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/*
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 * Licensed to the Apache Software Foundation (ASF) under one
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 * or more contributor license agreements. See the NOTICE file
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 * distributed with this work for additional information
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 * regarding copyright ownership. The ASF licenses this file
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 * to you under the Apache License, Version 2.0 (the
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 * "License"); you may not use this file except in compliance
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 * with the License. You may obtain a copy of the License at
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 *
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 *   http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing,
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 * software distributed under the License is distributed on an
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 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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 * KIND, either express or implied. See the License for the
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 * specific language governing permissions and limitations
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 * under the License.
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 */
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#ifndef _THRIFT_TREFLECTIONLOCAL_H_
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#define _THRIFT_TREFLECTIONLOCAL_H_ 1
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#include <stdint.h>
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#include <cstring>
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#include <protocol/TProtocol.h>
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/**
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 * Local Reflection is a blanket term referring to the the structure
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 * and generation of this particular representation of Thrift types.
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 * (It is called local because it cannot be serialized by Thrift).
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 *
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 */
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namespace apache { namespace thrift { namespace reflection { namespace local {
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using apache::thrift::protocol::TType;
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// We include this many bytes of the structure's fingerprint when serializing
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// a top-level structure.  Long enough to make collisions unlikely, short
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// enough to not significantly affect the amount of memory used.
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const int FP_PREFIX_LEN = 4;
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struct FieldMeta {
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  int16_t tag;
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  bool is_optional;
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};
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struct TypeSpec {
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  TType ttype;
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  uint8_t    fp_prefix[FP_PREFIX_LEN];
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  // Use an anonymous union here so we can fit two TypeSpecs in one cache line.
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  union {
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    struct {
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      // Use parallel arrays here for denser packing (of the arrays).
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      FieldMeta* metas;
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      TypeSpec** specs;
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    } tstruct;
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    struct {
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      TypeSpec *subtype1;
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      TypeSpec *subtype2;
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    } tcontainer;
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  };
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  // Static initialization of unions isn't really possible,
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  // so take the plunge and use constructors.
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  // Hopefully they'll be evaluated at compile time.
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  TypeSpec(TType ttype) : ttype(ttype) {
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    std::memset(fp_prefix, 0, FP_PREFIX_LEN);
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  }
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  TypeSpec(TType ttype,
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           const uint8_t* fingerprint,
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           FieldMeta* metas,
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           TypeSpec** specs) :
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    ttype(ttype)
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  {
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    std::memcpy(fp_prefix, fingerprint, FP_PREFIX_LEN);
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    tstruct.metas = metas;
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    tstruct.specs = specs;
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  }
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  TypeSpec(TType ttype, TypeSpec* subtype1, TypeSpec* subtype2) :
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    ttype(ttype)
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  {
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    std::memset(fp_prefix, 0, FP_PREFIX_LEN);
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    tcontainer.subtype1 = subtype1;
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    tcontainer.subtype2 = subtype2;
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  }
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};
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}}}} // apache::thrift::reflection::local
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#endif // #ifndef _THRIFT_TREFLECTIONLOCAL_H_