musique/include/musique.hh

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#ifndef Musique_Header_HH
#define Musique_Header_HH
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#include <chrono>
#include <concepts>
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#include <cstdint>
#include <cstring>
#include <functional>
#include <memory>
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#include <optional>
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#include <ostream>
#include <span>
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#include <string_view>
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#include <variant>
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#include <midi.hh>
#include <tl/expected.hpp>
#if defined(__cpp_lib_source_location)
#include <source_location>
#endif
// To make sure, that we don't collide with <cassert> macro
#ifdef assert
#undef assert
#endif
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using namespace std::string_literals;
using namespace std::string_view_literals;
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using u8 = std::uint8_t;
using u16 = std::uint16_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using i8 = std::int8_t;
using i16 = std::int16_t;
using i32 = std::int32_t;
using i64 = std::int64_t;
using usize = std::size_t;
using isize = std::ptrdiff_t;
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/// \brief Location describes code position in `file line column` format.
/// It's used both to represent position in source files provided
// to interpreter and internal interpreter usage.
struct Location
{
std::string_view filename = "<unnamed>"; ///< File that location is pointing to
usize line = 1; ///< Line number (1 based) that location is pointing to
usize column = 1; ///< Column number (1 based) that location is pointing to
/// Advances line and column numbers based on provided rune
///
/// If rune is newline, then column is reset to 1, and line number is incremented.
/// Otherwise column number is incremented.
///
/// @param rune Rune from which column and line numbers advancements are made.
Location& advance(u32 rune);
bool operator==(Location const& rhs) const = default;
//! Creates location at default filename with specified line and column number
static Location at(usize line, usize column);
// Used to describe location of function call in interpreter (internal use only)
#if defined(__cpp_lib_source_location)
static Location caller(std::source_location loc = std::source_location::current());
#elif (__has_builtin(__builtin_FILE) and __has_builtin(__builtin_LINE))
static Location caller(char const* file = __builtin_FILE(), usize line = __builtin_LINE());
#else
#error Cannot implement Location::caller function
/// Returns location of call in interpreter source code.
///
/// Example of reporting where `foo()` was beeing called:
/// @code
/// void foo(Location loc = Location::caller()) { std::cout << loc << '\n'; }
/// @endcode
static Location caller();
#endif
};
std::ostream& operator<<(std::ostream& os, Location const& location);
/// Error handling related functions and definitions
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namespace errors
{
/// When user puts emoji in the source code
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struct Unrecognized_Character
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{
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u32 invalid_character;
};
/// When parser was expecting code but encountered end of file
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struct Unexpected_Empty_Source
{
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enum { Block_Without_Closing_Bracket } reason;
std::optional<Location> start;
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};
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/// When user passed numeric literal too big for numeric type
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struct Failed_Numeric_Parsing
{
std::errc reason;
};
/// When user forgot semicolon or brackets
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struct Expected_Expression_Separator_Before
{
std::string_view what;
};
/// When some keywords are not allowed in given context
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struct Unexpected_Keyword
{
std::string_view keyword;
};
/// When user tried to use operator that was not defined
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struct Undefined_Operator
{
std::string_view op;
};
/// When user tried to call something that can't be called
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struct Not_Callable
{
std::string_view type;
};
/// When user provides literal where identifier should be
struct Literal_As_Identifier
{
std::string_view type_name;
std::string_view source;
std::string_view context;
};
/// When user provides wrong type for given operation
struct Unsupported_Types_For
{
/// Type of operation
enum Type { Operator, Function } type;
/// Name of operation
std::string_view name;
/// Possible ways to use it correctly
std::vector<std::string> possibilities;
};
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/// When user tries to use variable that has not been defined yet.
struct Missing_Variable
{
/// Name of variable
std::string name;
};
/// When user tries to invoke some MIDI action but haven't established MIDI connection
struct Operation_Requires_Midi_Connection
{
/// If its input or output connection missing
bool is_input;
/// Name of the operation that was beeing invoked
std::string name;
};
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/// When user tries to get element from collection with index higher then collection size
struct Out_Of_Range
{
/// Index that was required by the user
size_t required_index;
/// Size of accessed collection
size_t size;
};
struct Closing_Token_Without_Opening
{
enum {
Block = ']',
Paren = ')'
} type;
};
struct Arithmetic
{
enum Type
{
Division_By_Zero,
Fractional_Modulo,
Unable_To_Calculate_Modular_Multiplicative_Inverse
} type;
};
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/// Collection of messages that are considered internal and should not be printed to the end user.
