py/runtime: Allow multiple *args in a function call.
This is a partial implementation of PEP 448 to allow unpacking multiple star args in a function or method call. This is implemented by changing the emitted bytecodes so that both positional args and star args are stored as positional args. A bitmap is added to indicate if an argument at a given position is a positional argument or a star arg. In the generated code, this new bitmap takes the place of the old star arg. It is stored as a small int, so this means only the first N arguments can be star args where N is the number of bits in a small int. The runtime is modified to interpret this new bytecode format while still trying to perform as few memory reallocations as possible. Signed-off-by: David Lechner <david@pybricks.com>
This commit is contained in:
parent
1e99d29f36
commit
783b1a868f
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@ -8,7 +8,7 @@ Below is a list of finalised/accepted PEPs for Python 3.5 grouped into their imp
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+----------------------------------------------------------------------------------------------------------+---------------+
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| **Extensions to the syntax:** | **Status** |
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+--------------------------------------------------------+-------------------------------------------------+---------------+
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| `PEP 448 <https://www.python.org/dev/peps/pep-0448/>`_ | additional unpacking generalizations | |
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| `PEP 448 <https://www.python.org/dev/peps/pep-0448/>`_ | additional unpacking generalizations | Partial |
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+--------------------------------------------------------+-------------------------------------------------+---------------+
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| `PEP 465 <https://www.python.org/dev/peps/pep-0465/>`_ | a new matrix multiplication operator | Completed |
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+--------------------------------------------------------+-------------------------------------------------+---------------+
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37
py/compile.c
37
py/compile.c
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@ -37,6 +37,7 @@
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#include "py/asmbase.h"
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#include "py/nativeglue.h"
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#include "py/persistentcode.h"
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#include "py/smallint.h"
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#if MICROPY_ENABLE_COMPILER
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@ -2397,17 +2398,30 @@ STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_ar
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int n_positional = n_positional_extra;
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uint n_keyword = 0;
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uint star_flags = 0;
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mp_parse_node_struct_t *star_args_node = NULL;
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mp_uint_t star_args = 0;
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for (size_t i = 0; i < n_args; i++) {
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if (MP_PARSE_NODE_IS_STRUCT(args[i])) {
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mp_parse_node_struct_t *pns_arg = (mp_parse_node_struct_t *)args[i];
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if (MP_PARSE_NODE_STRUCT_KIND(pns_arg) == PN_arglist_star) {
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if (star_flags & MP_EMIT_STAR_FLAG_SINGLE) {
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compile_syntax_error(comp, (mp_parse_node_t)pns_arg, MP_ERROR_TEXT("can't have multiple *x"));
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if (star_flags & MP_EMIT_STAR_FLAG_DOUBLE) {
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compile_syntax_error(comp, (mp_parse_node_t)pns_arg, MP_ERROR_TEXT("* arg after **"));
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return;
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}
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#if MICROPY_DYNAMIC_COMPILER
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if (i > mp_dynamic_compiler.small_int_bits)
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#else
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if (i > MP_SMALL_INT_BITS)
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#endif
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{
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// If there are not enough bits in a small int to fit the flag, then we consider
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// it a syntax error. It should be unlikely to have this many args in practice.
