOLEAN | CHAR | STRING | IDENTIFIER | FunctionCallStatement | FunctionDefinition | LPAREN Expression RPAREN
     fn parse_primary_expression(self: *Parser) ParserError!*Node {
         errdefer if (!self.try_context) std.debug.print("Error parsing primary expression {any}\n", .{self.peek_token()});
 
@@ -542,6 +543,9 @@ pub const Parser = struct {
         const token = self.consume_token() orelse return ParserError.ParsingError;
 
         return switch (token.type) {
+            .NULL => try self.create_node(.{
+                .PRIMARY_EXPRESSION = .{ .NULL = void{} },
+            }),
             .NUMBER => |number_token| try self.create_node(.{
                 .PRIMARY_EXPRESSION = .{
                     .NUMBER = .{
diff --git a/src/tokenizer.zig b/src/tokenizer.zig
index 7ccb871..3b0ae4e 100644
--- a/src/tokenizer.zig
+++ b/src/tokenizer.zig
@@ -21,6 +21,7 @@ pub const TokenType = union(enum) {
     // Literals
     NUMBER: i64,
     BOOLEAN: bool,
+    NULL: void,
     CHAR: u8,
     STRING: []u8,
 
@@ -94,6 +95,7 @@ pub const Tokenizer = struct {
         if (self.accept_string("break")) return self.create_token(.{ .BREAK = void{} });
         if (self.accept_string("true")) return self.create_token(.{ .BOOLEAN = true });
         if (self.accept_string("false")) return self.create_token(.{ .BOOLEAN = false });
+        if (self.accept_string("null")) return self.create_token(.{ .NULL = void{} });
 
         if (self.accept_string("=>")) return self.create_token(.{ .ARROW = void{} });
         if (self.accept_string(";")) return self.create_token(.{ .SEMICOLON = void{} });
-- 
cgit 1.4.1