Test templates by comparing output with existing formatters

README.md

@@ -95,12 +95,12 @@ Log.Logger = new LoggerConfiguration()
 
 Note the use of `{Items[0]}`: "holes" in expression templates can include any valid expression.
 
-Newline-delimited JSON (for example, emulating the [CLEF format](https://github.com/serilog/serilog-formatting-compact)) can be generated
+Newline-delimited JSON (for example, replicating the [CLEF format](https://github.com/serilog/serilog-formatting-compact)) can be generated
 using object literals:
 
 ```csharp
     .WriteTo.Console(new ExpressionTemplate(
-        "{ {@t, @mt, @l: if @l = 'Information' then undefined() else @l, @x, ..@p} }\n"))
+        "{ {@t, @mt, @r, @l: if @l = 'Information' then undefined() else @l, @x, ..@p} }\n"))
 ```
 
 ## Language reference
@@ -116,6 +116,10 @@ The following properties are available in expressions:
  * `@l` - the event's level, as a `LogEventLevel`
  * `@x` - the exception associated with the event, if any, as an `Exception`
  * `@p` - a dictionary containing all first-class properties; this supports properties with non-identifier names, for example `@p['snake-case-name']`
+ * `@i` - event id; a 32-bit numeric hash of the event's message template
+ * `@r` - renderings; if any tokens in the message template include .NET-specific formatting, an array of rendered values for each such token
+
+The built-in properties mirror those available in the CLEF format.
 
 ### Literals
 
@@ -175,12 +179,15 @@ calling a function will be undefined if:
 | `IsDefined(x)` | Returns `true` if the expression `x` has a value, including `null`, or `false` if `x` is undefined. |
 | `LastIndexOf(s, t)` | Returns the last index of substring `t` in string `s`, or -1 if the substring does not appear. |
 | `Length(x)` | Returns the length of a string or array. |
+| `Now()` | Returns `DateTimeOffset.Now`. |
 | `Round(n, m)` | Round the number `n` to `m` decimal places. |
 | `StartsWith(s, t)` | Tests whether the string `s` starts with substring `t`. |
 | `Substring(s, start, [length])` | Return the substring of string `s` from `start` to the end of the string, or of `length` characters, if this argument is supplied. |
 | `TagOf(o)` | Returns the `TypeTag` field of a captured object (i.e. where `TypeOf(x)` is `'object'`). |
+| `ToString(x, f)` | Applies the format string `f` to the formattable value `x`. |
 | `TypeOf(x)` | Returns a string describing the type of expression `x`: a .NET type name if `x` is scalar and non-null, or, `'array'`, `'object'`, `'dictionary'`, `'null'`, or `'undefined'`. |
 | `Undefined()` | Explicitly mark an undefined value. |
+| `UtcDateTime(x)` | Convert a `DateTime` or `DateTimeOffset` into a UTC `DateTime`. |
 
 Functions that compare text accept an optional postfix `ci` modifier to select case-insensitive comparisons:
 

src/Serilog.Expressions/Expressions/BuiltInProperty.cs

@@ -1,5 +1,20 @@
+// Copyright © Serilog Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 namespace Serilog.Expressions
 {
+    // See https://github.com/serilog/serilog-formatting-compact#reified-properties
     static class BuiltInProperty
     {
         public const string Exception = "x";
@@ -8,5 +23,7 @@ static class BuiltInProperty
         public const string Message = "m";
         public const string MessageTemplate = "mt";
         public const string Properties = "p";
+        public const string Renderings = "r";
+        public const string EventId = "i";
     }
 }

