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package org.zwobble.hobgoblin.compiler.analysis;
import org.zwobble.hobgoblin.compiler.analysis.errors.SumTypeHasNoVariantsError;
import org.zwobble.hobgoblin.compiler.analysis.errors.TypeIsInfiniteError;
import org.zwobble.hobgoblin.compiler.builtins.NativeTypes;
import org.zwobble.hobgoblin.compiler.typechecker.TypesInfo;
import org.zwobble.hobgoblin.compiler.types.*;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.IntStream;
public class ArbitraryValueAnalysis {
public sealed interface ArbitraryValue {
void collectTypeParams(Set<TypeParam> typeParams);
record NativeFunctionCall(
SimpleNativeType type,
List<ArbitraryValue> args
) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
for (var arg : args) {
arg.collectTypeParams(typeParams);
}
}
}
record ConstructedStructBuilder(
ConstructedStructType type,
List<ArbitraryValue> args
) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
for (var arg : args) {
arg.collectTypeParams(typeParams);
}
}
}
record SimpleStructBuilder(SimpleStructType type) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
}
}
record EnumVariantValue(EnumType type, EnumVariant variant) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
}
}
record TypeParamThunk(TypeParam typeParam) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
typeParams.add(typeParam);
}
}
record Box(ArbitraryValue value) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
value.collectTypeParams(typeParams);
}
}
record Shared(ArbitraryValue value) implements ArbitraryValue {
@Override
public void collectTypeParams(Set<TypeParam> typeParams) {
value.collectTypeParams(typeParams);
}
}
}
public static ArbitraryValue arbitraryValue(Type type, TypesInfo typesInfo) {
return switch (type) {
case ConstructedNativeType constructedNativeType -> {
if (constructedNativeType.constructor().equals(NativeTypes.BOX)) {
yield new ArbitraryValue.Box(arbitraryValue(constructedNativeType.args().getFirst(), typesInfo));
}
if (constructedNativeType.constructor().equals(NativeTypes.SHARED)) {
yield new ArbitraryValue.Shared(arbitraryValue(constructedNativeType.args().getFirst(), typesInfo));
}
var args = constructedNativeType.args().stream()
.map(argType -> arbitraryValue(argType, typesInfo))
.toList();
yield new ArbitraryValue.NativeFunctionCall(
constructedNativeType.constructor().genericType(),
args
);
}
case ConstructedStructType constructedStructType -> {
var fields = typesInfo.fieldsOf(constructedStructType.constructor().genericType())
.orElse(List.of());
var usedTypeParams = new HashSet<TypeParam>();
for (var field : fields) {
arbitraryValue(field.type(), typesInfo).collectTypeParams(usedTypeParams);
}
var allTypeParams = constructedStructType.constructor().params();
var args = IntStream.range(0, constructedStructType.args().size())
.filter(paramIndex -> usedTypeParams.contains(allTypeParams.get(paramIndex)))
.mapToObj(paramIndex -> arbitraryValue(constructedStructType.args().get(paramIndex), typesInfo))
.toList();
yield new ArbitraryValue.ConstructedStructBuilder(
constructedStructType,
args
);
}
case EnumType enumType ->
new ArbitraryValue.EnumVariantValue(enumType, typesInfo.enumVariants(enumType).getFirst());
case SimpleNativeType simpleNativeType ->
new ArbitraryValue.NativeFunctionCall(simpleNativeType, List.of());
case SimpleStructType simpleStructType ->
new ArbitraryValue.SimpleStructBuilder(simpleStructType);
case SumType sumType -> {
var firstVariant = selectArbitraryVariant(sumType, typesInfo);
yield arbitraryValue(firstVariant, typesInfo);
}
case TypeLevelValueType _ ->
throw new UnsupportedOperationException("TODO");
case TypeParam typeParam ->
new ArbitraryValue.TypeParamThunk(typeParam);
};
}
private static void collectUsedTypeParams(
ConstructedStructType structType,
Set<TypeParam> usedTypeParams
) {
}
public static Type selectArbitraryVariant(SumType sumType, TypesInfo typesInfo) {
var sumTypeInfo = typesInfo.sumTypeInfo(sumType);
if (sumTypeInfo.variants().isEmpty()) {
throw new SumTypeHasNoVariantsError(sumType, sumTypeInfo.source());
}
var seenTypes = new HashSet<Type>();
seenTypes.add(sumType);
return sumTypeInfo.variants().stream()
.filter(variant -> isNonRecursivelyConstructable(variant.valueType(), seenTypes, typesInfo))
.findFirst()
.orElseThrow(() -> new TypeIsInfiniteError(sumType, sumTypeInfo.source()))
.containerType();
}
private static boolean isNonRecursivelyConstructable(Type type, Set<Type> seenTypes, TypesInfo typesInfo) {
if (seenTypes.contains(type)) {
return false;
}
return switch (type) {
case ConstructedType constructedType -> {
if (
constructedType.constructor().equals(NativeTypes.BOX) ||
constructedType.constructor().equals(NativeTypes.SHARED)
) {
yield isNonRecursivelyConstructable(
constructedType.args().getFirst(),
seenTypes,
typesInfo
);
} else if (
constructedType.constructor().equals(NativeTypes.LIST) ||
constructedType.constructor().equals(NativeTypes.OPTION)
) {
yield true;
} else {
throw new UnsupportedOperationException("TODO");
}
}
case EnumType _ ->
true;
case SimpleNativeType _ ->
true;
case SimpleStructType structType -> {
var newSeenTypes = new HashSet<>(seenTypes);
newSeenTypes.add(type);
var fields = typesInfo.fieldsOf(structType);
yield fields.orElse(List.of()).stream()
.allMatch(field -> isNonRecursivelyConstructable(field.type(), newSeenTypes, typesInfo));
}
case SumType sumType -> {
var newSeenTypes = new HashSet<>(seenTypes);
newSeenTypes.add(type);
yield typesInfo.sumVariants(sumType).stream()
.anyMatch(variant -> isNonRecursivelyConstructable(variant.valueType(), newSeenTypes, typesInfo));
}
case TypeLevelValueType _ ->
false;
case TypeParam _ ->
false;
};
}
}
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