php-src/Zend/zend_generators.c

/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) 1998-2013 Zend Technologies Ltd. (http://www.zend.com) |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: Nikita Popov <nikic@php.net>                                |
   +----------------------------------------------------------------------+
*/

/* $Id$ */

#include "zend.h"
#include "zend_API.h"
#include "zend_interfaces.h"
#include "zend_exceptions.h"
#include "zend_generators.h"

ZEND_API zend_class_entry *zend_ce_generator;
static zend_object_handlers zend_generator_handlers;

static zend_object_value zend_generator_create(zend_class_entry *class_type TSRMLS_DC);

ZEND_API void zend_generator_close(zend_generator *generator, zend_bool finished_execution TSRMLS_DC) /* {{{ */
{
	if (generator->value) {
		zval_ptr_dtor(&generator->value);
		generator->value = NULL;
	}

	if (generator->key) {
		zval_ptr_dtor(&generator->key);
		generator->key = NULL;
	}

	if (generator->execute_data) {
		zend_execute_data *execute_data = generator->execute_data;
		zend_op_array *op_array = execute_data->op_array;

		if (!execute_data->symbol_table) {
			zend_free_compiled_variables(execute_data);
		} else {
			zend_clean_and_cache_symbol_table(execute_data->symbol_table TSRMLS_CC);
		}

		if (execute_data->current_this) {
			zval_ptr_dtor(&execute_data->current_this);
		}

		/* A fatal error / die occurred during the generator execution. Trying to clean
		 * up the stack may not be safe in this case. */
		if (CG(unclean_shutdown)) {
			return;
		}

		/* If the generator is closed before it can finish execution (reach
		 * a return statement) we have to free loop variables manually, as
		 * we don't know whether the SWITCH_FREE / FREE opcodes have run */
		if (!finished_execution) {
			/* -1 required because we want the last run opcode, not the
			 * next to-be-run one. */
			zend_uint op_num = execute_data->opline - op_array->opcodes - 1;

			int i;
			for (i = 0; i < op_array->last_brk_cont; ++i) {
				zend_brk_cont_element *brk_cont = op_array->brk_cont_array + i;

				if (brk_cont->start < 0) {
					continue;
				} else if (brk_cont->start > op_num) {
					break;
				} else if (brk_cont->brk > op_num) {
					zend_op *brk_opline = op_array->opcodes + brk_cont->brk;

					switch (brk_opline->opcode) {
						case ZEND_SWITCH_FREE:
							{
								temp_variable *var = EX_TMP_VAR(execute_data, brk_opline->op1.var);
								zval_ptr_dtor(&var->var.ptr);
							}
							break;
						case ZEND_FREE:
							{
								temp_variable *var = EX_TMP_VAR(execute_data, brk_opline->op1.var);
								zval_dtor(&var->tmp_var);
							}
							break;
					}
				}
			}
		}

		/* Clear any backed up stack arguments */
		if (generator->stack != EG(argument_stack)) {
			void **ptr = generator->stack->top - 1;
			void **end = zend_vm_stack_frame_base(execute_data);

			/* If the top stack element is the argument count, skip it */
			if (execute_data->function_state.arguments) {
				ptr--;
			}

			for (; ptr >= end; --ptr) {
				zval_ptr_dtor((zval**) ptr);
			}
		}

		while (execute_data->call >= execute_data->call_slots) {
			if (execute_data->call->object) {
				zval_ptr_dtor(&execute_data->call->object);
			}
			execute_data->call--;
		}

		/* We have added an additional stack frame in prev_execute_data, so we
		 * have to free it. It also contains the arguments passed to the
		 * generator (for func_get_args) so those have to be freed too. */
		{
			zend_execute_data *prev_execute_data = execute_data->prev_execute_data;
			void **arguments = prev_execute_data->function_state.arguments;

			if (arguments) {
				int arguments_count = (int) (zend_uintptr_t) *arguments;
				zval **arguments_start = (zval **) (arguments - arguments_count);
				int i;

				for (i = 0; i < arguments_count; ++i) {
					zval_ptr_dtor(arguments_start + i);
				}
			}
		}

