switch hashFiles to extension function (#362)

src/Sdk/DTObjectTemplating/ObjectTemplating/Tokens/ExpressionToken.cs

@@ -1,7 +1,9 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
-using System.Linq;
+using System.Globalization;
 using System.Runtime.Serialization;
+using System.Text.RegularExpressions;
 using GitHub.DistributedTask.Expressions2;
 using GitHub.DistributedTask.Expressions2.Sdk;
 using GitHub.Services.WebApi.Internal;
@@ -35,11 +37,29 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             String[] allowedContext,
             out Exception ex)
         {
-            // Create dummy allowed contexts
-            INamedValueInfo[] namedValues = null;
+            // Create dummy named values and functions
+            var namedValues = new List<INamedValueInfo>();
+            var functions = new List<IFunctionInfo>();
             if (allowedContext?.Length > 0)
             {
-                namedValues = allowedContext.Select(x => new NamedValueInfo<ContextValueNode>(x)).ToArray();
+                foreach (var contextItem in allowedContext)
+                {
+                    var match = s_function.Match(contextItem);
+                    if (match.Success)
+                    {
+                        var functionName = match.Groups[1].Value;
+                        var minParameters = Int32.Parse(match.Groups[2].Value, NumberStyles.None, CultureInfo.InvariantCulture);
+                        var maxParametersRaw = match.Groups[3].Value;
+                        var maxParameters = String.Equals(maxParametersRaw, TemplateConstants.MaxConstant, StringComparison.Ordinal)
+                            ? Int32.MaxValue
+                            : Int32.Parse(maxParametersRaw, NumberStyles.None, CultureInfo.InvariantCulture);
+                        functions.Add(new FunctionInfo<DummyFunction>(functionName, minParameters, maxParameters));
+                    }
+                    else
+                    {
+                        namedValues.Add(new NamedValueInfo<ContextValueNode>(contextItem));
+                    }
+                }
             }
 
             // Parse
@@ -47,7 +67,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             ExpressionNode root = null;
             try
             {
-                root = new ExpressionParser().CreateTree(expression, null, namedValues, null) as ExpressionNode;
+                root = new ExpressionParser().CreateTree(expression, null, namedValues, functions) as ExpressionNode;
 
                 result = true;
                 ex = null;
@@ -60,5 +80,18 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
 
             return result;
         }
+
+        private sealed class DummyFunction : Function
+        {
+            protected override Object EvaluateCore(
+                EvaluationContext context,
+                out ResultMemory resultMemory)
+            {
+                resultMemory = null;
+                return null;
+            }
+        }
+
+        private static readonly Regex s_function = new Regex(@"^([a-zA-Z0-9_]+)\(([0-9]+),([0-9]+|MAX)\)$", RegexOptions.Compiled);
     }
 }

src/Sdk/DTObjectTemplating/ObjectTemplating/Tokens/TemplateTokenExtensions.cs

@@ -1,5 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
+using GitHub.DistributedTask.Expressions2;
+using GitHub.DistributedTask.Expressions2.Sdk;
 
 namespace GitHub.DistributedTask.ObjectTemplating.Tokens
 {
@@ -106,6 +109,43 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             throw new ArgumentException($"Error while reading '{objectDescription}'. Unexpected value '{literal.ToString()}'");
         }
 
+        /// <summary>
+        /// Traverses the token and checks whether all required expression values
+        /// and functions are provided.
+        /// </summary>
+        public static bool CheckHasRequiredContext(
+            this TemplateToken token,
+            IReadOnlyObject expressionValues,
+            IList<IFunctionInfo> expressionFunctions)
+        {
+            var expressionTokens = token.Traverse()
+                .OfType<BasicExpressionToken>()
+                .ToArray();
+            var parser = new ExpressionParser();
+            foreach (var expressionToken in expressionTokens)
+            {
+                var tree = parser.ValidateSyntax(expressionToken.Expression, null);
+                foreach (var node in tree.Traverse())
+                {
+                    if (node is NamedValue namedValue)
+                    {
+                        if (expressionValues?.Keys.Any(x => string.Equals(x, namedValue.Name, StringComparison.OrdinalIgnoreCase)) != true)
+                        {
+                            return false;
+                        }
+                    }
+                    else if (node is Function function &&
+                        !ExpressionConstants.WellKnownFunctions.ContainsKey(function.Name) &&
+                        expressionFunctions?.Any(x => string.Equals(x.Name, function.Name, StringComparison.OrdinalIgnoreCase)) != true)
+                    {
+                        return false;
+                    }
+                }
+            }
+
+            return true;
+        }
+
         /// <summary>
         /// Returns all tokens (depth first)
         /// </summary>