#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <glib.h>
#include "item.h"
#include "xmlconfig.h"
#include "main.h"
#include "navit.h"
#include "vehicle.h"
#include "speech.h"
#include "gui.h"
#include "debug.h"
#include "callback.h"
#include "command.h"
#include "event.h"
#include "navit_nls.h"

/*
gui.fullscreen=!gui.fullscreen
gui.menu()
gui.get_data() 
zoom_in() 
zoom_out()
speech.active=!speech.active
osd_configuration=1
osd[@type=="xxx"].active=0;osd[@type=="yyy"].active=0
*/


/**
 * The result, or interim result, of evaluating a saved command.
 */
struct result {
	struct attr attr;	/**< The attribute. If {@code allocated} is true, it stores an object that was
						 *   successfully retrieved. Else it is either a placeholder or a constant value.
						 */
	double val;
	const char *var;	/**< If {@code allocated} is false, the name of the object to be resolved.
						 *   Else, it is the name of the object successfully retrieved and stored in
						 *   {@code attr}, or {@code NULL} if retrieval failed.
						 *   Only the first {@code varlen} characters are significant.
						 */
	int varlen;			/**< Number of significant characters in {@code var} */
	const char *attrn;	/**< The name of an object that has been resolved but not yet retrieved,
						 *   {@code NULL} otherwise. Only the first {@code attrnlen} characters are
						 *   significant.
						 */
	int attrnlen;		/**< Number of significant characters in {@code attrn} */
	int allocated;		/**< Whether the result has been calculated */
};

struct result_list {
	struct attr **attrs;
};

struct context {
	struct attr *attr;
	int error;
	int skip;
	const char *expr;
	struct result res;
};

/**
 * Information about a callback function for a saved command.
 */
struct command_saved_cb {
	struct callback *cb;	/**< The callback function */
	struct attr attr;
};

/**
 * A saved command.
 */
struct command_saved {
	struct context ctx;
	struct result res;
	char *command;				/**< The command string itself **/
	struct event_idle *idle_ev;		/**< Event to update this command **/
	struct callback *idle_cb;
	struct callback *register_cb;			/**< Callback to register all the callbacks **/
	struct event_idle *register_ev;		/**< Idle event to register all the callbacks **/
	struct attr context_attr;			/**< The root of the object hierarchy, which will be assumed as
										 *   the parent of all unqualified or partially qualified object
										 *   references. **/
	int num_cbs;						/**< Number of entries in {@code cbs} **/
	struct command_saved_cb *cbs;		/**< List of callbacks for this saved command **/
	struct callback *cb; /**< Callback that should be called when we re-evaluate **/
	int error;
	int async;
};

enum error {
	no_error=0, missing_double_quote, missing_opening_parenthesis, missing_closing_parenthesis, missing_closing_brace, missing_colon, missing_semicolon, wrong_type, illegal_number_format, illegal_character, missing_closing_bracket, invalid_type, not_ready, internal, eof_reached
};

enum op_type {
	op_type_binary, op_type_prefix, op_type_suffix
};

enum set_type {
	set_type_symbol, set_type_string, set_type_integer, set_type_float
};



static void eval_comma(struct context *ctx, struct result *res);
static struct attr ** eval_list(struct context *ctx);

/**
 * @brief Converts an error to human-readable text.
 *
 * @param err The error code
 *
 * @return A string containing the error description. The caller is responsible for freeing up the string by
 * calling {@code g_free()} when it is no longer needed.
 */
char *command_error_to_text(int err) {
	switch (err) {
	case no_error:
		return g_strdup("no_error");
	case missing_double_quote:
		return g_strdup("missing_double_quote");
	case missing_opening_parenthesis:
		return g_strdup("missing_opening_parenthesis");
	case missing_closing_parenthesis:
		return g_strdup("missing_closing_parenthesis");
	case missing_closing_brace:
		return g_strdup("missing_closing_brace");
	case missing_colon:
		return g_strdup("missing_colon");
	case missing_semicolon:
		return g_strdup("missing_semicolon");
	case wrong_type:
		return g_strdup("wrong_type");
	case illegal_number_format:
		return g_strdup("illegal_number_format");
	case illegal_character:
		return g_strdup("illegal_character");
	case missing_closing_bracket:
		return g_strdup("missing_closing_bracket");
	case invalid_type:
		return g_strdup("invalid_type");
	case not_ready:
		return g_strdup("not_ready");
	case internal:
		return g_strdup("internal");
	case eof_reached:
		return g_strdup("eof_reached");
	default:
		return g_strdup("unknown");
	}
}

static void
result_free(struct result *res)
{
	if(res->allocated) {
		attr_free_content(&res->attr);
		res->allocated=0;
	} else {
		res->attr.type=type_none;
		res->attr.u.data=NULL;
	}
}



static int command_register_callbacks(struct command_saved *cs);

static const char *
get_op(struct context *ctx, int test, ...)
{
	char *op;
	const char *ret=NULL;
	va_list ap;

	while (*ctx->expr && g_ascii_isspace(*ctx->expr)) {
		ctx->expr++;
	}

	va_start(ap, test);
	while ((op = va_arg(ap, char *))) {
		if (!strncmp(ctx->expr, op, strlen(op))) {
			ret=op;
			if (! test)
				ctx->expr+=strlen(op);
			break;
		}
	}
	va_end(ap);
	return ret;
}

/*static int
is_int(struct result *res)
{
	return 1;
}*/

static int
is_double(struct result *res)
{
	return 0;
}

static void
dump(struct result *res)
{
#if 0
	char object[res->varlen+1];
	char attribute[res->attrnlen+1];
	if (res->var)
		strncpy(object, res->var, res->varlen);
	object[res->varlen]='\0';
	if (res->attrn)
		strncpy(attribute, res->attrn, res->attrnlen);
	attribute[res->attrnlen]='\0';
	dbg(lvl_debug,"type:%s\n", attr_to_name(res->attr.type));
	dbg(lvl_debug,"attribute '%s' from '%s'\n", attribute, object);
#endif
}

static enum attr_type
command_attr_type(struct result *res)
{
	char *attrn=g_alloca(sizeof(char)*(res->attrnlen+1));

	strncpy(attrn, res->attrn, res->attrnlen);
	attrn[res->attrnlen]='\0';
	return attr_from_name(attrn);
}