src/Serilog.Expressions/Expressions/Compilation/Linq/EventIdHash.cs

@@ -0,0 +1,55 @@
+// Copyright © Serilog Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+
+// ReSharper disable ForCanBeConvertedToForeach
+
+namespace Serilog.Expressions.Compilation.Linq
+{
+    /// <summary>
+    /// Hash functions for message templates. See <see cref="Compute"/>.
+    /// </summary>
+    public static class EventIdHash
+    {
+        /// <summary>
+        /// Compute a 32-bit hash of the provided <paramref name="messageTemplate"/>. The
+        /// resulting hash value can be uses as an event id in lieu of transmitting the
+        /// full template string.
+        /// </summary>
+        /// <param name="messageTemplate">A message template.</param>
+        /// <returns>A 32-bit hash of the template.</returns>
+        [CLSCompliant(false)]
+        public static uint Compute(string messageTemplate)
+        {
+            if (messageTemplate == null) throw new ArgumentNullException(nameof(messageTemplate));
+
+            // Jenkins one-at-a-time https://en.wikipedia.org/wiki/Jenkins_hash_function
+            unchecked
+            {
+                uint hash = 0;
+                for (var i = 0; i < messageTemplate.Length; ++i)
+                {
+                    hash += messageTemplate[i];
+                    hash += hash << 10;
+                    hash ^= hash >> 6;
+                }
+                hash += hash << 3;
+                hash ^= hash >> 11;
+                hash += hash << 15;
+                return hash;
+            }
+        }
+    }
+}

src/Serilog.Expressions/Expressions/Compilation/Linq/Intrinsics.cs

@@ -6,6 +6,7 @@
 using System.Text.RegularExpressions;
 using Serilog.Events;
 using Serilog.Formatting.Display;
+using Serilog.Parsing;
 
 // ReSharper disable ParameterTypeCanBeEnumerable.Global
 
@@ -15,6 +16,8 @@ static class Intrinsics
     {
         static readonly LogEventPropertyValue NegativeOne = new ScalarValue(-1);
         static readonly LogEventPropertyValue Tombstone = new ScalarValue("😬 (if you see this you have found a bug.)");
+
+        // TODO #19: formatting is culture-specific.
         static readonly MessageTemplateTextFormatter MessageFormatter = new MessageTemplateTextFormatter("{Message:lj}");
 
         public static List<LogEventPropertyValue?> CollectSequenceElements(LogEventPropertyValue?[] elements)
@@ -159,5 +162,25 @@ public static string RenderMessage(LogEvent logEvent)
             MessageFormatter.Format(logEvent, sw);
             return sw.ToString();
         }
+
+        public static LogEventPropertyValue? GetRenderings(LogEvent logEvent)
+        {
+            List<LogEventPropertyValue>? elements = null;
+            foreach (var token in logEvent.MessageTemplate.Tokens)
+            {
+                if (token is PropertyToken pt && pt.Format != null)
+                {
+                    elements ??= new List<LogEventPropertyValue>();
+
+                    var space = new StringWriter();
+
+                    // TODO #19: formatting is culture-specific.
+                    pt.Render(logEvent.Properties, space);
+                    elements.Add(new ScalarValue(space.ToString()));
+                }
+            }
+
+            return elements == null ? null : new SequenceValue(elements);
+        }
     }
 }

