From c24014662051e2fc6740e4c291f26210e1bfcf37 Mon Sep 17 00:00:00 2001
From: Anderson Silva <joyle@outlook.com>
Date: Wed, 12 Jun 2024 18:48:10 -0500
Subject: [PATCH] Public API to get list of functions call (#2474)

Issue https://github.com/microsoft/Power-Fx/issues/2455.
---
 .../Public/CheckResult.cs                     |  5 ++
 .../Syntax/Visitors/ListFunctionVisitor.cs    | 35 +++++++++++
 .../ListFunctionVisitorTests.cs               | 63 +++++++++++++++++++
 3 files changed, 103 insertions(+)
 create mode 100644 src/libraries/Microsoft.PowerFx.Core/Syntax/Visitors/ListFunctionVisitor.cs
 create mode 100644 src/tests/Microsoft.PowerFx.Core.Tests.Shared/ListFunctionVisitorTests.cs

diff --git a/src/libraries/Microsoft.PowerFx.Core/Public/CheckResult.cs b/src/libraries/Microsoft.PowerFx.Core/Public/CheckResult.cs
index f5db126d0f..b98ec1fdc3 100644
--- a/src/libraries/Microsoft.PowerFx.Core/Public/CheckResult.cs
+++ b/src/libraries/Microsoft.PowerFx.Core/Public/CheckResult.cs
@@ -706,6 +706,11 @@ public CheckContextSummary ApplyGetContextSummary()
 
             return summary;
         }
+
+        public IEnumerable<string> GetFunctionNames()
+        {
+            return ListFunctionVisitor.Run(ApplyParse());
+        }
     }
 
     // Internal interface to ensure that Result objects have a common contract
diff --git a/src/libraries/Microsoft.PowerFx.Core/Syntax/Visitors/ListFunctionVisitor.cs b/src/libraries/Microsoft.PowerFx.Core/Syntax/Visitors/ListFunctionVisitor.cs
new file mode 100644
index 0000000000..e98256a62f
--- /dev/null
+++ b/src/libraries/Microsoft.PowerFx.Core/Syntax/Visitors/ListFunctionVisitor.cs
@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+using System.Collections.Generic;
+
+namespace Microsoft.PowerFx.Syntax
+{
+    internal class ListFunctionVisitor : IdentityTexlVisitor
+    {
+        // FullName --> Name 
+        // Use Fullname as key because it's unique. 
+        private readonly HashSet<string> _functionNames = new HashSet<string>();
+
+        public static IEnumerable<string> Run(ParseResult parse)
+        {
+            var visitor = new ListFunctionVisitor();
+            parse.Root.Accept(visitor);
+            return visitor._functionNames;
+        }
+
+        public override bool PreVisit(CallNode node)
+        {
+            var hasNamespace = node.Head.Namespace.Length > 0;
+
+            var name = node.Head.Name;
+            var fullName = hasNamespace ?
+                    node.Head.Namespace + "." + name :
+                    name;
+
+            _functionNames.Add(fullName);
+
+            return base.PreVisit(node);
+        }
+    }
+}
diff --git a/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ListFunctionVisitorTests.cs b/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ListFunctionVisitorTests.cs
new file mode 100644
index 0000000000..2240556e16
--- /dev/null
+++ b/src/tests/Microsoft.PowerFx.Core.Tests.Shared/ListFunctionVisitorTests.cs
@@ -0,0 +1,63 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+using System;
+using Xunit;
+
+namespace Microsoft.PowerFx.Core.Tests
+{
+    public class ListFunctionVisitorTests : PowerFxTest
+    {
+        [Theory]
+        [InlineData("Abs(1)", "Abs")]
+        [InlineData("Abs(Abs(Abs(Abs(Abs(1)))))", "Abs")]
+        [InlineData("With({x:Today()}, x+1)", "With,Today")]
+        [InlineData("SomeNameSpace.Foo() + SomeNameSpace.Bar()", "SomeNameSpace.Foo,SomeNameSpace.Bar")]
+        [InlineData("true And true", "")]
+        [InlineData("If(true, Blank(),Error())", "If,Blank,Error")]
+        public void ListFunctionNamesTest(string expression, string expectedNames)
+        {
+            foreach (var textFirst in new bool[] { false, true })
+            {
+                if (textFirst)
+                {
+                    expression = $"={expression}";
+                }
+
+                CheckFunctionNames(textFirst, expression, expectedNames);
+            }
+        }
+
+        [Theory]
+        [InlineData("Hello ${Sum(1,Sqrt(2))} world", "Sum,Sqrt")]
+        [InlineData("3 ' {} ${Upper(3+3)} \" ${Lower($\"{7+7}\")}", "Upper,Lower")]
+        public void ListFunctionNamesTextFirstTest(string expression, string expectedNames)
+        {
+            CheckFunctionNames(true, expression, expectedNames);
+        }
+
+        [Fact]
+        public void ListFunctionNamesErrorTest()
+        {
+            var checkResult = new CheckResult(new Engine());
+            Assert.Throws<InvalidOperationException>(() => checkResult.GetFunctionNames());
+        }
+
+        private static void CheckFunctionNames(bool textFirst, string expression, string expectedNames)
+        {
+            var options = new ParserOptions() { TextFirst = textFirst };
+            var engine = new Engine();
+            var check = engine.Check(expression, options);
+            var checkResult = new CheckResult(engine).SetText(expression, options);
+
+            var functionsNames1 = check.GetFunctionNames();
+            var functionsNames2 = checkResult.GetFunctionNames();
+
+            var actualNames1 = string.Join(",", functionsNames1);
+            var actualNames2 = string.Join(",", functionsNames2);
+
+            Assert.Equal(expectedNames, actualNames1);
+            Assert.Equal(expectedNames, actualNames2);
+        }
+    }
+}