Add the ability to print a nearly arbitrary CBOR encoded value

LibCBOR/CMakeLists.txt

@@ -25,4 +25,5 @@ target_sources(LibCBOR
     "Source/Core.cpp"
     "Source/Decoder.cpp"
     "Source/Encoder.cpp"
+    "Source/Printer.cpp"
 )

LibCBOR/Include/CBOR/Decoder.hpp

@@ -3,6 +3,7 @@
 
 #include "Core.hpp"
 
+#include <limits>
 #include <span>
 #include <string_view>
 
@@ -20,6 +21,13 @@ namespace CBOR
         Item(class Decoder &decoder);
 
     public:
+        static constexpr
+        std::uint64_t ArgumentIndefinite = std::numeric_limits<std::uint64_t>::max();
+
+        MajorType GetMajor() const;
+        MinorType GetMinor() const;
+        std::uint64_t GetArgument() const;
+
         bool Bool();
         Special Special();
 
@@ -37,13 +45,13 @@ namespace CBOR
         float  Float();
         double Double();
 
-        std::span<std::uint8_t> Binary();
-        std::string_view        String();
-        class Binary            IndefiniteBinary();
-        class String            IndefiniteString();
-        class Array             Array();
-        class Map               Map();
-        class TaggedItem        TaggedItem();
+        std::span<const std::uint8_t> Binary();
+        std::string_view              String();
+        class Binary                  IndefiniteBinary();
+        class String                  IndefiniteString();
+        class Array                   Array();
+        class Map                     Map();
+        class TaggedItem              TaggedItem();
 
     private:
         friend class Decoder;
@@ -102,8 +110,8 @@ namespace CBOR
         Binary(class Decoder &decoder);
 
     public:
-        bool                    Done();
-        std::span<std::uint8_t> Next();
+        bool                          Done();
+        std::span<const std::uint8_t> Next();
 
     private:
         friend class Decoder;
@@ -175,7 +183,14 @@ namespace CBOR
     class Decoder
     {
     public:
-        Decoder(std::span<std::uint8_t> buffer);
+        Decoder(std::span<const std::uint8_t> buffer);
+
+        static constexpr
+        std::uint64_t ArgumentIndefinite = std::numeric_limits<std::uint64_t>::max();
+
+        MajorType GetMajor() const;
+        MinorType GetMinor() const;
+        std::uint64_t GetArgument() const;
 
         bool Bool();
         Special Special();
@@ -194,14 +209,15 @@ namespace CBOR
         float  Float();
         double Double();
 
-        std::span<std::uint8_t> Binary();
-        std::string_view        String();
-        class Binary            IndefiniteBinary();
-        class String            IndefiniteString();
-        class Array             Array();
-        class Map               Map();
-        class TaggedItem        TaggedItem();
+        std::span<const std::uint8_t> Binary();
+        std::string_view              String();
+        class Binary                  IndefiniteBinary();
+        class String                  IndefiniteString();
+        class Array                   Array();
+        class Map                     Map();
+        class TaggedItem              TaggedItem();
 
+        class Item                    AsItem();
     private:
         friend class Binary;
         friend class String;
@@ -209,8 +225,8 @@ namespace CBOR
         friend class Map;
         friend class TaggedItem;
 
-        std::size_t             mCurrent;
-        std::span<std::uint8_t> mBuffer;
+        std::size_t                   mCurrent;
+        std::span<const std::uint8_t> mBuffer;
     };
 }
 

LibCBOR/Include/CBOR/Printer.hpp

@@ -0,0 +1,12 @@
+#ifndef LIBCBOR_PRINTER_HPP
+#define LIBCBOR_PRINTER_HPP
+
+#include <ostream>
+#include <span>
+
+namespace CBOR
+{
+    void Print(std::ostream &out, std::span<const std::uint8_t> buffer);
+}
+
+#endif // LIBCBOR_PRINTER_HPP

LibCBOR/Source/Decoder.cpp

@@ -57,7 +57,7 @@ namespace CBOR
     {
         static constexpr std::size_t Indefinite = std::numeric_limits<std::size_t>::max();
 