src/Serilog.Expressions/Expressions/Compilation/Linq/LinqExpressionCompiler.cs

@@ -1,4 +1,18 @@
-using System;
+// Copyright © Serilog Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
@@ -124,25 +138,22 @@ protected override ExpressionBody Transform(AmbientPropertyExpression px)
         {
             if (px.IsBuiltIn)
             {
-                if (px.PropertyName == BuiltInProperty.Level)
-                    return Splice(context => new ScalarValue(context.Level));
-
-                if (px.PropertyName == BuiltInProperty.Message)
-                    return Splice(context => new ScalarValue(Intrinsics.RenderMessage(context)));
-
-                if (px.PropertyName == BuiltInProperty.Exception)
-                    return Splice(context => context.Exception == null ? null : new ScalarValue(context.Exception));
-
-                if (px.PropertyName == BuiltInProperty.Timestamp)
-                    return Splice(context => new ScalarValue(context.Timestamp));
-
-                if (px.PropertyName == BuiltInProperty.MessageTemplate)
-                    return Splice(context => new ScalarValue(context.MessageTemplate.Text));
-
-                if (px.PropertyName == BuiltInProperty.Properties)
-                    return Splice(context => new StructureValue(context.Properties.Select(kvp => new LogEventProperty(kvp.Key, kvp.Value)), null));
-
-                return LX.Constant(null, typeof(LogEventPropertyValue));
+                return px.PropertyName switch
+                {
+                    BuiltInProperty.Level => Splice(context => new ScalarValue(context.Level)),
+                    BuiltInProperty.Message => Splice(context => new ScalarValue(Intrinsics.RenderMessage(context))),
+                    BuiltInProperty.Exception => Splice(context =>
+                        context.Exception == null ? null : new ScalarValue(context.Exception)),
+                    BuiltInProperty.Timestamp => Splice(context => new ScalarValue(context.Timestamp)),
+                    BuiltInProperty.MessageTemplate => Splice(context => new ScalarValue(context.MessageTemplate.Text)),
+                    BuiltInProperty.Properties => Splice(context =>
+                        new StructureValue(context.Properties.Select(kvp => new LogEventProperty(kvp.Key, kvp.Value)),
+                            null)),
+                    BuiltInProperty.Renderings => Splice(context => Intrinsics.GetRenderings(context)),
+                    BuiltInProperty.EventId => Splice(context =>
+                        new ScalarValue(EventIdHash.Compute(context.MessageTemplate.Text))),
+                    _ => LX.Constant(null, typeof(LogEventPropertyValue))
+                };
             }
 
             var propertyName = px.PropertyName;

src/Serilog.Expressions/Expressions/Compilation/Wildcards/WildcardComprehensionTransformer.cs

@@ -1,4 +1,5 @@
-using Serilog.Expressions.Ast;
+using System.Linq;
+using Serilog.Expressions.Ast;
 using Serilog.Expressions.Compilation.Transformations;
 
 namespace Serilog.Expressions.Compilation.Wildcards
@@ -15,25 +16,34 @@ public static Expression Expand(Expression root)
 
         protected override Expression Transform(CallExpression lx)
         {
-            if (!Operators.WildcardComparators.Contains(lx.OperatorName) || lx.Operands.Length != 2)
+            if (!Operators.WildcardComparators.Contains(lx.OperatorName))
                 return base.Transform(lx);
 
-            var lhsIs = WildcardSearch.FindElementAtWildcard(lx.Operands[0]);
-            var rhsIs = WildcardSearch.FindElementAtWildcard(lx.Operands[1]);
-            if (lhsIs != null && rhsIs != null || lhsIs == null && rhsIs == null)
+            IndexerExpression? indexer = null;
+            Expression? wildcardPath = null;
+            var indexerOperand = -1;
+            for (var i = 0; i < lx.Operands.Length; ++i)
+            {
+                indexer = WildcardSearch.FindElementAtWildcard(lx.Operands[i]);
+                if (indexer != null)
+                {
+                    indexerOperand = i;
+                    wildcardPath = lx.Operands[i];
+                    break;
+                }
+            }
+
+            if (indexer == null || wildcardPath == null)
                 return base.Transform(lx); // N/A, or invalid
 
-            var wildcardPath = lhsIs != null ? lx.Operands[0] : lx.Operands[1];
-            var comparand = lhsIs != null ? lx.Operands[1] : lx.Operands[0];
-            var indexer = lhsIs ?? rhsIs!;
-
             var px = new ParameterExpression("p" + _nextParameter++);
             var nestedComparand = NodeReplacer.Replace(wildcardPath, indexer, px);
 
             var coll = indexer.Receiver;
             var wc = ((IndexerWildcardExpression)indexer.Index).Wildcard;
 