/**
 * @brief Retrieves an attribute from an object.
 *
 * This function will retrieve the first matching attribute by calling the {@code get_attr} method for
 * the object type. If {@code object} does not refer to a valid object, or the {@code get_attr} method
 * for the object type could not be defined, the function fails and zero is returned.
 *
 * @param ctx The context (ignored)
 * @param object The object for which the attribute is to be retrieved.
 * @param attr_type The type of attribute to retrieve
 * @param ret Points to a {@code struct attr} to which the attribute will be copied
 *
 * @return True if a matching attribute was found, false if no matching attribute was found or an error
 * occurred
 */
static int
command_object_get_attr(struct context *ctx, struct attr *object, enum attr_type attr_type, struct attr *ret)
{
	int r;
	struct attr dup;
	struct object_func *func=object_func_lookup(object->type);
	if (!object->u.data || !func || !func->get_attr) {
		dbg(lvl_warning, "cannot retrieve attributes from %s (%p), func=%p\n", attr_to_name(object->type), object->u.data, func)
		return 0;
	}
	r=func->get_attr(object->u.data, attr_type, &dup, NULL);
	if(r)
		attr_dup_content(&dup,ret);
	else
		dbg(lvl_warning, "%s (%p) has no attribute %s\n", attr_to_name(object->type), object->u.data, attr_to_name(attr_type))
	return r;
}

static int
command_object_add_attr(struct context *ctx, struct attr *object, struct attr *attr)
{
	struct object_func *func=object_func_lookup(object->type);
	if (!object->u.data || !func || !func->add_attr)
		return 0;
	return func->add_attr(object->u.data, attr);
}

static int
command_object_remove_attr(struct context *ctx, struct attr *object, struct attr *attr)
{
	struct object_func *func=object_func_lookup(object->type);
	if (!object->u.data || !func || !func->remove_attr)
		return 0;
	return func->remove_attr(object->u.data, attr);
}


/**
 * @brief Retrieves the current value of an attribute and stores it in {@code res}.
 *
 * If {@code ctx->skip} is true, the function aborts and no action is taken.
 *
 * Before calling this function, object references in {@code res} must be resolved. That is,
 * {@code res->attr} holds a copy of {@code ctx->attr} and the first {@code res->attrnlen} characters of
 * {@code res->attrn} correspond to the object name.
 *
 * After this function completes, {@code res->allocated} is true, and {@code res->attrn} and
 * {@code res->attrnlen} are reset.
 *
 * If the attribute was successfully retrieved, the first {@code res->varlen} characters of
 * {@code res->var} correspond to an object name and {@code res->attr} holds the attribute.
 *
 * If the attribute could not be retrieved, {@code res->attr.type} is set to {@code attr_none}, and
 * {@code res->var} and {@code res->varlen} are reset.
 *
 * @param ctx The context
 * @param res The result
 */
static void
command_get_attr(struct context *ctx, struct result *res)
{
	int result;
	struct result tmp={{0,},};
	enum attr_type attr_type=command_attr_type(res);
	enum attr_type parent_type = res->attr.type; /* for debugging only */
	if (ctx->skip)
		return;
	result=command_object_get_attr(ctx, &res->attr, attr_type, &tmp.attr);
	result_free(res);
	*res=tmp;
	res->allocated=1;
	if (result) {
		dbg(lvl_debug, "successfully retrieved '%s' from '%s'\n", attr_to_name(attr_type), attr_to_name(parent_type));
		res->var=res->attrn;
		res->varlen=res->attrnlen;
	} else {
		dbg(lvl_warning, "could not retrieve '%s' from '%s'\n", attr_to_name(attr_type), attr_to_name(parent_type));
		result_free(res);
		res->attr.type=attr_none;
		res->var=NULL;
		res->varlen=0;
	}
	res->attrn=NULL;
	res->attrnlen=0;
	dump(res);
}

static void
command_set_attr(struct context *ctx, struct result *res, struct result *newres)
{
	enum attr_type attr_type=command_attr_type(res);
	struct object_func *func=object_func_lookup(res->attr.type);
	if (ctx->skip)
		return;
	if (!res->attr.u.data || !func || !func->set_attr)
		return;
	if (attr_type == attr_attr_types) {
		char *attrn=g_alloca(sizeof(char)*(res->attrnlen+1));
		struct attr *tmp;
		strncpy(attrn, res->attrn, res->attrnlen);
		attrn[res->attrnlen]='\0';
		tmp=attr_new_from_text(attrn, newres->attr.u.str);
		newres->attr.u.data=tmp->u.data;
		newres->allocated=1;
		g_free(tmp);
	}
	newres->attr.type=attr_type;
	func->set_attr(res->attr.u.data, &newres->attr);
	result_free(res);
	*res=*newres;
}

/**
 * @brief Resolves an object reference.
 *
 * Prior to calling this function, {@code res} must contain a valid, unresolved object reference:
 * {@code res->attr.type} must be {@code attr_none}, and the first {@code res->varlen} characters of
 * {@code res->var} must correspond to an object name.
 *
 * After the function returns, {@code res->attr} holds a copy of {@code ctx->attr} and the first
 * {@code res->attrnlen} characters of {@code res->attrn} correspond to the object name.
 * {@code res->var} and {@code res->varlen} are reset.
 *
 * @param ctx The context
 * @param res The result
 */
static void
resolve_object(struct context *ctx, struct result *res)
{
	if (res->attr.type == attr_none && res->varlen) {
		res->attr=*ctx->attr;
		res->attrn=res->var;
		res->attrnlen=res->varlen;
		res->var=NULL;
		res->varlen=0;
	}
}

/**
 * @brief Resolves and retrieves an object and stores it in {@code res}.
 *
 * Prior to calling this function, {@code res} must contain a valid, unresolved object reference:
 * {@code res->attr.type} must be {@code attr_none}, and the first {@code res->varlen} characters of
 * {@code res->var} must correspond to an object name.
 *
 * If {@code ctx->skip} is true, the object reference will be resolved but the object will not be
 * retrieved: the first {@code res->attrnlen} characters of {@code res->attrn} correspond to the object
 * name after the function returns, while {@code res->var} and {@code res->varlen} are reset.
 *
 * If {@code ctx->skip} is false, {@code res->allocated} is true after this function completes. The
 * object is stored in {@code res->attr} if it was successfully retrieved, otherwise {@code res->var}
 * and {@code res->varlen} are reset.
 *
 * @param ctx The context
 * @param res The result
 */
static void
resolve(struct context *ctx, struct result *res)
{
	resolve_object(ctx, res);
	if (res->attrn)
		command_get_attr(ctx, res);
}

static double
get_double(struct context *ctx, struct result *res)
{
	resolve(ctx, res);
	return res->val;
}


/**
 * @brief Returns an integer or bool representation of the result of an expression
 *
 * This function evaluates the result of an expression ({@code res->attr}).
 *
 * If {@code res->attr} is of a numeric type, its integer part is returned.
 *
 * If {@code is_bool} is false and {@code res->attr} is not of a numeric type, 0 is returned.
 *
 * If {@code is_bool} is true and {@code res->attr} is of an object or string type, true is returned
 * for non-null, false otherwise.
 *
 * For all other types of {@code res->attr}, 0 (false) is returned.
 *
 * @param ctx The context for the expression
 * @param is_bool If true, return boolean representation, else return integer representation. See description.
 * @param res The result of the evaluation
 *
 * @return The result of the expression, see description.
 */
static int
get_int_bool(struct context *ctx, int is_bool, struct result *res)
{
	resolve(ctx, res);
	if (res->attr.type == attr_none)
		return 0;
	if (res->attr.type >= attr_type_int_begin && res->attr.type <= attr_type_int_end) {
		return res->attr.u.num;
	}
	if (res->attr.type >= attr_type_double_begin && res->attr.type <= attr_type_double_end) {
		return (int) (*res->attr.u.numd);
	}
	if (is_bool && ATTR_IS_OBJECT(res->attr.type)) 
		return res->attr.u.data != NULL;
	if (is_bool && ATTR_IS_STRING(res->attr.type)) 
		return res->attr.u.data != NULL;
	dbg(lvl_debug,"bool %d %s\n",is_bool,attr_to_name(res->attr.type));
	ctx->error=wrong_type;
	return 0;
}

