From 32da7cf2343ddc49f0764c923ae6d252fcd02c53 Mon Sep 17 00:00:00 2001
From: "Aaron L. Zeng" <a2z@mit.edu>
Date: Thu, 21 Sep 2017 16:42:09 -0400
Subject: [PATCH] Consistently implement Iterable<T>

---
 src/java/simpledb/Catalog.java   | 7 +++++--
 src/java/simpledb/HeapPage.java  | 2 +-
 src/java/simpledb/Tuple.java     | 4 ++--
 src/java/simpledb/TupleDesc.java | 2 +-
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/java/simpledb/Catalog.java b/src/java/simpledb/Catalog.java
index a39128f..c9fa051 100644
--- a/src/java/simpledb/Catalog.java
+++ b/src/java/simpledb/Catalog.java
@@ -16,7 +16,7 @@
  * 
  * @Threadsafe
  */
-public class Catalog {
+public class Catalog implements Iterable<Integer> {
 
     /**
      * Constructor.
@@ -90,7 +90,10 @@ public String getPrimaryKey(int tableid) {
         return null;
     }
 
-    public Iterator<Integer> tableIdIterator() {
+    /**
+     * Returns an Iterator over the table IDs in this Catalog.
+     */
+    public Iterator<Integer> iterator() {
         // some code goes here
         return null;
     }
diff --git a/src/java/simpledb/HeapPage.java b/src/java/simpledb/HeapPage.java
index 5befb41..95183a7 100644
--- a/src/java/simpledb/HeapPage.java
+++ b/src/java/simpledb/HeapPage.java
@@ -11,7 +11,7 @@
  * @see BufferPool
  *
  */
-public class HeapPage implements Page {
+public class HeapPage implements Page, Iterable<Tuple> {
 
     final HeapPageId pid;
     final TupleDesc td;
diff --git a/src/java/simpledb/Tuple.java b/src/java/simpledb/Tuple.java
index e18c0c0..de66c1d 100644
--- a/src/java/simpledb/Tuple.java
+++ b/src/java/simpledb/Tuple.java
@@ -9,7 +9,7 @@
  * specified schema specified by a TupleDesc object and contain Field objects
  * with the data for each field.
  */
-public class Tuple implements Serializable {
+public class Tuple implements Serializable, Iterable<Field> {
 
     private static final long serialVersionUID = 1L;
 
@@ -91,7 +91,7 @@ public String toString() {
      * @return
      *        An iterator which iterates over all the fields of this tuple
      * */
-    public Iterator<Field> fields()
+    public Iterator<Field> iterator()
     {
         // some code goes here
         return null;
diff --git a/src/java/simpledb/TupleDesc.java b/src/java/simpledb/TupleDesc.java
index 5e3d665..e2eeeb9 100644
--- a/src/java/simpledb/TupleDesc.java
+++ b/src/java/simpledb/TupleDesc.java
@@ -6,7 +6,7 @@
 /**
  * TupleDesc describes the schema of a tuple.
  */
-public class TupleDesc implements Serializable {
+public class TupleDesc implements Serializable, Iterable<TDItem> {
 
     /**
      * A help class to facilitate organizing the information of each field