-        std::size_t SpaceLeft(std::span<std::uint8_t> buffer, std::size_t offset)
+        std::size_t SpaceLeft(std::span<const std::uint8_t> buffer, std::size_t offset)
         {
             if (offset >= buffer.size()) {
                 return 0;
@@ -65,7 +65,7 @@ namespace CBOR
             return buffer.size() - offset;
         }
 
-        void EnsureEnoughSpace(std::span<std::uint8_t> buffer, std::size_t offset,
+        void EnsureEnoughSpace(std::span<const std::uint8_t> buffer, std::size_t offset,
                                std::size_t spaceRequired)
         {
             if (SpaceLeft(buffer, offset) < spaceRequired) {
@@ -75,19 +75,13 @@ namespace CBOR
             }
         }
 
-        std::uint8_t  Read1B(std::span<std::uint8_t> buffer, std::size_t current)
+        std::uint8_t  Read1B(std::span<const std::uint8_t> buffer, std::size_t current)
         {
             EnsureEnoughSpace(buffer, current, 1);
             return buffer[current];
         }
 
-        std::uint8_t  Consume1B(std::span<std::uint8_t> buffer, std::size_t &current)
-        {
-            EnsureEnoughSpace(buffer, current, 1);
-            return buffer[current++];
-        }
-
-        std::uint16_t Consume2B(std::span<std::uint8_t> buffer, std::size_t &current)
+        std::uint16_t Read2B(std::span<const std::uint8_t> buffer, std::size_t current)
         {
             EnsureEnoughSpace(buffer, current, 2);
             std::uint16_t result = 0;
@@ -96,7 +90,7 @@ namespace CBOR
             return NetworkToHost(result);
         }
 
-        std::uint32_t Consume4B(std::span<std::uint8_t> buffer, std::size_t &current)
+        std::uint32_t Read4B(std::span<const std::uint8_t> buffer, std::size_t current)
         {
             EnsureEnoughSpace(buffer, current, 4);
             std::uint32_t result = 0;
@@ -107,7 +101,48 @@ namespace CBOR
             return NetworkToHost(result);
         }
 
-        std::uint64_t Consume8B(std::span<std::uint8_t> buffer, std::size_t &current)
+        std::uint64_t Read8B(std::span<const std::uint8_t> buffer, std::size_t current)
+        {
+            EnsureEnoughSpace(buffer, current, 8);
+            std::uint64_t result = 0;
+            result |= std::uint64_t(buffer[current++])      ;
+            result |= std::uint64_t(buffer[current++]) <<  8;
+            result |= std::uint64_t(buffer[current++]) << 16;
+            result |= std::uint64_t(buffer[current++]) << 24;
+            result |= std::uint64_t(buffer[current++]) << 32;
+            result |= std::uint64_t(buffer[current++]) << 40;
+            result |= std::uint64_t(buffer[current++]) << 48;
+            result |= std::uint64_t(buffer[current++]) << 56;
+            return NetworkToHost(result);
+        }
+
+        std::uint8_t  Consume1B(std::span<const std::uint8_t> buffer, std::size_t &current)
+        {
+            EnsureEnoughSpace(buffer, current, 1);
+            return buffer[current++];
+        }
+
+        std::uint16_t Consume2B(std::span<const std::uint8_t> buffer, std::size_t &current)
+        {
+            EnsureEnoughSpace(buffer, current, 2);
+            std::uint16_t result = 0;
+            result |= std::uint16_t(buffer[current++])     ;
+            result |= std::uint16_t(buffer[current++]) << 8;
+            return NetworkToHost(result);
+        }
+
+        std::uint32_t Consume4B(std::span<const std::uint8_t> buffer, std::size_t &current)
+        {
+            EnsureEnoughSpace(buffer, current, 4);
+            std::uint32_t result = 0;
+            result |= std::uint32_t(buffer[current++])      ;
+            result |= std::uint32_t(buffer[current++]) <<  8;
+            result |= std::uint32_t(buffer[current++]) << 16;
+            result |= std::uint32_t(buffer[current++]) << 24;
+            return NetworkToHost(result);
+        }
+
+        std::uint64_t Consume8B(std::span<const std::uint8_t> buffer, std::size_t &current)
         {
             EnsureEnoughSpace(buffer, current, 8);
             std::uint64_t result = 0;
@@ -137,7 +172,8 @@ namespace CBOR
             return ArgumentPosition(header & std::to_underlying(ArgumentPosition::PositionMask));
         }
 