namespace internal
{
/// When encountered token that was supposed to be matched in higher branch of the parser
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struct Unexpected_Token
{
/// Type of the token
std::string_view type;
/// Source of the token
std::string_view source;
/// Where this token was encountered that was unexpected?
std::string_view when;
};
}
/// All possible error types
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using Details = std::variant<
Arithmetic,
Closing_Token_Without_Opening,
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Expected_Expression_Separator_Before,
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Failed_Numeric_Parsing,
Literal_As_Identifier,
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Missing_Variable,
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Not_Callable,
Operation_Requires_Midi_Connection,
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Out_Of_Range,
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Undefined_Operator,
Unexpected_Empty_Source,
Unexpected_Keyword,
Unrecognized_Character,
Unsupported_Types_For,
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internal::Unexpected_Token
>;
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}
/// All code related to pretty printing. Default mode is no_color
namespace pretty
{
/// Mark start of printing an error
std::ostream& begin_error(std::ostream&);
/// Mark start of printing a path
std::ostream& begin_path(std::ostream&);
/// Mark start of printing a comment
std::ostream& begin_comment(std::ostream&);
/// Mark end of any above
std::ostream& end(std::ostream&);
/// Switch to colorful output via ANSI escape sequences
void terminal_mode();
/// Switch to colorless output (default one)
void no_color_mode();
}
/// Combine several lambdas into one for visiting std::variant
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template<typename ...Lambdas>
struct Overloaded : Lambdas... { using Lambdas::operator()...; };
/// Guards that program exits if condition does not hold
void assert(bool condition, std::string message, Location loc = Location::caller());
/// Marks part of code that was not implemented yet
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[[noreturn]] void unimplemented(std::string_view message = {}, Location loc = Location::caller());
/// Marks location that should not be reached
[[noreturn]] void unreachable(Location loc = Location::caller());
/// Represents all recoverable error messages that interpreter can produce
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struct Error
{
/// Specific message details
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errors::Details details;
/// Location that coused all this trouble
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std::optional<Location> location = std::nullopt;
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/// Return self with new location
Error with(Location) &&;
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};
/// Error pretty printing
std::ostream& operator<<(std::ostream& os, Error const& err);
/// Returns if provided thingy is a given template
template<template<typename ...> typename Template, typename>
struct is_template : std::false_type {};
template<template<typename ...> typename Template, typename ...T>
struct is_template<Template, Template<T...>> : std::true_type {};
/// Returns if provided thingy is a given template
template<template<typename ...> typename Template, typename T>
constexpr auto is_template_v = is_template<Template, T>::value;
/// Holds either T or Error
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template<typename T>
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struct [[nodiscard("This value may contain critical error, so it should NOT be ignored")]] Result : tl::expected<T, Error>
{
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using Storage = tl::expected<T, Error>;
constexpr Result() = default;
template<typename ...Args> requires (not std::is_void_v<T>) && std::is_constructible_v<T, Args...>
constexpr Result(Args&& ...args)
: Storage( T{ std::forward<Args>(args)... } )
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{
}
template<typename Arg> requires std::is_constructible_v<Storage, Arg>
constexpr Result(Arg &&arg)
: Storage(std::forward<Arg>(arg))
{
}
inline Result(Error error)
: Storage(tl::unexpected(std::move(error)))
{
}
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template<typename Arg>
requires requires (Arg a) {
{ Error { .details = std::move(a) } };
}
inline Result(Arg a)
: Storage(tl::unexpected(Error { .details = std::move(a) }))
{
}
// Internal function used for definition of Try macro
inline auto value() &&
{
if constexpr (not std::is_void_v<T>) {
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// NOTE This line in ideal world should be `return Storage::value()`
// but C++ does not infer that this is rvalue context.