		/* Free a clone of closure */
		if (op_array->fn_flags & ZEND_ACC_CLOSURE) {
			destroy_op_array(op_array TSRMLS_CC);
			efree(op_array);
		}

		efree(generator->stack);
		if (generator->stack == EG(argument_stack)) {
			/* abnormal exit for running generator */
			EG(argument_stack) = NULL;
		}
		generator->execute_data = NULL;
	}
}
/* }}} */

static void zend_generator_dtor_storage(zend_generator *generator, zend_object_handle handle TSRMLS_DC) /* {{{ */
{
	zend_execute_data *ex = generator->execute_data;
	zend_uint op_num, finally_op_num;
	int i;

	if (!ex || !ex->op_array->has_finally_block) {
		return;
	}

	/* -1 required because we want the last run opcode, not the
	 * next to-be-run one. */
	op_num = ex->opline - ex->op_array->opcodes - 1;

	/* Find next finally block */
	finally_op_num = 0;
	for (i = 0; i < ex->op_array->last_try_catch; i++) {
		zend_try_catch_element *try_catch = &ex->op_array->try_catch_array[i];

		if (op_num < try_catch->try_op) {
			break;
		}

		if (op_num < try_catch->finally_op) {
			finally_op_num = try_catch->finally_op;
		}
	}

	/* If a finally block was found we jump directly to it and
	 * resume the generator. */
	if (finally_op_num) {
		ex->opline = &ex->op_array->opcodes[finally_op_num];
		ex->fast_ret = NULL;
		generator->flags |= ZEND_GENERATOR_FORCED_CLOSE;
		zend_generator_resume(generator TSRMLS_CC);
	}
}
/* }}} */

static void zend_generator_free_storage(zend_generator *generator TSRMLS_DC) /* {{{ */
{
	zend_generator_close(generator, 0 TSRMLS_CC);

	zend_object_std_dtor(&generator->std TSRMLS_CC);
	efree(generator);
}
/* }}} */

static zend_object_value zend_generator_create(zend_class_entry *class_type TSRMLS_DC) /* {{{ */
{
	zend_generator *generator;
	zend_object_value object;

	generator = emalloc(sizeof(zend_generator));
	memset(generator, 0, sizeof(zend_generator));

	/* The key will be incremented on first use, so it'll start at 0 */
	generator->largest_used_integer_key = -1;

	zend_object_std_init(&generator->std, class_type TSRMLS_CC);

	object.handle = zend_objects_store_put(generator,
		(zend_objects_store_dtor_t)          zend_generator_dtor_storage,
		(zend_objects_free_object_storage_t) zend_generator_free_storage,
		NULL TSRMLS_CC
	);
	object.handlers = &zend_generator_handlers;

	return object;
}
/* }}} */

/* Requires globals EG(scope), EG(current_scope), EG(This),
 * EG(active_symbol_table) and EG(current_execute_data). */
ZEND_API zval *zend_generator_create_zval(zend_op_array *op_array TSRMLS_DC) /* {{{ */
{
	zval *return_value;
	zend_generator *generator;
	zend_execute_data *current_execute_data;
	zend_op **opline_ptr;
	HashTable *current_symbol_table;
	zend_execute_data *execute_data;
	zend_vm_stack current_stack = EG(argument_stack);

	/* Create a clone of closure, because it may be destroyed */
	if (op_array->fn_flags & ZEND_ACC_CLOSURE) {
		zend_op_array *op_array_copy = (zend_op_array*)emalloc(sizeof(zend_op_array));
		*op_array_copy = *op_array;
		function_add_ref((zend_function *) op_array_copy);
		op_array = op_array_copy;
	}
	
	/* Create new execution context. We have to back up and restore
	 * EG(current_execute_data), EG(opline_ptr) and EG(active_symbol_table)
	 * here because the function modifies or uses them  */
	current_execute_data = EG(current_execute_data);
	opline_ptr = EG(opline_ptr);
	current_symbol_table = EG(active_symbol_table);
	EG(active_symbol_table) = NULL;
	execute_data = zend_create_execute_data_from_op_array(op_array, 0 TSRMLS_CC);
	EG(active_symbol_table) = current_symbol_table;
	EG(current_execute_data) = current_execute_data;
	EG(opline_ptr) = opline_ptr;

	ALLOC_INIT_ZVAL(return_value);
	object_init_ex(return_value, zend_ce_generator);

	if (EG(This)) {
		Z_ADDREF_P(EG(This));
	}

	/* Back up executor globals. */
	execute_data->current_scope = EG(scope);
	execute_data->current_called_scope = EG(called_scope);
	execute_data->symbol_table = EG(active_symbol_table);
	execute_data->current_this = EG(This);

