ivy/lang/parse/expr.c

#include "ctx.h"

#include <ivy/lang/ast.h>

enum expr_component {
	EXPR_C_NONE = 0,
	EXPR_C_BINARY_OP,
	EXPR_C_UNARY_OP,
	EXPR_C_OPERAND,
};

struct expr_parse_ctx {
	fx_queue expr_operator_stack, expr_out_queue;
	enum expr_component expr_prev;
	enum expr_parse_flags expr_flags;
};

static bool finalise_expr(
	struct expr_parse_ctx *ctx, struct ivy_ast_node **out,
	enum ivy_operator_precedence minimum_precedence);

bool peek_expr_start(struct ivy_parser *parser)
{
	struct ivy_token *tok = peek_token(parser);
	if (!tok) {
		return false;
	}

	switch (tok->t_type) {
	case IVY_TOK_INT:
	case IVY_TOK_ATOM:
	case IVY_TOK_DOUBLE:
	case IVY_TOK_IDENT:
	case IVY_TOK_STRING:
	case IVY_TOK_STR_START:
		return true;
	case IVY_TOK_KEYWORD:
		switch (tok->t_keyword) {
		case IVY_KW_IF:
		case IVY_KW_WHILE:
		case IVY_KW_FOR:
		case IVY_KW_TRY:
		case IVY_KW_UNLESS:
		case IVY_KW_CONTINUE:
		case IVY_KW_BREAK:
		case IVY_KW_MATCH:
		case IVY_KW_TRUE:
		case IVY_KW_FALSE:
		case IVY_KW_NULL:
			return true;
		default:
			return false;
		}
		break;
	case IVY_TOK_SYMBOL:
		switch (tok->t_symbol) {
		case IVY_SYM_LEFT_BRACE:
		case IVY_SYM_LEFT_BRACKET:
		case IVY_SYM_LEFT_PAREN:
		case IVY_SYM_CARET:
		case IVY_SYM_UNDERSCORE:
			return true;
		default:
			return false;
		}
		break;
	default:
		return false;
	}
}

static struct ivy_ast_node *pop_operand(
	struct expr_parse_ctx *expr, enum ivy_operator_precedence min_precedence)
{
	struct ivy_ast_node *out = NULL;
	bool ok = finalise_expr(expr, &out, min_precedence);
	if (!ok) {
		parse_trace(NULL, "sub-expression is invalid");
		return NULL;
	}

	return out;
}

static bool parse_simple_operand(
	struct ivy_parser *parser, struct expr_parse_ctx *expr)
{
	if (expr->expr_prev == EXPR_C_OPERAND) {
		parse_trace(parser, "encountered two operands in a row");
		return false;
	}

	expr->expr_prev = EXPR_C_OPERAND;
	struct ivy_token *tok = peek_token(parser);
	switch (tok->t_type) {
	case IVY_TOK_INT: {
		struct ivy_ast_int_node *v = create_node(IVY_AST_INT);
		v->n_value = parse_token(parser);
		fx_queue_push_back(&expr->expr_out_queue, &v->n_base.n_entry);
		return true;
	}
	case IVY_TOK_DOUBLE: {
		struct ivy_ast_double_node *v = create_node(IVY_AST_DOUBLE);
		v->n_value = parse_token(parser);
		fx_queue_push_back(&expr->expr_out_queue, &v->n_base.n_entry);
		return true;
	}
	case IVY_TOK_STRING: {
		struct ivy_ast_string_node *v = create_node(IVY_AST_STRING);
		v->n_value = parse_token(parser);
		fx_queue_push_back(&expr->expr_out_queue, &v->n_base.n_entry);
		return true;
	}
	case IVY_TOK_IDENT: {
		struct ivy_ast_ident_node *v = create_node(IVY_AST_IDENT);
		v->n_content = parse_token(parser);
		fx_queue_push_back(&expr->expr_out_queue, &v->n_base.n_entry);
		return true;
	}
	case IVY_TOK_ATOM: {
		struct ivy_ast_atom_node *v = create_node(IVY_AST_ATOM);
		v->n_content = parse_token(parser);
		fx_queue_push_back(&expr->expr_out_queue, &v->n_base.n_entry);
		return true;
	}
	case IVY_TOK_SYMBOL:
		switch (tok->t_symbol) {
		case IVY_SYM_UNDERSCORE: {
			struct ivy_ast_discard_node *v
				= create_node(IVY_AST_DISCARD);
			discard_token(parser);
			fx_queue_push_back(
				&expr->expr_out_queue, &v->n_base.n_entry);
			return true;
		}
		default:
			parse_trace(
				parser, "token %s is not a simple operand",
				ivy_symbol_to_string(tok->t_symbol));
			return false;
		}
		break;
	default:
		parse_trace(
			parser, "token %s is not a simple operand",
			ivy_lex_token_type_to_string(tok->t_type));
		return false;
	}
}

