Ensure unique identifiers for captured variables

2 files changed, 19 insertions, 3 deletions

diff --git a/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java b/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java
index fca7353..84e95e8 100644
--- a/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java
+++ b/src/main/java/org/zwobble/couscous/frontends/java/JavaReader.java
@@ -36,6 +36,7 @@ public class JavaReader {
         return cons(reader.readCompilationUnit(ast), reader.classes.build());
     }
 
+    private final UniqueIdentifiers identifiers = new UniqueIdentifiers();
     private final ImmutableList.Builder<ClassNode> classes;
     private int anonymousClassCount = 0;
 
@@ -105,11 +106,9 @@ public class JavaReader {
     }
 
     private ConstructorNode buildConstructor(TypeName type, List<VariableDeclaration> freeVariables) {
-        // TODO: find a more reliable of generating IDs. For instance, this clashes if
-        // the same variable is captured more than once
         Map<String, VariableDeclaration> argumentDeclarationsById = Maps.transformValues(
             Maps.uniqueIndex(freeVariables, VariableDeclaration::getId),
-            freeVariable -> var(freeVariable.getId() + "__capture", freeVariable.getName(), freeVariable.getType()));
+            freeVariable -> var(identifiers.generate(freeVariable.getId() + "__capture"), freeVariable.getName(), freeVariable.getType()));
         List<FormalArgumentNode> arguments = eagerMap(
             freeVariables,
             freeVariable -> formalArg(argumentDeclarationsById.get(freeVariable.getId())));
diff --git a/src/main/java/org/zwobble/couscous/frontends/java/UniqueIdentifiers.java b/src/main/java/org/zwobble/couscous/frontends/java/UniqueIdentifiers.java
new file mode 100644
index 0000000..1d28de0
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/frontends/java/UniqueIdentifiers.java
@@ -0,0 +1,17 @@
+package org.zwobble.couscous.frontends.java;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class UniqueIdentifiers {
+    private final Map<String, Integer> identifiers;
+
+    public UniqueIdentifiers() {
+        identifiers = new HashMap<>();
+    }
+
+    public String generate(String identifier) {
+        int index = identifiers.computeIfAbsent(identifier, x -> 0);
+        return identifier + "__" + index;
+    }
+}