	/* Save execution context in generator object. */
	generator = (zend_generator *) zend_object_store_get_object(return_value TSRMLS_CC);
	generator->execute_data = execute_data;
	generator->stack = EG(argument_stack);
	EG(argument_stack) = current_stack;

	return return_value;
}
/* }}} */

static zend_function *zend_generator_get_constructor(zval *object TSRMLS_DC) /* {{{ */
{
	zend_error(E_RECOVERABLE_ERROR, "The \"Generator\" class is reserved for internal use and cannot be manually instantiated");

	return NULL;
}
/* }}} */

ZEND_API void zend_generator_resume(zend_generator *generator TSRMLS_DC) /* {{{ */
{
	/* The generator is already closed, thus can't resume */
	if (!generator->execute_data) {
		return;
	}

	if (generator->flags & ZEND_GENERATOR_CURRENTLY_RUNNING) {
		zend_error(E_ERROR, "Cannot resume an already running generator");
	}

	/* Drop the AT_FIRST_YIELD flag */
	generator->flags &= ~ZEND_GENERATOR_AT_FIRST_YIELD;

	{
		/* Backup executor globals */
		zval **original_return_value_ptr_ptr = EG(return_value_ptr_ptr);
		zend_execute_data *original_execute_data = EG(current_execute_data);
		zend_op **original_opline_ptr = EG(opline_ptr);
		zend_op_array *original_active_op_array = EG(active_op_array);
		HashTable *original_active_symbol_table = EG(active_symbol_table);
		zval *original_This = EG(This);
		zend_class_entry *original_scope = EG(scope);
		zend_class_entry *original_called_scope = EG(called_scope);
		zend_vm_stack original_stack = EG(argument_stack);

		/* We (mis)use the return_value_ptr_ptr to provide the generator object
		 * to the executor, so YIELD will be able to set the yielded value */
		EG(return_value_ptr_ptr) = (zval **) generator;

		/* Set executor globals */
		EG(current_execute_data) = generator->execute_data;
		EG(opline_ptr) = &generator->execute_data->opline;
		EG(active_op_array) = generator->execute_data->op_array;
		EG(active_symbol_table) = generator->execute_data->symbol_table;
		EG(This) = generator->execute_data->current_this;
		EG(scope) = generator->execute_data->current_scope;
		EG(called_scope) = generator->execute_data->current_called_scope;
		EG(argument_stack) = generator->stack;

		/* We want the backtrace to look as if the generator function was
		 * called from whatever method we are current running (e.g. next()).
		 * The first prev_execute_data contains an additional stack frame,
		 * which makes the generator function show up in the backtrace and
		 * makes the arguments available to func_get_args(). So we have to
		 * set the prev_execute_data of that prev_execute_data :) */
		generator->execute_data->prev_execute_data->prev_execute_data = original_execute_data;

		/* Resume execution */
		generator->flags |= ZEND_GENERATOR_CURRENTLY_RUNNING;
		zend_execute_ex(generator->execute_data TSRMLS_CC);
		generator->flags &= ~ZEND_GENERATOR_CURRENTLY_RUNNING;

		/* Restore executor globals */
		EG(return_value_ptr_ptr) = original_return_value_ptr_ptr;
		EG(current_execute_data) = original_execute_data;
		EG(opline_ptr) = original_opline_ptr;
		EG(active_op_array) = original_active_op_array;
		EG(active_symbol_table) = original_active_symbol_table;
		EG(This) = original_This;
		EG(scope) = original_scope;
		EG(called_scope) = original_called_scope;
		EG(argument_stack) = original_stack;

		/* If an exception was thrown in the generator we have to internally
		 * rethrow it in the parent scope. */
		if (UNEXPECTED(EG(exception) != NULL)) {
			zend_throw_exception_internal(NULL TSRMLS_CC);
		}
	}
}
/* }}} */

static void zend_generator_ensure_initialized(zend_generator *generator TSRMLS_DC) /* {{{ */
{
	if (generator->execute_data && !generator->value) {
		zend_generator_resume(generator TSRMLS_CC);
		generator->flags |= ZEND_GENERATOR_AT_FIRST_YIELD;
	}
}
/* }}} */

static void zend_generator_rewind(zend_generator *generator TSRMLS_DC) /* {{{ */
{
	zend_generator_ensure_initialized(generator TSRMLS_CC);

	if (!(generator->flags & ZEND_GENERATOR_AT_FIRST_YIELD)) {
		zend_throw_exception(NULL, "Cannot rewind a generator that was already run", 0 TSRMLS_CC);
	}
}
/* }}} */

/* {{{ proto void Generator::rewind()
 * Rewind the generator */
ZEND_METHOD(Generator, rewind)
{
	zend_generator *generator;