void arith_push_operator(struct expr_parse_ctx *state, struct ivy_ast_node *node)
{
	const struct ivy_operator *op = get_operator_from_node(node);
	if (!op) {
		return;
	}

	while (true) {
		fx_queue_entry *top = fx_queue_last(&state->expr_operator_stack);
		if (!top) {
			break;
		}

		struct ivy_ast_node *top_node
			= fx_unbox(struct ivy_ast_node, top, n_entry);
		const struct ivy_operator *top_op = NULL;

		switch (top_node->n_type) {
		case IVY_AST_OP: {
			struct ivy_ast_op_node *op_node
				= (struct ivy_ast_op_node *)top_node;
			top_op = op_node->n_op;
			break;
		}
		case IVY_AST_MSG: {
			struct ivy_ast_msg_node *msg_node
				= (struct ivy_ast_msg_node *)top_node;
			top_op = ivy_operator_get_by_id(IVY_OP_MSG);
			break;
		}
		default:
			return;
		}

		if (top_op->op_precedence < op->op_precedence
		    || (top_op->op_precedence == op->op_precedence
		        && op->op_associativity != IVY_ASSOCIATIVITY_LEFT)) {
			break;
		}

		fx_queue_delete(&state->expr_operator_stack, top);
		fx_queue_push_back(&state->expr_out_queue, top);
	}

	fx_queue_push_back(&state->expr_operator_stack, &node->n_entry);
}

static bool parse_binary_operator(
	struct ivy_parser *parser, struct expr_parse_ctx *expr)
{
	struct ivy_token *tok = parse_token(parser);

	if (expr->expr_prev != EXPR_C_OPERAND) {
		parse_trace(parser, "expected operand before binary operator");
		return false;
	}

	expr->expr_prev = EXPR_C_BINARY_OP;

	struct ivy_ast_node *op_node = create_operator_node_from_token(tok);
	if (!op_node) {
		parse_trace(parser, "unrecognised binary operator");
		return false;
	}

	arith_push_operator(expr, op_node);
	return true;
}

static bool expr_is_empty(struct expr_parse_ctx *expr)
{
	return fx_queue_empty(&expr->expr_out_queue)
	    && fx_queue_empty(&expr->expr_operator_stack);
}

static bool op_node_is_complete(struct ivy_ast_op_node *node)
{
	if (!node->n_op) {
		return false;
	}

	switch (node->n_op->op_arity) {
	case IVY_OP_UNARY:
		return node->n_right != NULL;
	case IVY_OP_BINARY:
		return (node->n_left != NULL && node->n_right != NULL);
	default:
		return false;
	}
}

static bool finalise_expr(
	struct expr_parse_ctx *ctx, struct ivy_ast_node **out,
	enum ivy_operator_precedence minimum_precedence)
{
	fx_queue_entry *entry = NULL;
	while (true) {
		entry = fx_queue_pop_back(&ctx->expr_operator_stack);
		if (!entry) {
			break;
		}

		struct ivy_ast_node *node
			= fx_unbox(struct ivy_ast_node, entry, n_entry);
		if (!node) {
			/* this should never happen */
			return false;
		}

		const struct ivy_operator *op = NULL;

		switch (node->n_type) {
		case IVY_AST_OP: {
			struct ivy_ast_op_node *n = (struct ivy_ast_op_node *)node;
			op = n->n_op;
			break;
		}
		case IVY_AST_MSG:
			/* all unary message operators have the same
			 * pre-defined precedence */
			op = ivy_operator_get_by_id(IVY_OP_MSG);
			break;
		default:
			return false;
		}

