misc(json): Add jsoncons as a vendored library (facebookincubator#12406)

Summary:
Pull Request resolved: facebookincubator#12406

This is part of an effort to add support for complete set of json path tokens. As a first step we add jsoncons as a vendored library and in the upcoming changes we will start to incrementally use it.

The code for the library has been pulled from https://github.com/danielaparker/jsoncons with some changes. The changes include:

- Only files relevant to json and json parsing have been included
- The #include directives have been updated to point to local paths
- Prepend Apache license while preserving the existing boost license
- The namespaces have been prepended with facebook::velox to avoid namespace conflict if velox is included in projects that already use jsoncons
- Made changes to the json path parser to conform with jayway library which is a json library currently used by presto java.
- Added a flag to the json path parser that returns an error for paths not currently supported by velox.

Changes made to the parser include:
- Added support for unquoted identifier after bracket `$[<identifier>]` that can also start with a number like `$[Key]` or `$[30day]`
- Added support for bracket (`[`) after dot `$.['key']` (redundant use of dot operator)
- Added support for dash (`-`) in the middle of an unquoted string
- Added support for prepending by default `$.` in not included at the beginning of the path. This is to support cases like `[0]` or `key` which will now be equivalent to `$.[0]` or `$.key`

Reviewed By: xiaoxmeng

Differential Revision: D68564596

Author: Bikramjeet Vig

velox/external/jsoncons/allocator_holder.hpp

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// Copyright 2013-2025 Daniel Parker
+// Distributed under the Boost license, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See https://github.com/danielaparker/jsoncons for latest version
+
+#ifndef JSONCONS_ALLOCATOR_HOLDER_HPP
+#define JSONCONS_ALLOCATOR_HOLDER_HPP
+
+namespace facebook::velox::jsoncons {
+
+template <typename Allocator>
+class allocator_holder
+{
+public:
+    using allocator_type = Allocator;
+private:
+    allocator_type alloc_;
+public:
+    allocator_holder() = default;
+    allocator_holder(const allocator_holder&)  = default;
+    allocator_holder(allocator_holder&&)  = default;
+    allocator_holder& operator=(const allocator_holder&) = delete;
+    allocator_holder(const allocator_type& alloc)
+        : alloc_(alloc)
+        {}
+    ~allocator_holder() = default;
+    
+    allocator_type get_allocator() const
+    {
+        return alloc_;
+    }
+};
+
+} // namespace facebook::velox::jsoncons
+
+#endif // JSONCONS_ALLOCATOR_HOLDER_HPP

velox/external/jsoncons/allocator_set.hpp

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// Copyright 2013-2025 Daniel Parker
+// Distributed under the Boost license, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See https://github.com/danielaparker/jsoncons for latest version
+
+#ifndef JSONCONS_ALLOCATOR_SET_HPP
+#define JSONCONS_ALLOCATOR_SET_HPP
+
+#include <memory>
+
+#include "velox/external/jsoncons/tag_type.hpp"
+
+namespace facebook::velox::jsoncons {
+
+template <typename Allocator,typename TempAllocator >
+class allocator_set
+{
+    Allocator result_alloc_;
+    TempAllocator temp_alloc_;
+public:
+    using allocator_type = Allocator;
+    using temp_allocator_type = TempAllocator;
+
+    allocator_set(const Allocator& alloc=Allocator(), 
+        const TempAllocator& temp_alloc=TempAllocator())
+        : result_alloc_(alloc), temp_alloc_(temp_alloc)
+    {
+    }
+
+    allocator_set(const allocator_set&)  = default;
+    allocator_set(allocator_set&&)  = default;
+    allocator_set& operator=(const allocator_set&)  = delete;
+    allocator_set& operator=(allocator_set&&)  = delete;
+    ~allocator_set() = default;
+
+    Allocator get_allocator() const {return result_alloc_;}
+    TempAllocator get_temp_allocator() const {return temp_alloc_;}
+};
+
+inline
+allocator_set<std::allocator<char>,std::allocator<char>> combine_allocators()
+{
+    return allocator_set<std::allocator<char>,std::allocator<char>>(std::allocator<char>(), std::allocator<char>());
+}
+
+template <typename Allocator>
+allocator_set<Allocator,std::allocator<char>> combine_allocators(const Allocator& alloc)
+{
+    return allocator_set<Allocator,std::allocator<char>>(alloc, std::allocator<char>());
+}
+
+template <typename Allocator,typename TempAllocator >
+allocator_set<Allocator,TempAllocator> combine_allocators(const Allocator& alloc, const TempAllocator& temp_alloc)
+{
+    return allocator_set<Allocator,TempAllocator>(alloc, temp_alloc);
+}
+
+template <typename TempAllocator >
+allocator_set<std::allocator<char>,TempAllocator> temp_allocator_only(const TempAllocator& temp_alloc)
+{
+    return allocator_set<std::allocator<char>,TempAllocator>(std::allocator<char>(), temp_alloc);
+}
+
+} // namespace facebook::velox::jsoncons
+
+#endif // JSONCONS_ALLOCATOR_SET_HPP