Create separate evaluator tests

7 files changed, 48 insertions, 22 deletions

diff --git a/src/main/java/org/zwobble/couscous/ast/Assignment.java b/src/main/java/org/zwobble/couscous/ast/Assignment.java
index aa7f89b..d8bdaaf 100644
--- a/src/main/java/org/zwobble/couscous/ast/Assignment.java
+++ b/src/main/java/org/zwobble/couscous/ast/Assignment.java
@@ -2,10 +2,16 @@ package org.zwobble.couscous.ast;
 
 import org.zwobble.couscous.ast.visitors.ExpressionNodeVisitor;
 
+import static org.zwobble.couscous.ast.VariableReferenceNode.reference;
+
 import lombok.Value;
 
 @Value
 public class Assignment implements ExpressionNode {
+    public static Assignment assign(VariableNode target, ExpressionNode value) {
+        return new Assignment(reference(target), value);
+    }
+    
     VariableReferenceNode target;
     ExpressionNode value;
     
diff --git a/src/main/java/org/zwobble/couscous/ast/LiteralNode.java b/src/main/java/org/zwobble/couscous/ast/LiteralNode.java
index 38688d8..594187d 100644
--- a/src/main/java/org/zwobble/couscous/ast/LiteralNode.java
+++ b/src/main/java/org/zwobble/couscous/ast/LiteralNode.java
@@ -9,7 +9,7 @@ import lombok.Value;
 
 @Value
 public class LiteralNode implements ExpressionNode {
-    public static LiteralNode of(String value) {
+    public static LiteralNode literal(String value) {
         return new LiteralNode(new StringValue(value));
     }
     
diff --git a/src/main/java/org/zwobble/couscous/interpreter/Environment.java b/src/main/java/org/zwobble/couscous/interpreter/Environment.java
index ef91916..a3b3871 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/Environment.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/Environment.java
@@ -1,5 +1,6 @@
 package org.zwobble.couscous.interpreter;
 
+import java.util.HashMap;
 import java.util.Map;
 
 import org.zwobble.couscous.values.InterpreterValue;
@@ -8,7 +9,7 @@ public class Environment {
     private Map<Integer, InterpreterValue> stackFrame;
 
     public Environment(Map<Integer, InterpreterValue> stackFrame) {
-        this.stackFrame = stackFrame;
+        this.stackFrame = new HashMap<>(stackFrame);
     }
 
     public InterpreterValue get(int referentId) {
diff --git a/src/main/java/org/zwobble/couscous/interpreter/Evaluator.java b/src/main/java/org/zwobble/couscous/interpreter/Evaluator.java
index 02acbe3..863ccb0 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/Evaluator.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/Evaluator.java
@@ -10,9 +10,13 @@ import org.zwobble.couscous.values.InterpreterValue;
 import lombok.val;
 
 public class Evaluator implements ExpressionNodeVisitor<InterpreterValue> {
+    public static InterpreterValue eval(Environment environment, ExpressionNode expression) {
+        return new Evaluator(environment).eval(expression);
+    }
+    
     private final Environment environment;
 
-    public Evaluator(Environment environment) {
+    private Evaluator(Environment environment) {
         this.environment = environment;
     }
     
diff --git a/src/main/java/org/zwobble/couscous/interpreter/Interpreter.java b/src/main/java/org/zwobble/couscous/interpreter/Interpreter.java
index d68f4df..bc82fee 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/Interpreter.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/Interpreter.java
@@ -13,6 +13,7 @@ import org.zwobble.couscous.values.InterpreterValue;
 
 import static com.google.common.collect.Iterables.find;
 import static java.util.stream.Collectors.toMap;
+import static org.zwobble.couscous.interpreter.Evaluator.eval;
 import static org.zwobble.couscous.values.UnitValue.UNIT;
 
 import lombok.val;
@@ -31,7 +32,7 @@ public class Interpreter {
         val environment = buildEnvironment(method, arguments);
         
         for (val statement : method.getBody()) {
-            val result = statement.accept(new Executor(new Evaluator(environment)));
+            val result = statement.accept(new Executor(environment));
             if (result.isPresent()) {
                 return result.get();
             }
@@ -56,20 +57,20 @@ public class Interpreter {
     }
     
     private class Executor implements StatementNodeVisitor<Optional<InterpreterValue>> {
-        private Evaluator evaluator;
+        private Environment environment;
 