		/* if we aren't processing operators below a certain precedence
		 * then leave them on the stack and stop here. */
		if (op->op_precedence < minimum_precedence) {
			fx_queue_push_back(&ctx->expr_operator_stack, entry);
			break;
		}

		fx_queue_push_back(&ctx->expr_out_queue, entry);
	}

	fx_queue q = FX_QUEUE_INIT;
	fx_queue_entry *tmp = NULL;
	entry = fx_queue_first(&ctx->expr_out_queue);
	int i = 0;

	while (entry) {
		struct ivy_ast_node *item
			= fx_unbox(struct ivy_ast_node, entry, n_entry);
		fx_queue_entry *next = fx_queue_next(entry);
		fx_queue_delete(&ctx->expr_out_queue, entry);

		/* if the node is an operand, just push it to a
		 * temporary queue and come back to it later. */
		if (item->n_type != IVY_AST_OP && item->n_type != IVY_AST_MSG) {
			/* operand */
			fx_queue_push_back(&q, &item->n_entry);
			goto next;
		}

		const struct ivy_operator *op = NULL;

		if (item->n_type == IVY_AST_MSG) {
			struct ivy_ast_msg_node *msg
				= (struct ivy_ast_msg_node *)item;
			/* if the message has no recipient, it is a unary message,
			 * and the recipient is located on the operand stack.
			 *
			 * if the message DOES have a recipient, it is a
			 * self-contained keyword message, and can be pushed to
			 * the operand queue as-is. */
			if (!msg->n_recipient) {
				tmp = fx_queue_pop_back(&q);
				msg->n_recipient = fx_unbox(
					struct ivy_ast_node, tmp, n_entry);
			}
			fx_queue_push_back(&q, &msg->n_base.n_entry);
			goto next;
		}

		struct ivy_ast_op_node *op_node = (struct ivy_ast_op_node *)item;
		/* if an operator node is already complete (i.e. it
		 * already has all the operands it needs, it can be
		 * pushed to the operand queue as-is */
		if (op_node_is_complete(op_node)) {
			fx_queue_push_back(&q, &item->n_entry);
			goto next;
		}

		/* otherwise, pop the relevant operands from the operand
		 * queue... */
		op = op_node->n_op;
		tmp = fx_queue_pop_back(&q);
		op_node->n_right = fx_unbox(struct ivy_ast_node, tmp, n_entry);

		if (op_node->n_right) {
			op_node->n_right->n_parent = (struct ivy_ast_node *)op_node;

			ivy_ast_node_extend_bounds_recursive(
				(struct ivy_ast_node *)op_node,
				(struct ivy_ast_node *)tmp);
		}

		if (op->op_arity == IVY_OP_BINARY) {
			tmp = fx_queue_pop_back(&q);
			op_node->n_left
				= fx_unbox(struct ivy_ast_node, tmp, n_entry);

			if (op_node->n_left) {
				op_node->n_left->n_parent
					= (struct ivy_ast_node *)op_node;

				ivy_ast_node_extend_bounds_recursive(
					(struct ivy_ast_node *)op_node,
					(struct ivy_ast_node *)tmp);
			}
		}

		/* ...and push the newly-completed operator node to the
		 * operand queue */
		fx_queue_push_back(&q, &op_node->n_base.n_entry);
	next:
		entry = next;
	}

#if 0
	debug_printf("** after hierarchisation:\n");
	print_expr_queues(state);
#endif

	/* if we are not processing operators below a certain precedence,
	 * i.e. when determining the recipient of a keyword-message), these
	 * operators will still be on the parser state's operator stack, but
	 * their operands have just been moved to the temporary operand stack
	 * used above. move them back to the parser state's output queue here
	 * so they can be used later. */
	entry = fx_queue_first(&ctx->expr_operator_stack);
	while (entry) {
		fx_queue_entry *entry2 = fx_queue_pop_front(&q);
		if (!entry2) {
			return false;
		}

		fx_queue_push_back(&ctx->expr_out_queue, entry2);
		entry = fx_queue_next(entry);
	}