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compile_syntax_error(comp, (mp_parse_node_t)pns_arg, MP_ERROR_TEXT("too many args"));
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return;
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}
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star_flags |= MP_EMIT_STAR_FLAG_SINGLE;
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star_args_node = pns_arg;
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star_args |= 1 << i;
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compile_node(comp, pns_arg->nodes[0]);
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n_positional++;
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} else if (MP_PARSE_NODE_STRUCT_KIND(pns_arg) == PN_arglist_dbl_star) {
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star_flags |= MP_EMIT_STAR_FLAG_DOUBLE;
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// double-star args are stored as kw arg with key of None
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@ -2438,12 +2452,12 @@ STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_ar
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}
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} else {
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normal_argument:
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if (star_flags) {
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compile_syntax_error(comp, args[i], MP_ERROR_TEXT("non-keyword arg after */**"));
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if (star_flags & MP_EMIT_STAR_FLAG_DOUBLE) {
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compile_syntax_error(comp, args[i], MP_ERROR_TEXT("positional arg after **"));
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return;
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}
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if (n_keyword > 0) {
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compile_syntax_error(comp, args[i], MP_ERROR_TEXT("non-keyword arg after keyword arg"));
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compile_syntax_error(comp, args[i], MP_ERROR_TEXT("positional arg after keyword arg"));
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return;
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}
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compile_node(comp, args[i]);
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@ -2451,14 +2465,9 @@ STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_ar
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}
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}
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// compile the star/double-star arguments if we had them
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// if we had one but not the other then we load "null" as a place holder
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if (star_flags != 0) {
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if (star_args_node == NULL) {
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EMIT(load_null);
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} else {
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compile_node(comp, star_args_node->nodes[0]);
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}
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// one extra object that contains the star_args map
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EMIT_ARG(load_const_small_int, star_args);
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}
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// emit the function/method call
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91
py/runtime.c
91
py/runtime.c
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@ -701,9 +701,9 @@ void mp_call_prepare_args_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_
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}
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uint n_args = n_args_n_kw & 0xff;
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uint n_kw = (n_args_n_kw >> 8) & 0xff;
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mp_obj_t pos_seq = args[n_args + 2 * n_kw]; // may be MP_OBJ_NULL
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mp_uint_t star_args = mp_obj_get_int_truncated(args[n_args + 2 * n_kw]);
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DEBUG_OP_printf("call method var (fun=%p, self=%p, n_args=%u, n_kw=%u, args=%p, seq=%p)\n", fun, self, n_args, n_kw, args, pos_seq);
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DEBUG_OP_printf("call method var (fun=%p, self=%p, n_args=%u, n_kw=%u, args=%p, map=%u)\n", fun, self, n_args, n_kw, args, star_args);
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// We need to create the following array of objects:
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// args[0 .. n_args] unpacked(pos_seq) args[n_args .. n_args + 2 * n_kw] unpacked(kw_dict)
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@ -714,6 +714,20 @@ void mp_call_prepare_args_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_
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uint args2_alloc;
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uint args2_len = 0;
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// Try to get a hint for unpacked * args length
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uint list_len = 0;
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if (star_args != 0) {
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for (uint i = 0; i < n_args; i++) {
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if (star_args & (1 << i)) {
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mp_obj_t len = mp_obj_len_maybe(args[i]);
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if (len != MP_OBJ_NULL) {
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list_len += mp_obj_get_int(len);
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}
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}
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}
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}
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// Try to get a hint for the size of the kw_dict
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uint kw_dict_len = 0;
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@ -727,8 +741,8 @@ void mp_call_prepare_args_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_
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// Extract the pos_seq sequence to the new args array.
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// Note that it can be arbitrary iterator.
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if (pos_seq == MP_OBJ_NULL) {
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// no sequence
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if (star_args == 0) {
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// no star args to unpack
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// allocate memory for the new array of args
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args2_alloc = 1 + n_args + 2 * (n_kw + kw_dict_len);
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// copy the fixed pos args
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mp_seq_copy(args2 + args2_len, args, n_args, mp_obj_t);
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args2_len += n_args;
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} else {
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// at least one star arg to unpack
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} else if (mp_obj_is_type(pos_seq, &mp_type_tuple) || mp_obj_is_type(pos_seq, &mp_type_list)) {
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// allocate memory for the new array of args
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args2_alloc = 1 + n_args + list_len + 2 * (n_kw + kw_dict_len);
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args2 = mp_nonlocal_alloc(args2_alloc * sizeof(mp_obj_t));
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// copy the self
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if (self != MP_OBJ_NULL) {
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args2[args2_len++] = self;