// `std::add_rvalue_reference_t<Storage>::value()`
// also does not work, so this is probably the best way to express this:
return std::move(*static_cast<Storage*>(this)).value();
}
}
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/// Fill error location if it's empty and we have an error
inline Result<T> with_location(Location location) &&
{
if (!Storage::has_value()) {
if (auto& target = Storage::error().location; !target || target == Location{}) {
target = location;
}
}
return *this;
}
inline tl::expected<T, Error> to_expected() &&
{
return *static_cast<Storage*>(this);
}
template<typename Map>
requires is_template_v<Result, std::invoke_result_t<Map, T&&>>
auto and_then(Map &&map) &&
{
return std::move(*static_cast<Storage*>(this)).and_then(
[map = std::forward<Map>(map)](T &&value) {
return std::move(map)(std::move(value)).to_expected();
});
}
using Storage::and_then;
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operator std::optional<Error>() &&
{
return Storage::has_value() ? std::nullopt : std::optional(Storage::error());
}
};
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/// Shorthand for forwarding error values with Result type family.
///
/// This implementation requires C++ language extension: statement expressions
/// It's supported by GCC and Clang, other compilers i don't know.
/// Inspired by SerenityOS TRY macro
#define Try(Value) \
({ \
auto try_value = (Value); \
if (not try_value.has_value()) [[unlikely]] \
return tl::unexpected(try_value.error()); \
std::move(try_value).value(); \
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})
/// Drop in replacement for bool when C++ implcit conversions stand in your way
struct Explicit_Bool
{
bool value;
constexpr Explicit_Bool(bool b) : value(b)
{
}
constexpr Explicit_Bool(auto &&) = delete;
constexpr operator bool() const
{
return value;
}
};
/// All unicode related operations
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namespace unicode
{
inline namespace special_runes
{
[[maybe_unused]] constexpr u32 Rune_Error = 0xfffd;
[[maybe_unused]] constexpr u32 Rune_Self = 0x80;
[[maybe_unused]] constexpr u32 Max_Bytes = 4;
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}
/// is_digit returns true if `digit` is ASCII digit
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bool is_digit(u32 digit);
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/// is_space return true if `space` is ASCII blank character
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bool is_space(u32 space);
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/// is_letter returns true if `letter` is considered a letter by Unicode
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bool is_letter(u32 letter);
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/// is_identifier returns true if `letter` is valid character for identifier.
///
/// It's modifier by is_first_character flag to determine some character classes
/// allowance like numbers, which are only allowed NOT at the front of the identifier
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enum class First_Character : bool { Yes = true, No = false };
bool is_identifier(u32 letter, First_Character is_first_character);
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}
/// utf8 encoding and decoding
namespace utf8
{
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using namespace unicode::special_runes;
/// Decodes rune and returns remaining string
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auto decode(std::string_view s) -> std::pair<u32, std::string_view>;
/// Returns length of the first rune in the provided string
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auto length(std::string_view s) -> usize;
struct Print { u32 rune; };
}
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std::ostream& operator<<(std::ostream& os, utf8::Print const& print);
/// Lexical token representation for Musique language
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struct Token
{
/// Type of Token
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enum class Type
{
Symbol, ///< like repeat or choose or chord
Keyword, ///< like true, false, nil
Operator, ///< like "+", "-", "++", "<"
Chord, ///< chord or single note literal, like "c125"
Numeric, ///< numeric literal (floating point or integer)
Parameter_Separator, ///< "|" separaters arguments from block body
Expression_Separator, ///< ";" separates expressions. Used mainly to separate calls, like `foo 1 2; bar 3 4`
Open_Block, ///< "[" delimits anonymous block of code (potentially a function)
Close_Block, ///< "]" delimits anonymous block of code (potentially a function)
Open_Paren, ///< "(" used in arithmetic or as function invocation sarrounding
Close_Paren ///< ")" used in arithmetic or as function invocation sarrounding
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};
/// Type of token
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Type type;
/// Matched source code to the token type
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std::string_view source;
/// Location of encountered token
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Location location;
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};
static constexpr usize Keywords_Count = 6;
static constexpr usize Operators_Count = 16;
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std::string_view type_name(Token::Type type);
/// Token debug printing
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std::ostream& operator<<(std::ostream& os, Token const& tok);
/// Token type debug printing
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std::ostream& operator<<(std::ostream& os, Token::Type type);
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struct Lines
{
static Lines the;
/// Region of lines in files
std::unordered_map<std::string, std::vector<std::string_view>> lines;
/// Add lines from file
void add_file(std::string filename, std::string_view source);
/// Add single line into file (REPL usage)
void add_line(std::string const& filename, std::string_view source, unsigned line_number);
/// Print selected region
void print(std::ostream& os, std::string const& file, unsigned first_line, unsigned last_line) const;
};
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/// Explicit marker of the end of file
struct End_Of_File {};
/// Lexer takes source code and turns it into list of tokens
///
/// It allows for creating sequence of tokens by using next_token() method.