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	zend_generator_rewind(generator TSRMLS_CC);
}
/* }}} */

/* {{{ proto bool Generator::valid()
 * Check whether the generator is valid */
ZEND_METHOD(Generator, valid)
{
	zend_generator *generator;

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	RETURN_BOOL(generator->value != NULL);
}
/* }}} */

/* {{{ proto mixed Generator::current()
 * Get the current value */
ZEND_METHOD(Generator, current)
{
	zend_generator *generator;

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	if (generator->value) {
		RETURN_ZVAL_FAST(generator->value);
	}
}
/* }}} */

/* {{{ proto mixed Generator::key()
 * Get the current key */
ZEND_METHOD(Generator, key)
{
	zend_generator *generator;

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	if (generator->key) {
		RETURN_ZVAL_FAST(generator->key);
	}
}
/* }}} */

/* {{{ proto void Generator::next()
 * Advances the generator */
ZEND_METHOD(Generator, next)
{
	zend_generator *generator;

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	zend_generator_resume(generator TSRMLS_CC);
}
/* }}} */

/* {{{ proto mixed Generator::send(mixed $value)
 * Sends a value to the generator */
ZEND_METHOD(Generator, send)
{
	zval *value;
	zend_generator *generator;

	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &value) == FAILURE) {
		return;
	}

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	zend_generator_ensure_initialized(generator TSRMLS_CC); 

	/* The generator is already closed, thus can't send anything */
	if (!generator->execute_data) {
		return;
	}

	/* Put sent value into the TMP_VAR slot */
	MAKE_COPY_ZVAL(&value, &generator->send_target->tmp_var);

	zend_generator_resume(generator TSRMLS_CC);

	if (generator->value) {
		RETURN_ZVAL_FAST(generator->value);
	}
}
/* }}} */

/* {{{ proto mixed Generator::throw(Exception $exception)
 * Throws an exception into the generator */
ZEND_METHOD(Generator, throw)
{
	zval *exception, *exception_copy;
	zend_generator *generator;

	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &exception) == FAILURE) {
		return;
	}

	ALLOC_ZVAL(exception_copy);
	MAKE_COPY_ZVAL(&exception, exception_copy);

	generator = (zend_generator *) zend_object_store_get_object(getThis() TSRMLS_CC);

	if (generator->execute_data) {
		/* Throw the exception in the context of the generator */
		zend_execute_data *current_execute_data = EG(current_execute_data);
		EG(current_execute_data) = generator->execute_data;

		zend_throw_exception_object(exception_copy TSRMLS_CC);

		EG(current_execute_data) = current_execute_data;

		zend_generator_resume(generator TSRMLS_CC);

		if (generator->value) {
			RETURN_ZVAL_FAST(generator->value);
		}
	} else {
		/* If the generator is already closed throw the exception in the
		 * current context */
		zend_throw_exception_object(exception_copy TSRMLS_CC);
	}
}
/* }}} */

/* {{{ proto void Generator::__wakeup()
 * Throws an Exception as generators can't be serialized */
ZEND_METHOD(Generator, __wakeup)
{
	/* Just specifying the zend_class_unserialize_deny handler is not enough,
	 * because it is only invoked for C unserialization. For O the error has
	 * to be thrown in __wakeup. */

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	zend_throw_exception(NULL, "Unserialization of 'Generator' is not allowed", 0 TSRMLS_CC);
}
/* }}} */

/* get_iterator implementation */

static void zend_generator_iterator_dtor(zend_object_iterator *iterator TSRMLS_DC) /* {{{ */
{
	zval *object = ((zend_generator_iterator *) iterator)->object;

	zval_ptr_dtor(&object);
}
/* }}} */

static int zend_generator_iterator_valid(zend_object_iterator *iterator TSRMLS_DC) /* {{{ */
{
	zend_generator *generator = (zend_generator *) iterator->data;

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	return generator->value != NULL ? SUCCESS : FAILURE;
}
/* }}} */

static void zend_generator_iterator_get_data(zend_object_iterator *iterator, zval ***data TSRMLS_DC) /* {{{ */
{
	zend_generator *generator = (zend_generator *) iterator->data;

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	if (generator->value) {
		*data = &generator->value;
	} else {
		*data = NULL;
	}
}
/* }}} */

static void zend_generator_iterator_get_key(zend_object_iterator *iterator, zval *key TSRMLS_DC) /* {{{ */
{
	zend_generator *generator = (zend_generator *) iterator->data;

