Strength compile-time guarantees of AST operators

source/ona/kym/Ast.zig

@@ -9,6 +9,32 @@ arena: coral.arena.Stacking,
 statements: StatementList,
 error_message: []const u8,
 
+pub const BinaryOperator = enum {
+	addition,
+	subtraction,
+	multiplication,
+	divsion,
+	equals_comparison,
+	greater_than_comparison,
+	greater_equals_comparison,
+	less_than_comparison,
+	less_equals_comparison,
+
+	fn token(self: BinaryOperator) tokens.Token {
+		return switch (self) {
+			.addition => .symbol_plus,
+			.subtraction => .symbol_minus,
+			.multiplication => .symbol_asterisk,
+			.divsion => .symbol_forward_slash,
+			.equals_comparison => .symbol_double_equals,
+			.greater_than_comparison => .symbol_greater_than,
+			.greater_equals_comparison => .symbol_greater_equals,
+			.less_than_comparison => .symbol_less_than,
+			.less_equals_comparison => .symbol_less_equals,
+		};
+	}
+};
+
 pub const Expression = union (enum) {
 	nil_literal,
 	true_literal,
@@ -26,13 +52,13 @@ pub const Expression = union (enum) {
 	grouped_expression: *Expression,
 
 	binary_operation: struct {
-		operator: tokens.Token,
+		operator: BinaryOperator,
 		lhs_expression: *Expression,
 		rhs_expression: *Expression,
 	},
 
 	unary_operation: struct {
-		operator: tokens.Token,
+		operator: UnaryOperator,
 		expression: *Expression,
 	},
 };
@@ -48,12 +74,12 @@ pub const Statement = union (enum) {
 
 const StatementList = coral.list.Stack(Statement);
 
-const UnaryOperation = enum {
+const UnaryOperator = enum {
 	boolean_negation,
 	numeric_negation,
 };
 
-fn binary_operation_parser(comptime parse_next: ExpressionParser, comptime operators: []const tokens.Token) ExpressionParser {
+fn binary_operation_parser(comptime parse_next: ExpressionParser, comptime operators: []const BinaryOperator) ExpressionParser {
 	return struct {
 		fn parse(self: *Self, tokenizer: *tokens.Tokenizer) types.ParseError!Expression {
 			var expression = try parse_next(self, tokenizer);
@@ -62,10 +88,12 @@ fn binary_operation_parser(comptime parse_next: ExpressionParser, comptime opera
 				const allocator = self.arena.as_allocator();
 
 				inline for (operators) |operator| {
-					if (tokenizer.current_token == coral.io.tag_of(operator)) {
+					const token = comptime operator.token();
+
+					if (tokenizer.current_token == coral.io.tag_of(token)) {
 						try self.check_syntax(
 							tokenizer.step(.{.include_newlines = true}),
-							"expected right-hand side of expression after `" ++ comptime operator.text() ++ "`");
+							"expected right-hand side of expression after `" ++ comptime token.text() ++ "`");
 
 						expression = .{
 							.binary_operation = .{
@@ -156,19 +184,19 @@ pub fn parse(self: *Self, tokenizer: *tokens.Tokenizer) types.ParseError!void {
 }
 
 const parse_comparison = binary_operation_parser(parse_term, &.{
-	.symbol_greater_than,
-	.symbol_greater_equals,
-	.symbol_less_than,
-	.symbol_less_equals
+	.greater_than_comparison,
+	.greater_equals_comparison,
+	.less_than_comparison,
+	.less_equals_comparison
 });
 
 const parse_equality = binary_operation_parser(parse_comparison, &.{
-	.symbol_double_equals,
+	.equals_comparison,
 });
 
 const parse_expression = binary_operation_parser(parse_equality, &.{
-	.symbol_plus,
-	.symbol_minus,
+	.addition,
+	.subtraction,
 });
 
 fn parse_factor(self: *Self, tokenizer: *tokens.Tokenizer) types.ParseError!Expression {
@@ -305,7 +333,7 @@ fn parse_factor(self: *Self, tokenizer: *tokens.Tokenizer) types.ParseError!Expr
 						self.arena.as_allocator(),
 						try self.parse_factor(tokenizer)),
 
-					.operator = .symbol_minus,
+					.operator = .numeric_negation,
 				},
 			};
 		},
@@ -321,7 +349,7 @@ fn parse_factor(self: *Self, tokenizer: *tokens.Tokenizer) types.ParseError!Expr
 						self.arena.as_allocator(),
 						try self.parse_factor(tokenizer)),
 
-					.operator = .symbol_bang,
+					.operator = .boolean_negation,
 				},
 			};
 		},
@@ -331,8 +359,8 @@ fn parse_factor(self: *Self, tokenizer: *tokens.Tokenizer) types.ParseError!Expr
 }
 
 const parse_term = binary_operation_parser(parse_factor, &.{
-	.symbol_asterisk,
-	.symbol_forward_slash,
+	.multiplication,
+	.divsion,
 });
 
 pub fn reset(self: *Self) void {

source/ona/kym/Chunk.zig

@@ -151,16 +151,15 @@ pub fn compile_expression(self: *Self, expression: Ast.Expression) types.Runtime
 			try self.compile_expression(operation.rhs_expression.*);
 
 			try self.emit_opcode(switch (operation.operator) {
-				.symbol_plus => .add,
-				.symbol_minus => .sub,
-				.symbol_asterisk => .mul,
-				.symbol_forward_slash => .div,
-				.symbol_double_equals => .compare_eq,
-				.symbol_greater_than => .compare_gt,
-				.symbol_greater_equals => .compare_ge,
-				.symbol_less_than => .compare_lt,
-				.symbol_less_equals => .compare_le,
-				else => unreachable,
+				.addition => .add,
+				.subtraction => .sub,
+				.multiplication => .mul,
+				.divsion => .div,
+				.greater_equals_comparison => .compare_eq,
+				.greater_than_comparison => .compare_gt,
+				.equals_comparison => .compare_ge,
+				.less_than_comparison => .compare_lt,
+				.less_equals_comparison => .compare_le,
 			});
 		},
 
@@ -168,9 +167,8 @@ pub fn compile_expression(self: *Self, expression: Ast.Expression) types.Runtime
 			try self.compile_expression(operation.expression.*);
 
 			try self.emit_opcode(switch (operation.operator) {
-				.symbol_bang => .not,
-				.symbol_minus => .neg,
-				else => unreachable,
+				.boolean_negation => .not,
+				.numeric_negation => .neg,
 			});
 		},