/**
 * @brief Returns an integer representation of the result of an expression
 *
 * This function is a wrapper around {@code get_int_bool()}. It is equivalent to
 * {@code get_int_bool(ctx, 0, res)}. See {@code get_int_bool()} for a description.
 */
static int
get_int(struct context *ctx, struct result *res)
{
	return get_int_bool(ctx, 0, res);
}

/**
 * @brief Returns a boolean representation of the result of an expression
 *
 * This function is a wrapper around {@code get_int_bool()}. It is equivalent to
 * {@code get_int_bool(ctx, 1, res)}. See {@code get_int_bool()} for a description.
 */
static int
get_bool(struct context *ctx, struct result *res)
{
	return !!get_int_bool(ctx, 1, res);
}


static char *
get_string(struct context *ctx, struct result *res)
{
	resolve(ctx, res);
	return attr_to_text(&res->attr, NULL, 0);
}

static void
set_double(struct result *res, double val)
{
	result_free(res);
	res->attr.type=attr_type_double_begin;
	res->attr.u.numd=&res->val;
	res->val=val;
}

static void
set_int(struct result *res, int val)
{
	result_free(res);
	res->attr.type=attr_type_int_begin;
	res->attr.u.num=val;
}

static void
result_op(struct context *ctx, enum op_type op_type, const char *op, struct result *inout, struct result *in)
{
	if (ctx->skip)
		return;
	switch (op_type) {
	case op_type_prefix:
		switch ((op[0] << 8) | op[1]) {
		case ('!' << 8):
			set_int(inout, !get_bool(ctx, inout));
			return;
		case ('~' << 8):
			set_int(inout, ~get_int(ctx, inout));
			return;
		}
		break;
	case op_type_binary:
		resolve(ctx, inout);
		resolve(ctx, in);
		switch ((op[0] << 8) | op[1]) {
		case ('=' << 8)|'=':
			if (inout->attr.type == attr_none || in->attr.type == attr_none) {
				set_int(inout, 0);
			} else if (ATTR_IS_STRING(inout->attr.type) && ATTR_IS_STRING(in->attr.type)) {
				char *s1=get_string(ctx, inout),*s2=get_string(ctx, in);
				set_int(inout, (!strcmp(s1,s2)));
				g_free(s1);
				g_free(s2);
			} else if (ATTR_IS_OBJECT(inout->attr.type) && ATTR_IS_OBJECT(in->attr.type)) {
				set_int(inout, inout->attr.u.data == in->attr.u.data);
			} else
				set_int(inout, (get_int(ctx, inout) == get_int(ctx, in)));
			return;
		case ('!' << 8)|'=':
			if (inout->attr.type == attr_none || in->attr.type == attr_none) {
				set_int(inout, 1);
			} else if (ATTR_IS_STRING(inout->attr.type) && ATTR_IS_STRING(in->attr.type)) {
				char *s1=get_string(ctx, inout),*s2=get_string(ctx, in);
				set_int(inout, (!!strcmp(s1,s2)));
				g_free(s1);
				g_free(s2);
			} else if (ATTR_IS_OBJECT(inout->attr.type) && ATTR_IS_OBJECT(in->attr.type)) {
				set_int(inout, inout->attr.u.data != in->attr.u.data);
			} else
				set_int(inout, (get_int(ctx, inout) != get_int(ctx, in)));
			return;
		case ('<' << 8):
			set_int(inout, (get_int(ctx, inout) < get_int(ctx, in)));
			return;
		case ('<' << 8)|'=':
			set_int(inout, (get_int(ctx, inout) <= get_int(ctx, in)));
			return;
		case ('>' << 8):
			set_int(inout, (get_int(ctx, inout) > get_int(ctx, in)));
			return;
		case ('>' << 8)|'=':
			set_int(inout, (get_int(ctx, inout) >= get_int(ctx, in)));
			return;
		case ('*' << 8):
			if (is_double(inout) || is_double(in)) 
				set_double(inout, get_double(ctx, inout) * get_double(ctx, in));
			else
				set_int(inout, get_int(ctx, inout) * get_int(ctx, in));
			return;
		case ('/' << 8):
			if (is_double(inout) || is_double(in)) 
				set_double(inout, get_double(ctx, inout) * get_double(ctx, in));
			else
				set_int(inout, get_int(ctx, inout) * get_int(ctx, in));
			return;
		case ('%' << 8):
			set_int(inout, get_int(ctx, inout) % get_int(ctx, in));
			return;
		case ('+' << 8):
			if (is_double(inout) || is_double(in)) 
				set_double(inout, get_double(ctx, inout) + get_double(ctx, in));
			else if (ATTR_IS_STRING(inout->attr.type) && ATTR_IS_STRING(in->attr.type)) {
				char *str=g_strdup_printf("%s%s",inout->attr.u.str,in->attr.u.str);
				result_free(inout);
				inout->attr.type=attr_type_string_begin;
				inout->attr.u.str=str;
				inout->allocated=1;
			} else
				set_int(inout, get_int(ctx, inout) + get_int(ctx, in));
			return;
		case ('-' << 8):
			if (is_double(inout) || is_double(in)) 
				set_int(inout, get_int(ctx, inout) - get_int(ctx, in));
			else
				set_double(inout, get_double(ctx, inout) - get_double(ctx, in));
			return;
		case ('&' << 8):
			set_int(inout, get_int(ctx, inout) & get_int(ctx, in));
			return;
		case ('^' << 8):
			set_int(inout, get_int(ctx, inout) ^ get_int(ctx, in));
			return;
		case ('|' << 8):
			set_int(inout, get_int(ctx, inout) | get_int(ctx, in));
			return;
		case (('&' << 8) | '&'):
			set_int(inout, get_int(ctx, inout) && get_int(ctx, in));
			return;
		case (('|' << 8) | '|'):
			set_int(inout, get_int(ctx, inout) || get_int(ctx, in));
			return;
		default:
			break;
		}
	default:
		break;
	}
	dbg(lvl_error,"Unkown op %d %s\n",op_type,op);
	ctx->error=internal;
}

static void
result_set(struct context *ctx, enum set_type set_type, const char *op, int len, struct result *out)
{
	if (ctx->skip)
		return;
	switch (set_type) {
	case set_type_symbol:
		out->attr.type=attr_none;
		out->var=op;
		out->varlen=len;
		return;
	case set_type_integer:
		out->attr.type=attr_type_int_begin;
		out->attr.u.num=atoi(ctx->expr);
		return;
	case set_type_float:
		out->val = strtod(ctx->expr, NULL);
		out->attr.type=attr_type_double_begin;
		out->attr.u.numd=&out->val;
		return;
	case set_type_string:
		if (len >= 2) {
			out->attr.type=attr_type_string_begin;
			out->attr.u.str=g_malloc(len-1);
			strncpy(out->attr.u.str, op+1, len-2);
			out->attr.u.str[len-2]='\0';
			out->allocated=1;
			return;
		}
		break;
	default:
		break;
	}
	dbg(lvl_error,"unknown set type %d %s\n",set_type,op);
	ctx->error=internal;
}

