Adds API documentation (#37)

Amazon.IonHashDotnet/CryptoIonHasherProvider.cs

@@ -15,6 +15,9 @@
 
 namespace Amazon.IonHashDotnet
 {
+    /// <summary>
+    /// IIonHasherProvider implementation based on System.Security.Cryptography.
+    /// </summary>
     public class CryptoIonHasherProvider : IIonHasherProvider
     {
         private readonly string algorithm;

Amazon.IonHashDotnet/IIonHashReader.cs

@@ -17,8 +17,28 @@ namespace Amazon.IonHashDotnet
 {
     using Amazon.IonDotnet;
 
+    /// <summary>
+    /// IIonReader extension that provides the hash of the IonValue just nexted
+    /// past or stepped out of, as defined by the Amazon Ion Hash Specification.
+    /// <p/>
+    /// Implementations of this interface are not thread-safe.
+    /// </summary>
+    /// <see cref="IIonReader"/>
     public interface IIonHashReader : IIonReader
     {
+        /// <summary>
+        /// Provides the hash of the Ion value just nexted past or stepped out of;
+        /// hashes of partial Ion values are not provided.  If there is no current
+        /// hash value, returns an empty array.
+        /// <p/>
+        /// Implementations must calculate the hash independently of how the Ion
+        /// is traversed (e.g., the hash of a container must be identical whether
+        /// the caller skips over it, steps into it, or any combination thereof).
+        /// </summary>
+        /// <returns>
+        /// Array of bytes representing the hash of the Ion value just
+        /// nexted past;  if there is no hash, returns an empty array.
+        /// </returns>
         byte[] Digest();
     }
 }

Amazon.IonHashDotnet/IIonHashWriter.cs

@@ -17,8 +17,24 @@ namespace Amazon.IonHashDotnet
 {
     using Amazon.IonDotnet;
 
+    /// <summary>
+    /// IIonWriter extension that provides the hash of the Ion value just written
+    /// or stepped out of, as defined by the Amazon Ion Hash Specification.
+    /// <p/>
+    /// Implementations of this interface are not thread-safe.
+    /// </summary>
+    /// <see cref="IIonWriter"/>
     public interface IIonHashWriter : IIonWriter
     {
+        /// <summary>
+        /// Provides the hash of the Ion value just nexted past or stepped out of;
+        /// hashes of partial Ion values are not provided.  If there is no current
+        /// hash value, returns an empty array.
+        /// </summary>
+        /// <returns>
+        /// Array of bytes representing the hash of the Ion value just
+        /// written or stepped out of;  if there is no hash, returns an empty array.
+        /// </returns>
         byte[] Digest();
     }
 }

Amazon.IonHashDotnet/IIonHasher.cs

@@ -15,10 +15,23 @@
 
 namespace Amazon.IonHashDotnet
 {
+    /// <summary>
+    /// User-provided hash function that is required by the Amazon Ion Hash
+    /// Specification.
+    /// </summary>
     public interface IIonHasher
     {
+        /// <summary>
+        /// Updates the hash with the specified array of bytes.
+        /// </summary>
+        /// <param name="bytes">The bytes to hash.</param>
         void Update(byte[] bytes);
 
+        /// <summary>
+        /// Returns the computed hash bytes and resets any internal state
+        /// so the hasher may be reused.
+        /// </summary>
+        /// <returns>The computed hash bytes.</returns>
         byte[] Digest();
     }
 }

Amazon.IonHashDotnet/IIonHasherProvider.cs

@@ -15,8 +15,18 @@
 
 namespace Amazon.IonHashDotnet
 {
+    /// <summary>
+    /// An implementation of this interface provides IIonHasher instances
+    /// to an Ion hash implementation as needed.
+    /// <p/>
+    /// Implementations must be thread-safe.
+    /// </summary>
     public interface IIonHasherProvider
     {
+        /// <summary>
+        /// Produces a new IIonHasher instance.
+        /// </summary>
+        /// <returns>The new IIonHasher instance.</returns>
         IIonHasher NewHasher();
     }
 }

Amazon.IonHashDotnet/IonHashException.cs

@@ -18,6 +18,9 @@ namespace Amazon.IonHashDotnet
     using System;
     using Amazon.IonDotnet;
 
