py: Make long ints hashable.

Addresses issue #765.

py/mpz.c

@@ -1213,6 +1213,22 @@ mpz_t *mpz_mod(const mpz_t *lhs, const mpz_t *rhs) {
 }
 #endif
 
+// must return actual int value if it fits in mp_int_t
+mp_int_t mpz_hash(const mpz_t *z) {
+    mp_int_t val = 0;
+    mpz_dig_t *d = z->dig + z->len;
+
+    while (--d >= z->dig) {
+        val = (val << DIG_SIZE) | *d;
+    }
+
+    if (z->neg != 0) {
+        val = -val;
+    }
+
+    return val;
+}
+
 // TODO check that this correctly handles overflow in all cases
 mp_int_t mpz_as_int(const mpz_t *i) {
     mp_int_t val = 0;

py/mpz.h

@@ -96,6 +96,7 @@ void mpz_divmod_inpl(mpz_t *dest_quo, mpz_t *dest_rem, const mpz_t *lhs, const m
 mpz_t *mpz_div(const mpz_t *lhs, const mpz_t *rhs);
 mpz_t *mpz_mod(const mpz_t *lhs, const mpz_t *rhs);
 
+mp_int_t mpz_hash(const mpz_t *z);
 mp_int_t mpz_as_int(const mpz_t *z);
 bool mpz_as_int_checked(const mpz_t *z, mp_int_t *value);
 #if MICROPY_PY_BUILTINS_FLOAT

py/obj.c

@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include <stdint.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <assert.h>
@@ -33,6 +34,8 @@
 #include "misc.h"
 #include "qstr.h"
 #include "obj.h"
+#include "mpz.h"
+#include "objint.h"
 #include "runtime0.h"
 #include "runtime.h"
 #include "stackctrl.h"
@@ -152,6 +155,8 @@ mp_int_t mp_obj_hash(mp_obj_t o_in) {
         return 1; // needs to hash to same as the integer 1, since True==1
     } else if (MP_OBJ_IS_SMALL_INT(o_in)) {
         return MP_OBJ_SMALL_INT_VALUE(o_in);
+    } else if (MP_OBJ_IS_TYPE(o_in, &mp_type_int)) {
+        return mp_obj_int_hash(o_in);
     } else if (MP_OBJ_IS_STR(o_in) || MP_OBJ_IS_TYPE(o_in, &mp_type_bytes)) {
         return mp_obj_str_get_hash(o_in);
     } else if (MP_OBJ_IS_TYPE(o_in, &mp_type_NoneType)) {

py/objint.c

@@ -215,6 +215,10 @@ char *mp_obj_int_formatted(char **buf, int *buf_size, int *fmt_size, mp_const_ob
 
 #if MICROPY_LONGINT_IMPL == MICROPY_LONGINT_IMPL_NONE
 
+mp_int_t mp_obj_int_hash(mp_obj_t self_in) {
+    return MP_OBJ_SMALL_INT_VALUE(self_in);
+}
+
 bool mp_obj_int_is_positive(mp_obj_t self_in) {
     return mp_obj_get_int(self_in) >= 0;
 }

py/objint.h

@@ -38,6 +38,7 @@ char *mp_obj_int_formatted(char **buf, int *buf_size, int *fmt_size, mp_const_ob
                            int base, const char *prefix, char base_char, char comma);
 char *mp_obj_int_formatted_impl(char **buf, int *buf_size, int *fmt_size, mp_const_obj_t self_in,
                                 int base, const char *prefix, char base_char, char comma);
+mp_int_t mp_obj_int_hash(mp_obj_t self_in);
 bool mp_obj_int_is_positive(mp_obj_t self_in);
 mp_obj_t mp_obj_int_unary_op(int op, mp_obj_t o_in);
 mp_obj_t mp_obj_int_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in);

py/objint_longlong.c

@@ -55,6 +55,16 @@
 const mp_obj_int_t mp_maxsize_obj = {{&mp_type_int}, INT_MAX};
 #endif
 
+mp_int_t mp_obj_int_hash(mp_obj_t self_in) {
+    if (MP_OBJ_IS_SMALL_INT(self_in)) {
+        return MP_OBJ_SMALL_INT_VALUE(self_in);
+    }
+    mp_obj_int_t *self = self_in;
+    // truncate value to fit in mp_int_t, which gives the same hash as
+    // small int if the value fits without truncation
+    return self->val;
+}
+
 bool mp_obj_int_is_positive(mp_obj_t self_in) {
     if (MP_OBJ_IS_SMALL_INT(self_in)) {
         return MP_OBJ_SMALL_INT_VALUE(self_in) >= 0;

py/objint_mpz.c

@@ -96,6 +96,14 @@ char *mp_obj_int_formatted_impl(char **buf, int *buf_size, int *fmt_size, mp_con
     return str;
 }
 
+mp_int_t mp_obj_int_hash(mp_obj_t self_in) {
+    if (MP_OBJ_IS_SMALL_INT(self_in)) {
+        return MP_OBJ_SMALL_INT_VALUE(self_in);
+    }
+    mp_obj_int_t *self = self_in;
+    return mpz_hash(&self->mpz);
+}
+
 bool mp_obj_int_is_positive(mp_obj_t self_in) {
     if (MP_OBJ_IS_SMALL_INT(self_in)) {
         return MP_OBJ_SMALL_INT_VALUE(self_in) >= 0;