circuitpython/py/objgenerator.c

#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>

#include "nlr.h"
#include "misc.h"
#include "mpconfig.h"
#include "obj.h"
#include "runtime.h"
#include "bc.h"

/******************************************************************************/
/* generator wrapper                                                          */

typedef struct _mp_obj_gen_wrap_t {
    mp_obj_base_t base;
    int n_state;
    mp_obj_t *fun;
} mp_obj_gen_wrap_t;

// args are in reverse order in the array
mp_obj_t gen_wrap_call_n(mp_obj_t self_in, int n_args, const mp_obj_t *args) {
    mp_obj_gen_wrap_t *self = self_in;
    mp_obj_t self_fun = self->fun;
    assert(MP_OBJ_IS_TYPE(self_fun, &fun_bc_type));
    int bc_n_args;
    uint bc_n_state;
    const byte *bc_code;
    mp_obj_fun_bc_get(self_fun, &bc_n_args, &bc_n_state, &bc_code);
    if (n_args != bc_n_args) {
        nlr_jump(mp_obj_new_exception_msg_2_args(rt_q_TypeError, "function takes %d positional arguments but %d were given", (const char*)(machine_int_t)bc_n_args, (const char*)(machine_int_t)n_args));
    }
    mp_obj_t *state = m_new(mp_obj_t, 1 + self->n_state);
    // put function object at first slot in state (to keep u_gen_instance small)
    state[0] = self_fun;
    // init args
    for (int i = 0; i < n_args; i++) {
        state[1 + i] = args[n_args - 1 - i];
    }

    // TODO
    // prelude for making cells (closed over variables)
    // for now we just make sure there are no cells variables
    // need to work out how to implement closed over variables in generators
    assert(bc_code[0] == 0);
    bc_code += 1;

    return mp_obj_new_gen_instance(state, bc_code, state + self->n_state);
}

const mp_obj_type_t gen_wrap_type = {
    { &mp_const_type },
    "generator",
    NULL, // print
    gen_wrap_call_n, // call_n
    NULL, // unary_op
    NULL, // binary_op
    NULL, // getiter
    NULL, // iternext
    {{NULL, NULL},}, // method list
};

mp_obj_t mp_obj_new_gen_wrap(uint n_locals, uint n_stack, mp_obj_t fun) {
    mp_obj_gen_wrap_t *o = m_new_obj(mp_obj_gen_wrap_t);
    o->base.type = &gen_wrap_type;
    // we have at least 3 locals so the bc can write back fast[0,1,2] safely; should improve how this is done
    o->n_state = (n_locals < 3 ? 3 : n_locals) + n_stack;
    o->fun = fun;
    return o;
}

/******************************************************************************/
/* generator instance                                                         */

typedef struct _mp_obj_gen_instance_t {
    mp_obj_base_t base;
    mp_obj_t *state;
    const byte *ip;
    mp_obj_t *sp;
} mp_obj_gen_instance_t;

void gen_instance_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in) {
    print(env, "<generator object 'fun-name' at %p>", self_in);
}

mp_obj_t gen_instance_getiter(mp_obj_t self_in) {
    return self_in;
}

mp_obj_t gen_instance_iternext(mp_obj_t self_in) {
    mp_obj_gen_instance_t *self = self_in;
    //mp_obj_base_t *fun = self->u_gen_instance.state[0];
    //assert(fun->kind == O_FUN_BC);
    bool yield = mp_execute_byte_code_2(&self->ip, &self->state[1], &self->sp);
    if (yield) {
        return *self->sp;
    } else {
        if (*self->sp == mp_const_none) {
            return mp_const_stop_iteration;
        } else {
            // TODO return StopIteration with value *self->sp
            return mp_const_stop_iteration;
        }
    }
}

const mp_obj_type_t gen_instance_type = {
    { &mp_const_type },
    "generator",
    gen_instance_print, // print
    NULL, // call_n
    NULL, // unary_op
    NULL, // binary_op
    gen_instance_getiter, // getiter
    gen_instance_iternext, // iternext
    {{NULL, NULL},}, // method list
};

mp_obj_t mp_obj_new_gen_instance(mp_obj_t state, const byte *ip, mp_obj_t *sp) {
    mp_obj_gen_instance_t *o = m_new_obj(mp_obj_gen_instance_t);
    o->base.type = &gen_instance_type;
    o->state = state;
    o->ip = ip;
    o->sp = sp;
    return o;
}