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}
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for (uint i = 0; i < n_args; i++) {
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mp_obj_t arg = args[i];
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if (star_args & (1 << i)) {
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// star arg
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if (mp_obj_is_type(arg, &mp_type_tuple) || mp_obj_is_type(arg, &mp_type_list)) {
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// optimise the case of a tuple and list
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// get the items
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size_t len;
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mp_obj_t *items;
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mp_obj_get_array(pos_seq, &len, &items);
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// allocate memory for the new array of args
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args2_alloc = 1 + n_args + len + 2 * (n_kw + kw_dict_len);
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args2 = mp_nonlocal_alloc(args2_alloc * sizeof(mp_obj_t));
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// copy the self
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if (self != MP_OBJ_NULL) {
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args2[args2_len++] = self;
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}
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// copy the fixed and variable position args
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mp_seq_cat(args2 + args2_len, args, n_args, items, len, mp_obj_t);
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args2_len += n_args + len;
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mp_obj_get_array(arg, &len, &items);
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// copy the items
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assert(args2_len + len <= args2_alloc);
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mp_seq_copy(args2 + args2_len, items, len, mp_obj_t);
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args2_len += len;
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} else {
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// generic iterator
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// allocate memory for the new array of args
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args2_alloc = 1 + n_args + 2 * (n_kw + kw_dict_len) + 3;
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args2 = mp_nonlocal_alloc(args2_alloc * sizeof(mp_obj_t));
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// copy the self
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if (self != MP_OBJ_NULL) {
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args2[args2_len++] = self;
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}
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// copy the fixed position args
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mp_seq_copy(args2 + args2_len, args, n_args, mp_obj_t);
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args2_len += n_args;
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// extract the variable position args from the iterator
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mp_obj_iter_buf_t iter_buf;
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mp_obj_t iterable = mp_getiter(pos_seq, &iter_buf);
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mp_obj_t iterable = mp_getiter(arg, &iter_buf);
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mp_obj_t item;
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while ((item = mp_iternext(iterable)) != MP_OBJ_STOP_ITERATION) {
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if (args2_len >= args2_alloc) {
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args2 = mp_nonlocal_realloc(args2, args2_alloc * sizeof(mp_obj_t), args2_alloc * 2 * sizeof(mp_obj_t));
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args2 = mp_nonlocal_realloc(args2, args2_alloc * sizeof(mp_obj_t),
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args2_alloc * 2 * sizeof(mp_obj_t));
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args2_alloc *= 2;
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}
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args2[args2_len++] = item;
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}
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}
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} else {
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// normal argument
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assert(args2_len < args2_alloc);
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args2[args2_len++] = arg;
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}
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}
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}
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// The size of the args2 array now is the number of positional args.
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uint pos_args_len = args2_len;
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// ensure there is still enough room for kw args
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if (args2_len + 2 * (n_kw + kw_dict_len) > args2_alloc) {
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uint new_alloc = args2_len + 2 * (n_kw + kw_dict_len);
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args2 = mp_nonlocal_realloc(args2, args2_alloc * sizeof(mp_obj_t),
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new_alloc * sizeof(mp_obj_t));
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args2_alloc = new_alloc;
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}
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// Copy the kw args.
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for (uint i = 0; i < n_kw; i++) {
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mp_obj_t kw_key = args[n_args + i * 2];
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4
py/vm.c
4
py/vm.c
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@ -949,7 +949,7 @@ unwind_jump:;
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// unum & 0xff == n_positional
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// (unum >> 8) & 0xff == n_keyword
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// We have following stack layout here:
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// fun arg0 arg1 ... kw0 val0 kw1 val1 ... seq <- TOS
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// fun arg0 arg1 ... kw0 val0 kw1 val1 ... bitmap <- TOS
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sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe) + 1;
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#if MICROPY_STACKLESS
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if (mp_obj_get_type(*sp) == &mp_type_fun_bc) {
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// unum & 0xff == n_positional
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// (unum >> 8) & 0xff == n_keyword
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// We have following stack layout here:
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// fun self arg0 arg1 ... kw0 val0 kw1 val1 ... seq <- TOS
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// fun self arg0 arg1 ... kw0 val0 kw1 val1 ... bitmap <- TOS
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sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe) + 2;
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#if MICROPY_STACKLESS
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if (mp_obj_get_type(*sp) == &mp_type_fun_bc) {
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@ -3,10 +3,16 @@
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def foo(a, b, c):
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print(a, b, c)
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foo(*(), 1, 2, 3)
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foo(*(1,), 2, 3)
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foo(*(1, 2), 3)
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foo(*(1, 2, 3))