-        public Executor(Evaluator evaluator) {
-            this.evaluator = evaluator;
+        public Executor(Environment environment) {
+            this.environment = environment;
         }
         
         @Override
         public Optional<InterpreterValue> visit(ReturnNode returnNode) {
-            return Optional.of(evaluator.eval(returnNode.getValue()));
+            return Optional.of(eval(environment, returnNode.getValue()));
         }
 
         @Override
         public Optional<InterpreterValue> visit(ExpressionStatementNode expressionStatement) {
-            evaluator.eval(expressionStatement.getExpression());
+            eval(environment, expressionStatement.getExpression());
             return Optional.empty();
         }
     }
diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
new file mode 100644
index 0000000..075d9b3
--- /dev/null
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
@@ -0,0 +1,25 @@
+package org.zwobble.couscous.tests.interpreter;
+
+import org.junit.Test;
+import org.zwobble.couscous.ast.FormalArgumentNode;
+import org.zwobble.couscous.interpreter.Environment;
+import org.zwobble.couscous.values.StringValue;
+
+import com.google.common.collect.ImmutableMap;
+
+import static org.junit.Assert.assertEquals;
+import static org.zwobble.couscous.ast.Assignment.assign;
+import static org.zwobble.couscous.ast.LiteralNode.literal;
+import static org.zwobble.couscous.interpreter.Evaluator.eval;
+
+import lombok.val;
+
+public class EvaluatorTests {
+    @Test
+    public void valueOfAssignmentExpressionIsNewValue() {
+        val arg = new FormalArgumentNode(42, "x");
+        val environment = new Environment(ImmutableMap.of(arg.getId(), new StringValue("[initial value]")));
+        val result = eval(environment, assign(arg, literal("[updated value]")));
+        assertEquals(new StringValue("[updated value]"), result);
+    }
+}
diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
index d3bc21c..54abd8a 100644
--- a/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
@@ -31,7 +31,7 @@ public class InterpreterTests {
     @Test
     public void canReturnLiteralValue() {
         val method = staticMethod("hello")
-            .statement(new ReturnNode(LiteralNode.of("hello, world!")));
+            .statement(new ReturnNode(LiteralNode.literal("hello, world!")));
         val result = runMethod(method);
         
         assertEquals(new StringValue("hello, world!"), result);
@@ -63,7 +63,7 @@ public class InterpreterTests {
         val arg = new FormalArgumentNode(42, "x");
         val method = staticMethod("hello")
             .argument(arg)
-            .statement(new ExpressionStatementNode(new Assignment(reference(arg), LiteralNode.of("[updated value]"))))
+            .statement(new ExpressionStatementNode(new Assignment(reference(arg), LiteralNode.literal("[updated value]"))))
             .statement(new ReturnNode(reference(arg)));
         val result = runMethod(method, new StringValue("[initial value]"));
         
@@ -71,17 +71,6 @@ public class InterpreterTests {
     }
     
     @Test
-    public void valueOfAssignmentExpressionIsNewValue() {
-        val arg = new FormalArgumentNode(42, "x");
-        val method = staticMethod("hello")
-            .argument(arg)
-            .statement(new ReturnNode(new Assignment(reference(arg), LiteralNode.of("[updated value]"))));
-        val result = runMethod(method, new StringValue("[initial value]"));
-        
-        assertEquals(new StringValue("[updated value]"), result);
-    }
-    
-    @Test
     public void methodWithNoStatementsReturnsUnit() {
         val method = staticMethod("hello");
         val result = runMethod(method);