#if 0
	debug_printf("** after de-linearisation:\n");
	print_expr_queues(state);
	ivy_ast_node_print(*expr_tree);
	debug_printf("------\n");
#endif

	/* the final node remaining on the temp operand stack is the
	 * root node of the new expression tree */
	tmp = fx_queue_pop_back(&q);
	*out = fx_unbox(struct ivy_ast_node, tmp, n_entry);

	return true;
}

static bool parse_call(
	struct ivy_parser *parser, struct ivy_ast_node *target,
	struct ivy_ast_node **out)
{
	if (!parse_symbol(parser, IVY_SYM_LEFT_PAREN)) {
		parse_trace(parser, "expected `(` before call arguments");
	}

	struct ivy_ast_msg_node *call = create_node(IVY_AST_MSG);
	call->n_recipient = target;
	call->n_sel = create_node(IVY_AST_SELECTOR);

	call->n_sel->n_msg_name = ivy_token_create_ident("call");

	bool ok = true;
	while (ok) {
		if (parse_symbol(parser, IVY_SYM_RIGHT_PAREN)) {
			break;
		}

		if (!fx_queue_empty(&call->n_arg)
		    && !parse_symbol(parser, IVY_SYM_COMMA)) {
			parse_trace(
				parser,
				"expected `,` or `)` after call argument");
			ok = false;
			break;
		}

		struct ivy_ast_node *arg = NULL;
		if (!parse_expr(parser, EXPR_PARSE_STOP_COMMA, &arg)) {
			parse_trace(parser, "invalid call argument");
			ok = false;
			break;
		}

		struct ivy_token *label = ivy_token_create_discard();
		fx_queue_push_back(&call->n_sel->n_arg_labels, &label->t_entry);
		fx_queue_push_back(&call->n_arg, &arg->n_entry);
	}

	*out = generic_node(call);
	return true;
}

static bool cleanup_expr(struct expr_parse_ctx *ctx)
{
	return false;
}

bool parse_expr(
	struct ivy_parser *parser, enum expr_parse_flags flags,
	struct ivy_ast_node **out)
{
	struct expr_parse_ctx ctx = {0};
	ctx.expr_flags = flags;
	bool ok = true;
	bool done = false;
	bool return_expr = false;
	bool end_without_dot = false;

	while (ok && !done) {
		struct ivy_token *tok = peek_token(parser);
		if (!tok) {
			break;
		}

		if ((flags & EXPR_PARSE_STOP_TUPLE_TERMINATOR)
		    && is_tuple_terminator(tok)) {
			done = true;
			break;
		}

		switch (tok->t_type) {
		case IVY_TOK_LINEFEED:
			discard_token(parser);
			break;
		case IVY_TOK_IDENT:
			if (ctx.expr_prev == EXPR_C_OPERAND) {
				struct ivy_ast_node *msg = NULL;
				ok = parse_unary_msg(parser, NULL, &msg);
				if (!ok) {
					break;
				}

				fx_queue_push_back(
					&ctx.expr_out_queue, &msg->n_entry);
				ctx.expr_prev = EXPR_C_OPERAND;
			} else {
				ok = parse_simple_operand(parser, &ctx);
			}
			break;
		case IVY_TOK_INT:
		case IVY_TOK_STRING:
		case IVY_TOK_DOUBLE:
		case IVY_TOK_ATOM:
			ok = parse_simple_operand(parser, &ctx);
			break;
		case IVY_TOK_STR_START: {
			struct ivy_ast_node *v = NULL;
			ok = parse_fstring(parser, &v);
			if (!ok) {
				break;
			}

			fx_queue_push_back(&ctx.expr_out_queue, &v->n_entry);
			ctx.expr_prev = EXPR_C_OPERAND;
			break;
		}

		case IVY_TOK_LABEL: {
			if (flags & EXPR_PARSE_STOP_LABEL) {
				done = true;
				break;
			}