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	if (generator->key) {
		ZVAL_ZVAL(key, generator->key, 1, 0);
	} else {
		ZVAL_NULL(key);
	}
}
/* }}} */

static void zend_generator_iterator_move_forward(zend_object_iterator *iterator TSRMLS_DC) /* {{{ */
{
	zend_generator *generator = (zend_generator *) iterator->data;

	zend_generator_ensure_initialized(generator TSRMLS_CC);

	zend_generator_resume(generator TSRMLS_CC);
}
/* }}} */

static void zend_generator_iterator_rewind(zend_object_iterator *iterator TSRMLS_DC) /* {{{ */
{
	zend_generator *generator = (zend_generator *) iterator->data;

	zend_generator_rewind(generator TSRMLS_CC);
}
/* }}} */

static zend_object_iterator_funcs zend_generator_iterator_functions = {
	zend_generator_iterator_dtor,
	zend_generator_iterator_valid,
	zend_generator_iterator_get_data,
	zend_generator_iterator_get_key,
	zend_generator_iterator_move_forward,
	zend_generator_iterator_rewind
};

zend_object_iterator *zend_generator_get_iterator(zend_class_entry *ce, zval *object, int by_ref TSRMLS_DC) /* {{{ */
{
	zend_generator_iterator *iterator;
	zend_generator *generator;

	generator = (zend_generator *) zend_object_store_get_object(object TSRMLS_CC);

	if (!generator->execute_data) {
		zend_throw_exception(NULL, "Cannot traverse an already closed generator", 0 TSRMLS_CC);
		return NULL;
	}

	if (by_ref && !(generator->execute_data->op_array->fn_flags & ZEND_ACC_RETURN_REFERENCE)) {
		zend_throw_exception(NULL, "You can only iterate a generator by-reference if it declared that it yields by-reference", 0 TSRMLS_CC);
		return NULL;
	}

	iterator = &generator->iterator;
	iterator->intern.funcs = &zend_generator_iterator_functions;
	iterator->intern.data = (void *) generator;

	/* We have to keep a reference to the generator object zval around,
	 * otherwise the generator may be destroyed during iteration. */
	Z_ADDREF_P(object);
	iterator->object = object;

	return (zend_object_iterator *) iterator;
}
/* }}} */

ZEND_BEGIN_ARG_INFO(arginfo_generator_void, 0)
ZEND_END_ARG_INFO()

ZEND_BEGIN_ARG_INFO_EX(arginfo_generator_send, 0, 0, 1)
	ZEND_ARG_INFO(0, value)
ZEND_END_ARG_INFO()

ZEND_BEGIN_ARG_INFO_EX(arginfo_generator_throw, 0, 0, 1)
	ZEND_ARG_INFO(0, exception)
ZEND_END_ARG_INFO()

static const zend_function_entry generator_functions[] = {
	ZEND_ME(Generator, rewind,   arginfo_generator_void, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, valid,    arginfo_generator_void, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, current,  arginfo_generator_void, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, key,      arginfo_generator_void, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, next,     arginfo_generator_void, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, send,     arginfo_generator_send, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, throw,    arginfo_generator_throw, ZEND_ACC_PUBLIC)
	ZEND_ME(Generator, __wakeup, arginfo_generator_void, ZEND_ACC_PUBLIC)
	ZEND_FE_END
};

void zend_register_generator_ce(TSRMLS_D) /* {{{ */
{
	zend_class_entry ce;

	INIT_CLASS_ENTRY(ce, "Generator", generator_functions);
	zend_ce_generator = zend_register_internal_class(&ce TSRMLS_CC);
	zend_ce_generator->ce_flags |= ZEND_ACC_FINAL_CLASS;
	zend_ce_generator->create_object = zend_generator_create;
	zend_ce_generator->serialize = zend_class_serialize_deny;
	zend_ce_generator->unserialize = zend_class_unserialize_deny;

	/* get_iterator has to be assigned *after* implementing the inferface */
	zend_class_implements(zend_ce_generator TSRMLS_CC, 1, zend_ce_iterator);
	zend_ce_generator->get_iterator = zend_generator_get_iterator;
	zend_ce_generator->iterator_funcs.funcs = &zend_generator_iterator_functions;

	memcpy(&zend_generator_handlers, zend_get_std_object_handlers(), sizeof(zend_object_handlers));
	zend_generator_handlers.get_constructor = zend_generator_get_constructor;
	zend_generator_handlers.clone_obj = NULL;
}
/* }}} */

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 */