Add function that checks if Matchers A is subset of Matchers B

Test: bit statsd_test:*
Change-Id: I3ee5ff74cf9f79d104e12e555ff417529cf0f915
diff --git a/cmds/statsd/src/FieldValue.cpp b/cmds/statsd/src/FieldValue.cpp
index 84a0607..82e8cd8 100644
--- a/cmds/statsd/src/FieldValue.cpp
+++ b/cmds/statsd/src/FieldValue.cpp
@@ -435,6 +435,25 @@
     return eq;
 }
 
+bool subsetDimensions(const std::vector<Matcher>& dimension_a,
+                      const std::vector<Matcher>& dimension_b) {
+    if (dimension_a.size() > dimension_b.size()) {
+        return false;
+    }
+    for (size_t i = 0; i < dimension_a.size(); ++i) {
+        bool found = false;
+        for (size_t j = 0; j < dimension_b.size(); ++j) {
+            if (dimension_a[i] == dimension_b[j]) {
+                found = true;
+            }
+        }
+        if (!found) {
+            return false;
+        }
+    }
+    return true;
+}
+
 bool HasPositionANY(const FieldMatcher& matcher) {
     if (matcher.has_position() && matcher.position() == Position::ANY) {
         return true;
diff --git a/cmds/statsd/src/FieldValue.h b/cmds/statsd/src/FieldValue.h
index 0e033e0..6fc1e23 100644
--- a/cmds/statsd/src/FieldValue.h
+++ b/cmds/statsd/src/FieldValue.h
@@ -396,6 +396,10 @@
 
 bool equalDimensions(const std::vector<Matcher>& dimension_a,
                      const std::vector<Matcher>& dimension_b);
+
+// Returns true if dimension_a is a subset of dimension_b.
+bool subsetDimensions(const std::vector<Matcher>& dimension_a,
+                      const std::vector<Matcher>& dimension_b);
 }  // namespace statsd
 }  // namespace os
 }  // namespace android
diff --git a/cmds/statsd/tests/FieldValue_test.cpp b/cmds/statsd/tests/FieldValue_test.cpp
index f1cad92..f4a59ed 100644
--- a/cmds/statsd/tests/FieldValue_test.cpp
+++ b/cmds/statsd/tests/FieldValue_test.cpp
@@ -480,6 +480,137 @@
     EXPECT_EQ(999, atom.num_results());
 }
 
+/*
+ * Test two Matchers is not a subset of one Matcher.
+ * Test one Matcher is subset of two Matchers.
+ */
+TEST(AtomMatcherTest, TestSubsetDimensions1) {
+    // Initialize first set of matchers
+    FieldMatcher matcher1;
+    matcher1.set_field(10);
+
+    FieldMatcher* child = matcher1.add_child();
+    child->set_field(1);
+    child->set_position(Position::ALL);
+    child->add_child()->set_field(1);
+    child->add_child()->set_field(2);
+
+    vector<Matcher> matchers1;
+    translateFieldMatcher(matcher1, &matchers1);
+    EXPECT_EQ(2, matchers1.size());
+
+    // Initialize second set of matchers
+    FieldMatcher matcher2;
+    matcher2.set_field(10);
+
+    child = matcher2.add_child();
+    child->set_field(1);
+    child->set_position(Position::ALL);
+    child->add_child()->set_field(1);
+
+    vector<Matcher> matchers2;
+    translateFieldMatcher(matcher2, &matchers2);
+    EXPECT_EQ(1, matchers2.size());
+
+    EXPECT_FALSE(subsetDimensions(matchers1, matchers2));
+    EXPECT_TRUE(subsetDimensions(matchers2, matchers1));
+}
+/*
+ * Test not a subset with one matching Matcher, one non-matching Matcher.
+ */
+TEST(AtomMatcherTest, TestSubsetDimensions2) {
+    // Initialize first set of matchers
+    FieldMatcher matcher1;
+    matcher1.set_field(10);
+
+    FieldMatcher* child = matcher1.add_child();
+    child->set_field(1);
+
+    child = matcher1.add_child();
+    child->set_field(2);
+
+    vector<Matcher> matchers1;
+    translateFieldMatcher(matcher1, &matchers1);
+
+    // Initialize second set of matchers
+    FieldMatcher matcher2;
+    matcher2.set_field(10);
+
+    child = matcher2.add_child();
+    child->set_field(1);
+
+    child = matcher2.add_child();
+    child->set_field(3);
+
+    vector<Matcher> matchers2;
+    translateFieldMatcher(matcher2, &matchers2);
+
+    EXPECT_FALSE(subsetDimensions(matchers1, matchers2));
+}
+
+/*
+ * Test not a subset if parent field is not equal.
+ */
+TEST(AtomMatcherTest, TestSubsetDimensions3) {
+    // Initialize first set of matchers
+    FieldMatcher matcher1;
+    matcher1.set_field(10);
+
+    FieldMatcher* child = matcher1.add_child();
+    child->set_field(1);
+
+    vector<Matcher> matchers1;
+    translateFieldMatcher(matcher1, &matchers1);
+
+    // Initialize second set of matchers
+    FieldMatcher matcher2;
+    matcher2.set_field(5);
+
+    child = matcher2.add_child();
+    child->set_field(1);
+
+    vector<Matcher> matchers2;
+    translateFieldMatcher(matcher2, &matchers2);
+
+    EXPECT_FALSE(subsetDimensions(matchers1, matchers2));
+}
+
+/*
+ * Test is subset with two matching Matchers.
+ */
+TEST(AtomMatcherTest, TestSubsetDimensions4) {
+    // Initialize first set of matchers
+    FieldMatcher matcher1;
+    matcher1.set_field(10);
+
+    FieldMatcher* child = matcher1.add_child();
+    child->set_field(1);
+
+    child = matcher1.add_child();
+    child->set_field(2);
+
+    vector<Matcher> matchers1;
+    translateFieldMatcher(matcher1, &matchers1);
+
+    // Initialize second set of matchers
+    FieldMatcher matcher2;
+    matcher2.set_field(10);
+
+    child = matcher2.add_child();
+    child->set_field(1);
+
+    child = matcher2.add_child();
+    child->set_field(2);
+
+    child = matcher2.add_child();
+    child->set_field(3);
+
+    vector<Matcher> matchers2;
+    translateFieldMatcher(matcher2, &matchers2);
+
+    EXPECT_TRUE(subsetDimensions(matchers1, matchers2));
+    EXPECT_FALSE(subsetDimensions(matchers2, matchers1));
+}
 
 }  // namespace statsd
 }  // namespace os