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foo(1, *(2, 3))
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foo(1, 2, *(3,))
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foo(1, 2, 3, *())
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foo(*(1,), 2, *(3,))
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foo(*(1, 2), *(3,))
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foo(*(1,), *(2, 3))
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# Another sequence type
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foo(1, 2, *[100])
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@ -29,10 +35,16 @@ class A:
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print(a, b, c)
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a = A()
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a.foo(*(), 1, 2, 3)
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a.foo(*(1,), 2, 3)
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a.foo(*(1, 2), 3)
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a.foo(*(1, 2, 3))
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a.foo(1, *(2, 3))
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a.foo(1, 2, *(3,))
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a.foo(1, 2, 3, *())
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a.foo(*(1,), 2, *(3,))
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a.foo(*(1, 2), *(3,))
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a.foo(*(1,), *(2, 3))
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# Another sequence type
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a.foo(1, 2, *[100])
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@ -6,6 +6,11 @@ def f(a, b, c, d):
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f(*(1, 2), **{'c':3, 'd':4})
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f(*(1, 2), **{['c', 'd'][i]:(3 + i) for i in range(2)})
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try:
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eval("f(**{'a': 1}, *(2, 3, 4))")
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except SyntaxError:
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print("SyntaxError")
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# test calling a method with *tuple and **dict
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class A:
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a = A()
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a.f(*(1, 2), **{'c':3, 'd':4})
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a.f(*(1, 2), **{['c', 'd'][i]:(3 + i) for i in range(2)})
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try:
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eval("a.f(**{'a': 1}, *(2, 3, 4))")
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except SyntaxError:
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print("SyntaxError")
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@ -23,3 +23,16 @@ def f4(*vargs, **kwargs):
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f4(*(1, 2))
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f4(kw_arg=3)
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f4(*(1, 2), kw_arg=3)
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# test evaluation order of arguments
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def f5(*vargs, **kwargs):
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print(vargs, kwargs)
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def print_ret(x):
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print(x)
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return x
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f5(*print_ret(["a", "b"]), kw_arg=print_ret(None))
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@ -6,26 +6,23 @@ except NameError:
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print("SKIP")
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raise SystemExit
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# from basics/fun_kwvarargs.py
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# test evaluation order of arguments (in 3.4 it's backwards, 3.5 it's fixed)
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def f4(*vargs, **kwargs):
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print(vargs, kwargs)
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def print_ret(x):
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print(x)
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return x
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f4(*print_ret(['a', 'b']), kw_arg=print_ret(None))
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# test evaluation order of dictionary key/value pair (in 3.4 it's backwards)
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{print_ret(1):print_ret(2)}
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# from basics/syntaxerror.py
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def test_syntax(code):
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try:
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exec(code)
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except SyntaxError:
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print("SyntaxError")
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test_syntax("f(*a, *b)") # can't have multiple * (in 3.5 we can)
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test_syntax("f(*a, b)") # can't have positional after *
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test_syntax("f(**a, b)") # can't have positional after **
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test_syntax("() = []") # can't assign to empty tuple (in 3.6 we can)
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test_syntax("del ()") # can't delete empty tuple (in 3.6 we can)
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@ -1,13 +1,8 @@
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None
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['a', 'b']
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('a', 'b') {'kw_arg': None}
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2
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1
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SyntaxError
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SyntaxError
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SyntaxError
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SyntaxError
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SyntaxError
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3.4
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3 4
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IndexError('foo',)
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@ -0,0 +1,23 @@
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"""
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categories: Syntax
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description: Argument unpacking does not work if the argument being unpacked is the nth or greater argument where n is the number of bits in an MP_SMALL_INT.
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cause: The implementation uses an MP_SMALL_INT to flag args that need to be unpacked.
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workaround: Use fewer arguments.
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"""
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def example(*args):
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print(len(args))
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MORE = ["a", "b", "c"]
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# fmt: off
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example(
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
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32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
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48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
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*MORE,
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)
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# fmt: on
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