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ton/crypto/func/unify-types.cpp
2019-09-07 14:33:36 +04:00

385 lines
9.2 KiB
C++

/*
This file is part of TON Blockchain Library.
TON Blockchain Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
TON Blockchain Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
Copyright 2017-2019 Telegram Systems LLP
*/
#include "func.h"
namespace funC {
/*
*
* TYPE EXPRESSIONS
*
*/
int TypeExpr::holes = 0, TypeExpr::type_vars = 0; // not thread safe, but it is ok for now
void TypeExpr::compute_width() {
switch (constr) {
case te_Atomic:
case te_Map:
minw = maxw = 1;
break;
case te_Tensor:
minw = maxw = 0;
for (TypeExpr* arg : args) {
minw += arg->minw;
maxw += arg->maxw;
}
if (minw > w_inf) {
minw = w_inf;
}
if (maxw > w_inf) {
maxw = w_inf;
}
break;
case te_Indirect:
minw = args[0]->minw;
maxw = args[0]->maxw;
break;
default:
minw = 0;
maxw = w_inf;
break;
}
}
bool TypeExpr::recompute_width() {
switch (constr) {
case te_Tensor:
case te_Indirect: {
int min = 0, max = 0;
for (TypeExpr* arg : args) {
min += arg->minw;
max += arg->maxw;
}
if (min > maxw || max < minw) {
return false;
}
if (min > w_inf) {
min = w_inf;
}
if (max > w_inf) {
max = w_inf;
}
if (minw < min) {
minw = min;
}
if (maxw > max) {
maxw = max;
}
return true;
}
default:
return false;
}
}
int TypeExpr::extract_components(std::vector<TypeExpr*>& comp_list) {
if (constr != te_Indirect && constr != te_Tensor) {
comp_list.push_back(this);
return 1;
}
int res = 0;
for (TypeExpr* arg : args) {
res += arg->extract_components(comp_list);
}
return res;
}
TypeExpr* TypeExpr::new_map(TypeExpr* from, TypeExpr* to) {
return new TypeExpr{te_Map, std::vector<TypeExpr*>{from, to}};
}
void TypeExpr::replace_with(TypeExpr* te2) {
if (te2 == this) {
return;
}
constr = te_Indirect;
value = 0;
minw = te2->minw;
maxw = te2->maxw;
args.clear();
args.push_back(te2);
}
bool TypeExpr::remove_indirect(TypeExpr*& te, TypeExpr* forbidden) {
assert(te);
while (te->constr == te_Indirect) {
te = te->args[0];
}
if (te->constr == te_Unknown) {
return te != forbidden;
}
bool res = true;
for (auto& x : te->args) {
res &= remove_indirect(x, forbidden);
}
return res;
}
bool TypeExpr::remove_forall(TypeExpr*& te) {
assert(te);
if (te->constr != te_ForAll) {
return false;
}
assert(te->args.size() >= 1);
std::vector<TypeExpr*> new_vars;
for (std::size_t i = 1; i < te->args.size(); i++) {
new_vars.push_back(new_hole(1));
}
TypeExpr* te2 = te;
// std::cerr << "removing universal quantifier in " << te << std::endl;
te = te->args[0];
remove_forall_in(te, te2, new_vars);
// std::cerr << "-> " << te << std::endl;
return true;
}
bool TypeExpr::remove_forall_in(TypeExpr*& te, TypeExpr* te2, const std::vector<TypeExpr*>& new_vars) {
assert(te);
assert(te2 && te2->constr == te_ForAll);
if (te->constr == te_Unknown) {
for (std::size_t i = 0; i < new_vars.size(); i++) {
if (te == te2->args[i + 1]) {
te = new_vars[i];
return true;
}
}
return false;
}
if (te->constr == te_ForAll) {
return false;
}
if (te->args.empty()) {
return false;
}
auto te1 = new TypeExpr(*te);
bool res = false;
for (auto& arg : te1->args) {
res |= remove_forall_in(arg, te2, new_vars);
}
if (res) {
te = te1;
} else {
delete te1;
}
return res;
}
void TypeExpr::show_width(std::ostream& os) {
os << minw;
if (maxw != minw) {
os << "..";
if (maxw < w_inf) {
os << maxw;
}
}
}
std::ostream& operator<<(std::ostream& os, TypeExpr* type_expr) {
if (!type_expr) {
return os << "(null-type-ptr)";
}
return type_expr->print(os);
}
std::ostream& TypeExpr::print(std::ostream& os, int lex_level) {
switch (constr) {
case te_Unknown:
if (value >= 0) {
return os << "??" << value;
} else if (value >= -26) {
return os << (char)(64 - value);
} else {
return os << "TVAR" << -value;
}
case te_Indirect:
return os << args[0];