/**
 * @brief Evaluates a value and stores its result.
 *
 * This function evaluates the first value in {@code ctx->expr}. A value can be either an object name
 * (such as {@code vehicle.position_speed}) or a literal value.
 *
 * If evaluation is successful, the result is stored in {@code res->attr}.
 *
 * If an object name is encountered, the result has an attribute type of {@code attr_none} and the first
 * {@code res->varlen} characters of {@code res->var} will point to the object name.
 *
 * If a literal value is encountered, the result's attribute type is set to the corresponding generic
 * data type and its value is stored with the attribute.
 *
 * After this function returns, {@code ctx->expr} contains the rest of the expression string, which was
 * not evaluated. Leading spaces before the value will be discarded with the value.
 *
 * If {@code ctx->expr}, after eliminating any leading whitespace, does not begin with a valid value,
 * one of the following errors is stored in {@code ctx->error}:
 * <ul>
 * <li>{@code illegal_number_format} An illegal number format, such as a second decimal dot, was
 * encountered.</li>
 * <li>{@code missing_double_quote} A double quote without a matching second double quote was found.</li>
 * <li>{@code eof_reached} The expression string is empty.</li>
 * <li>{@code illegal_character} The expression string begins with a character which is illegal in a
 * value. This may happen when the expression string begins with an operator.</li>
 * </ul>
 *
 * @param ctx The context to evaluate
 * @param res Points to a {@code struct res} in which the result will be stored
 */
static void
eval_value(struct context *ctx, struct result *res) {
	const char *op;
	int dots=0;

	result_free(res);

	res->varlen=0;
	res->var=NULL;
	res->attrnlen=0;
	res->attrn=NULL;

	while (g_ascii_isspace(*(ctx->expr))) {
		ctx->expr++;
	}
	op = ctx->expr;

	if ((op[0] >= 'a' && op[0] <= 'z') || (op[0] >= 'A' && op[0] <= 'Z') || op[0] == '_') {
		const char *s=op;
		for (;;) {
			while ((op[0] >= 'a' && op[0] <= 'z') || (op[0] >= 'A' && op[0] <= 'Z') || (op[0] >= '0' && op[0] <= '9') || op[0] == '_') {
				op++;
			}
			if (op-s == 3 && !strncmp(s,"new",3) && op[0] == ' ') {
				op++;
			} else
				break;
		}
		result_set(ctx, set_type_symbol, ctx->expr, op-ctx->expr, res);
		ctx->expr=op;
		return;
	}
	if ((op[0] >= '0' && op[0] <= '9') ||
	    (op[0] == '.' && op[1] >= '0' && op[1] <= '9') ||
	    (op[0] == '-' && op[1] >= '0' && op[1] <= '9') ||
	    (op[0] == '-' && op[1] == '.' && op[2] >= '0' && op[2] <= '9')) {
		while ((op[0] >= '0' && op[0] <= '9') || op[0] == '.' || (res->varlen == 0 && op[0] == '-')) {
			if (op[0] == '.')
				dots++;
			if (dots > 1) {
				ctx->error=illegal_number_format;
				return;
			}
			op++;
		}
		result_set(ctx, dots?set_type_float:set_type_integer, ctx->expr, op-ctx->expr, res);
		ctx->expr=op;
		return;
	}
	if (op[0] == '"') {
		int escaped=0;
		do {
			if (op[0] == '\\') {
				escaped=1;
			       	if (op[1] == '"')
					op++;
			}
			op++;
		} while (op[0] && op[0] != '"');
		if(!*op) {
			ctx->error=missing_double_quote;
			return;
		}
		op++;
		if (escaped) {
			char *tmpstr=g_malloc(op-ctx->expr+1),*s=tmpstr;
			op=ctx->expr;
			do {
				if (op[0] == '\\') 
					op++;
				*s++=*op++;
			} while (op[0] != '"');
			*s++=*op++;
			result_set(ctx, set_type_string, tmpstr, s-tmpstr, res);
			g_free(tmpstr);
		} else
			result_set(ctx, set_type_string, ctx->expr, op-ctx->expr, res);
		ctx->expr=op;
		return;
	}
	if (!*op)
		ctx->error=eof_reached;
	else {
		/*
		 * If we get here, ctx->expr does not begin with a variable or a literal value. This is not an
		 * error if this function is being called to test if an expression begins with a value.
		 */
		dbg(lvl_debug, "character 0x%x is illegal in a value\n",*op);
		ctx->error=illegal_character;
	}
}

/**
 * @brief Retrieves the next object reference from an expression.
 *
 * This function scans the expression string {@code ctx->expr} for the next object reference. Anything
 * other than an object reference (whitespace characters, literal values, operators and even illegal
 * characters) is discarded until either the end of the string is reached or an object reference is
 * encountered.
 *
 * After this function completes successfully, {@code res->attr.type} is {@code attr_none} and the first
 * {@code res->varlen} characters of {@code res->var} point to the object name.
 *
 * Object names retrieved by this function are unqualified, i.e. {@code vehicle.position_speed} will be
 * retrieved as {@code vehicle} on the first call (return value 2) and {@code position_speed} on the
 * second call (return value 1).
 *
 * @param ctx The context
 * @param res Points to a {@code struct result} where the result will be stored.
 *
 * @return If a complete object name has been retrieved, the return value is 1. If a partial object name
 * has been retrieved (e.g. {@code vehicle} from {@code vehicle.position_speed}), the return value is 2.
 * If no object references were found, the return value is 0.
 */
static int
get_next_object(struct context *ctx, struct result *res) {
	
	while (*ctx->expr) {
		res->varlen = 0;
		ctx->error = 0;

		eval_value(ctx,res);
		
		if ((res->attr.type == attr_none) && (res->varlen > 0)) {
			if (ctx->expr[0] != '.') {
				return 1;		// 1 means "this is the final object name"
			} else {
				return 2;		// 2 means "there are more object names following" (e.g. we just hit 'vehicle' in 'vehicle.position_speed'
			}
		}

		if (ctx->error) {
			// Probably hit an operator
			ctx->expr++;
		}
	}

	return 0;
}

static void
eval_brace(struct context *ctx, struct result *res)
{
	if (get_op(ctx,0,"(",NULL)) {
		eval_comma(ctx, res);
		if (ctx->error) return;
		if (!get_op(ctx,0,")",NULL)) 
			ctx->error=missing_closing_parenthesis;
		return;
	}
	eval_value(ctx, res);
}

static void
command_call_function(struct context *ctx, struct result *res)
{
	struct attr cbl,**list=NULL;
	char *function=g_alloca(sizeof(char)*(res->attrnlen+1));
	if (res->attrn)
		strncpy(function, res->attrn, res->attrnlen);
	function[res->attrnlen]='\0';
	dbg(lvl_debug,"function=%s\n", function);
	if (ctx->expr[0] != ')') {
		list=eval_list(ctx);	
		if (ctx->error) {
			attr_list_free(list);
			return;
		}
	}
	if (!get_op(ctx,0,")",NULL)) {
		attr_list_free(list);
		ctx->error=missing_closing_parenthesis;
		return;
	}
	if (!ctx->skip) {	
		if (!strcmp(function,"_") && list && list[0] && list[0]->type >= attr_type_string_begin && list[0]->type <= attr_type_string_end) {
			result_free(res);
			res->attr.type=list[0]->type;
			res->attr.u.str=g_strdup(navit_nls_gettext(list[0]->u.str));
			res->allocated=1;
			
