Adds full supposed for Wasm in the swift lib (#7328)

Adds tests for wasm module & github action

swift/Sources/FlatBuffers/ByteBuffer.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// `ByteBuffer` is the interface that stores the data for a `Flatbuffers` object
 /// it allows users to write and read data directly from memory thus the use of its
@@ -125,6 +129,7 @@ public struct ByteBuffer {
     }
   }
 
+  #if !os(WASI)
   /// Constructor that creates a Flatbuffer from the Swift Data type object
   /// - Parameter data: Swift data Object
   public init(data: Data) {
@@ -135,6 +140,7 @@ public struct ByteBuffer {
       self._storage.copy(from: bufferPointer.baseAddress!, count: data.count)
     }
   }
+  #endif
 
   /// Constructor that creates a Flatbuffer instance with a size
   /// - Parameter size: Length of the buffer
@@ -144,7 +150,7 @@ public struct ByteBuffer {
     _storage.initialize(for: size)
   }
 
-  #if swift(>=5.0)
+  #if swift(>=5.0) && !os(WASI)
   /// Constructor that creates a Flatbuffer object from a ContiguousBytes
   /// - Parameters:
   ///   - contiguousBytes: Binary stripe to use as the buffer
@@ -367,6 +373,7 @@ public struct ByteBuffer {
     return Array(array)
   }
 
+  #if !os(WASI)
   /// Reads a string from the buffer and encodes it to a swift string
   /// - Parameters:
   ///   - index: index of the string in the buffer
@@ -386,6 +393,26 @@ public struct ByteBuffer {
     let bufprt = UnsafeBufferPointer(start: start, count: count)
     return String(bytes: Array(bufprt), encoding: type)
   }
+  #else
+  /// Reads a string from the buffer and encodes it to a swift string
+  /// - Parameters:
+  ///   - index: index of the string in the buffer
+  ///   - count: length of the string
+  ///   - type: Encoding of the string
+  @inline(__always)
+  public func readString(
+    at index: Int,
+    count: Int) -> String?
+  {
+    assert(
+      index + count <= _storage.capacity,
+      "Reading out of bounds is illegal")
+    let start = _storage.memory.advanced(by: index)
+      .assumingMemoryBound(to: UInt8.self)
+    let bufprt = UnsafeBufferPointer(start: start, count: count)
+    return String(cString: bufprt.baseAddress!)
+  }
+  #endif
 
   /// Creates a new Flatbuffer object that's duplicated from the current one
   /// - Parameter removeBytes: the amount of bytes to remove from the current Size

swift/Sources/FlatBuffers/Constants.swift

@@ -14,15 +14,21 @@
  * limitations under the License.
  */
 
-#if os(Linux)
-import CoreFoundation
+#if !os(WASI)
+  #if os(Linux)
+  import CoreFoundation
+  #else
+  import Foundation
+  #endif
 #else
-import Foundation
+import SwiftOverlayShims
 #endif
 
 /// A boolean to see if the system is littleEndian
-let isLitteEndian = CFByteOrderGetCurrent() ==
-  Int(CFByteOrderLittleEndian.rawValue)
+let isLitteEndian: Bool = {
+  let number: UInt32 = 0x12345678
+  return number == number.littleEndian
+}()
 /// Constant for the file id length
 let FileIdLength = 4
 /// Type aliases

swift/Sources/FlatBuffers/Enum.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Enum is a protocol that all flatbuffers enums should conform to
 /// Since it allows us to get the actual `ByteSize` and `Value` from

swift/Sources/FlatBuffers/FlatBufferBuilder.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// ``FlatBufferBuilder`` builds a `FlatBuffer` through manipulating its internal state.
 ///
@@ -55,6 +59,7 @@ public struct FlatBufferBuilder {
   /// Gives a read access to the buffer's size
   public var size: UOffset { _bb.size }
 
+  #if !os(WASI)
   /// Data representation of the buffer
   ///
   /// Should only be used after ``finish(offset:addPrefix:)`` is called
@@ -64,6 +69,7 @@ public struct FlatBufferBuilder {
       bytes: _bb.memory.advanced(by: _bb.writerIndex),
       count: _bb.capacity &- _bb.writerIndex)
   }
+  #endif
 
   /// Returns the underlying bytes in the ``ByteBuffer``
   ///

swift/Sources/FlatBuffers/FlatBufferObject.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// NativeStruct is a protocol that indicates if the struct is a native `swift` struct
 /// since now we will be serializing native structs into the buffer.

swift/Sources/FlatBuffers/FlatBuffersUtils.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// FlatBuffersUtils hosts some utility functions that might be useful
 public enum FlatBuffersUtils {

swift/Sources/FlatBuffers/FlatbuffersErrors.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Collection of thrown from the Flatbuffer verifier
 public enum FlatbuffersErrors: Error, Equatable {
@@ -57,10 +61,17 @@ public enum FlatbuffersErrors: Error, Equatable {
     fieldName: String)
   case apparentSizeTooLarge
 
-  public static func == (
-    lhs: FlatbuffersErrors,
-    rhs: FlatbuffersErrors) -> Bool
-  {
-    lhs.localizedDescription == rhs.localizedDescription
-  }
 }
+
+#if !os(WASI)
+
+extension FlatbuffersErrors {
+    public static func == (
+      lhs: FlatbuffersErrors,
+      rhs: FlatbuffersErrors) -> Bool
+    {
+      lhs.localizedDescription == rhs.localizedDescription
+    }
+}
+
+#endif

swift/Sources/FlatBuffers/Int+extension.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 extension Int {
 

swift/Sources/FlatBuffers/Message.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// FlatBufferGRPCMessage protocol that should allow us to invoke
 /// initializers directly from the GRPC generated code

swift/Sources/FlatBuffers/Mutable.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Mutable is a protocol that allows us to mutate Scalar values within a ``ByteBuffer``
 public protocol Mutable {

swift/Sources/FlatBuffers/NativeObject.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// NativeObject is a protocol that all of the `Object-API` generated code should be
 /// conforming to since it allows developers the ease of use to pack and unpack their

swift/Sources/FlatBuffers/Offset.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Offset object for all the Objects that are written into the buffer
 public struct Offset {

swift/Sources/FlatBuffers/Root.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Takes in a prefixed sized buffer, where the prefixed size would be skipped.
 /// And would verify that the buffer passed is a valid `Flatbuffers` Object.

swift/Sources/FlatBuffers/String+extension.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 extension String: Verifiable {
 

swift/Sources/FlatBuffers/Struct.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Struct is a representation of a mutable `Flatbuffers` struct
 /// since native structs are value types and cant be mutated

swift/Sources/FlatBuffers/Table.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// `Table` is a Flatbuffers object that can read,
 /// mutate scalar fields within a valid flatbuffers buffer

swift/Sources/FlatBuffers/TableVerifier.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// `TableVerifier` verifies a table object is within a provided memory.
 /// It checks if all the objects for a specific generated table, are within

swift/Sources/FlatBuffers/VeriferOptions.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// `VerifierOptions` is a set of options to verify a flatbuffer
 public struct VerifierOptions {

swift/Sources/FlatBuffers/Verifiable.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Verifiable is a protocol all swift flatbuffers object should conform to,
 /// since swift is similar to `cpp` and `rust` where the data is read directly

swift/Sources/FlatBuffers/Verifier.swift

@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
+#if !os(WASI)
 import Foundation
+#else
+import SwiftOverlayShims
+#endif
 
 /// Verifier that check if the buffer passed into it is a valid,
 /// safe, aligned Flatbuffers object since swift read from `unsafeMemory`