[ASTGen] Add Encoder/Decoder implementation backed by llvm::json::Value

Preparation for a future use.

include/swift/Basic/CBasicBridging.h

@@ -0,0 +1,124 @@
+//===--- CBasicBridging.h - header for the swift SILBridging module -------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_C_BASIC_BASICBRIDGING_H
+#define SWIFT_C_BASIC_BASICBRIDGING_H
+
+#include "swift/Basic/Compiler.h"
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#if __clang__
+// Provide macros to temporarily suppress warning about the use of
+// _Nullable and _Nonnull.
+#define SWIFT_BEGIN_NULLABILITY_ANNOTATIONS                                    \
+  _Pragma("clang diagnostic push")                                             \
+      _Pragma("clang diagnostic ignored \"-Wnullability-extension\"")          \
+          _Pragma("clang assume_nonnull begin")
+
+#define SWIFT_END_NULLABILITY_ANNOTATIONS                                      \
+  _Pragma("clang diagnostic pop") _Pragma("clang assume_nonnull end")
+#else
+#define SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
+#define SWIFT_END_NULLABILITY_ANNOTATIONS
+#define _Nullable
+#define _Nonnull
+#endif
+
+SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct BridgedData {
+  const char *_Nullable baseAddress;
+  size_t size;
+} BridgedData;
+
+void BridgedData_free(BridgedData data);
+
+//===----------------------------------------------------------------------===//
+// Plugins
+//===----------------------------------------------------------------------===//
+
+/// Create a new root 'null' JSON value. Clients must call \c JSON_value_delete
+/// after using it.
+void *JSON_newValue();
+
+/// Parse \p data as a JSON data and return the top-level value. Clients must
+/// call \c JSON_value_delete after using it.
+void *JSON_deserializedValue(BridgedData data);
+
+/// Serialize a value and populate \p result with the result data. Clients
+/// must call \c BridgedData_free after using the \p result.
+void JSON_value_serialize(void *valuePtr, BridgedData *result);
+
+/// Destroy and release the memory for \p valuePtr that is a result from
+/// \c JSON_newValue() or \c JSON_deserializedValue() .
+void JSON_value_delete(void *valuePtr);
+
+bool JSON_value_getAsNull(void *valuePtr);
+bool JSON_value_getAsBoolean(void *valuePtr, bool *result);
+bool JSON_value_getAsString(void *valuePtr, BridgedData *result);
+bool JSON_value_getAsDouble(void *valuePtr, double *result);
+bool JSON_value_getAsInteger(void *valuePtr, int64_t *result);
+bool JSON_value_getAsObject(void *valuePtr, void *_Nullable *_Nonnull result);
+bool JSON_value_getAsArray(void *valuePtr, void *_Nullable *_Nonnull result);
+
+size_t JSON_object_getSize(void *objectPtr);
+BridgedData JSON_object_getKey(void *objectPtr, size_t i);
+bool JSON_object_hasKey(void *objectPtr, const char *key);
+void *JSON_object_getValue(void *objectPtr, const char *key);
+
+int64_t JSON_array_getSize(void *arrayPtr);
+void *JSON_array_getValue(void *arrayPtr, int64_t index);
+
+void JSON_value_emplaceNull(void *valuePtr);
+void JSON_value_emplaceBoolean(void *valuePtr, bool value);
+void JSON_value_emplaceString(void *valuePtr, const char *value);
+void JSON_value_emplaceDouble(void *valuePtr, double value);
+void JSON_value_emplaceInteger(void *valuePtr, int64_t value);
+void *JSON_value_emplaceNewObject(void *valuePtr);
+void *JSON_value_emplaceNewArray(void *valuePtr);
+
+void JSON_object_setNull(void *objectPtr, const char *key);
+void JSON_object_setBoolean(void *objectPtr, const char *key, bool value);
+void JSON_object_setString(void *objectPtr, const char *key, const char *value);
+void JSON_object_setDouble(void *objectPtr, const char *key, double value);
+void JSON_object_setInteger(void *objectPtr, const char *key, int64_t value);
+void *JSON_object_setNewObject(void *objectPtr, const char *key);
+void *JSON_object_setNewArray(void *objectPtr, const char *key);
+void *JSON_object_setNewValue(void *objectPtr, const char *key);
+
+void JSON_array_pushNull(void *arrayPtr);
+void JSON_array_pushBoolean(void *arrayPtr, bool value);
+void JSON_array_pushString(void *arrayPtr, const char *value);
+void JSON_array_pushDouble(void *arrayPtr, double value);
+void JSON_array_pushInteger(void *arrayPtr, int64_t value);
+void *JSON_array_pushNewObject(void *arrayPtr);
+void *JSON_array_pushNewArray(void *arrayPtr);
+void *JSON_array_pushNewValue(void *arrayPtr);
+
+#ifdef __cplusplus
+}
+#endif
+
+SWIFT_END_NULLABILITY_ANNOTATIONS
+
+#undef SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
+#undef SWIFT_END_NULLABILITY_ANNOTATIONS
+
+#endif // SWIFT_C_BASIC_BASICBRIDGING_H