Use slice syntax instead of __getitem__

4 files changed, 38 insertions, 8 deletions

diff --git a/src/main/java/org/zwobble/couscous/backends/python/PrimitiveMethods.java b/src/main/java/org/zwobble/couscous/backends/python/PrimitiveMethods.java
index 32d4272..67f66ea 100644
--- a/src/main/java/org/zwobble/couscous/backends/python/PrimitiveMethods.java
+++ b/src/main/java/org/zwobble/couscous/backends/python/PrimitiveMethods.java
@@ -11,8 +11,8 @@ import org.zwobble.couscous.values.TypeReference;
 import com.google.common.collect.ImmutableMap;
 
 import static java.util.Arrays.asList;
-import static org.zwobble.couscous.backends.python.ast.PythonAttributeAccessNode.pythonAttributeAccess;
 import static org.zwobble.couscous.backends.python.ast.PythonCallNode.pythonCall;
+import static org.zwobble.couscous.backends.python.ast.PythonGetSliceNode.pythonGetSlice;
 import static org.zwobble.couscous.backends.python.ast.PythonVariableReferenceNode.pythonVariableReference;
 
 public class PrimitiveMethods {
@@ -25,13 +25,7 @@ public class PrimitiveMethods {
                     asList(receiver)))
             
             .put("substring", (receiver, arguments) ->
-                pythonCall(
-                    pythonAttributeAccess(
-                        receiver,
-                        "__getitem__"),
-                    asList(pythonCall(
-                        pythonVariableReference("slice"),
-                        arguments))))
+                pythonGetSlice(receiver, arguments))
             
             .build();
     
diff --git a/src/main/java/org/zwobble/couscous/backends/python/PythonSerializer.java b/src/main/java/org/zwobble/couscous/backends/python/PythonSerializer.java
index 1e10315..abab1bf 100644
--- a/src/main/java/org/zwobble/couscous/backends/python/PythonSerializer.java
+++ b/src/main/java/org/zwobble/couscous/backends/python/PythonSerializer.java
@@ -9,6 +9,7 @@ import org.zwobble.couscous.backends.python.ast.PythonClassNode;
 import org.zwobble.couscous.backends.python.ast.PythonConditionalExpressionNode;
 import org.zwobble.couscous.backends.python.ast.PythonExpressionNode;
 import org.zwobble.couscous.backends.python.ast.PythonFunctionDefinitionNode;
+import org.zwobble.couscous.backends.python.ast.PythonGetSliceNode;
 import org.zwobble.couscous.backends.python.ast.PythonIntegerLiteralNode;
 import org.zwobble.couscous.backends.python.ast.PythonModuleNode;
 import org.zwobble.couscous.backends.python.ast.PythonNode;
@@ -96,6 +97,21 @@ public class PythonSerializer implements PythonNodeVisitor {
     }
 
     @Override
+    public void visit(PythonGetSliceNode getSlice) {
+        writeParenthesised(getSlice.getReceiver());
+        writer.writeSymbol("[");
+        // TODO: remove this duplication
+        if (!getSlice.getArguments().isEmpty()) {
+            write(getSlice.getArguments().get(0));
+            for (val argumentName : skip(getSlice.getArguments(), 1)) {
+                writer.writeSymbol(":");
+                write(argumentName);
+            }
+        }
+        writer.writeSymbol("]");
+    }
+
+    @Override
     public void visit(PythonReturnNode pythonReturn) {
         writer.writeStatement(() -> {
             writer.writeKeyword("return");
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonGetSliceNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonGetSliceNode.java
new file mode 100644
index 0000000..27c191e
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonGetSliceNode.java
@@ -0,0 +1,18 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import java.util.List;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonGetSlice")
+public class PythonGetSliceNode implements PythonExpressionNode {
+    PythonExpressionNode receiver;
+    List<PythonExpressionNode> arguments;
+    
+    @Override
+    public void accept(PythonNodeVisitor visitor) {
+        visitor.visit(this);
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java b/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java
index 2e38d3b..29d6108 100644
--- a/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java
@@ -7,6 +7,7 @@ import org.zwobble.couscous.backends.python.ast.PythonCallNode;
 import org.zwobble.couscous.backends.python.ast.PythonClassNode;
 import org.zwobble.couscous.backends.python.ast.PythonConditionalExpressionNode;
 import org.zwobble.couscous.backends.python.ast.PythonFunctionDefinitionNode;
+import org.zwobble.couscous.backends.python.ast.PythonGetSliceNode;
 import org.zwobble.couscous.backends.python.ast.PythonIntegerLiteralNode;
 import org.zwobble.couscous.backends.python.ast.PythonModuleNode;
 import org.zwobble.couscous.backends.python.ast.PythonPassNode;
@@ -22,6 +23,7 @@ public interface PythonNodeVisitor {
     void visit(PythonConditionalExpressionNode conditional);
     void visit(PythonAttributeAccessNode attributeAccess);
     void visit(PythonCallNode call);
+    void visit(PythonGetSliceNode getSlice);
     
     void visit(PythonReturnNode pythonReturn);
     void visit(PythonPassNode pass);