-        std::uint64_t ArgumentValue(std::uint8_t header, std::span<std::uint8_t> buffer, std::size_t &current)
+        std::uint64_t ArgumentValue(std::uint8_t header, std::span<const std::uint8_t> buffer,
+                                    std::size_t &current)
         {
             ArgumentPosition position = GetArgumentPosition(header);
             if (std::to_underlying(position) <= 23) {
@@ -158,8 +194,30 @@ namespace CBOR
             }
         }
 
+        std::uint64_t ReadArgumentValue(std::uint8_t header, std::span<const std::uint8_t> buffer,
+                                        std::size_t current)
+        {
+            ArgumentPosition position = GetArgumentPosition(header);
+            if (std::to_underlying(position) <= 23) {
+                return std::to_underlying(position);
+            }
+            switch (position) {
+            case ArgumentPosition::Next1B:
+                return Read1B(buffer, current);
+            case ArgumentPosition::Next2B:
+                return Read2B(buffer, current);
+            case ArgumentPosition::Next4B:
+                return Read4B(buffer, current);
+            case ArgumentPosition::Next8B:
+                return Read8B(buffer, current);
+            default:
+                throw MalformedDataError("argument position is reserved for future use, incorrect, "
+                                         "or the parser is out of date");
+            }
+        }
+
         template <std::unsigned_integral T>
-        T ExtractUnsigned(std::span<std::uint8_t> buffer, std::size_t &current)
+        T ExtractUnsigned(std::span<const std::uint8_t> buffer, std::size_t &current)
         {
             static constexpr std::uint64_t maxValue = std::numeric_limits<T>::max();
 
@@ -214,7 +272,8 @@ namespace CBOR
 
         // Note(3011): In this case it includes zero, even though zero is not technically positive.
         template <std::signed_integral T>
-        T SignedPositive(std::uint8_t header, std::span<std::uint8_t> buffer, std::size_t &current)
+        T SignedPositive(std::uint8_t header, std::span<const std::uint8_t> buffer,
+                         std::size_t &current)
         {
             static constexpr std::uint64_t maxValue = std::numeric_limits<T>::max();
 
@@ -266,7 +325,8 @@ namespace CBOR
         }
 
         template <std::signed_integral T>
-        T SignedNegative(std::uint8_t header, std::span<std::uint8_t> buffer, std::size_t &current)
+        T SignedNegative(std::uint8_t header, std::span<const std::uint8_t> buffer,
+                         std::size_t &current)
         {
             static constexpr auto actualMin = std::numeric_limits<T>::min();
             static constexpr std::uint64_t minValue = -std::int64_t(actualMin + 1);
@@ -319,7 +379,7 @@ namespace CBOR
         }
 
         template <std::signed_integral T>
-        T ExtractSigned(std::span<std::uint8_t> buffer, std::size_t &current)
+        T ExtractSigned(std::span<const std::uint8_t> buffer, std::size_t &current)
         {
             std::uint8_t header = Consume1B(buffer, current);
             MajorType major = GetMajorType(header);
@@ -335,15 +395,17 @@ namespace CBOR
             }
         }
 
-        std::span<std::uint8_t> ExtractBinary(std::size_t size, std::span<std::uint8_t> buffer, std::size_t &current)
+        std::span<const std::uint8_t>
+        ExtractBinary(std::size_t size, std::span<const std::uint8_t> buffer, std::size_t &current)
         {
             EnsureEnoughSpace(buffer, current, size);
-            std::span<std::uint8_t> result(buffer.data() + current, size);
+            std::span<const std::uint8_t> result(buffer.data() + current, size);
             current += size;
             return result;
         }
 