			struct ivy_ast_node *recipient
				= pop_operand(&ctx, IVY_PRECEDENCE_KEYWORD_MSG);
			if (!recipient) {
				parse_trace(
					parser,
					"no valid recipient for keyword msg");
				ok = false;
				break;
			}

			struct ivy_ast_node *v = NULL;
			ok = parse_keyword_msg(
				parser, recipient, ctx.expr_flags, &v);

			if (!ok) {
				break;
			}

			fx_queue_push_back(&ctx.expr_out_queue, &v->n_entry);
			ctx.expr_prev = EXPR_C_OPERAND;
			break;
		}
		case IVY_TOK_KEYWORD: {
			struct ivy_ast_node *operand = NULL;
			if (expr_is_empty(&ctx)) {
				end_without_dot = true;
			}

			switch (tok->t_keyword) {
			case IVY_KW_ELSE:
			case IVY_KW_CATCH:
				done = true;
				break;
			case IVY_KW_MATCH:
				ok = parse_match(parser, &operand);
				break;
			case IVY_KW_DO: {
				discard_token(parser);
				struct ivy_ast_do_node *do_node
					= create_node(IVY_AST_DO);
				ok = parse_block(parser, &do_node->n_block);
				if (!ok) {
					break;
				}

				operand = generic_node(do_node);
				break;
			}
			case IVY_KW_IF:
				if (flags & EXPR_PARSE_STOP_KW_CONTROL) {
					done = true;
					break;
				}

				if (ctx.expr_prev == EXPR_C_OPERAND) {
					struct ivy_ast_node *body = pop_operand(
						&ctx, IVY_PRECEDENCE_IF_ELSE);
					if (!body) {
						parse_trace(
							parser,
							"invalid "
							"inline-if "
							"body");
					}

					ok = parse_if_inline(parser, body, &operand);
				} else {
					ok = parse_if(parser, &operand);
				}
				break;
			case IVY_KW_FOR:
				if (flags & EXPR_PARSE_STOP_KW_CONTROL) {
					done = true;
					break;
				}

				if (ctx.expr_prev == EXPR_C_OPERAND) {
					struct ivy_ast_node *body = pop_operand(
						&ctx, IVY_PRECEDENCE_IF_ELSE);
					if (!body) {
						parse_trace(
							parser,
							"invalid "
							"inline-for "
							"body");
					}

					ok = parse_for_inline(
						parser, body, &operand);
				} else {
					ok = parse_for(parser, &operand);
				}

				break;
			case IVY_KW_WHILE:
				if (flags & EXPR_PARSE_STOP_KW_CONTROL) {
					done = true;
					break;
				}

				if (ctx.expr_prev == EXPR_C_OPERAND) {
					struct ivy_ast_node *body = pop_operand(
						&ctx, IVY_PRECEDENCE_IF_ELSE);
					if (!body) {
						parse_trace(
							parser,
							"invalid "
							"inline-while "
							"body");
					}

					ok = parse_while_inline(
						parser, body, &operand);
				} else {
					ok = parse_while(parser, &operand);
				}
				break;
			case IVY_KW_IN:
				if (flags & EXPR_PARSE_STOP_KW_IN) {
					done = true;
					break;
				}

			case IVY_KW_IS:
				ok = parse_binary_operator(parser, &ctx);
				break;
			case IVY_KW_TRY:
				if (flags & EXPR_PARSE_STOP_KW_CONTROL) {
					done = true;
					break;
				}

				ok = parse_try(parser, &operand);
				break;
			default:
				parse_trace(
					parser, "unrecognised keyword %s",
					ivy_keyword_to_string(tok->t_keyword));
				ok = false;
				break;
			}

			if (ok && operand) {
				fx_queue_push_back(
					&ctx.expr_out_queue, &operand->n_entry);
				ctx.expr_prev = EXPR_C_OPERAND;

