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package org.zwobble.couscous.tests.interpreter;
import java.util.Map;
import org.junit.Test;
import org.zwobble.couscous.Project;
import org.zwobble.couscous.ast.Assignment;
import org.zwobble.couscous.ast.ClassNode;
import org.zwobble.couscous.ast.ExpressionStatementNode;
import org.zwobble.couscous.ast.FormalArgumentNode;
import org.zwobble.couscous.ast.LiteralNode;
import org.zwobble.couscous.ast.MethodNode;
import org.zwobble.couscous.ast.ReturnNode;
import org.zwobble.couscous.interpreter.Interpreter;
import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
import org.zwobble.couscous.values.InterpreterValue;
import org.zwobble.couscous.values.StringValue;
import com.google.common.collect.ImmutableMap;
import static java.util.Arrays.asList;
import static org.junit.Assert.assertEquals;
import static org.zwobble.couscous.ast.MethodNode.staticMethod;
import static org.zwobble.couscous.ast.VariableReferenceNode.reference;
import static org.zwobble.couscous.tests.util.ExtraAsserts.assertThrows;
import static org.zwobble.couscous.values.UnitValue.UNIT;
import lombok.val;
public class InterpreterTests {
@Test
public void methodWithNoStatementsReturnsUnit() {
val method = staticMethod("hello");
val result = runMethod(method);
assertEquals(UNIT, result);
}
@Test
public void canReturnLiteralValue() {
val method = staticMethod("hello")
.statement(new ReturnNode(LiteralNode.literal("hello, world!")));
val result = runMethod(method);
assertEquals(new StringValue("hello, world!"), result);
}
@Test
public void canPassValueToMethod() {
val arg = new FormalArgumentNode(42, "x");
val method = staticMethod("hello")
.argument(arg)
.statement(new ReturnNode(reference(arg)));
val result = runMethod(method, new StringValue("hello, world!"));
assertEquals(new StringValue("hello, world!"), result);
}
@Test
public void errorIfWrongNumberOfArgumentsArePassed() {
val method = staticMethod("hello");
val exception = assertThrows(WrongNumberOfArguments.class,
() -> runMethod(method, new StringValue("hello, world!")));
assertEquals(new WrongNumberOfArguments(0, 1), exception);
}
@Test
public void canReassignValueToArgument() {
val arg = new FormalArgumentNode(42, "x");
val method = staticMethod("hello")
.argument(arg)
.statement(new ExpressionStatementNode(new Assignment(reference(arg), LiteralNode.literal("[updated value]"))))
.statement(new ReturnNode(reference(arg)));
val result = runMethod(method, new StringValue("[initial value]"));
assertEquals(new StringValue("[updated value]"), result);
}
private InterpreterValue runMethod(MethodNode.MethodNodeBuilder methodBuilder, InterpreterValue... arguments) {
val method = methodBuilder.build();
val classNode = ClassNode.builder()
.method(method)
.build();
val className = "com.example.Program";
val interpreter = new Interpreter(new MapBackedProject(ImmutableMap.of(
className, classNode)));
return interpreter.run(className, method.getName(), asList(arguments));
}
private static class MapBackedProject implements Project {
private Map<String, ClassNode> classes;
public MapBackedProject(Map<String, ClassNode> classes) {
this.classes = classes;
}
@Override
public ClassNode findClass(String name) {
return classes.get(name);
}
}
}
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