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carbon-lang/executable_semantics/interpreter/value.cpp
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "executable_semantics/interpreter/value.h"
#include <algorithm>
#include "common/check.h"
#include "executable_semantics/common/arena.h"
#include "executable_semantics/common/error.h"
#include "executable_semantics/interpreter/action.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Casting.h"
namespace Carbon {
using llvm::cast;
auto StructValue::FindField(const std::string& name) const
-> std::optional<Nonnull<const Value*>> {
for (const NamedValue& element : elements_) {
if (element.name == name) {
return element.value;
}
}
return std::nullopt;
}
namespace {
auto GetMember(Nonnull<Arena*> arena, Nonnull<const Value*> v,
const std::string& f, SourceLocation source_loc)
-> Nonnull<const Value*> {
switch (v->kind()) {
case Value::Kind::StructValue: {
std::optional<Nonnull<const Value*>> field =
cast<StructValue>(*v).FindField(f);
if (field == std::nullopt) {
FATAL_RUNTIME_ERROR(source_loc) << "member " << f << " not in " << *v;
}
return *field;
}
case Value::Kind::NominalClassValue: {
std::optional<Nonnull<const Value*>> field =
cast<StructValue>(cast<NominalClassValue>(*v).inits()).FindField(f);
if (field == std::nullopt) {
FATAL_RUNTIME_ERROR(source_loc) << "member " << f << " not in " << *v;
}
return *field;
}
case Value::Kind::ChoiceType: {
const auto& choice = cast<ChoiceType>(*v);
if (!choice.FindAlternative(f)) {
FATAL_RUNTIME_ERROR(source_loc)
<< "alternative " << f << " not in " << *v;
}
return arena->New<AlternativeConstructorValue>(f, choice.name());
}
default:
FATAL() << "field access not allowed for value " << *v;
}
}
} // namespace
auto Value::GetField(Nonnull<Arena*> arena, const FieldPath& path,
SourceLocation source_loc) const -> Nonnull<const Value*> {
Nonnull<const Value*> value(this);
for (const std::string& field : path.components_) {
value = GetMember(arena, value, field, source_loc);
}
return value;
}
namespace {
auto SetFieldImpl(Nonnull<Arena*> arena, Nonnull<const Value*> value,
std::vector<std::string>::const_iterator path_begin,
std::vector<std::string>::const_iterator path_end,
Nonnull<const Value*> field_value, SourceLocation source_loc)
-> Nonnull<const Value*> {
if (path_begin == path_end) {
return field_value;
}
switch (value->kind()) {
case Value::Kind::StructValue: {
std::vector<NamedValue> elements = cast<StructValue>(*value).elements();
auto it = std::find_if(elements.begin(), elements.end(),
[path_begin](const NamedValue& element) {
return element.name == *path_begin;
});
if (it == elements.end()) {
FATAL_RUNTIME_ERROR(source_loc)
<< "field " << *path_begin << " not in " << *value;
}
it->value = SetFieldImpl(arena, it->value, path_begin + 1, path_end,
field_value, source_loc);
return arena->New<StructValue>(elements);
}
case Value::Kind::NominalClassValue: {
return SetFieldImpl(arena, &cast<NominalClassValue>(*value).inits(),
path_begin, path_end, field_value, source_loc);
}
case Value::Kind::TupleValue: {
std::vector<Nonnull<const Value*>> elements =
cast<TupleValue>(*value).elements();
// TODO(geoffromer): update FieldPath to hold integers as well as strings.
