Counterproposal to 182733007: Add iterator to SkTDynamicHash

BUG=skia:
R=egdaniel@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/177263005

git-svn-id: http://skia.googlecode.com/svn/trunk@13663 2bbb7eff-a529-9590-31e7-b0007b416f81

src/core/SkTDynamicHash.h

@@ -28,6 +28,33 @@ public:
         sk_free(fArray);
     }
 
+    class Iter {
+    public:
+        explicit Iter(SkTDynamicHash* hash) : fHash(hash), fCurrentIndex(-1) {
+            SkASSERT(hash);
+            ++(*this);
+        }
+        bool done() const {
+            SkASSERT(fCurrentIndex <= fHash->fCapacity);
+            return fCurrentIndex == fHash->fCapacity;
+        }
+        T& operator*() const {
+            SkASSERT(!this->done());
+            return *this->current();
+        }
+        void operator++() {
+            do {
+                fCurrentIndex++;
+            } while (!this->done() && (this->current() == Empty() || this->current() == Deleted()));
+        }
+
+    private:
+        T* current() const { return fHash->fArray[fCurrentIndex]; }
+
+        SkTDynamicHash* fHash;
+        int fCurrentIndex;
+    };
+
     int count() const { return fCount; }
 
     // Return the entry with this key if we have it, otherwise NULL.

tests/DynamicHashTest.cpp

@@ -35,7 +35,7 @@ private:
 
 #define ASSERT(x) REPORTER_ASSERT(reporter, x)
 
-static void test_growth(skiatest::Reporter* reporter) {
+DEF_TEST(DynamicHash_growth, reporter) {
     Entry a = { 1, 2.0 };
     Entry b = { 2, 3.0 };
     Entry c = { 3, 4.0 };
@@ -63,7 +63,7 @@ static void test_growth(skiatest::Reporter* reporter) {
     ASSERT(hash.count() == 5);
 }
 
-static void test_add(skiatest::Reporter* reporter) {
+DEF_TEST(DynamicHash_add, reporter) {
     Hash hash;
     Entry a = { 1, 2.0 };
     Entry b = { 2, 3.0 };
@@ -75,7 +75,7 @@ static void test_add(skiatest::Reporter* reporter) {
     ASSERT(hash.count() == 2);
 }
 
-static void test_lookup(skiatest::Reporter* reporter) {
+DEF_TEST(DynamicHash_lookup, reporter) {
     Hash hash;
 
     // These collide.
@@ -110,7 +110,7 @@ static void test_lookup(skiatest::Reporter* reporter) {
     ASSERT(hash.find(9) == NULL);
 }
 
-static void test_remove(skiatest::Reporter* reporter) {
+DEF_TEST(DynamicHash_remove, reporter) {
     Hash hash;
 
     // These collide.
@@ -136,9 +136,51 @@ static void test_remove(skiatest::Reporter* reporter) {
     ASSERT(hash.find(5)->value == 3.0);
 }
 
-DEF_TEST(DynamicHash, reporter) {
-    test_growth(reporter);
-    test_add(reporter);
-    test_lookup(reporter);
-    test_remove(reporter);
+DEF_TEST(DynamicHash_iterator, reporter) {
+    Hash hash;
+
+    int count = 0;
+    // this should fall out of loop immediately
+    for (Hash::Iter iter(&hash); !iter.done(); ++iter) {
+        ++count;
+    }
+    ASSERT(0 == count);
+
+    // These collide.
+    Entry a = { 1, 2.0 };
+    Entry b = { 5, 3.0 };
+    Entry c = { 9, 4.0 };
+
+    hash.add(&a);
+    hash.add(&b);
+    hash.add(&c);
+
+    // should see all 3 unique keys when iterating over hash
+    count = 0;
+    int keys[3] = {0, 0, 0};
+    for (Hash::Iter iter(&hash); !iter.done(); ++iter) {
+        int key = (*iter).key;
+        keys[count] = key;
+        ASSERT(hash.find(key) != NULL);
+        ++count;
+    }
+    ASSERT(3 == count);
+    ASSERT(keys[0] != keys[1]);
+    ASSERT(keys[0] != keys[2]);
+    ASSERT(keys[1] != keys[2]);
+
+    // should see 2 unique keys when iterating over hash that aren't 1
+    hash.remove(1);
+    count = 0;
+    memset(keys,0,sizeof(keys));
+    for (Hash::Iter iter(&hash); !iter.done(); ++iter) {
+        int key = (*iter).key;
+        keys[count] = key;
+        ASSERT(key != 1);
+        ASSERT(hash.find(key) != NULL);
+        ++count;
+    }
+    ASSERT(2 == count);
+    ASSERT(keys[0] != keys[1]);
 }
+