From bd717883dd37d4e3578c1e46c3dba484b6ad4f79 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Mon, 5 Oct 2015 18:15:10 +0100
Subject: Support String::length in Python backend

---
 .../backends/python/PythonCodeGenerator.java       | 37 ++++++++++++++++------
 .../backends/python/PythonCompilerEvalTests.java   |  9 ------
 2 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java b/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java
index 690375d..023d257 100644
--- a/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java
+++ b/src/main/java/org/zwobble/couscous/backends/python/PythonCodeGenerator.java
@@ -156,20 +156,39 @@ public class PythonCodeGenerator {
 
         @Override
         public PythonExpressionNode visit(MethodCallNode methodCall) {
-            val arguments = methodCall.getArguments().stream()
-                .map(PythonCodeGenerator::generateExpression)
-                .collect(Collectors.toList());
-            return pythonCall(
-                pythonAttributeAccess(
-                    generateExpression(methodCall.getReceiver()),
-                    methodCall.getMethodName()),
-                arguments);
+            if (isPrimitive(methodCall.getReceiver())) {
+                val isStringLength = methodCall.getReceiver().getType().equals(StringValue.REF) &&
+                    methodCall.getMethodName() == "length";
+                if (isStringLength) {
+                    return pythonCall(
+                        pythonVariableReference("len"),
+                        asList(generateExpression(methodCall.getReceiver())));
+                } else {
+                    throw new UnsupportedOperationException();
+                }
+            } else {
+                val arguments = methodCall.getArguments().stream()
+                    .map(PythonCodeGenerator::generateExpression)
+                    .collect(Collectors.toList());
+                return pythonCall(
+                    pythonAttributeAccess(
+                        generateExpression(methodCall.getReceiver()),
+                        methodCall.getMethodName()),
+                    arguments);
+            }
         }
 
         @Override
         public PythonExpressionNode visit(StaticMethodCallNode staticMethodCall) {
             throw new UnsupportedOperationException();
         }
-        
+    }
+
+    private static boolean isPrimitive(ExpressionNode value) {
+        val type = value.getType();
+        return type.equals(IntegerValue.REF) || 
+            type.equals(StringValue.REF) ||
+            type.equals(BooleanValue.REF) ||
+            type.equals(UnitValue.REF);
     }
 }
diff --git a/src/test/java/org/zwobble/couscous/tests/backends/python/PythonCompilerEvalTests.java b/src/test/java/org/zwobble/couscous/tests/backends/python/PythonCompilerEvalTests.java
index ff51f60..6f19eb3 100644
--- a/src/test/java/org/zwobble/couscous/tests/backends/python/PythonCompilerEvalTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/backends/python/PythonCompilerEvalTests.java
@@ -1,7 +1,5 @@
 package org.zwobble.couscous.tests.backends.python;
 
-import org.junit.Ignore;
-import org.junit.Test;
 import org.zwobble.couscous.ast.ClassNode;
 import org.zwobble.couscous.ast.ExpressionNode;
 import org.zwobble.couscous.ast.MethodNode;
@@ -14,13 +12,6 @@ import com.google.common.collect.ImmutableList;
 import lombok.val;
 
 public class PythonCompilerEvalTests extends BackendEvalTests {
-    @Override
-    @Test
-    @Ignore("Work in progress")
-    public void canCallMethodWithNoArgumentsOnBuiltin() {
-        
-    }
-    
     @Override
     protected PrimitiveValue evalExpression(ExpressionNode expression) {
         val runner = new PythonMethodRunner();
-- 
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