		} else if (!strncmp(function,"new ",4)) {
			enum attr_type attr_type=attr_from_name(function+4);
			result_free(res);
			if (ATTR_IS_INT(attr_type)) {
				if (list && list[0] && ATTR_IS_INT(list[0]->type)) {
					res->attr.type=attr_type;
					res->attr.u.num=list[0]->u.num;
					res->allocated=0;
				} else {
					dbg(lvl_error,"don't know how to create int of args\n");
				}
			} else if (ATTR_IS_STRING(attr_type)) {
				if (list && list[0] && ATTR_IS_STRING(list[0]->type)) {
					res->attr.type=attr_type;
					res->attr.u.str=g_strdup(list[0]->u.str);
					res->allocated=1;
				} else {
					dbg(lvl_error,"don't know how to create string of args\n");
				}
			} else if (ATTR_IS_OBJECT(attr_type)) {
				struct object_func *func=object_func_lookup(attr_type);
				if (func && func->create) {
					res->attr.type=attr_type;
					res->attr.u.data=func->create(list[0], list+1);
					/* Setting allocated to 1 here will make object to be destroyed when last reference is destroyed. 
					   So created persistent objects should be stored with set_attr_var command. */
					res->allocated=1;
				}
			} else {
				dbg(lvl_error,"don't know how to create %s (%s)\n",attr_to_name(attr_type),function+4);
			}
		} else if (!strcmp(function,"add_attr")) {
			command_object_add_attr(ctx, &res->attr, list[0]);
		} else if (!strcmp(function,"remove_attr")) {
			command_object_remove_attr(ctx, &res->attr, list[0]);
		} else {
			if (command_object_get_attr(ctx, &res->attr, attr_callback_list, &cbl)) {
				int valid =0;
				struct attr **out=NULL;
				dbg(lvl_debug,"function call %s from %s\n",function, attr_to_name(res->attr.type));
				callback_list_call_attr_4(cbl.u.callback_list, attr_command, function, list, &out, &valid);
				if (valid!=1){
					dbg(lvl_error, "invalid command ignored: \"%s\"; see http://wiki.navit-project.org/index.php/"
					    "OSD#Navit_commands for valid commands.\n", function);
				}
				if (out && out[0]) {
					result_free(res);
					attr_dup_content(out[0], &res->attr);
					res->allocated=1;
					attr_list_free(out);
				} else
					result_free(res);
			} else
				result_free(res);
		}
	}
	attr_list_free(list);
	res->var=NULL;
	res->varlen=0;
	res->attrn=NULL;
	res->attrnlen=0;
}

static void
eval_postfix(struct context *ctx, struct result *res)
{
	struct result tmp={{0,},};
	const char *op;

    	eval_brace(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!(op=get_op(ctx,0,"[","(",".",NULL)))
			return;
		if (op[0] == '.') {
    			eval_brace(ctx, &tmp);
			if (ctx->error) return;
			resolve(ctx, res);
			if (ctx->error) return;
			res->attrn=tmp.var;
			res->attrnlen=tmp.varlen;
			dump(res);
		} else if (op[0] == '[') {
			resolve_object(ctx, res);
			if (ctx->error) return;
			if (get_op(ctx,0,"@",NULL)) {
				if (!ctx->skip) {
					struct object_func *obj_func=object_func_lookup(res->attr.type);
					struct attr_iter *iter;
					struct attr attr;
					enum attr_type attr_type=command_attr_type(res);
					void *obj=res->attr.u.data;
					if (!obj) {
						dbg(lvl_error,"no object\n");
						return;
					}
					if (!obj_func) {
						dbg(lvl_error,"no object func\n");
						return;
					}
					if (!obj_func->iter_new || !obj_func->iter_destroy) {
						dbg(lvl_error,"no iter func\n");
						return;
					}
					iter = obj_func->iter_new(NULL);
					result_free(res);
					res->varlen=0;
					res->attrn=NULL;
					while (obj_func->get_attr(obj, attr_type, &attr, iter)) {
						if (command_evaluate_to_boolean(&attr, ctx->expr, &ctx->error)) {
							result_free(res);
							res->attr=attr;
						}
					}
					obj_func->iter_destroy(iter);
				}
				if (ctx->error) return;
				ctx->expr+=command_evaluate_to_length(ctx->expr, &ctx->error);
			}
			if (!get_op(ctx,0,"]",NULL)) {
				ctx->error=missing_closing_bracket;
				return;
			}
		} else if (op[0] == '(') {
			dbg(lvl_debug,"function call\n");
			resolve_object(ctx, res);
			command_call_function(ctx, res);
		}
	}
}

static void
eval_unary(struct context *ctx, struct result *res) 
{
	const char *op;
	op=get_op(ctx,0,"~","!",NULL);
	if (op) {
	    	eval_unary(ctx, res);
		if (ctx->error) return;
		result_op(ctx, op_type_prefix, op, res, NULL);
	} else
		eval_postfix(ctx, res);
}

static void
eval_multiplicative(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};
	const char *op;

    	eval_unary(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!(op=get_op(ctx,0,"*","/","%",NULL))) return;
    		eval_unary(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, op, res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_additive(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};
	const char *op;

    	eval_multiplicative(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!(op=get_op(ctx,0,"-","+",NULL))) return;
    		eval_multiplicative(ctx, &tmp);
		if (!ctx->error)
			result_op(ctx, op_type_binary, op, res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_equality(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};
	const char *op;

    	eval_additive(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!(op=get_op(ctx,0,"==","!=","<=",">=","<",">",NULL))) return;
    		eval_additive(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, op, res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}


static void
eval_bitwise_and(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};

    	eval_equality(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (get_op(ctx,1,"&&",NULL)) return;
		if (!get_op(ctx,0,"&",NULL)) return;
    		eval_equality(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, "&", res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_bitwise_xor(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};

    	eval_bitwise_and(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!get_op(ctx,0,"^",NULL)) return;
    		eval_bitwise_and(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, "^", res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_bitwise_or(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};

    	eval_bitwise_xor(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (get_op(ctx,1,"||",NULL)) return;
		if (!get_op(ctx,0,"|",NULL)) return;
    		eval_bitwise_xor(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, "|", res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_logical_and(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};

    	eval_bitwise_or(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!get_op(ctx,0,"&&",NULL)) return;
    		eval_bitwise_or(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, "&&", res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_logical_or(struct context *ctx, struct result *res) 
{
	struct result tmp={{0,},};

    	eval_logical_and(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!get_op(ctx,0,"||",NULL)) return;
    		eval_logical_and(ctx, &tmp);
		if (!ctx->error) 
			result_op(ctx, op_type_binary, "||", res, &tmp);
		result_free(&tmp);
		if (ctx->error) return;
	}
}

static void
eval_conditional(struct context *ctx, struct result *res)
{
	struct result tmp={{0,},};
	int cond=0;
	int skip;

    	eval_logical_or(ctx, res);
	if (ctx->error) return;
	if (!get_op(ctx,0,"?",NULL)) return;
	skip=ctx->skip;
	cond=get_bool(ctx, res);
	result_free(res);
	if (ctx->error) return;
	ctx->skip=!cond || skip;
    	eval_logical_or(ctx, &tmp);
	ctx->skip=skip;
	if (ctx->error) {
		result_free(&tmp);
		return;
	}

