Teach OpenApiJsonWriter to produce a terse output

Author: nulltoken

src/Microsoft.OpenApi/Writers/OpenApiJsonWriter.cs

@@ -18,6 +18,16 @@ public OpenApiJsonWriter(TextWriter textWriter) : base(textWriter, null)
         {
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OpenApiJsonWriter"/> class.
+        /// </summary>
+        /// <param name="textWriter">The text writer.</param>
+        /// <param name="settings">Settings for controlling how the OpenAPI document will be written out.</param>
+        public OpenApiJsonWriter(TextWriter textWriter, OpenApiJsonWriterSettings settings) : base(textWriter, settings)
+        {
+            _produceTerseOutput = settings.Terse;
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="OpenApiJsonWriter"/> class.
         /// </summary>
@@ -27,6 +37,11 @@ public OpenApiJsonWriter(TextWriter textWriter, OpenApiWriterSettings settings)
         {
         }
 
+        /// <summary>
+        /// Indicates whether or not the produced document will be written in a compact or pretty fashion.
+        /// </summary>
+        private bool _produceTerseOutput = false;
+
         /// <summary>
         /// Base Indentation Level.
         /// This denotes how many indentations are needed for the property in the base object.
@@ -51,7 +66,7 @@ public override void WriteStartObject()
                     Writer.Write(WriterConstants.ArrayElementSeparator);
                 }
 
-                Writer.WriteLine();
+                WriteLine();
                 WriteIndentation();
             }
 
@@ -68,13 +83,16 @@ public override void WriteEndObject()
             var currentScope = EndScope(ScopeType.Object);
             if (currentScope.ObjectCount != 0)
             {
-                Writer.WriteLine();
+                WriteLine();
                 DecreaseIndentation();
                 WriteIndentation();
             }
             else
             {
-                Writer.Write(WriterConstants.WhiteSpaceForEmptyObject);
+                if (!_produceTerseOutput)
+                {
+                    Writer.Write(WriterConstants.WhiteSpaceForEmptyObject);
+                }
                 DecreaseIndentation();
             }
 
@@ -99,7 +117,7 @@ public override void WriteStartArray()
                     Writer.Write(WriterConstants.ArrayElementSeparator);
                 }
 
-                Writer.WriteLine();
+                WriteLine();
                 WriteIndentation();
             }
 
@@ -115,7 +133,7 @@ public override void WriteEndArray()
             var current = EndScope(ScopeType.Array);
             if (current.ObjectCount != 0)
             {
-                Writer.WriteLine();
+                WriteLine();
                 DecreaseIndentation();
                 WriteIndentation();
             }
@@ -143,7 +161,7 @@ public override void WritePropertyName(string name)
                 Writer.Write(WriterConstants.ObjectMemberSeparator);
             }
 
-            Writer.WriteLine();
+            WriteLine();
 
             currentScope.ObjectCount++;
 
@@ -154,6 +172,11 @@ public override void WritePropertyName(string name)
             Writer.Write(name);
 
             Writer.Write(WriterConstants.NameValueSeparator);
+
+            if (!_produceTerseOutput)
+            {
+                Writer.Write(WriterConstants.NameValueSeparatorWhiteSpaceSuffix);
+            }
         }
 
         /// <summary>
@@ -198,7 +221,7 @@ protected override void WriteValueSeparator()
                     Writer.Write(WriterConstants.ArrayElementSeparator);
                 }
 
-                Writer.WriteLine();
+                WriteLine();
                 WriteIndentation();
                 currentScope.ObjectCount++;
             }
@@ -212,5 +235,31 @@ public override void WriteRaw(string value)
             WriteValueSeparator();
             Writer.Write(value);
         }
+
+        /// <summary>
+        /// Write the indentation.
+        /// </summary>
+        public override void WriteIndentation()
+        {
+            if (_produceTerseOutput)
+            {
+                return;
+            }
+
+            base.WriteIndentation();
+        }
+
+        /// <summary>
+        /// Writes a line terminator to the text string or stream.
+        /// </summary>
+        private void WriteLine()
+        {
+            if (_produceTerseOutput)
+            {
+                return;
+            }
+
+            Writer.WriteLine();
+        }
     }
 }

src/Microsoft.OpenApi/Writers/OpenApiJsonWriterSettings.cs

@@ -0,0 +1,19 @@
+namespace Microsoft.OpenApi.Writers
+{
+    /// <summary>
+    /// Configuration settings to control how OpenAPI Json documents are written
+    /// </summary>
+    public class OpenApiJsonWriterSettings : OpenApiWriterSettings
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OpenApiJsonWriterSettings"/> class.
+        /// </summary>
+        public OpenApiJsonWriterSettings()
+        { }
+
+        /// <summary>
+        /// Indicates whether or not the produced document will be written in a compact or pretty fashion.
+        /// </summary>
+        public bool Terse { get; set; } = false;
+    }
+}

src/Microsoft.OpenApi/Writers/WriterConstants.cs

@@ -81,7 +81,13 @@ internal static class WriterConstants
         /// <summary>
         /// The separator between the name and the value.
         /// </summary>
-        internal const string NameValueSeparator = ": ";
+        internal const string NameValueSeparator = ":";
+
+        /// <summary>
+        /// The white space postfixing <see cref="NameValueSeparator"/>
+        /// when producing pretty content.
+        /// </summary>
+        internal const string NameValueSeparatorWhiteSpaceSuffix = " ";
 
         /// <summary>
         /// The white space for empty object

test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt

@@ -1253,10 +1253,12 @@ namespace Microsoft.OpenApi.Writers
     public class OpenApiJsonWriter : Microsoft.OpenApi.Writers.OpenApiWriterBase
     {
         public OpenApiJsonWriter(System.IO.TextWriter textWriter) { }
+        public OpenApiJsonWriter(System.IO.TextWriter textWriter, Microsoft.OpenApi.Writers.OpenApiJsonWriterSettings settings) { }
         public OpenApiJsonWriter(System.IO.TextWriter textWriter, Microsoft.OpenApi.Writers.OpenApiWriterSettings settings) { }
         protected override int BaseIndentation { get; }
         public override void WriteEndArray() { }
         public override void WriteEndObject() { }
+        public override void WriteIndentation() { }
         public override void WriteNull() { }
         public override void WritePropertyName(string name) { }
         public override void WriteRaw(string value) { }
@@ -1265,6 +1267,11 @@ namespace Microsoft.OpenApi.Writers
         public override void WriteValue(string value) { }
         protected override void WriteValueSeparator() { }
     }
+    public class OpenApiJsonWriterSettings : Microsoft.OpenApi.Writers.OpenApiWriterSettings
+    {
+        public OpenApiJsonWriterSettings() { }
+        public bool Terse { get; set; }
+    }
     public static class OpenApiWriterAnyExtensions
     {
         public static void WriteAny<T>(this Microsoft.OpenApi.Writers.IOpenApiWriter writer, T any)