Support simple for-loops

5 files changed, 80 insertions, 0 deletions

diff --git a/src/main/java/org/zwobble/couscous/frontends/java/JavaStatementReader.java b/src/main/java/org/zwobble/couscous/frontends/java/JavaStatementReader.java
index a766cce..97a235e 100644
--- a/src/main/java/org/zwobble/couscous/frontends/java/JavaStatementReader.java
+++ b/src/main/java/org/zwobble/couscous/frontends/java/JavaStatementReader.java
@@ -7,6 +7,7 @@ import org.zwobble.couscous.values.BooleanValue;
 import java.util.List;
 import java.util.Optional;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import static java.util.Arrays.asList;
 import static org.zwobble.couscous.ast.ExpressionStatementNode.expressionStatement;
@@ -15,6 +16,8 @@ import static org.zwobble.couscous.ast.WhileNode.whileLoop;
 import static org.zwobble.couscous.frontends.java.JavaExpressionReader.readExpression;
 import static org.zwobble.couscous.frontends.java.JavaExpressionReader.readExpressionWithoutBoxing;
 import static org.zwobble.couscous.frontends.java.JavaTypes.typeOf;
+import static org.zwobble.couscous.util.ExtraLists.append;
+import static org.zwobble.couscous.util.ExtraLists.concat;
 import static org.zwobble.couscous.util.ExtraLists.eagerMap;
 
 class JavaStatementReader {
@@ -41,6 +44,9 @@ class JavaStatementReader {
             case ASTNode.WHILE_STATEMENT:
                 return asList(readWhileStatement((WhileStatement)statement));
 
+            case ASTNode.FOR_STATEMENT:
+                return readForStatement((ForStatement)statement);
+
             case ASTNode.VARIABLE_DECLARATION_STATEMENT:
                 return readVariableDeclarationStatement((VariableDeclarationStatement)statement);
 
@@ -78,10 +84,34 @@ class JavaStatementReader {
             readStatement(statement.getBody()));
     }
 
+    private List<StatementNode> readForStatement(ForStatement statement) {
+        List javaInitialisers = statement.initializers();
+        if (javaInitialisers.size() != 1) {
+            throw new UnsupportedOperationException();
+        }
+        VariableDeclarationExpression javaDeclaration = (VariableDeclarationExpression) javaInitialisers.get(0);
+        @SuppressWarnings("unchecked")
+        List<VariableDeclarationFragment> fragments = javaDeclaration.fragments();
+        @SuppressWarnings("unchecked")
+        List<Expression> updaters = statement.updaters();
+
+        return append(
+            readDeclarationFragments(fragments, typeOf(javaDeclaration.getType())),
+            whileLoop(
+                readExpression(BooleanValue.REF, statement.getExpression()),
+                concat(
+                    readStatement(statement.getBody()),
+                    eagerMap(updaters, updater -> expressionStatement(readExpressionWithoutBoxing(updater))))));
+    }
+
     private static List<StatementNode> readVariableDeclarationStatement(VariableDeclarationStatement statement) {
         @SuppressWarnings("unchecked")
         List<VariableDeclarationFragment> fragments = statement.fragments();
         TypeName type = typeOf(statement.getType());
+        return readDeclarationFragments(fragments, type);
+    }
+
+    private static List<StatementNode> readDeclarationFragments(List<VariableDeclarationFragment> fragments, TypeName type) {
         return eagerMap(fragments, fragment ->
             localVariableDeclaration(
                 fragment.resolveBinding().getKey(),
diff --git a/src/main/java/org/zwobble/couscous/util/ExtraLists.java b/src/main/java/org/zwobble/couscous/util/ExtraLists.java
index be8ffb3..8c282e8 100644
--- a/src/main/java/org/zwobble/couscous/util/ExtraLists.java
+++ b/src/main/java/org/zwobble/couscous/util/ExtraLists.java
@@ -7,6 +7,18 @@ import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
 public class ExtraLists {
+    public static <T> List<T> cons(T value, List<T> list) {
+        return Stream.concat(Stream.of(value), list.stream()).collect(Collectors.toList());
+    }
+
+    public static <T> List<T> append(List<T> list, T value) {
+        return Stream.concat(list.stream(), Stream.of(value)).collect(Collectors.toList());
+    }
+
+    public static <T> List<T> concat(List<T> first, List<T> second) {
+        return Stream.concat(first.stream(), second.stream()).collect(Collectors.toList());
+    }
+
     @SuppressWarnings("unchecked")
     public static <T, R, E extends Exception> List<R> map(
             Stream<T> stream,
diff --git a/src/test/java/org/zwobble/couscous/tests/JavaToPythonTests.java b/src/test/java/org/zwobble/couscous/tests/JavaToPythonTests.java
index f17f42b..8c6c3b1 100644
--- a/src/test/java/org/zwobble/couscous/tests/JavaToPythonTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/JavaToPythonTests.java
@@ -69,6 +69,17 @@ public class JavaToPythonTests {
                 "factorial",
                 asList(value(6))));
     }
+
+    @Test
+    public void forFactorial() throws Exception {
+        assertEquals(
+            value(720),
+            execTestProgram(
+                "for-factorial",
+                TypeName.of("com.example.ForFactorial"),
+                "factorial",
+                asList(value(6))));
+    }
     