	*res=tmp;
	memset(&tmp,0,sizeof(tmp));

	if (!get_op(ctx,0,":",NULL)) {
		dbg(lvl_debug,"ctxerr\n");
		ctx->error=missing_colon;
		return;
	}
	ctx->skip=cond || skip;
    	eval_logical_or(ctx, &tmp);
	ctx->skip=skip;
	if (ctx->error) {
		result_free(&tmp);
		return;
	}
	if (!cond) {
		result_free(res);
		*res=tmp;
	} else
		result_free(&tmp);
}

/* = *= /= %= += -= >>= <<= &= ^= |= */

static void
eval_assignment(struct context *ctx, struct result *res)
{
	struct result tmp={{0,},};
    	eval_conditional(ctx, res);
	if (ctx->error) return;
	if (!get_op(ctx,0,"=",NULL)) return;
    	eval_conditional(ctx, &tmp);
	if (ctx->error) {
		result_free(&tmp);
		return;
	}
	resolve(ctx, &tmp);
	if (ctx->error) {
		result_free(&tmp);
		return;
	}
	resolve_object(ctx, res);
	command_set_attr(ctx, res, &tmp);
}

/* , */
static void
eval_comma(struct context *ctx, struct result *res)
{
	struct result tmp={{0,},};

	eval_assignment(ctx, res);
	if (ctx->error) return;
	for (;;) {
		if (!get_op(ctx,0,",",NULL)) return;
    		eval_assignment(ctx, &tmp);
		if (ctx->error) return;
		result_free(res);
		*res=tmp;
	}
}

static struct attr **
eval_list(struct context *ctx)
{
	struct result tmp={{0,},};

	struct attr **ret=NULL;
	for (;;) {
    		eval_assignment(ctx, &tmp);
		if (ctx->error) {
			result_free(&tmp);
			attr_list_free(ret);
			return NULL;
		}
		resolve(ctx, &tmp);
		ret=attr_generic_add_attr(ret, &tmp.attr);
		result_free(&tmp);
		if (!get_op(ctx,0,",",NULL)) return ret;
	}
}

#if 0

void command(struct attr *attr, char *expr)
{
	struct result res;
	struct context ctx;
	memset(&res, 0, sizeof(res));
	memset(&ctx, 0, sizeof(ctx));
	ctx.attr=attr;
	ctx.error=0;
	ctx.expr=expr;
	printf("command='%s'\n", expr);
	eval_comma(&ctx,&res);
	printf("err=%d %s\n", ctx.error, ctx.expr);
	dump(&res);
	printf("***\n");
	resolve(&ctx, &res);
	dump(&res);
	printf("%s\n", get_string(&ctx, &res));
}
#endif

static void
command_evaluate_to(struct attr *attr, const char *expr, struct context *ctx, struct result *res)
{
	result_free(res);
	memset(res, 0, sizeof(*res));
	memset(ctx, 0, sizeof(*ctx));
	ctx->attr=attr;
	ctx->expr=expr;
	eval_comma(ctx,res);
}

enum attr_type
command_evaluate_to_attr(struct attr *attr, char *expr, int *error, struct attr *ret)
{
	struct result res={{0,},};
	struct context ctx;
	command_evaluate_to(attr, expr, &ctx, &res);
	if (ctx.error)
		return attr_none;
	resolve_object(&ctx, &res);
	*ret=res.attr;
	dbg(lvl_debug,"type %s\n",attr_to_name(command_attr_type(&res)));
	return command_attr_type(&res);
}

void
command_evaluate_to_void(struct attr *attr, char *expr, int *error)
{
	struct result res={{0,},};
	struct context ctx;
	command_evaluate_to(attr, expr, &ctx, &res);
	if (!ctx.error)
		resolve(&ctx, &res);
	if (error)
		*error=ctx.error;
	result_free(&res);

}

char *
command_evaluate_to_string(struct attr *attr, char *expr, int *error)
{
	struct result res={{0,},};
	struct context ctx;
	char *ret=NULL;

	command_evaluate_to(attr, expr, &ctx, &res);
	if (!ctx.error)
		resolve(&ctx, &res);
	if (!ctx.error)
		ret=get_string(&ctx, &res);
	if (error)
		*error=ctx.error;

	result_free(&res);

	if (ctx.error)
		return NULL;
	else
		return ret;
}

int
command_evaluate_to_int(struct attr *attr, char *expr, int *error)
{
	struct result res={{0,},};
	struct context ctx;
	int ret=0;

	command_evaluate_to(attr, expr, &ctx, &res);
	if (!ctx.error)
		resolve(&ctx, &res);
	if (!ctx.error)
		ret=get_int(&ctx, &res);
	if (error)
		*error=ctx.error;

	result_free(&res);

	if (ctx.error)
		return 0;
	else
		return ret;
}

int
command_evaluate_to_boolean(struct attr *attr, const char *expr, int *error)
{
	struct result res={{0,},};
	struct context ctx;
	int ret=0;

	command_evaluate_to(attr, expr, &ctx, &res);
	if (!ctx.error)
		resolve(&ctx, &res);
	if (!ctx.error) {
		if (res.attr.type == attr_none)
			ret=0;
		else if ((res.attr.type >= attr_type_int_begin && res.attr.type <= attr_type_int_end) ||
			 (res.attr.type >= attr_type_double_begin && res.attr.type <= attr_type_double_end))
			ret=get_int(&ctx, &res);
		else 
			ret=res.attr.u.data != NULL;
	}

	result_free(&res);

	if (error)
		*error=ctx.error;
	if (ctx.error)
		return 0;
	else	
		return ret;
}

int
command_evaluate_to_length(const char *expr, int *error)
{
	struct attr attr;
	struct result res={{0,},};
	struct context ctx;

	attr.type=attr_none;
	attr.u.data=NULL;
	command_evaluate_to(&attr, expr, &ctx, &res);

	result_free(&res);
	
