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package org.zwobble.couscous.interpreter;
import java.util.Map;
import java.util.Optional;
import org.zwobble.couscous.ast.TypeName;
import org.zwobble.couscous.ast.VariableDeclaration;
import org.zwobble.couscous.ast.VariableNode;
import org.zwobble.couscous.ast.identifiers.Identifier;
import org.zwobble.couscous.interpreter.values.ConcreteType;
import org.zwobble.couscous.interpreter.values.InterpreterValue;
import static java.util.stream.Collectors.toMap;
public class Environment {
private final Project project;
private final Optional<InterpreterValue> thisValue;
private final Map<Identifier, VariableEntry> stackFrame;
public Environment(Project project, Optional<InterpreterValue> thisValue, Map<VariableDeclaration, Optional<InterpreterValue>> stackFrame) {
this.project = project;
this.thisValue = thisValue;
this.stackFrame = stackFrame.entrySet().stream()
.collect(toMap(
entry -> entry.getKey().getId(),
entry -> VariableEntry.of(entry.getKey().getType(), entry.getValue())));
}
public Optional<InterpreterValue> getThis() {
return thisValue;
}
public InterpreterValue get(Identifier variableId) {
checkVariableIsInScope(variableId);
final org.zwobble.couscous.interpreter.Environment.VariableEntry entry = stackFrame.get(variableId);
return entry.getValue().orElseThrow(() -> new UnboundVariable(variableId));
}
public void put(Identifier variableId, InterpreterValue value) {
checkVariableIsInScope(variableId);
checkVariableType(variableId, value);
stackFrame.get(variableId).setValue(Optional.of(value));
}
public void put(VariableNode variable, InterpreterValue value) {
put(variable.getDeclaration().getId(), value);
}
public ConcreteType findClass(TypeName className) {
return project.findClass(className);
}
public Environment withStackFrame(Optional<InterpreterValue> thisValue, Map<VariableDeclaration, Optional<InterpreterValue>> stackFrame) {
return new Environment(project, thisValue, stackFrame);
}
private void checkVariableIsInScope(Identifier variableId) {
if (!stackFrame.containsKey(variableId)) {
throw new VariableNotInScope(variableId);
}
}
private void checkVariableType(Identifier variableId, InterpreterValue value) {
TypeName variableType = stackFrame.get(variableId).getType();
InterpreterTypes.checkIsInstance(variableType, value);
}
private static class VariableEntry {
private final TypeName type;
private Optional<InterpreterValue> value;
private VariableEntry(final TypeName type, final Optional<InterpreterValue> value) {
this.type = type;
this.value = value;
}
public static VariableEntry of(final TypeName type, final Optional<InterpreterValue> value) {
return new VariableEntry(type, value);
}
public TypeName getType() {
return this.type;
}
public Optional<InterpreterValue> getValue() {
return this.value;
}
public void setValue(final Optional<InterpreterValue> value) {
this.value = value;
}
}
}
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