Throw error on wrong number of arguments

5 files changed, 41 insertions, 29 deletions

diff --git a/src/main/java/org/zwobble/couscous/interpreter/Arguments.java b/src/main/java/org/zwobble/couscous/interpreter/Arguments.java
index d08393d..af674a1 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/Arguments.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/Arguments.java
@@ -4,26 +4,14 @@ import java.util.List;
 
 import org.zwobble.couscous.values.InterpreterValue;
 
-import lombok.val;
-
 public class Arguments {
-    private int index = 0;
     private List<InterpreterValue> values;
     
     public Arguments(List<InterpreterValue> values) {
         this.values = values;
     }
-
-    @SuppressWarnings("unchecked")
-    public <T extends InterpreterValue> T pop(Class<T> valueType) {
-        val value = values.get(index);
-        index++;
-        if (valueType.isInstance(value)) {
-            return (T) value;            
-        } else {
-            // TODO: throw a more specific error
-            throw new UnsupportedOperationException();
-        }
-        
+    
+    public InterpreterValue get(int index) {
+        return values.get(index);
     }
 }
diff --git a/src/main/java/org/zwobble/couscous/values/ConcreteType.java b/src/main/java/org/zwobble/couscous/values/ConcreteType.java
index c3ead74..ef6665e 100644
--- a/src/main/java/org/zwobble/couscous/values/ConcreteType.java
+++ b/src/main/java/org/zwobble/couscous/values/ConcreteType.java
@@ -6,6 +6,7 @@ import java.util.function.BiFunction;
 
 import org.zwobble.couscous.interpreter.Arguments;
 import org.zwobble.couscous.interpreter.NoSuchMethod;
+import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
 
 import com.google.common.collect.ImmutableMap;
 
@@ -13,11 +14,14 @@ import lombok.val;
 
 public class ConcreteType<T> {
     public static class Builder<T> {
-        private final ImmutableMap.Builder<String, BiFunction<T, Arguments, InterpreterValue>> methods =
+        private final ImmutableMap.Builder<String, MethodValue<T>> methods =
             ImmutableMap.builder();
         
-        public Builder<T> method(String name, BiFunction<T, Arguments, InterpreterValue> method) {
-            methods.put(name, method);
+        public Builder<T> method(
+                String name,
+                List<ConcreteType<?>> argumentsTypes,
+                BiFunction<T, Arguments, InterpreterValue> method) {
+            methods.put(name, new MethodValue<T>(argumentsTypes, method));
             return this;
         }
         
@@ -26,9 +30,9 @@ public class ConcreteType<T> {
         }
     }
 
-    private Map<String, BiFunction<T, Arguments, InterpreterValue>> methods;
+    private Map<String, MethodValue<T>> methods;
 
-    public ConcreteType(Map<String, BiFunction<T, Arguments, InterpreterValue>> methods) {
+    public ConcreteType(Map<String, MethodValue<T>> methods) {
         this.methods = methods;
     }
 
@@ -41,6 +45,9 @@ public class ConcreteType<T> {
             throw new NoSuchMethod(methodName);
         }
         val method = methods.get(methodName);
+        if (method.getArgumentTypes().size() != arguments.size()) {
+            throw new WrongNumberOfArguments(method.getArgumentTypes().size(), arguments.size());
+        }
         return method.apply((T)receiver, new Arguments(arguments));
     }
 }
diff --git a/src/main/java/org/zwobble/couscous/values/IntegerValue.java b/src/main/java/org/zwobble/couscous/values/IntegerValue.java
index eb7031d..8b5b423 100644
--- a/src/main/java/org/zwobble/couscous/values/IntegerValue.java
+++ b/src/main/java/org/zwobble/couscous/values/IntegerValue.java
@@ -4,7 +4,7 @@ import lombok.Value;
 
 @Value
 public class IntegerValue implements InterpreterValue {
-    private static final ConcreteType<?> TYPE = ConcreteType.<IntegerValue>builder()
+    public static final ConcreteType<?> TYPE = ConcreteType.<IntegerValue>builder()
         .build();
     
     int value;
diff --git a/src/main/java/org/zwobble/couscous/values/MethodValue.java b/src/main/java/org/zwobble/couscous/values/MethodValue.java
index 38ef1d5..fe23f94 100644
--- a/src/main/java/org/zwobble/couscous/values/MethodValue.java
+++ b/src/main/java/org/zwobble/couscous/values/MethodValue.java
@@ -1,7 +1,21 @@
 package org.zwobble.couscous.values;
 
 import java.util.List;
+import java.util.function.BiFunction;
 
-public interface MethodValue {
-    InterpreterValue call(List<InterpreterValue> arguments);
+import org.zwobble.couscous.interpreter.Arguments;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.Value;
+
+@Value
+public class MethodValue<T> {
+    List<ConcreteType<?>> argumentTypes;
+    @Getter(value=AccessLevel.NONE)
+    BiFunction<T, Arguments, InterpreterValue> apply;
+    
+    public InterpreterValue apply(T receiver, Arguments arguments) {
+        return apply.apply(receiver, arguments);
+    }
 }
diff --git a/src/main/java/org/zwobble/couscous/values/StringValue.java b/src/main/java/org/zwobble/couscous/values/StringValue.java
index da45f02..2d4bf17 100644
--- a/src/main/java/org/zwobble/couscous/values/StringValue.java
+++ b/src/main/java/org/zwobble/couscous/values/StringValue.java
@@ -1,18 +1,21 @@
 package org.zwobble.couscous.values;
 
+import static java.util.Arrays.asList;
+
 import lombok.Value;
 import lombok.val;
 
 @Value
 public class StringValue implements InterpreterValue {
     private static final ConcreteType<?> TYPE = ConcreteType.<StringValue>builder()
-        .method("length", (receiver, arguments) -> new IntegerValue(receiver.value.length()))
+        .method("length", asList(), (receiver, arguments) -> new IntegerValue(receiver.value.length()))
         
-        .method("substring", (receiver, arguments) -> {
-            val startIndex = arguments.pop(IntegerValue.class);
-            val endIndex = arguments.pop(IntegerValue.class);
-            return new StringValue(receiver.value.substring(startIndex.getValue(), endIndex.getValue()));
-        })
+        .method("substring", asList(IntegerValue.TYPE, IntegerValue.TYPE),
+            (receiver, arguments) -> {
+                val startIndex = (IntegerValue)arguments.get(0);
+                val endIndex = (IntegerValue)arguments.get(1);
+                return new StringValue(receiver.value.substring(startIndex.getValue(), endIndex.getValue()));
+            })
         
         .build();