From 86ac5d4b2d510ebf7ca2d74e59a94a839e686fb0 Mon Sep 17 00:00:00 2001
From: Stefano Cossu <stefano@cossu.cc>
Date: Mon, 21 Feb 2022 17:47:30 -0800
Subject: [PATCH 1/4] Add hashmap_iter function.

---
 hashmap.c | 39 +++++++++++++++++++++++++++++++++++++++
 hashmap.h |  1 +
 2 files changed, 40 insertions(+)

diff --git a/hashmap.c b/hashmap.c
index b05231e..3547cb1 100644
--- a/hashmap.c
+++ b/hashmap.c
@@ -408,6 +408,38 @@ bool hashmap_scan(struct hashmap *map,
     return true;
 }
 
+
+// hashmap_iter iterates one key at a time yielding a reference to an
+// entry at each iteration. Useful to write simple loops and avoid writing
+// dedicated callbacks and udata structures, as in hashmap_scan.
+//
+// map is a hash map handle. i is a pointer to a size_t cursor that
+// should be initialized to 0 at the beginning of the loop. item is a void
+// pointer pointer that is populated with the retrieved item. Note that this
+// is NOT a copy of the item stored in the hash map and can be directly
+// modified.
+//
+// This function has not been tested for thread safety.
+//
+// The function returns true if an item was retrieved; false if the end of the
+// iteration has been reached.
+bool hashmap_iter(struct hashmap *map, size_t *i, void **item)
+{
+    struct bucket *bucket;
+
+    do {
+        if (*i >= map->nbuckets) return false;
+
+        bucket = bucket_at(map, *i);
+        *i++;
+    } while (!bucket->dib);
+
+    *item = bucket_item(bucket);
+
+    return true;
+}
+
+
 //-----------------------------------------------------------------------------
 // SipHash reference C implementation
 //
@@ -738,6 +770,13 @@ static void all() {
     while (!(vals2 = xmalloc(N * sizeof(int)))) {}
     memset(vals2, 0, N * sizeof(int));
     assert(hashmap_scan(map, iter_ints, &vals2));
+
+    // Test hashmap_iter. This does the same as hashmap_scan above.
+    size_t iter = 0;
+    void *iter_val;
+    while (hashmap_iter (map, &iter, &iter_val)) {
+        assert (iter_ints(iter_val, &vals2));
+    }
     for (int i = 0; i < N; i++) {
         assert(vals2[i] == 1);
     }
diff --git a/hashmap.h b/hashmap.h
index d5cb64a..95eb659 100644
--- a/hashmap.h
+++ b/hashmap.h
@@ -41,6 +41,7 @@ void *hashmap_delete(struct hashmap *map, void *item);
 void *hashmap_probe(struct hashmap *map, uint64_t position);
 bool hashmap_scan(struct hashmap *map,
                   bool (*iter)(const void *item, void *udata), void *udata);
+bool hashmap_iter(struct hashmap *map, size_t *i, void **item);
 
 uint64_t hashmap_sip(const void *data, size_t len, 
                      uint64_t seed0, uint64_t seed1);

From 774694ec6dd36f1bb8e5fd3a55a2c47e48295e21 Mon Sep 17 00:00:00 2001
From: Stefano Cossu <stefano@cossu.cc>
Date: Mon, 7 Mar 2022 20:38:21 -0800
Subject: [PATCH 2/4] Correct cursor increase.

---
 hashmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hashmap.c b/hashmap.c
index 3547cb1..faa88c8 100644
--- a/hashmap.c
+++ b/hashmap.c
@@ -431,7 +431,7 @@ bool hashmap_iter(struct hashmap *map, size_t *i, void **item)
         if (*i >= map->nbuckets) return false;
 
         bucket = bucket_at(map, *i);
-        *i++;
+        (*i)++;
     } while (!bucket->dib);
 
     *item = bucket_item(bucket);

From cdd1eff2eecd1b95fd3b2384b08bfaf18e10b0ef Mon Sep 17 00:00:00 2001
From: Stefano Cossu <stefano@cossu.cc>
Date: Fri, 18 Mar 2022 09:43:55 -0700
Subject: [PATCH 3/4] Add comment about hashmap_delete.

---
 hashmap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hashmap.c b/hashmap.c
index faa88c8..fa21374 100644
--- a/hashmap.c
+++ b/hashmap.c
@@ -248,7 +248,7 @@ static bool resize(struct hashmap *map, size_t new_cap) {
 // replaced then it is returned otherwise NULL is returned. This operation
 // may allocate memory. If the system is unable to allocate additional
 // memory then NULL is returned and hashmap_oom() returns true.
-void *hashmap_set(struct hashmap *map, void *item) {
+void *hashmap_set(struct hashmap *map, const void *item) {
     if (!item) {
         panic("item is null");
     }
@@ -419,6 +419,10 @@ bool hashmap_scan(struct hashmap *map,
 // is NOT a copy of the item stored in the hash map and can be directly
 // modified.
 //
+// Note that if hashmap_delete() is called on the hashmap being iterated,
+// the buckets are rearranged and the iterator must be reset to 0, otherwise
+// unexpected results may be returned after deletion.
+//
 // This function has not been tested for thread safety.
 //
 // The function returns true if an item was retrieved; false if the end of the

From d9b23a5a4df7e572ec897357292cf377eca9b229 Mon Sep 17 00:00:00 2001
From: Stefano Cossu <stefano@cossu.cc>
Date: Fri, 18 Mar 2022 09:56:42 -0700
Subject: [PATCH 4/4] Remove unintended signature change.

---
 hashmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hashmap.c b/hashmap.c
index fa21374..4b97cce 100644
--- a/hashmap.c
+++ b/hashmap.c
@@ -248,7 +248,7 @@ static bool resize(struct hashmap *map, size_t new_cap) {
 // replaced then it is returned otherwise NULL is returned. This operation
 // may allocate memory. If the system is unable to allocate additional
 // memory then NULL is returned and hashmap_oom() returns true.
-void *hashmap_set(struct hashmap *map, const void *item) {
+void *hashmap_set(struct hashmap *map, void *item) {
     if (!item) {
         panic("item is null");
     }