int index = std::stoi(*path_begin);
if (index < 0 || static_cast<size_t>(index) >= elements.size()) {
FATAL_RUNTIME_ERROR(source_loc)
<< "index " << *path_begin << " out of range in " << *value;
}
elements[index] = SetFieldImpl(arena, elements[index], path_begin + 1,
path_end, field_value, source_loc);
return arena->New<TupleValue>(elements);
}
default:
FATAL() << "field access not allowed for value " << *value;
}
}
} // namespace
auto Value::SetField(Nonnull<Arena*> arena, const FieldPath& path,
Nonnull<const Value*> field_value,
SourceLocation source_loc) const -> Nonnull<const Value*> {
return SetFieldImpl(arena, Nonnull<const Value*>(this),
path.components_.begin(), path.components_.end(),
field_value, source_loc);
}
void Value::Print(llvm::raw_ostream& out) const {
switch (kind()) {
case Value::Kind::AlternativeConstructorValue: {
const auto& alt = cast<AlternativeConstructorValue>(*this);
out << alt.choice_name() << "." << alt.alt_name();
break;
}
case Value::Kind::BindingPlaceholderValue: {
const auto& placeholder = cast<BindingPlaceholderValue>(*this);
if (placeholder.name().has_value()) {
out << *placeholder.name();
} else {
out << "_";
}
out << ": " << placeholder.type();
break;
}
case Value::Kind::AlternativeValue: {
const auto& alt = cast<AlternativeValue>(*this);
out << "alt " << alt.choice_name() << "." << alt.alt_name() << " "
<< alt.argument();
break;
}
case Value::Kind::StructValue: {
const auto& struct_val = cast<StructValue>(*this);
out << "{";
llvm::ListSeparator sep;
for (const NamedValue& element : struct_val.elements()) {
out << sep << "." << element.name << " = " << *element.value;
}
out << "}";
break;
}
case Value::Kind::NominalClassValue: {
const auto& s = cast<NominalClassValue>(*this);
out << cast<NominalClassType>(s.type()).name() << s.inits();
break;
}
case Value::Kind::TupleValue: {
out << "(";
llvm::ListSeparator sep;
for (Nonnull<const Value*> element : cast<TupleValue>(*this).elements()) {
out << sep << *element;
}
out << ")";
break;
}
case Value::Kind::IntValue:
out << cast<IntValue>(*this).value();
break;
case Value::Kind::BoolValue:
out << (cast<BoolValue>(*this).value() ? "true" : "false");
break;
case Value::Kind::FunctionValue:
out << "fun<" << cast<FunctionValue>(*this).declaration().name() << ">";
break;
case Value::Kind::PointerValue:
out << "ptr<" << cast<PointerValue>(*this).value() << ">";
break;
case Value::Kind::BoolType:
out << "Bool";
break;
case Value::Kind::IntType:
out << "i32";
break;
case Value::Kind::TypeType:
out << "Type";
break;
case Value::Kind::AutoType:
out << "auto";
break;
case Value::Kind::ContinuationType:
out << "Continuation";
break;
case Value::Kind::PointerType:
out << cast<PointerType>(*this).type() << "*";
break;
case Value::Kind::FunctionType: {
const auto& fn_type = cast<FunctionType>(*this);
out << "fn ";
if (fn_type.deduced().size() > 0) {
out << "[";
unsigned int i = 0;
for (Nonnull<const GenericBinding*> deduced : fn_type.deduced()) {
if (i != 0) {
out << ", ";
}
out << deduced->name() << ":! " << deduced->type();
++i;
}
out << "]";
}
out << fn_type.parameters() << " -> " << fn_type.return_type();
break;
}
case Value::Kind::StructType: {
out << "{";
llvm::ListSeparator sep;
for (const auto& [name, type] : cast<StructType>(*this).fields()) {
out << sep << "." << name << ": " << *type;
}
out << "}";
break;
}
case Value::Kind::NominalClassType:
out << "class " << cast<NominalClassType>(*this).name();
break;
case Value::Kind::ChoiceType:
out << "choice " << cast<ChoiceType>(*this).name();
break;
case Value::Kind::VariableType:
out << cast<VariableType>(*this).name();
break;
case Value::Kind::ContinuationValue: {
out << "{";
llvm::ListSeparator sep(" :: ");
for (Nonnull<const Action*> action :
cast<ContinuationValue>(*this).stack()) {
out << sep << *action;
}
out << "}";
break;
}
case Value::Kind::StringType:
out << "String";
break;
case Value::Kind::StringValue:
out << "\"";
out.write_escaped(cast<StringValue>(*this).value());
out << "\"";
break;
}
}
auto TypeEqual(Nonnull<const Value*> t1, Nonnull<const Value*> t2) -> bool {
if (t1->kind() != t2->kind()) {
return false;
}
switch (t1->kind()) {
case Value::Kind::PointerType:
return TypeEqual(&cast<PointerType>(*t1).type(),
&cast<PointerType>(*t2).type());
case Value::Kind::FunctionType: {
const auto& fn1 = cast<FunctionType>(*t1);
const auto& fn2 = cast<FunctionType>(*t2);
return TypeEqual(&fn1.parameters(), &fn2.parameters()) &&
TypeEqual(&fn1.return_type(), &fn2.return_type());
}
case Value::Kind::StructType: {
const auto& struct1 = cast<StructType>(*t1);
const auto& struct2 = cast<StructType>(*t2);
if (struct1.fields().size() != struct2.fields().size()) {
return false;
}
for (size_t i = 0; i < struct1.fields().size(); ++i) {
if (struct1.fields()[i].name != struct2.fields()[i].name ||
!TypeEqual(struct1.fields()[i].value, struct2.fields()[i].value)) {
return false;
}
}
return true;
}
case Value::Kind::NominalClassType:
return cast<NominalClassType>(*t1).name() ==
cast<NominalClassType>(*t2).name();
case Value::Kind::ChoiceType:
return cast<ChoiceType>(*t1).name() == cast<ChoiceType>(*t2).name();
case Value::Kind::TupleValue: {
const auto& tup1 = cast<TupleValue>(*t1);
const auto& tup2 = cast<TupleValue>(*t2);
if (tup1.elements().size() != tup2.elements().size()) {
return false;
}
for (size_t i = 0; i < tup1.elements().size(); ++i) {
if (!TypeEqual(tup1.elements()[i], tup2.elements()[i])) {
return false;
}
}
return true;
}
case Value::Kind::IntType:
case Value::Kind::BoolType:
case Value::Kind::ContinuationType:
case Value::Kind::TypeType:
case Value::Kind::StringType:
return true;
case Value::Kind::VariableType:
return cast<VariableType>(*t1).name() == cast<VariableType>(*t2).name();
default:
FATAL() << "TypeEqual used to compare non-type values\n"
<< *t1 << "\n"
<< *t2;
}
}
// Returns true if the two values are equal and returns false otherwise.