case te_Atomic: {
switch (value) {
case _Int:
return os << "int";
case _Cell:
return os << "cell";
case _Slice:
return os << "slice";
case _Builder:
return os << "builder";
case _Cont:
return os << "cont";
case _Tuple:
return os << "tuple";
case _Type:
return os << "type";
default:
return os << "atomic-type-" << value;
}
}
case te_Tensor: {
os << "(";
auto c = args.size();
if (c) {
for (const auto& x : args) {
x->print(os);
if (--c) {
os << ", ";
}
}
}
return os << ")";
}
case te_Map: {
assert(args.size() == 2);
if (lex_level > 0) {
os << "(";
}
args[0]->print(os, 1);
os << " -> ";
args[1]->print(os);
if (lex_level > 0) {
os << ")";
}
return os;
}
case te_ForAll: {
assert(args.size() >= 1);
if (lex_level > 0) {
os << '(';
}
os << "Forall ";
for (std::size_t i = 1; i < args.size(); i++) {
os << (i > 1 ? ' ' : '(');
args[i]->print(os);
}
os << ") ";
args[0]->print(os);
if (lex_level > 0) {
os << ')';
}
return os;
}
default:
return os << "unknown-type-expr-" << constr;
}
}
void UnifyError::print_message(std::ostream& os) const {
os << "cannot unify type " << te1 << " with " << te2;
if (!msg.empty()) {
os << ": " << msg;
}
}
std::ostream& operator<<(std::ostream& os, const UnifyError& ue) {
ue.print_message(os);
return os;
}
std::string UnifyError::message() const {
std::ostringstream os;
UnifyError::print_message(os);
return os.str();
}
void check_width_compat(TypeExpr* te1, TypeExpr* te2) {
if (te1->minw > te2->maxw || te2->minw > te1->maxw) {
std::ostringstream os{"cannot unify types of widths "};
te1->show_width(os);
os << " and ";
te2->show_width(os);
throw UnifyError{te1, te2, os.str()};
}
}
void check_update_widths(TypeExpr* te1, TypeExpr* te2) {
check_width_compat(te1, te2);
te1->minw = te2->minw = std::max(te1->minw, te2->minw);
te1->maxw = te2->maxw = std::min(te1->maxw, te2->maxw);
assert(te1->minw <= te2->minw);
}
void unify(TypeExpr*& te1, TypeExpr*& te2) {
assert(te1 && te2);
// std::cerr << "unify( " << te1 << " , " << te2 << " )\n";
while (te1->constr == TypeExpr::te_Indirect) {
te1 = te1->args[0];
}
while (te2->constr == TypeExpr::te_Indirect) {
te2 = te2->args[0];
}
if (te1 == te2) {
return;
}
if (te1->constr == TypeExpr::te_ForAll) {
TypeExpr* te = te1;
if (!TypeExpr::remove_forall(te)) {
throw UnifyError{te1, te2, "cannot remove universal type quantifier while performing type unification"};
}
unify(te, te2);
return;
}
if (te2->constr == TypeExpr::te_ForAll) {
TypeExpr* te = te2;
if (!TypeExpr::remove_forall(te)) {
throw UnifyError{te2, te1, "cannot remove universal type quantifier while performing type unification"};
}
unify(te1, te);
return;
}
if (te1->constr == TypeExpr::te_Unknown) {
if (te2->constr == TypeExpr::te_Unknown) {
assert(te1->value != te2->value);
}
if (!TypeExpr::remove_indirect(te2, te1)) {
throw UnifyError{te1, te2, "type unification results in an infinite cyclic type"};
}
check_update_widths(te1, te2);
te1->replace_with(te2);
te1 = te2;
return;
}
if (te2->constr == TypeExpr::te_Unknown) {
if (!TypeExpr::remove_indirect(te1, te2)) {
throw UnifyError{te2, te1, "type unification results in an infinite cyclic type"};
}
check_update_widths(te2, te1);
te2->replace_with(te1);
te2 = te1;
return;
}
if (te1->constr != te2->constr || te1->value != te2->value || te1->args.size() != te2->args.size()) {
throw UnifyError{te1, te2};
}
for (std::size_t i = 0; i < te1->args.size(); i++) {
unify(te1->args[i], te2->args[i]);
}
if (te1->constr == TypeExpr::te_Tensor) {
if (!te1->recompute_width()) {
throw UnifyError{te1, te2, "type unification incompatible with known width of first type"};
}
if (!te2->recompute_width()) {
throw UnifyError{te2, te1, "type unification incompatible with known width of first type"};
}
check_update_widths(te1, te2);
}
te1->replace_with(te2);
te1 = te2;
}
} // namespace funC