-        std::string_view ExtractString(std::size_t size, std::span<std::uint8_t> buffer, std::size_t &current)
+        std::string_view ExtractString(std::size_t size, std::span<const std::uint8_t> buffer,
+                                       std::size_t &current)
         {
             EnsureEnoughSpace(buffer, current, size);
             std::string_view result(reinterpret_cast<const char *>(buffer.data() + current), size);
@@ -356,6 +418,21 @@ namespace CBOR
         : mDecoder(&decoder)
     {}
 
+    MajorType Item::GetMajor() const
+    {
+        return mDecoder->GetMajor();
+    }
+
+    MinorType Item::GetMinor() const
+    {
+        return mDecoder->GetMinor();
+    }
+
+    std::uint64_t Item::GetArgument() const
+    {
+        return mDecoder->GetArgument();
+    }
+
     bool Item::Bool()
     {
         return mDecoder->Bool();
@@ -416,7 +493,7 @@ namespace CBOR
         return mDecoder->Double();
     }
 
-    std::span<std::uint8_t> Item::Binary()
+    std::span<const std::uint8_t> Item::Binary()
     {
         return mDecoder->Binary();
     }
@@ -531,7 +608,7 @@ namespace CBOR
         return mDone;
     }
 
-    std::span<std::uint8_t> Binary::Next()
+    std::span<const std::uint8_t> Binary::Next()
     {
         if (!mHeaderParsed) {
             std::uint8_t header = Consume1B(mDecoder->mBuffer, mDecoder->mCurrent);
@@ -767,10 +844,37 @@ namespace CBOR
         return KeyValue(*mDecoder);
     }
 
-    Decoder::Decoder(std::span<std::uint8_t> buffer)
+    Decoder::Decoder(std::span<const std::uint8_t> buffer)
         : mCurrent(0), mBuffer(buffer)
     {}
 
+    MajorType Decoder::GetMajor() const
+    {
+        std::uint8_t header = Read1B(mBuffer, mCurrent);
+        return GetMajorType(header);
+    }
+
+    MinorType Decoder::GetMinor() const
+    {
+        std::uint8_t header = Read1B(mBuffer, mCurrent);
+        if (GetMajorType(header) != MajorType::Other) {
+            throw InvalidUsageError("use the GetArgument function instead");
+        }
+        return GetMinorType(header);
+    }
+
+    std::uint64_t Decoder::GetArgument() const
+    {
+        std::uint8_t header = Read1B(mBuffer, mCurrent);
+        if (GetMajorType(header) != MajorType::Other) {
+            throw InvalidUsageError("use the GetMinor function instead");
+        }
+        if (GetArgumentPosition(header) == ArgumentPosition::Indefinite) {
+            return Decoder::ArgumentIndefinite;
+        }
+        return ReadArgumentValue(header, mBuffer, mCurrent);
+    }
+
     bool Decoder::Bool()
     {
         std::uint8_t header = Consume1B(mBuffer, mCurrent);
@@ -881,7 +985,7 @@ namespace CBOR
         throw TypeMismatchError("double", ToString(major));
     }
 
-    std::span<std::uint8_t> Decoder::Binary()
+    std::span<const std::uint8_t> Decoder::Binary()
     {
         std::uint8_t header = Consume1B(mBuffer, mCurrent);
         MajorType major = GetMajorType(header);
@@ -937,4 +1041,9 @@ namespace CBOR
     {
         return { *this };
     }
+
+    Item Decoder::AsItem()
+    {
+        return { *this };
+    }
 }

