SERVER-44623 Rework JSON generation from BSONObj

- Extended Canonical/Relaxed 2.0.0 is supported
- Using libfmt instead of stringstream as internal buffer
- JSON parser can parse Extended Canonical/Relaxed and Strict formats
- Removed TenGen format

1 files changed, 159 insertions, 0 deletions

diff --git a/src/mongo/bson/generator_legacy_strict.h b/src/mongo/bson/generator_legacy_strict.h
new file mode 100644
index 00000000000..bfe027328d1
--- /dev/null
+++ b/src/mongo/bson/generator_legacy_strict.h
@@ -0,0 +1,159 @@
+/**
+ *    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 "mongo/bson/generator_extended_canonical_2_0_0.h"
+#include "mongo/bson/util/builder.h"
+#include "mongo/util/str.h"
+
+#include <fmt/format.h>
+
+namespace mongo {
+class LegacyStrictGenerator : private ExtendedCanonicalV200Generator {
+public:
+    using ExtendedCanonicalV200Generator::writeBool;
+    using ExtendedCanonicalV200Generator::writeNull;
+
+    void writeUndefined(fmt::memory_buffer& buffer) const {
+        appendTo(buffer, R"({ "$undefined" : true })"_sd);
+    }
+
+    void writeString(fmt::memory_buffer& buffer, StringData str) const {
+        fmt::format_to(buffer, R"("{}")", str::escape(str));
+    }
+
+    void writeSymbol(fmt::memory_buffer& buffer, StringData symbol) const {
+        writeString(buffer, symbol);
+    }
+
+    void writeInt32(fmt::memory_buffer& buffer, int32_t val) const {
+        writeDouble(buffer, val);
+    }
+
+    void writeInt64(fmt::memory_buffer& buffer, int64_t val) const {
+        fmt::format_to(buffer, R"({{ "$numberLong" : "{}" }})", val);
+    }
+
+    void writeDouble(fmt::memory_buffer& buffer, double val) const {
+        if (val >= std::numeric_limits<double>::lowest() &&
+            val <= std::numeric_limits<double>::max())
+            fmt::format_to(buffer, R"({:.16g})", val);
+        else if (std::isnan(val))
+            appendTo(buffer, "NaN"_sd);
+        else if (std::isinf(val)) {
+            if (val > 0)
+                appendTo(buffer, "Infinity"_sd);
+            else
+                appendTo(buffer, "-Infinity"_sd);
+        } else {
+            StringBuilder ss;
+            ss << "Number " << val << " cannot be represented in JSON";
+            uassert(10311, ss.str(), false);
+        }
+    }
+
+    void writeDecimal128(fmt::memory_buffer& buffer, Decimal128 val) const {
+        if (val.isNaN())
+            appendTo(buffer, R"({ "$numberDecimal" : "NaN" })"_sd);
+        else if (val.isInfinite())
+            fmt::format_to(buffer,
+                           R"({{ "$numberDecimal" : "{}" }})",
+                           val.isNegative() ? "-Infinity"_sd : "Infinity"_sd);
+        else {
+            fmt::format_to(buffer, R"({{ "$numberDecimal" : "{}" }})", val.toString());
+        }
+    }
+
+    void writeDate(fmt::memory_buffer& buffer, Date_t val) const {
+        // The two cases in which we cannot convert Date_t::millis to an ISO Date string are
+        // when the date is too large to format (SERVER-13760), and when the date is before
+        // the epoch (SERVER-11273).  Since Date_t internally stores millis as an unsigned
+        // long long, despite the fact that it is logically signed (SERVER-8573), this check
+        // handles both the case where Date_t::millis is too large, and the case where
+        // Date_t::millis is negative (before the epoch).
+        if (val.isFormattable()) {
+            fmt::format_to(buffer, R"({{ "$date" : "{}" }})", dateToISOStringLocal(val));
+        } else {
+            fmt::format_to(
+                buffer, R"({{ "$date" : {{ "$numberLong" : "{}" }} }})", val.toMillisSinceEpoch());
+        }
+    }
+
+    void writeDBRef(fmt::memory_buffer& buffer, StringData ref, OID id) const {
+        fmt::format_to(buffer, R"({{ "$ref" : "{}", "$id" : "{}" }})", ref, id.toString());
+    }
+
+    void writeOID(fmt::memory_buffer& buffer, OID val) const {
+        fmt::format_to(buffer, R"({{ "$oid" : "{}" }})", val.toString());
+    }
+
+    void writeBinData(fmt::memory_buffer& buffer, StringData data, BinDataType type) const {
+        appendTo(buffer, R"({ "$binary" : ")");
+        base64::encode(buffer, data);
+        fmt::format_to(buffer, R"(", "$type" : "{:02x}" }})", type);
+    }
+
+    void writeRegex(fmt::memory_buffer& buffer, StringData pattern, StringData options) const {
+        fmt::format_to(
+            buffer, R"({{ "$regex" : "{}", "$options" : "{}" }})", str::escape(pattern), options);
+    }
+
+    void writeCode(fmt::memory_buffer& buffer, StringData code) const {
+        fmt::format_to(buffer, R"({{ "$code" : "{}" }})", str::escape(code));
+    }
+
+    void writeCodeWithScope(fmt::memory_buffer& buffer,
+                            StringData code,
+                            BSONObj const& scope) const {
+        fmt::format_to(buffer, R"({{ "$code" : "{}", "$scope" : )", str::escape(code));
+        scope.jsonStringGenerator(*this, 0, false, buffer);
+        appendTo(buffer, R"( })");
+    }
+
+    void writeTimestamp(fmt::memory_buffer& buffer, Timestamp val) const {
+        fmt::format_to(buffer,
+                       R"({{ "$timestamp" : {{ "t" : {}, "i" : {} }} }})",
+                       val.getSecs(),
+                       val.getInc());
+    }
+
+    void writeMinKey(fmt::memory_buffer& buffer) const {
+        appendTo(buffer, R"({ "$minKey" : 1 })"_sd);
+    }
+
+    void writeMaxKey(fmt::memory_buffer& buffer) const {
+        appendTo(buffer, R"({ "$maxKey" : 1 })"_sd);
+    }
+
+    void writePadding(fmt::memory_buffer& buffer) const {
+        buffer.push_back(' ');
+    }
+};
+}  // namespace mongo