Leaky - Modern C++ based JSON parser

Features:

• Recursive Descent Parser
• Tokenization using C++11 regex library
• Token types declared using C++17 std::variant
• Parsing using concrete structure types
• Minimal overhead of token parsing
• Write to the standard output stream or a specified file
• Read input from the standard input stream or a specified file
• Complete unicode support
• Complete JSON parsing according to the JSON RFC
• Output using C++23 std::print and std::println

Build Dependencies:

• C++23 compatible compiler (gcc-14+ or clang-19+)
• Catch2 testing framework

Build Instructions:

$> mkdir build && cd build
$> cmake -DCMAKE_BUILD_TYPE=Release ..
$> cmake --build .

Concrete lexer types:

• token - base class for token classes
• string - JSON string tokens matched using STRINGS
• number - JSON number tokens matched using NUMBERS
• separator - JSON allowed character symbols matched using SEPARATORS
• true_token - JSON true symbol token
• false_token - JSON false symbol token
• null - JSON null symbol token

Concrete parser types:

• json_value - std::variant class representing all valid value types
• json_array - class representing the JSON array type
• array_elements - collection of json_value for JSON values in an array
• json_object - class representing the JSON object type
• json_pair - class representing key value pairs in a JSON object
• object_members - collection of key-value pairs for a JSON object

Context Free Grammar for JSON LL(1) grammar:

• <json> ::= <value>
• <value> ::= <object> | <array> | "string" | "number" | <true> | <false> | <null>
• <object> ::= "{" <members> "}"
• <members> ::= <pair> | <pair>, <members> | epsilon
• <pair> ::= "string" ":" <value>
• <array> ::= "[" <elements> "]
• <elements> := <value> | <value>, <elements>
• <true> ::= "true"
• <false> ::= "false"
• <null> ::= "null"