//
// This function implements the `==` operator of Carbon.
auto ValueEqual(Nonnull<const Value*> v1, Nonnull<const Value*> v2,
SourceLocation source_loc) -> bool {
if (v1->kind() != v2->kind()) {
return false;
}
switch (v1->kind()) {
case Value::Kind::IntValue:
return cast<IntValue>(*v1).value() == cast<IntValue>(*v2).value();
case Value::Kind::BoolValue:
return cast<BoolValue>(*v1).value() == cast<BoolValue>(*v2).value();
case Value::Kind::FunctionValue: {
std::optional<Nonnull<const Statement*>> body1 =
cast<FunctionValue>(*v1).declaration().body();
std::optional<Nonnull<const Statement*>> body2 =
cast<FunctionValue>(*v2).declaration().body();
return body1.has_value() == body2.has_value() &&
(!body1.has_value() || *body1 == *body2);
}
case Value::Kind::TupleValue: {
const std::vector<Nonnull<const Value*>>& elements1 =
cast<TupleValue>(*v1).elements();
const std::vector<Nonnull<const Value*>>& elements2 =
cast<TupleValue>(*v2).elements();
if (elements1.size() != elements2.size()) {
return false;
}
for (size_t i = 0; i < elements1.size(); ++i) {
if (!ValueEqual(elements1[i], elements2[i], source_loc)) {
return false;
}
}
return true;
}
case Value::Kind::StructValue: {
const auto& struct_v1 = cast<StructValue>(*v1);
const auto& struct_v2 = cast<StructValue>(*v2);
CHECK(struct_v1.elements().size() == struct_v2.elements().size());
for (size_t i = 0; i < struct_v1.elements().size(); ++i) {
CHECK(struct_v1.elements()[i].name == struct_v2.elements()[i].name);
if (!ValueEqual(struct_v1.elements()[i].value,
struct_v2.elements()[i].value, source_loc)) {
return false;
}
}
return true;
}
case Value::Kind::StringValue:
return cast<StringValue>(*v1).value() == cast<StringValue>(*v2).value();
case Value::Kind::IntType:
case Value::Kind::BoolType:
case Value::Kind::TypeType:
case Value::Kind::FunctionType:
case Value::Kind::PointerType:
case Value::Kind::AutoType:
case Value::Kind::StructType:
case Value::Kind::NominalClassType:
case Value::Kind::ChoiceType:
case Value::Kind::ContinuationType:
case Value::Kind::VariableType:
case Value::Kind::StringType:
return TypeEqual(v1, v2);
case Value::Kind::NominalClassValue:
case Value::Kind::AlternativeValue:
case Value::Kind::BindingPlaceholderValue:
case Value::Kind::AlternativeConstructorValue:
case Value::Kind::ContinuationValue:
case Value::Kind::PointerValue:
// TODO: support pointer comparisons once we have a clearer distinction
// between pointers and lvalues.
FATAL() << "ValueEqual does not support this kind of value: " << *v1;
}
}
auto ChoiceType::FindAlternative(std::string_view name) const
-> std::optional<Nonnull<const Value*>> {
for (const NamedValue& alternative : alternatives_) {
if (alternative.name == name) {
return alternative.value;
}
}
return std::nullopt;
}
} // namespace Carbon
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