From 467e46c3027b55d3d5e5157b44415e1de6ced461 Mon Sep 17 00:00:00 2001
From: Lovro Lugovic <lovro.lugovic@memgraph.io>
Date: Thu, 11 Oct 2018 13:39:36 +0200
Subject: [PATCH] Add inDegree and outDegree functions

Reviewers: teon.banek, mtomic

Reviewed By: mtomic

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1651
---
 .../interpret/awesome_memgraph_functions.cpp  | 38 +++++++++++++++++++
 tests/unit/query_expression_evaluator.cpp     | 30 +++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/src/query/interpret/awesome_memgraph_functions.cpp b/src/query/interpret/awesome_memgraph_functions.cpp
index afdbc222f..2cd292b1d 100644
--- a/src/query/interpret/awesome_memgraph_functions.cpp
+++ b/src/query/interpret/awesome_memgraph_functions.cpp
@@ -182,6 +182,42 @@ TypedValue Degree(TypedValue *args, int64_t nargs, const EvaluationContext &,
   }
 }
 
+TypedValue InDegree(TypedValue *args, int64_t nargs, const EvaluationContext &,
+                    database::GraphDbAccessor *) {
+  if (nargs != 1) {
+    throw QueryRuntimeException("'inDegree' requires exactly one argument.");
+  }
+
+  switch (args[0].type()) {
+    case TypedValue::Type::Null:
+      return TypedValue::Null;
+    case TypedValue::Type::Vertex: {
+      auto &vertex = args[0].Value<VertexAccessor>();
+      return static_cast<int64_t>(vertex.in_degree());
+    }
+    default:
+      throw QueryRuntimeException("'inDegree' argument must be a node.");
+  }
+}
+
+TypedValue OutDegree(TypedValue *args, int64_t nargs, const EvaluationContext &,
+                     database::GraphDbAccessor *) {
+  if (nargs != 1) {
+    throw QueryRuntimeException("'outDegree' requires exactly one argument.");
+  }
+
+  switch (args[0].type()) {
+    case TypedValue::Type::Null:
+      return TypedValue::Null;
+    case TypedValue::Type::Vertex: {
+      auto &vertex = args[0].Value<VertexAccessor>();
+      return static_cast<int64_t>(vertex.out_degree());
+    }
+    default:
+      throw QueryRuntimeException("'outDegree' argument must be a node.");
+  }
+}
+
 TypedValue ToBoolean(TypedValue *args, int64_t nargs, const EvaluationContext &,
                      database::GraphDbAccessor *) {
   if (nargs != 1) {
@@ -853,6 +889,8 @@ NameToFunction(const std::string &function_name) {
   // Scalar functions
   if (function_name == "COALESCE") return Coalesce;
   if (function_name == "DEGREE") return Degree;
+  if (function_name == "INDEGREE") return InDegree;
+  if (function_name == "OUTDEGREE") return OutDegree;
   if (function_name == "ENDNODE") return EndNode;
   if (function_name == "HEAD") return Head;
   if (function_name == "ID") return Id;
diff --git a/tests/unit/query_expression_evaluator.cpp b/tests/unit/query_expression_evaluator.cpp
index a544f0f44..71a7e52f0 100644
--- a/tests/unit/query_expression_evaluator.cpp
+++ b/tests/unit/query_expression_evaluator.cpp
@@ -999,6 +999,36 @@ TEST_F(FunctionTest, Degree) {
   ASSERT_THROW(EvaluateFunction("DEGREE", {e12}), QueryRuntimeException);
 }
 
+TEST_F(FunctionTest, InDegree) {
+  ASSERT_THROW(EvaluateFunction("INDEGREE", {}), QueryRuntimeException);
+  ASSERT_TRUE(EvaluateFunction("INDEGREE", {TypedValue::Null}).IsNull());
+  auto v1 = dba->InsertVertex();
+  auto v2 = dba->InsertVertex();
+  auto v3 = dba->InsertVertex();
+  auto e12 = dba->InsertEdge(v1, v2, dba->EdgeType("t"));
+  dba->InsertEdge(v3, v2, dba->EdgeType("t"));
+  ASSERT_EQ(EvaluateFunction("INDEGREE", {v1}).ValueInt(), 0);
+  ASSERT_EQ(EvaluateFunction("INDEGREE", {v2}).ValueInt(), 2);
+  ASSERT_EQ(EvaluateFunction("INDEGREE", {v3}).ValueInt(), 0);
+  ASSERT_THROW(EvaluateFunction("INDEGREE", {2}), QueryRuntimeException);
+  ASSERT_THROW(EvaluateFunction("INDEGREE", {e12}), QueryRuntimeException);
+}
+
+TEST_F(FunctionTest, OutDegree) {
+  ASSERT_THROW(EvaluateFunction("OUTDEGREE", {}), QueryRuntimeException);
+  ASSERT_TRUE(EvaluateFunction("OUTDEGREE", {TypedValue::Null}).IsNull());
+  auto v1 = dba->InsertVertex();
+  auto v2 = dba->InsertVertex();
+  auto v3 = dba->InsertVertex();
+  auto e12 = dba->InsertEdge(v1, v2, dba->EdgeType("t"));
+  dba->InsertEdge(v3, v2, dba->EdgeType("t"));
+  ASSERT_EQ(EvaluateFunction("OUTDEGREE", {v1}).ValueInt(), 1);
+  ASSERT_EQ(EvaluateFunction("OUTDEGREE", {v2}).ValueInt(), 0);
+  ASSERT_EQ(EvaluateFunction("OUTDEGREE", {v3}).ValueInt(), 1);
+  ASSERT_THROW(EvaluateFunction("OUTDEGREE", {2}), QueryRuntimeException);
+  ASSERT_THROW(EvaluateFunction("OUTDEGREE", {e12}), QueryRuntimeException);
+}
+
 TEST_F(FunctionTest, ToBoolean) {
   ASSERT_THROW(EvaluateFunction("TOBOOLEAN", {}), QueryRuntimeException);
   ASSERT_TRUE(EvaluateFunction("TOBOOLEAN", {TypedValue::Null}).IsNull());