	if (!ctx.error)
		return ctx.expr-expr;
	return 0;
}

static int
command_evaluate_single(struct context *ctx)
{
	struct result res={{0,},},tmp={{0,},};
	const char *op,*a,*f,*end;
	enum attr_type attr_type;
	void *obj;
	struct object_func *obj_func;
	struct attr_iter *iter;
	struct attr attr;
	int cond=0;
	int skip=ctx->skip;
	if (!(op=get_op(ctx,0,"foreach","if","{",NULL))) {
		eval_comma(ctx,&res);
		if (ctx->error)
			return 0;
		resolve(ctx, &res);
		result_free(&res);
		if (ctx->error)
			return 0;
		return get_op(ctx,0,";",NULL) != NULL;
	}
	switch (op[0]) {
	case 'f':
		if (!get_op(ctx,0,"(",NULL)) {
			ctx->error=missing_opening_parenthesis;
			return 0;
		}
		ctx->skip=1;
		a=ctx->expr;
    		eval_conditional(ctx, &res);
		resolve_object(ctx, &res);
		ctx->skip=skip;
		if (!get_op(ctx,0,";",NULL)) {
			ctx->error=missing_semicolon;
			return 0;
		}
		eval_comma(ctx,&res);
		attr_type=command_attr_type(&res);
		obj=res.attr.u.data;
		obj_func=object_func_lookup(res.attr.type);
		if (!get_op(ctx,0,")",NULL)) {
			ctx->error=missing_closing_parenthesis;
			return 0;
		}
		f=ctx->expr;
		ctx->skip=1;
		if (!command_evaluate_single(ctx)) {
			ctx->skip=skip;
			return 0;
		}
		ctx->skip=skip;
		if (ctx->skip) {
			result_free(&res);
			return 1;
		}
		end=ctx->expr;
		if (!obj) {
			dbg(lvl_error,"no object\n");
			return 0;
		}
		if (!obj_func) {
			dbg(lvl_error,"no object func\n");
			return 0;
		}
		if (!obj_func->iter_new || !obj_func->iter_destroy) {
			dbg(lvl_error,"no iter func\n");
			return 0;
		}
		iter = obj_func->iter_new(NULL);
		while (obj_func->get_attr(obj, attr_type, &attr, iter)) {
			ctx->expr=a;
    			eval_conditional(ctx, &res);
			resolve_object(ctx, &res);
			tmp.attr=attr;
			resolve(ctx, &tmp);
			if (ctx->error) {
				result_free(&tmp);
				return 0;
			}
			command_set_attr(ctx, &res, &tmp);
			result_free(&tmp);
			ctx->expr=f;
			if (!command_evaluate_single(ctx)) {
				obj_func->iter_destroy(iter);
				return 0;
			}
		}
		obj_func->iter_destroy(iter);
		ctx->expr=end;
		return 1;
	case 'i':
		if (!get_op(ctx,0,"(",NULL)) {
			ctx->error=missing_opening_parenthesis;
			return 0;
		}
		eval_comma(ctx,&res);
		if (!skip && !ctx->error)
			cond=get_bool(ctx, &res);
		result_free(&res);
		if (ctx->error)
			return 0;
		if (!get_op(ctx,0,")",NULL)) {
			ctx->error=missing_closing_parenthesis;
			return 0;
		}
		ctx->skip=!cond || skip;
		command_evaluate_single(ctx);
		ctx->skip=skip;
		if (ctx->error)
			return 0;
		if (get_op(ctx,0,"else",NULL)) {
			ctx->skip=cond || skip;
			command_evaluate_single(ctx);
			ctx->skip=skip;
			if (ctx->error)
				return 0;
		}
		return 1;
	case '{':
		while (!get_op(ctx,0,"}",NULL)) {
			if (!command_evaluate_single(ctx))
				return 0;
		}
		return 1;
	default:
		return 0;
	}
}

void
command_evaluate(struct attr *attr, const char *expr)
{
	/* Once the eval has started we can't rely anymore on the content of
	 * expr which may be freed when the calling widget is destroyed by a
	 * subsequent command call. Hence the g_strdup. */

	char *expr_dup;
	char *err = NULL;	/* Error description */
	struct context ctx={0,};
	ctx.attr=attr;
	ctx.error=0;
	ctx.expr=expr_dup=g_strdup(expr);
	for (;;) {
		if (!command_evaluate_single(&ctx))
			break;
	}
	if (ctx.error && ctx.error != eof_reached) {
		char expr[32];
		strncpy(expr, ctx.expr, 32);
		expr[31]='\0';
		err = command_error_to_text(ctx.error);
		dbg(lvl_error, "error %s starting at %s\n", err, expr);
		g_free(err);
	}
	g_free(expr_dup);
}

#if 0
void
command_interpreter(struct attr *attr)
{
                char buffer[4096];
                int size;
                for (;;) {
                size=read(0, buffer, 4095);
                buffer[size]='\0';
                if (size) {
                        buffer[size-1]='\0';
                }
                command(attr, buffer);
                }
}
#endif

static void
command_table_call(struct command_table *table, int count, void *data, char *command, struct attr **in, struct attr ***out, int *valid)
{
	int i;
	for (i = 0 ; i < count ; i++) {
		if (!strcmp(command,table->command)) {
			if (valid)
				*valid=1;
			table->func(data, command, in, out);
		}
		table++;
	}
}

void
command_add_table_attr(struct command_table *table, int count, void *data, struct attr *attr)
{
	attr->type=attr_callback;
	attr->u.callback=callback_new_attr_3(callback_cast(command_table_call),attr_command, table, count, data);
}

void
command_add_table(struct callback_list *cbl, struct command_table *table, int count, void *data)
{
	struct attr attr;
	command_add_table_attr(table, count, data, &attr);
	callback_list_add(cbl, attr.u.callback);
}

void
command_saved_set_cb (struct command_saved *cs, struct callback *cb)
{
	cs->cb = cb;
}

/**
 * @brief Returns an integer representation of the evaluation result of a saved command
 *
 * This function is a wrapper around {@code get_int()}. It is equivalent to
 * {@code get_int(&cs->ctx, &cs->res)}. See {@code get_int()} for a description.
 */
int
command_saved_get_int (struct command_saved *cs)
{
	return get_int(&cs->ctx, &cs->res);
}

int 
command_saved_error (struct command_saved *cs)
{
	return cs->error;
}

/**
 * @brief Idle function to evaluate a command
 *
 * This function is called from an idle loop for asynchronous evaluation but may also be called in-line.
 *
 * The result of the evaluation can be retrieved from {@code cs->res} after this function returns. If an
 * error occurred, it will be stored in {@code cs->error}.
 *
 * @param cs The command to evaluate
 */
static void
command_saved_evaluate_idle (struct command_saved *cs) 
{
	dbg(lvl_debug, "enter: cs=%p, cs->command=%s\n", cs, cs->command);
	// Only run once at a time
	if (cs->idle_ev) {
		event_remove_idle(cs->idle_ev);
		cs->idle_ev = NULL;
	}

	command_evaluate_to(&cs->context_attr, cs->command, &cs->ctx, &cs->res);

	if (!cs->ctx.error) {
		cs->error = 0;

		if (cs->cb) {
			callback_call_1(cs->cb, cs);
		}
	} else {
		cs->error = cs->ctx.error;
	}
}

