feat: Add WriteLines/AppendLines/Truncate extension methods (#46)

Author: gigi81

src/System.IO.Abstractions.Extensions/IFileInfoExtensions.cs

@@ -1,41 +1,130 @@
-using System.Collections;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Text;
 
 namespace System.IO.Abstractions
 {
     public static class IFileInfoExtensions
     {
         /// <summary>
-        /// Throws an exception if the file <paramref name="info"/> doesn't exists
+        /// Throws an exception if the <paramref name="file"/> doesn't exists
         /// </summary>
-        /// <param name="info">File that will be checked for existance</param>
+        /// <param name="file">File that will be checked for existance</param>
         /// <exception cref="FileNotFoundException">Exception thrown if the file is not found</exception>
-        public static void ThrowIfNotFound(this IFileInfo info)
+        public static void ThrowIfNotFound(this IFileInfo file)
         {
-            if (!info.Exists)
-                throw new FileNotFoundException(StringResources.Format("COULD_NOT_FIND_FILE_EXCEPTION", info.FullName));
+            if (!file.Exists)
+                throw new FileNotFoundException(StringResources.Format("COULD_NOT_FIND_FILE_EXCEPTION", file.FullName));
         }
 
         /// <summary>
-        /// Creates an <see cref="IEnumerable{String}"/> that can enumerate the lines of text in the <paramref name="info"/> file
+        /// Creates an <see cref="IEnumerable{String}"/> that can enumerate the lines of text in the <paramref name="file"/>
         /// </summary>
-        /// <param name="info">File to enumerate content</param>
+        /// <param name="file">File to enumerate content</param>
         /// <returns>Returns an <see cref="IEnumerable{String}"/> to enumerate the content of the file</returns>
-        public static IEnumerable<string> EnumerateLines(this IFileInfo info)
+        public static IEnumerable<string> EnumerateLines(this IFileInfo file)
         {
-            return new LineEnumerable(info, null);
+            return new LineEnumerable(file, null);
         }
 
         /// <summary>
-        /// Creates an <see cref="IEnumerable{String}"/> that can enumerate the lines of text in the <paramref name="info"/> file
+        /// Creates an <see cref="IEnumerable{String}"/> that can enumerate the lines of text in the specified <paramref name="file"/>
         /// using the specified <paramref name="encoding"/>
         /// </summary>
-        /// <param name="info">File to enumerate content</param>
+        /// <param name="file">File to enumerate content</param>
         /// <returns>Returns an <see cref="IEnumerable{String}"/> to enumerate the content of the file</returns>
-        public static IEnumerable<string> EnumerateLines(this IFileInfo info, Encoding encoding)
+        public static IEnumerable<string> EnumerateLines(this IFileInfo file, Encoding encoding)
         {
-            return new LineEnumerable(info, encoding);
+            return new LineEnumerable(file, encoding);
+        }
+
+        /// <summary>
+        /// Opens a <see cref="FileSystemStream"/> for the <paramref name="file"/> in the specified <paramref name="mode"/>
+        /// </summary>
+        /// <param name="file">File to open stream on</param>
+        /// <param name="mode">Mode to use when opening the file</param>
+        /// <returns>A <see cref="FileSystemStream"/> that can read or write data to the specified <paramref name="file"/></returns>
+        public static FileSystemStream OpenFileStream(this IFileInfo file, FileMode mode)
+        {
+            return file.FileSystem.FileStream.New(file.FullName, mode);
+        }
+
+        /// <summary>
+        /// Creates a new empty <paramref name="file"/>.
+        /// If the file already exists, the file is truncated.
+        /// </summary>
+        /// <param name="file">File to create</param>
+        /// <returns>The original <see cref="IFileInfo"/> so that methods calls can be chained</returns>
+        public static IFileInfo Truncate(this IFileInfo file)
+        {
+            using(var stream = file.OpenFileStream(FileMode.Create))
+            {
+                stream.Dispose();
+            }
+
+            return file;
+        }
+
+        /// <summary>
+        /// Writes the specified <paramref name="lines"/> to the specified <paramref name="file"/> using the UTF-8 encoding.
+        /// If the file already exists and the <paramref name="overwrite"/> flag is set to true, the file will be truncated.
+        /// </summary>
+        /// <param name="file">File to write to</param>
+        /// <param name="lines">Lines to write to file as text</param>
+        /// <param name="overwrite">Flag that specifies if the file can be overwritten if it exists</param>
+        /// <exception cref="IOException">Exception thrown if the file already exists and the <paramref name="overwrite"/> flag is set to <see cref="false"/></exception>
+        public static void WriteLines(this IFileInfo file, IEnumerable<string> lines, bool overwrite = false)
+        {
+            using (var stream = file.OpenFileStream(GetWriteFileMode(file, overwrite)))
+            using (var writer = new StreamWriter(stream))
+            foreach(var line in lines)
+            {
+                writer.WriteLine(line);
+            }
+        }
+
+        /// <summary>
+        /// Writes the specified <paramref name="lines"/> to the specified <paramref name="file"/>
+        /// using the specified <paramref name="encoding"/>.
+        /// If the file already exists and the <paramref name="overwrite"/> flag is set to true, the file will be truncated.
+        /// </summary>
+        /// <param name="file">File to write to</param>
+        /// <param name="lines">Lines to write to file as text</param>
+        /// <param name="encoding">Encoding to use when writing the <paramref name="lines"/> to the text file</param>
+        /// <param name="overwrite">Flag that specifies if the file can be overwritten if it exists</param>
+        /// <exception cref="IOException">Exception thrown if the file already exists and the <paramref name="overwrite"/> flag is set to <see cref="false"/></exception>
+        public static void WriteLines(this IFileInfo file, IEnumerable<string> lines, Encoding encoding, bool overwrite = false)
+        {
+            using (var stream = file.OpenFileStream(GetWriteFileMode(file, overwrite)))
+            using (var writer = new StreamWriter(stream, encoding))
+            foreach (var line in lines)
+            {
+                writer.WriteLine(line);
+            }
+        }
+
+        /// <summary>
+        /// Appends the specified <paramref name="lines"/> to the specified <paramref name="file"/>
+        /// </summary>
+        /// <param name="file">File to append to</param>
+        /// <param name="lines">Lines to append to file as text</param>
+        public static void AppendLines(this IFileInfo file, IEnumerable<string> lines)
+        {
+            using (var writer = file.AppendText())
+            foreach (var line in lines)
+            {
+                writer.WriteLine(line);
+            }
+        }
+
+        private static FileMode GetWriteFileMode(IFileInfo info, bool overwrite)
+        {
+            if (!overwrite && info.Exists)
+            {
+                throw new IOException(StringResources.Format("CANNOT_OVERWRITE", info.FullName));
+            }
+
+            //if the file already exists it will be truncated
+            return FileMode.Create;
         }
     }
 }

src/System.IO.Abstractions.Extensions/Resources.Designer.cs

@@ -117,13 +117,16 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="CANNOT_OVERWRITE" xml:space="preserve">
+    <value>The file '{0}' already exists.</value>
+  </data>
   <data name="COULD_NOT_FIND_FILE_EXCEPTION" xml:space="preserve">
     <value>Could not find file '{0}'.</value>
   </data>
   <data name="COULD_NOT_FIND_PART_OF_PATH_EXCEPTION" xml:space="preserve">
     <value>Could not find a part of the path '{0}'.</value>
   </data>
   <data name="NOT_AN_ANCESTOR" xml:space="preserve">
-    <value>'{0}' is not an ancestor of '{1}'</value>
+    <value>'{0}' is not an ancestor of '{1}'.</value>
   </data>
 </root>