LibCBOR/Source/Printer.cpp

@@ -0,0 +1,146 @@
+#include "Printer.hpp"
+
+#include "Core.hpp"
+#include "Decoder.hpp"
+
+#include <print>
+#include <string>
+
+namespace CBOR
+{
+    namespace
+    {
+        void Print(std::ostream &out, std::size_t depth, CBOR::Item item);
+
+        char AsChar(std::uint8_t nibble)
+        {
+            if (nibble < 10) {
+                return nibble + '0';
+            }
+            if (nibble < 16) {
+                return nibble + 'A';
+            }
+            return 'X';
+        }
+
+        std::string AsString(std::uint8_t byte)
+        {
+            std::string result;
+            result.push_back(AsChar((byte >> 4) & 15));
+            result.push_back(AsChar((byte     ) & 15));
+            return result;
+        }
+
+        void PrintBinary(std::ostream &out, CBOR::Binary binary)
+        {
+            out << "b\"";
+            while (!binary.Done()) {
+                std::span<const std::uint8_t> chunk = binary.Next();
+                for (std::uint8_t byte: chunk) {
+                    out << AsString(byte);
+                }
+            }
+            out << '\"';
+        }
+
+        void PrintString(std::ostream &out, CBOR::String string)
+        {
+            out << '\"';
+            while (!string.Done()) {
+                out << string.Next();
+            }
+            out << '\"';
+        }
+
+        void PrintArray(std::ostream &out, std::size_t depth, CBOR::Array array)
+        {
+            out << "[\n";
+            while (!array.Done()) {
+                out << std::string((depth + 1) * 4, ' ');
+                Print(out, depth + 1, array.Next());
+                out << ",\n";
+            }
+            out << std::string(depth * 4, ' ') << "]";
+        }
+
+        void PrintMap(std::ostream &out, std::size_t depth, CBOR::Map map)
+        {
+            out << "{\n";
+            while (!map.Done()) {
+                CBOR::KeyValue kv = map.Next();
+                out << std::string((depth + 1) * 4, ' ');
+                Print(out, depth + 1, kv.Key());
+                out << ": ";
+                Print(out, depth + 1, kv.Value());
+                out << ",\n";
+            }
+            out << std::string(depth * 4, ' ') << "}";
+        }
+
+        void PrintTagged(std::ostream &out, std::size_t depth, CBOR::TaggedItem item)
+        {
+            out << item.Tag();
+            out << '(';
+            Print(out, depth, item.Item());
+            out << ')';
+        }
+
+        void Print(std::ostream &out, std::size_t depth, CBOR::Item item)
+        {
+            switch (item.GetMajor()) {
+            case MajorType::Unsigned:
+                out << item.Uint64();
+                break;
+            case MajorType::Negative:
+                out << item.Int64();
+                break;
+            case MajorType::Binary:
+                PrintBinary(out, item.IndefiniteBinary());
+                break;
+            case MajorType::String:
+                PrintString(out, item.IndefiniteString());
+                break;
+            case MajorType::Array:
+                PrintArray(out, depth, item.Array());
+                break;
+            case MajorType::Map:
+                PrintMap(out, depth, item.Map());
+                break;
+            case MajorType::Tag:
+                PrintTagged(out, depth, item.TaggedItem());
+                break;
+            case MajorType::Other:
+                switch (item.GetMinor()) {
+                case MinorType::False:
+                    out << "false";
+                    break;
+                case MinorType::True:
+                    out << "true";
+                    break;
+                case MinorType::Null:
+                    out << "null";
+                    break;
+                case MinorType::Undefined:
+                    out << "undefined";
+                    break;
+                case MinorType::Float:
+                    std::print(out, "{:.6f}", item.Float());
+                    break;
+                case MinorType::Double:
+                    std::print(out, "{:.15f}", item.Double());
+                    break;
+                default:
+                    out << "invalid_value";
+                    break;
+                }
+            }
+        }
+    }
+
+    void Print(std::ostream &out, std::span<const std::uint8_t> buffer)
+    {
+        CBOR::Decoder dec(buffer);
+        Print(out, 0, dec.AsItem());
+        out << '\n';
+    }
+}

Tests/Main.cpp

@@ -1,7 +1,9 @@
 #include "CBOR/Decoder.hpp"
 #include "CBOR/Encoder.hpp"
+#include "Cbor/Printer.hpp"
 #include <array>
 #include <cstdint>
+#include <iostream>
 #include <print>
 #include <ranges>
 #include <stdexcept>
@@ -206,6 +208,9 @@ int main()
         SomeStruct result1 = Decode1(std::span<std::uint8_t>(buffer.data(), encodedSize));
         SomeStruct result2 = Decode2(std::span<std::uint8_t>(buffer.data(), encodedSize));
 
+        std::println("JSON-esque serialization:");
+        CBOR::Print(std::cout, std::span<std::uint8_t>(buffer.data(), encodedSize));
+
         Compare(expected, result1);
         Compare(expected, result2);
         std::println("The test has been completed successfully.");