				if (end_without_dot && parse_linefeed(parser)) {
					done = true;
				}
			}

			break;
		}
		case IVY_TOK_SYMBOL:
			switch (tok->t_symbol) {
			case IVY_SYM_DOUBLE_COLON:
			case IVY_SYM_PLUS:
			case IVY_SYM_HYPHEN:
			case IVY_SYM_FORWARD_SLASH:
			case IVY_SYM_ASTERISK:
			case IVY_SYM_PERCENT:
			case IVY_SYM_AMPERSAND:
			case IVY_SYM_EQUAL:
			case IVY_SYM_HYPHEN_RIGHT_ANGLE:
			case IVY_SYM_DOUBLE_EQUAL:
			case IVY_SYM_LEFT_ANGLE:
			case IVY_SYM_RIGHT_ANGLE:
			case IVY_SYM_DOUBLE_LEFT_ANGLE:
			case IVY_SYM_DOUBLE_RIGHT_ANGLE:
			case IVY_SYM_LEFT_ANGLE_EQUAL:
			case IVY_SYM_RIGHT_ANGLE_EQUAL:
			case IVY_SYM_DOUBLE_LEFT_ANGLE_EQUAL:
			case IVY_SYM_DOUBLE_RIGHT_ANGLE_EQUAL:
			case IVY_SYM_PLUS_EQUAL:
			case IVY_SYM_HYPHEN_EQUAL:
			case IVY_SYM_FORWARD_SLASH_EQUAL:
			case IVY_SYM_ASTERISK_EQUAL:
			case IVY_SYM_AMPERSAND_EQUAL:
			case IVY_SYM_PIPE_EQUAL:
			case IVY_SYM_PERCENT_EQUAL:
			case IVY_SYM_CARET_EQUAL:
			case IVY_SYM_BANG_EQUAL:
				ok = parse_binary_operator(parser, &ctx);
				break;
			case IVY_SYM_EQUAL_RIGHT_ANGLE:
				done = true;
				break;
			case IVY_SYM_UNDERSCORE:
				ok = parse_simple_operand(parser, &ctx);
				break;
			case IVY_SYM_COMMA: {
				if (flags & EXPR_PARSE_STOP_COMMA) {
					done = true;
					break;
				}

				struct ivy_ast_node *first = pop_operand(
					&ctx, IVY_PRECEDENCE_KEYWORD_MSG);
				if (!first) {
					parse_trace(
						parser,
						"no valid item for tuple");
					return false;
				}

				struct ivy_ast_node *v = NULL;
				ok = parse_tuple(parser, first, &v);
				if (!ok) {
					break;
				}

				fx_queue_push_back(&ctx.expr_out_queue, &v->n_entry);
				ctx.expr_prev = EXPR_C_OPERAND;
				break;
			}

			case IVY_SYM_SEMICOLON: {
				if (flags & EXPR_PARSE_STOP_SEMICOLON) {
					done = true;
					break;
				}

				struct ivy_ast_node *first = pop_operand(
					&ctx, IVY_PRECEDENCE_CASCADE);
				if (!first) {
					parse_trace(
						parser,
						"no valid recipient for "
						"cascade");
					return false;
				}

				struct ivy_ast_node *v = NULL;
				ok = parse_cascade(parser, first, &v);
				if (!ok) {
					break;
				}

				fx_queue_push_back(&ctx.expr_out_queue, &v->n_entry);
				ctx.expr_prev = EXPR_C_OPERAND;
				break;
			}

			case IVY_SYM_LEFT_PAREN: {
				if (ctx.expr_prev == EXPR_C_OPERAND) {
					fx_queue_entry *entry = fx_queue_pop_back(
						&ctx.expr_out_queue);
					if (!entry) {
						parse_trace(
							parser,
							"no valid recipient "
							"for complex msg");
						return false;
					}

					struct ivy_ast_node *target = fx_unbox(
						struct ivy_ast_node, entry,
						n_entry);
					if (target->n_type == IVY_AST_MSG) {
						ok = parse_complex_msg(
							parser, target, &target);
					} else {
						ok = parse_call(
							parser, target, &target);
					}

					if (!ok) {
						break;
					}

					fx_queue_push_back(
						&ctx.expr_out_queue,
						&target->n_entry);
					ctx.expr_prev = EXPR_C_OPERAND;
					break;
				}