+    /// <summary>
+    /// Thrown for unexpected or error conditions while hashing Ion data.
+    /// </summary>
     public class IonHashException : IonException
     {
         public IonHashException(Exception inner)

Amazon.IonHashDotnet/IonHashReaderBuilder.cs

@@ -18,6 +18,12 @@ namespace Amazon.IonHashDotnet
     using System;
     using Amazon.IonDotnet;
 
+    /// <summary>
+    /// Build a new <see cref="IIonHashReader"/> for the given <see cref="IIonReader"/>
+    /// and <see cref="IIonHasherProvider"/>.
+    /// <p/>
+    /// Instances of this class are not thread-safe.
+    /// </summary>
     public class IonHashReaderBuilder
     {
         private IIonHasherProvider hasherProvider = null;
@@ -28,23 +34,41 @@ private IonHashReaderBuilder()
         {
         }
 
+        /// <summary>
+        /// The standard builder of <see cref="IonHashReaderBuilder"/>s.
+        /// </summary>
+        /// <returns>The standard builder.</returns>
         public static IonHashReaderBuilder Standard()
         {
             return new IonHashReaderBuilder();
         }
 
+        /// <summary>
+        /// Specifies the reader to compute hashes over.
+        /// </summary>
+        /// <param name="reader">The IIonReader to compute hasher over.</param>
+        /// <returns>This builder.</returns>
         public IonHashReaderBuilder WithReader(IIonReader reader)
         {
             this.reader = reader;
             return this;
         }
 
+        /// <summary>
+        /// Specifies the hasher provider to use.
+        /// </summary>
+        /// <param name="hasherProvider">The IIonHasherProvider instance to use.</param>
+        /// <returns>This builder.</returns>
         public IonHashReaderBuilder WithHasherProvider(IIonHasherProvider hasherProvider)
         {
             this.hasherProvider = hasherProvider;
             return this;
         }
 
+        /// <summary>
+        /// Constructs a new IIonHashReader, which decorates the IIonReader with hashes.
+        /// </summary>
+        /// <returns>A new IIonHashReader object.</returns>
         public IIonHashReader Build()
         {
             if (this.hasherProvider == null || this.reader == null)

Amazon.IonHashDotnet/IonHashWriterBuilder.cs

@@ -18,6 +18,12 @@ namespace Amazon.IonHashDotnet
     using System;
     using Amazon.IonDotnet;
 
+    /// <summary>
+    /// Build a new <see cref="IIonHashWriter"/> for the given <see cref="IIonWriter"/>
+    /// and <see cref="IIonHasherProvider"/>.
+    /// <p/>
+    /// Instances of this class are not thread-safe.
+    /// </summary>
     public class IonHashWriterBuilder
     {
         private IIonHasherProvider hasherProvider;
@@ -28,23 +34,41 @@ private IonHashWriterBuilder()
         {
         }
 
+        /// <summary>
+        /// The standard builder of <see cref="IonHashWriterBuilder"/>s.
+        /// </summary>
+        /// <returns>The standard builder.</returns>
         public static IonHashWriterBuilder Standard()
         {
             return new IonHashWriterBuilder();
         }
 
+        /// <summary>
+        /// Specifies the writer to compute hashes over.
+        /// </summary>
+        /// <param name="writer">The IIonWriter to compute hashes over.</param>
+        /// <returns>This builder.</returns>
         public IonHashWriterBuilder WithWriter(IIonWriter writer)
         {
             this.writer = writer;
             return this;
         }
 
+        /// <summary>
+        /// Specifies the hasher provider to use.
+        /// </summary>
+        /// <param name="hasherProvider">The IIonHasherProvider instance to use.</param>
+        /// <returns>This builder.</returns>
         public IonHashWriterBuilder WithHasherProvider(IIonHasherProvider hasherProvider)
         {
             this.hasherProvider = hasherProvider;
             return this;
         }
 
+        /// <summary>
+        /// Constructs a new IIonHashWriter, which decorates the IIonWriter with hashes.
+        /// </summary>
+        /// <returns>A new IIonHashWriter object.</returns>
         public IIonHashWriter Build()
         {
             if (this.hasherProvider == null || this.writer == null)