PHP7 create symbol table

[Jurigag]

Is there any reason why create_symbol_table function is not implementend in ZendEngine3? Like all code there is just commented. For example zephir just uses wrong symbol table for example in this issue - phalcon/cphalcon#12648 on php5 just create_symbol_table() before setting variables is enough but what about php7?

[sjinks]

As far as I can tell, symbol tables in ZE3 are linked to the execution context, and it is not trivial to replace the existing symbol table with a newly created one.

What I suggest is: because new symbol tables are used mostly to create an isolated scope for require and company, we add a new argument to zephir_require family:

int zephir_require_ret(zval *return_value_ptr, const char *require_path, zval * symbol_table) ZEPHIR_ATTR_NONNULL1(2);

symbol_table is supposed to be an array or NULL; if it is an array, it is used as a symbol table for the require'd file.

The issue is that this would introduce a change to Zephir syntax:

require path, symtable

or, as an alternative, we can create an optimizer for a function (say, require_with_symtable($file, $symtable = NULL)).

What do you guys think?

[sergeyklay]

I like the second option for now

[Jurigag]

What does this mean? We would need to create some weird empty array or pass view params with this require?

[sjinks]

$symtable = ['var1' => 1, 'var2' => true, /* ... */];
require_with_symtable('somefile.php', $symtable);
// somefile.php sees only variables passed in the $symtable as local ones

[Jurigag]

Oh okay i understand. But then what with calling $this->xyz in such file if it's required in some class? Will this still work?

[sjinks]

Good question. No idea until I test

[dreamsxin]

Set the scope, like op_array->scope = Z_OBJCE_P(object);

[steffengy]

just FYI:
There is no reason this was not implemented (except being not important enough for the initial port).
And yes it's technically possible (and not really different to how it's done for ZE2).

[sjinks]

static zend_array* add_symtable(zend_execute_data* ex)
{
    zend_array* old_table;
    zend_array* symbol_table = (zend_array*)emalloc(sizeof(zend_array));
    zend_hash_init(symbol_table, 0, NULL, ZVAL_PTR_DTOR, 0);
    zend_hash_real_init(symbol_table, 0);

    zend_rebuild_symbol_table();
    zend_detach_symbol_table(ex);
    old_table = ex->symbol_table;
    ex->symbol_table = symbol_table;

    return old_table;
}

static void restore_symtable(zend_execute_data* ex, zend_array* tbl)
{
    zend_hash_destroy(ex->symbol_table);
    efree(ex->symbol_table);
    ex->symbol_table = tbl;
    zend_attach_symbol_table(ex);
    zend_rebuild_symbol_table();
}

If add_symtable and del_symtable are implemented as Zend functions, they will need to use ex->prev_execute_data instead of ex.

[sjinks]

OK, let us move to #1488 to discuss this further.