				struct ivy_ast_node *subexpr = NULL;
				discard_token(parser);
				ok = parse_expr(parser, EXPR_PARSE_NORMAL, &subexpr);
				if (!ok) {
					break;
				}

				if (!parse_symbol(parser, IVY_SYM_RIGHT_PAREN)) {
					parse_trace(
						parser,
						"expected `)` after "
						"parenthesized "
						"expression");
					ok = false;
					break;
				}

				fx_queue_push_back(
					&ctx.expr_out_queue, &subexpr->n_entry);
				ctx.expr_prev = EXPR_C_OPERAND;
				break;
			}

			case IVY_SYM_LEFT_BRACKET: {
				if (flags & EXPR_PARSE_STOP_LEFT_BRACKET) {
					done = true;
					break;
				}

				if (ctx.expr_prev == EXPR_C_OPERAND) {
					struct ivy_ast_node *container = pop_operand(
						&ctx, IVY_PRECEDENCE_SUBSCRIPT);
					if (!container) {
						parse_trace(
							parser,
							"invalid subscript "
							"container");
						return false;
					}

					struct ivy_ast_node *v = NULL;
					ok = parse_index(parser, container, &v);
					if (!ok) {
						break;
					}

					fx_queue_push_back(
						&ctx.expr_out_queue, &v->n_entry);
					ctx.expr_prev = EXPR_C_OPERAND;
					break;
				}

				struct ivy_ast_node *block = NULL;
				ok = parse_block(parser, &block);
				if (ok) {
					fx_queue_push_back(
						&ctx.expr_out_queue,
						&block->n_entry);
					ctx.expr_prev = EXPR_C_OPERAND;
				}
				break;
			}

			case IVY_SYM_LEFT_BRACE: {
				if (ctx.expr_prev == EXPR_C_OPERAND) {
					parse_trace(
						parser,
						"package cannot be "
						"used after "
						"operand");
					ok = false;
					break;
				}

				struct ivy_ast_node *pkg = NULL;
				ok = parse_package(parser, &pkg);
				if (ok) {
					fx_queue_push_back(
						&ctx.expr_out_queue, &pkg->n_entry);
					ctx.expr_prev = EXPR_C_OPERAND;
				}
				break;
			}
			case IVY_SYM_DOT: {
				struct ivy_token *dot = tok;
				struct ivy_token *next = peek_next_token(parser);
				if (next && next->t_type == IVY_TOK_LINEFEED) {
					if (flags & EXPR_PARSE_CONSUME_TERMINATOR) {
						discard_token(parser);
					}

					done = true;
					break;
				}

				ok = parse_binary_operator(parser, &ctx);
				break;
			}
			case IVY_SYM_CARET: {
				if (expr_is_empty(&ctx)) {
					if (return_expr) {
						parse_trace(
							parser,
							"`^` can only "
							"be used "
							"once in "
							"an "
							"expression");
						ok = false;
						break;
					}

					discard_token(parser);
					return_expr = true;
					break;
				}

				ok = parse_binary_operator(parser, &ctx);
				break;
			}
			case IVY_SYM_RIGHT_PAREN:
			case IVY_SYM_RIGHT_BRACE:
			case IVY_SYM_RIGHT_BRACKET:
				done = true;
				break;
			default:
				parse_trace(
					parser, "unrecognised symbol %s",
					ivy_symbol_to_string(tok->t_symbol));
				ok = false;
				break;
			}
			break;
		default:
			parse_trace(
				parser, "unrecognised token %s",
				ivy_lex_token_type_to_string(tok->t_type));
			ok = false;
			break;
		}

		if (!ok) {
			break;
		}
	}

	if (!ok) {
		cleanup_expr(&ctx);
		return false;
	}

	ok = finalise_expr(&ctx, out, IVY_PRECEDENCE_ASSIGN);
	if (!ok) {
		cleanup_expr(&ctx);
		return false;
	}

	if (return_expr) {
		struct ivy_ast_return_node *ret = create_node(IVY_AST_RETURN);
		ret->n_val = *out;
		*out = generic_node(ret);
	}

	return true;
}