/**
 * @brief Evaluates a command
 *
 * This function examines {@code cs->async} to determine if the command should be evaluated immediately.
 * If {@code cs->async} is true, an idle event is registered to register the command. Else the command
 * is evaluated immediately and the result can be retrieved immediately after this function returns.
 *
 * See {@link command_saved_evaluate_idle(struct command_saved *)} for details.
 *
 * @param cs The command to evaluate
 */
static void
command_saved_evaluate(struct command_saved *cs)
{	
	dbg(lvl_debug, "enter: cs=%p, cs->async=%d, cs->command=%s\n", cs, cs->async, cs->command);
	if (!cs->async) {
		command_saved_evaluate_idle(cs);
		return;
	}
	if (cs->idle_ev) {
		// We're already scheduled for reevaluation
		return;
	}

	if (!cs->idle_cb) {
		cs->idle_cb = callback_new_1(callback_cast(command_saved_evaluate_idle), cs);
	}

	cs->idle_ev = event_add_idle(100, cs->idle_cb);
}

/**
 * @brief Recreates all callbacks for a saved command
 *
 * @param cs The saved command
 */
static void
command_saved_callbacks_changed(struct command_saved *cs)
{
	// For now, we delete each and every callback and then re-create them
	int i;
	struct object_func *func;
	struct attr attr;

	dbg(lvl_debug, "enter: cs=%p, cs->async=%d, cs->command=%s\n", cs, cs->async, cs->command);

	if (cs->register_ev) {
		event_remove_idle(cs->register_ev);
		cs->register_ev = NULL;
	}

	attr.type = attr_callback;

	for (i = 0; i < cs->num_cbs; i++) {
		func = object_func_lookup(cs->cbs[i].attr.type);
		
		if (!func->remove_attr) {
			dbg(lvl_error, "Could not remove command-evaluation callback because remove_attr is missing for type %i!\n", cs->cbs[i].attr.type);
			continue;
		}

		attr.u.callback = cs->cbs[i].cb;

		func->remove_attr(cs->cbs[i].attr.u.data, &attr);
		callback_destroy(cs->cbs[i].cb);
	}

	g_free(cs->cbs);
	cs->cbs = NULL;
	cs->num_cbs = 0;

	// Now, re-create all the callbacks
	command_register_callbacks(cs);
}

/**
 * @brief Registers callbacks for a saved command
 *
 * This function registers callbacks for each attribute used in a saved command, causing the command to
 * be re-evaluated whenever its value might change.
 *
 * This function will fail if an object used in the expression could not be resolved. This may happen
 * during startup if this function is called before all objects have been created. In this case, the
 * caller should schedule the function to be called again at a later time.
 *
 * It will also fail if an error is encountered. This can be determined by examining
 * {@code cs->ctx.error} after the function returns.
 *
 * @param cs The command
 *
 * @return True if all callbacks were successfully registered, false if the function failed
 */
static int
command_register_callbacks(struct command_saved *cs)
{
	struct attr prev;	/* The parent of the next object which will be retrieved. */
	struct attr cb_attr;
	int status;
	struct object_func *func;
	struct callback *cb;
	int tmpoffset;	/* For debugging. Because we work with pointers into the same string instance.
					 * we can figure out offsets by using simple pointer arithmetics.
					 */
	
	dbg(lvl_debug, "enter: cs=%p, cs->async=%d, cs->command=%s\n", cs, cs->async, cs->command);
	cs->ctx.expr = cs->command;
	prev = cs->context_attr;

	while ((status = get_next_object(&cs->ctx, &cs->res)) != 0) {
		tmpoffset = cs->res.var - cs->command;
		cs->ctx.attr = &prev;
		resolve(&cs->ctx, &cs->res);

		if (cs->ctx.error) {
			/* An error occurred while parsing the command */
			tmpoffset = cs->ctx.expr - cs->command;
			dbg(lvl_error, "parsing error: cs=%p, cs->ctx.error=%d\n\t%s\n\t%*s\n", cs, cs->ctx.error, cs->command, tmpoffset + 1, "^");
			return 0;
		} else if (cs->res.attr.type == attr_none) {
			/* We could not resolve an object, perhaps because it has not been created */
			dbg(lvl_error, "could not resolve object in cs=%p:\n\t%s\n\t%*s\n", cs, cs->command, tmpoffset + 1, "^");
			return 0;
		}

		if (prev.type != attr_none) {
			func = object_func_lookup(prev.type);

			if (func->add_attr) {
				if (status == 2) { // This is not the final attribute name
					cb = callback_new_attr_1(callback_cast(command_saved_callbacks_changed), cs->res.attr.type, (void*)cs);
				} else if (status == 1) { // This is the final attribute name
					cb = callback_new_attr_1(callback_cast(command_saved_evaluate), cs->res.attr.type, (void*)cs);
					cs->ctx.attr = &cs->context_attr;
				} else {
					dbg(lvl_error, "Error: Strange status returned from get_next_object()\n");
				}

				cs->num_cbs++;
				cs->cbs = g_realloc(cs->cbs, (sizeof(struct command_saved_cb) * cs->num_cbs));
				cs->cbs[cs->num_cbs-1].cb = cb;
				cs->cbs[cs->num_cbs-1].attr = prev;
					
				cb_attr.u.callback = cb;
				cb_attr.type = attr_callback;

				func->add_attr(prev.u.data, &cb_attr);

			} else {
				dbg(lvl_error, "Could not add callback because add_attr is missing for type %i\n", prev.type);
			}
		}

		if (status == 2) {
			prev = cs->res.attr;
		} else {
			prev = cs->context_attr;
		}
	}

	command_saved_evaluate_idle(cs);

	dbg(lvl_debug, "done: cs=%p, cs->command=%s\n", cs, cs->command);
	return 1;
}

/**
 * @brief Creates a new saved command.
 *
 * @param command The command string
 * @param attr The context attribute for the saved command
 * @param cb The callback to call whenver the command is re-evaluated
 * @param async Whether the saved command should be flagged as asynchronous, causing it to be evaluated
 * in an idle callback
 */
struct command_saved *
command_saved_attr_new(char *command, struct attr *attr, struct callback *cb, int async)
{
	struct command_saved *ret;

	ret = g_new0(struct command_saved, 1);
	dbg(lvl_debug, "enter, ret=%p, command=%s\n", ret, command);
	ret->command = g_strdup(command);
	ret->context_attr = *attr;
	ret->cb = cb;
	ret->error = not_ready;
	ret->async = async;

	if (!command_register_callbacks(ret)) {
		// We try this as an idle call again
		dbg(lvl_debug, "could not register callbacks, will retry as an idle call\n");
		ret->register_cb = callback_new_1(callback_cast(command_saved_callbacks_changed), ret);
		ret->register_ev = event_add_idle(300, ret->register_cb);
	}		

	return ret;
}

struct command_saved *
command_saved_new(char *command, struct navit *navit, struct callback *cb, int async)
{
	struct attr attr=ATTR_OBJECT(navit, navit);
	return command_saved_attr_new(command, &attr, cb, async);
}

void 
command_saved_destroy(struct command_saved *cs)
{
	g_free(cs->command);
	g_free(cs);
}