diff options
Diffstat (limited to 'erts/emulator')
| -rw-r--r-- | erts/emulator/beam/erl_db_util.c | 145 |
1 files changed, 111 insertions, 34 deletions
diff --git a/erts/emulator/beam/erl_db_util.c b/erts/emulator/beam/erl_db_util.c index 3b2e7f4407..ab45c3fe0f 100644 --- a/erts/emulator/beam/erl_db_util.c +++ b/erts/emulator/beam/erl_db_util.c @@ -1119,17 +1119,111 @@ error: return NULL; } +/* + * Compare a matching term 'a' with a constructing term 'b' for equality. + * + * Returns true if 'b' is guaranteed to always construct + * the same term as 'a' has matched. + */ +static int db_match_eq_body(Eterm a, Eterm b) +{ + DECLARE_ESTACK(s); + Uint arity; + Eterm *ap, *bp; + int const_mode = 0; + const Eterm CONST_MODE_OFF = THE_NON_VALUE; + + while (1) { + switch(b & _TAG_PRIMARY_MASK) { + case TAG_PRIMARY_LIST: + if (!is_list(a)) + return 0; + ESTACK_PUSH2(s, CDR(list_val(a)), CDR(list_val(b))); + a = CAR(list_val(a)); + b = CAR(list_val(b)); + continue; /* loop without pop */ + + case TAG_PRIMARY_BOXED: + if (is_tuple(b)) { + bp = tuple_val(b); + if (!const_mode) { + if (bp[0] == make_arityval(1) && is_tuple(bp[1])) { + b = bp[1]; /* double-tuple syntax */ + } + else if (bp[0] == make_arityval(2) && bp[1] == am_const) { + ESTACK_PUSH(s, CONST_MODE_OFF); + const_mode = 1; /* {const, term()} syntax */ + b = bp[2]; + continue; /* loop without pop */ + } + else + return 0; /* function call or invalid tuple syntax */ + } + if (!is_tuple(a)) + return 0; + + ap = tuple_val(a); + bp = tuple_val(b); + if (ap[0] != bp[0]) + return 0; + arity = arityval(ap[0]); + if (arity > 0) { + a = *(++ap); + b = *(++bp); + while(--arity) { + ESTACK_PUSH2(s, *(++ap), *(++bp)); + } + continue; /* loop without pop */ + } + } + else if (is_map(b)) { + /* We don't know what other pairs the matched map may contain */ + return 0; + } + else if (!eq(a,b)) /* other boxed */ + return 0; + break; + + case TAG_PRIMARY_IMMED1: + if (a != b || a == am_Underscore || a == am_DollarDollar + || a == am_DollarUnderscore + || (const_mode && db_is_variable(a) >= 0)) { + + return 0; + } + break; + default: + erts_exit(ERTS_ABORT_EXIT, "db_compare: " + "Bad object on ESTACK: 0x%bex\n", b); + } + +pop_next: + if (ESTACK_ISEMPTY(s)) + break; /* done */ + + b = ESTACK_POP(s); + if (b == CONST_MODE_OFF) { + ASSERT(const_mode); + const_mode = 0; + goto pop_next; + } + a = ESTACK_POP(s); + } + + DESTROY_ESTACK(s); + return 1; +} + /* This is used by select_replace */ -int db_match_keeps_key(int keypos, Eterm match, Eterm guard, Eterm body) { - Eterm match_key = NIL; - int match_key_variable = -1; - Eterm* body_list = NULL; - Eterm single_body_term = NIL; - Eterm* single_body_term_tpl = NULL; - Eterm single_body_subterm = NIL; - Eterm single_body_subterm_key = NIL; - int single_body_subterm_key_variable = -1; - Eterm* single_body_subterm_key_tpl = NULL; +int db_match_keeps_key(int keypos, Eterm match, Eterm guard, Eterm body) +{ + Eterm match_key; + Eterm* body_list; + Eterm single_body_term; + Eterm* single_body_term_tpl; + Eterm single_body_subterm; + Eterm single_body_subterm_key; + Eterm* single_body_subterm_key_tpl; if (!is_list(body)) { return 0; @@ -1169,9 +1263,7 @@ int db_match_keeps_key(int keypos, Eterm match, Eterm guard, Eterm body) { return 0; } - match_key_variable = db_is_variable(match_key); - single_body_subterm_key_variable = db_is_variable(single_body_subterm_key); - if (match_key_variable != -1 && match_key_variable == single_body_subterm_key_variable) { + if (db_match_eq_body(match_key, single_body_subterm_key)) { /* tuple with same key is returned */ return 1; } @@ -1187,30 +1279,15 @@ int db_match_keeps_key(int keypos, Eterm match, Eterm guard, Eterm body) { return 0; } - if (single_body_subterm_key_tpl[1] != am_element) { - /* tag is not of an element instruction */ - return 0; - } - if (single_body_subterm_key_tpl[3] != am_DollarUnderscore) { - /* even if it's an element instruction, it's not fetching from the original tuple */ - return 0; - } - - if (is_big(single_body_subterm_key_tpl[2]) - && (big_to_uint32(single_body_subterm_key_tpl[2]) != keypos)) - { - /* the key comes from a different position */ - return 0; - } - - if (is_small(single_body_subterm_key_tpl[2]) - && (unsigned_val(single_body_subterm_key_tpl[2]) != keypos)) + if (single_body_subterm_key_tpl[1] == am_element && + single_body_subterm_key_tpl[3] == am_DollarUnderscore && + single_body_subterm_key_tpl[2] == make_small(keypos)) { - /* the key comes from a different position */ - return 0; + /* {element, KeyPos, '$_'} */ + return 1; } - return 1; + return 0; } /* This is used when tracing */ |