-            var comparisonArgs = lhsIs != null ? new[] { nestedComparand, comparand } : new[] { comparand, nestedComparand };
+            var comparisonArgs = lx.Operands.ToArray();
+            comparisonArgs[indexerOperand] = nestedComparand;
             var body = new CallExpression(lx.IgnoreCase, lx.OperatorName, comparisonArgs);
 
             var lambda = new LambdaExpression(new[] { px }, body);

src/Serilog.Expressions/Expressions/Operators.cs

@@ -24,12 +24,15 @@ static class Operators
         public const string OpIsDefined = "IsDefined";
         public const string OpLastIndexOf = "LastIndexOf";
         public const string OpLength = "Length";
+        public const string OpNow = "Now";
         public const string OpRound = "Round";
         public const string OpStartsWith = "StartsWith";
         public const string OpSubstring = "Substring";
         public const string OpTagOf = "TagOf";
+        public const string OpToString = "ToString";
         public const string OpTypeOf = "TypeOf";
         public const string OpUndefined = "Undefined";
+        public const string OpUtcDateTime = "UtcDateTime";
 
         public const string IntermediateOpLike = "_Internal_Like";
         public const string IntermediateOpNotLike = "_Internal_NotLike";

src/Serilog.Expressions/Expressions/Runtime/RuntimeOperators.cs

@@ -467,5 +467,38 @@ public static LogEventPropertyValue _Internal_IsNotNull(LogEventPropertyValue? v
         {
             return Coerce.IsTrue(condition) ? consequent : alternative;
         }
+
+        public static LogEventPropertyValue? ToString(LogEventPropertyValue? value, LogEventPropertyValue? format)
+        {
+            if (!(value is ScalarValue sv && sv.Value is IFormattable formattable) ||
+                !Coerce.String(format, out var fmt))
+            {
+                return null;
+            }
+
+            // TODO #19: formatting is culture-specific.
+            return new ScalarValue(formattable.ToString(fmt, null));
+        }
+
+        public static LogEventPropertyValue? UtcDateTime(LogEventPropertyValue? dateTime)
+        {
+            if (dateTime is ScalarValue sv)
+            {
+                if (sv.Value is DateTimeOffset dto)
+                    return new ScalarValue(dto.UtcDateTime);
+
+                if (sv.Value is DateTime dt)
+                    return new ScalarValue(dt.ToUniversalTime());
+            }
+
+            return null;
+        }
+
+        // ReSharper disable once UnusedMember.Global
+        public static LogEventPropertyValue? Now()
+        {
+            // DateTimeOffset.Now is the generator for LogEvent.Timestamp.
+            return new ScalarValue(DateTimeOffset.Now);
+        }
     }
 }

src/Serilog.Expressions/Serilog.Expressions.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <Description>An embeddable mini-language for filtering, enriching, and formatting Serilog
       events, ideal for use with JSON or XML configuration.</Description>
-    <VersionPrefix>1.0.1</VersionPrefix>
+    <VersionPrefix>1.1.0</VersionPrefix>
     <Authors>Serilog Contributors</Authors>
     <TargetFramework>netstandard2.1</TargetFramework>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>

test/Serilog.Expressions.Tests/Cases/expression-evaluation-cases.asv

@@ -217,7 +217,13 @@ if undefined() then 1 else 2         ⇶ 2
 if 'string' then 1 else 2            ⇶ 2
 if true then if false then 1 else 2 else 3 ⇶ 2
 
-// Typeof
+// ToString
+tostring(16, '000')                  ⇶ '016'
+tostring('test', '000')              ⇶ undefined()
+tostring(16, undefined())            ⇶ undefined()
+tostring(16, null)                   ⇶ undefined()
+
+// TypeOf
 typeof(undefined())                  ⇶ 'undefined'
 typeof('test')                       ⇶ 'System.String'
 typeof(10)                           ⇶ 'System.Decimal'
@@ -226,6 +232,9 @@ typeof(null)                         ⇶ 'null'
 typeof([])                           ⇶ 'array'
 typeof({})                           ⇶ 'object'
 
+// UtcDateTime
+tostring(utcdatetime(now()), 'o') like '20%' ⇶ true
+
 // Case comparison
 'test' = 'TEST'                      ⇶ false
 'tschüß' = 'TSCHÜSS'                 ⇶ false