[Swift] Adds GRPC to Swift (#5758)

* Adds the basic structure for required to add grpc support

Added the message implementation

Updated the code to confirm to the protocol flatbuffersobject

Adds an example for Swift flatbuffers GRPC

Started implementing the swift GRPC code Gen

Generator generates protocols now

Fixing ci issues

Migrated the logic to use grpc_generator::File instead of string

Refactored swift project

Implemented GRPC in swift

Finished implementing GRPC in swift

Fixes issues

Adds contiguousBytes initializer to swift

Adds documentation + fixes buffer nameing in tables + structs

Adds documentation + fixes buffer nameing in tables + structs

Updated tests

* Updated version

swift/FlatBuffers.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FlatBuffers'
-  s.version          = '0.1.0'
+  s.version          = '0.2.0'
   s.summary          = 'FlatBuffers: Memory Efficient Serialization Library'
 
   s.description      = "FlatBuffers is a cross platform serialization library architected for

swift/Sources/FlatBuffers/ByteBuffer.swift

@@ -51,6 +51,35 @@ public final class ByteBuffer {
         _memory.initializeMemory(as: UInt8.self, repeating: 0, count: size)
         _capacity = size
     }
+
+#if swift(>=5.0)
+    /// Constructor that creates a Flatbuffer object from a ContiguousBytes
+    /// - Parameters:
+    ///   - contiguousBytes: Binary stripe to use as the buffer
+    ///   - count: amount of readable bytes
+    public init<Bytes: ContiguousBytes>(
+        contiguousBytes: Bytes,
+        count: Int
+    ) {
+        _memory = UnsafeMutableRawPointer.allocate(byteCount: count, alignment: alignment)
+        _capacity = count
+        _writerSize = _capacity
+        contiguousBytes.withUnsafeBytes { buf in
+            _memory.copyMemory(from: buf.baseAddress!, byteCount: buf.count)
+        }
+    }
+#endif
+    
+    /// Creates a copy of the buffer that's being built by calling sizedBuffer
+    /// - Parameters:
+    ///   - memory: Current memory of the buffer
+    ///   - count: count of bytes
+    internal init(memory: UnsafeMutableRawPointer, count: Int) {
+        _memory = UnsafeMutableRawPointer.allocate(byteCount: count, alignment: alignment)
+        _memory.copyMemory(from: memory, byteCount: count)
+        _capacity = count
+        _writerSize = _capacity
+    }
     
     /// Creates a copy of the existing flatbuffer, by copying it to a different memory.
     /// - Parameters:

swift/Sources/FlatBuffers/FlatBufferBuilder.swift

@@ -50,6 +50,12 @@ public final class FlatBufferBuilder {
     /// Returns the buffer
     public var buffer: ByteBuffer { return _bb }
     
+    /// Returns A sized Buffer from the readable bytes
+    public var sizedBuffer: ByteBuffer {
+        assert(finished, "Data shouldn't be called before finish()")
+        return ByteBuffer(memory: _bb.memory.advanced(by: _bb.reader), count: _bb.reader)
+    }
+    
     // MARK: - Init
     
     /// initialize the buffer with a size

swift/Sources/FlatBuffers/FlatBufferObject.swift

@@ -2,6 +2,7 @@ import Foundation
 
 /// FlatbufferObject structures all the Flatbuffers objects
 public protocol FlatBufferObject {
+    var __buffer: ByteBuffer! { get }
     init(_ bb: ByteBuffer, o: Int32)
 }
 

swift/Sources/FlatBuffers/Message.swift

@@ -0,0 +1,41 @@
+public protocol FlatBufferGRPCMessage {
+    
+    /// Raw pointer which would be pointing to the beginning of the readable bytes
+    var rawPointer: UnsafeMutableRawPointer { get }
+    
+    /// Size of readable bytes in the buffer
+    var size: Int { get }
+    
+    init(byteBuffer: ByteBuffer)
+}
+
+/// Message is a wrapper around Buffers to to able to send Flatbuffers `Buffers` through the
+/// GRPC library
+public final class Message<T: FlatBufferObject>: FlatBufferGRPCMessage {
+    internal var buffer: ByteBuffer
+    
+    /// Returns the an object of type T that would be  read from the buffer
+    public var object: T {
+        T.init(buffer, o: Int32(buffer.read(def: UOffset.self, position: buffer.reader)) + Int32(buffer.reader))
+    }
+    
+    public var rawPointer: UnsafeMutableRawPointer { return buffer.memory.advanced(by: buffer.reader) }
+    
+    public var size: Int { return Int(buffer.size) }
+    
+    /// Initializes the message with the type Flatbuffer.Bytebuffer that is transmitted over
+    /// GRPC
+    /// - Parameter byteBuffer: Flatbuffer ByteBuffer object
+    public init(byteBuffer: ByteBuffer) {
+        buffer = byteBuffer
+    }
+    
+    /// Initializes the message by copying the buffer to the message to be sent.
+    /// from the builder
+    /// - Parameter builder: FlatbufferBuilder that has the bytes created in
+    /// - Note: Use  `builder.finish(offset)` before passing the builder without prefixing anything to it
+    public init(builder: inout FlatBufferBuilder) {
+        buffer = builder.sizedBuffer
+        builder.clear()
+    }
+}