4 files changed, 84 insertions, 1 deletions

diff --git a/build.zig b/build.zig
index 5627e43..1894e3f 100644
--- a/build.zig
+++ b/build.zig
@@ -31,6 +31,12 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
+    const ast_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/ast.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
     const token_unit_tests = b.addTest(.{
         .root_source_file = b.path("src/tokenize.zig"),
         .target = target,
@@ -38,9 +44,11 @@ pub fn build(b: *std.Build) void {
     });
 
     const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+    const run_ast_unit_tests = b.addRunArtifact(ast_unit_tests);
     const run_token_unit_tests = b.addRunArtifact(token_unit_tests);
 
     const test_step = b.step("test", "Run unit tests");
     test_step.dependOn(&run_exe_unit_tests.step);
+    test_step.dependOn(&run_ast_unit_tests.step);
     test_step.dependOn(&run_token_unit_tests.step);
 }
diff --git a/src/ast.zig b/src/ast.zig
new file mode 100644
index 0000000..2f8f209
--- /dev/null
+++ b/src/ast.zig
@@ -0,0 +1,67 @@
+const std = @import("std");
+const tok = @import("tokenize.zig");
+
+const SyntaxError = error{SyntaxError};
+const expectedToken = error{ExpectedToken};
+
+pub const BinOp = enum {
+    Add,
+    Sub,
+    Mul,
+    Div,
+};
+
+pub const Literal = union(enum) {
+    Int: i32,
+};
+
+pub const Ast = union(enum) {
+    Expr: struct {
+        kind: ExprKind,
+    },
+    Stmt: struct {
+        kind: StmtKind,
+    },
+};
+
+const StmtKind = union(enum) {
+    exit: Ast.Expr,
+};
+
+const ExprKind = union(enum) {
+    Literal: Literal,
+    BinaryOp: struct {
+        op: BinOp,
+        left: Ast.Expr,
+        right: Ast.Expr,
+    },
+};
+
+fn checkType(token: tok.Token, typ: tok.TokenType) bool {
+    return switch (token) {
+        typ => true,
+        else => false,
+    };
+}
+
+const AstParser = struct {
+    tokens: tok.Iterator(tok.Token),
+    fn parseStmt(self: *AstParser) !Ast.Stmt {
+        return switch (self.tokens.peek().?) {
+            .ret => try self.exitStmt(),
+        };
+    }
+
+    fn parseExpr(self: *AstParser) !Ast.Expr {
+
+    }
+
+    fn exitStmt(self: *AstParser) !Ast.Stmt {
+        if (!checkType(self.tokens.consume().?, tok.TokenType.ret)) return expectedToken;
+        const value = self.parseExpr();
+
+        if (!checkType(self.tokens.consume().?, tok.TokenType.semiCol)) return expectedToken;
+        const kind = StmtKind{ .exit = value };
+        return Ast.Stmt{ .kind = kind };
+    }
+};
diff --git a/src/main.zig b/src/main.zig
index c24f8a8..4a0bbca 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const tok = @import("tokenize.zig");
+const ast = @import("ast.zig");
 
 const gftCompilerError = error{NoInputFile};
 
diff --git a/src/tokenize.zig b/src/tokenize.zig
index 37080b4..93a3ac9 100644
--- a/src/tokenize.zig
+++ b/src/tokenize.zig
@@ -1,8 +1,15 @@
 const std = @import("std");
 
 const TokenError = error{UnknownToken};
+const TokenType = enum {
+    ret,
+    intLit,
+    binaryOp,
+    semiCol,
+    nil,
+};
 
-pub const Token = union(enum) {
+pub const Token = union(TokenType) {
     ret: []const u8,
     intLit: i32,
     binaryOp: u8,