     private PrimitiveValue execTestProgram(
             String directoryName,
diff --git a/src/test/java/org/zwobble/couscous/tests/frontends/java/JavaReaderTests.java b/src/test/java/org/zwobble/couscous/tests/frontends/java/JavaReaderTests.java
index ad8bcbb..9d21ed2 100644
--- a/src/test/java/org/zwobble/couscous/tests/frontends/java/JavaReaderTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/frontends/java/JavaReaderTests.java
@@ -24,6 +24,7 @@ import static org.zwobble.couscous.ast.FieldAccessNode.fieldAccess;
 import static org.zwobble.couscous.ast.FieldDeclarationNode.field;
 import static org.zwobble.couscous.ast.IfStatementNode.ifStatement;
 import static org.zwobble.couscous.ast.LiteralNode.literal;
+import static org.zwobble.couscous.ast.LocalVariableDeclarationNode.localVariableDeclaration;
 import static org.zwobble.couscous.ast.MethodCallNode.*;
 import static org.zwobble.couscous.ast.ReturnNode.returns;
 import static org.zwobble.couscous.ast.StaticMethodCallNode.boxBoolean;
@@ -504,6 +505,21 @@ public class JavaReaderTests {
                 asList(returns(literal(1)))),
             readStatement("int", "while (true) { return 1; }"));
     }
+
+    @Test
+    public void canReadForLoops() {
+        List<StatementNode> statements = readStatements("int", "for (int x = 0; true; ++x) { return 1; }");
+        LocalVariableDeclarationNode declaration = (LocalVariableDeclarationNode) statements.get(0);
+        assertEquals(
+            asList(
+                localVariableDeclaration(declaration.getDeclaration(), literal(0)),
+                whileLoop(
+                    literal(true),
+                    asList(
+                        returns(literal(1)),
+                        expressionStatement(assign(declaration, integerAdd(reference(declaration), literal(1))))))),
+            statements);
+    }
     
     @Test
     public void canDeclareConstructor() {
diff --git a/src/test/resources/java/for-factorial/com/example/ForFactorial.java b/src/test/resources/java/for-factorial/com/example/ForFactorial.java
new file mode 100644
index 0000000..a5fef50
--- /dev/null
+++ b/src/test/resources/java/for-factorial/com/example/ForFactorial.java
@@ -0,0 +1,11 @@
+package com.example;
+
+public class ForFactorial {
+    public static int factorial(int n) {
+        int result = 1;
+        for (int i = 2; i <= n; ++i) {
+            result *= i;
+        }
+        return result;
+    }
+}