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/**
* Copyright (C) 2019-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <array>
#include <ostream>
#include "mongo/base/string_data.h"
#include "mongo/bson/bsonelement.h"
#include "mongo/util/stacktrace.h"
namespace mongo::stacktrace_detail {
/**
* A utility for uint64_t <=> uppercase hex string conversions. It
* can be used to produce a StringData.
*
* sink << Hex(x).str(); // as a temporary
*
* Hex hx(x);
* StringData sd = hx.str() // sd storage is in `hx`.
*/
class Hex {
public:
using Buf = std::array<char, 16>;
static StringData toHex(uint64_t x, Buf& buf);
static uint64_t fromHex(StringData s);
explicit Hex(uint64_t x) : _str(toHex(x, _buf)) {}
StringData str() const {
return _str;
}
private:
Buf _buf;
StringData _str;
};
/** An append-only, async-safe, malloc-free Json emitter. */
class CheapJson {
public:
class Value;
explicit CheapJson(StackTraceSink& sink);
// Create an empty JSON document.
Value doc();
private:
StackTraceSink& _sink;
};
/**
* A Json Value node being emitted. Emits {}/[] braces, keyval ":" separators, commas,
* and quotes. To use this, make a Value for the root document and call `append*`
* members, adding a nested structure of objects, arrays, and scalars to the active
* Value.
*
* The constructor emits any appropriate opening brace, and the destructor emits any
* appropriate closing brace. Keeps an internal state so that a comma is emitted on the
* second and subsequent append call.
*/
class CheapJson::Value {
public:
/** The empty root document, which emits no braces. */
explicit Value(CheapJson* env) : Value(env, kNop) {}
/** Emit the closing brace if any. */
~Value();
/** Begin a Json Array. Returns a Value that can be used to append elements to it. */
Value appendArr();
/** Begin a Json Object. Returns a Value that can be used to append elements to it. */
Value appendObj();
/** Append key `k` to this Json Object. Returns the empty Value mapped to `k`. */
Value appendKey(StringData k);
/** Append string `v`, surrounded by doublequote characters. */
void append(StringData v);
/** Append integer `v`, in decimal. */
void append(uint64_t v);
/**
* Append the elements of `be` to this Object or Array.
* Behavior depends on the kind of Value this is.
* - If object: append `be` keys and values.
* - If array: append `be` values only.
*/
void append(const BSONElement& be);
private:
enum Kind {
kNop, // A blank Value, not an aggregate, emits no punctuation. Can emit one element.
kObj, // Object: can emit multiple key-value pairs: {k1:v1, k2:v2, ...}
kArr, // Array: can emit multiple scalars [v1, v2, ...]
};
/* Emit the opening brace corresponding to the specified `k`. */
Value(CheapJson* env, Kind k);
void _copyBsonElementValue(const BSONElement& be);
void _next();
CheapJson* _env;
Kind _kind;
StringData _sep; // Emitted upon append. Starts empty, then set to ",".
};
} // namespace mongo::stacktrace_detail
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