/// On each call to next_token() when source is non empty token is lexed and
/// source is beeing advanced by removing matched token from string.
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struct Lexer
{
/// Source that is beeing lexed
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std::string_view source;
/// Location in source of the last rune
///
/// Used only for rewinding
u32 last_rune_length = 0;
/// Start of the token that is currently beeing matched
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char const* token_start = nullptr;
/// Bytes matched so far
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usize token_length = 0;
/// Location of the start of a token that is currently beeing matched
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Location token_location{};
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/// Current location of Lexer in source
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Location location{};
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/// Previous location of Lexer in source
///
/// Used only for rewinding
Location prev_location{};
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/// Try to tokenize next token.
auto next_token() -> Result<std::variant<Token, End_Of_File>>;
/// Skip whitespace and comments from the beggining of the source
///
/// Utility function for next_token()
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void skip_whitespace_and_comments();
/// Finds next rune in source
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auto peek() const -> u32;
/// Finds next rune in source and returns it, advancing the string
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auto consume() -> u32;
/// For test beeing
/// callable, current rune is passed to test
/// integral, current rune is tested for equality with test
/// string, current rune is tested for beeing in it
/// otherwise, current rune is tested for beeing in test
///
/// When testing above yields truth, current rune is consumed.
/// Returns if rune was consumed
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auto consume_if(auto test) -> bool;
/// Consume two runes with given tests otherwise backtrack
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auto consume_if(auto first, auto second) -> bool;
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/// Goes back last rune
void rewind();
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/// Marks begin of token
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void start();
/// Marks end of token and returns it's matching source
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std::string_view finish();
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};
/// Representation of a node in program tree
struct Ast
{
/// Constructs binary operator
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static Ast binary(Token, Ast lhs, Ast rhs);
/// Constructs block
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static Ast block(Location location, Ast seq = sequence({}));
/// Constructs call expression
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static Ast call(std::vector<Ast> call);
/// Constructs block with parameters
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static Ast lambda(Location location, Ast seq = sequence({}), std::vector<Ast> parameters = {});
/// Constructs constants, literals and variable identifiers
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static Ast literal(Token);
/// Constructs sequence of operations
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static Ast sequence(std::vector<Ast> call);
/// Constructs variable declaration
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static Ast variable_declaration(Location loc, std::vector<Ast> lvalues, std::optional<Ast> rvalue);
/// Available ASt types
enum class Type
{
Binary, ///< Binary operator application like `1` + `2`
Block, ///< Block expressions like `[42; hello]`
Lambda, ///< Block expression beeing functions like `[i|i+1]`
Call, ///< Function call application like `print 42`
Literal, ///< Compile time known constant like `c` or `1`
Sequence, ///< Several expressions sequences like `42`, `42; 32`
Variable_Declaration, ///< Declaration of a variable with optional value assigment like `var x = 10` or `var y`
};
/// Type of AST node
Type type;
/// Location that introduced this node
Location location;
/// Associated token
Token token;
/// Child nodes
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std::vector<Ast> arguments{};
};
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bool operator==(Ast const& lhs, Ast const& rhs);
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std::ostream& operator<<(std::ostream& os, Ast::Type type);
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std::ostream& operator<<(std::ostream& os, Ast const& tree);
/// Pretty print program tree for debugging purposes
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void dump(Ast const& ast, unsigned indent = 0);
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/// Source code to program tree converter
///
/// Intended to be used by library user only by Parser::parse() static function.
struct Parser
{
/// List of tokens yielded from source
std::vector<Token> tokens;
/// Current token id (offset in tokens array)
unsigned token_id = 0;
/// Parses whole source code producing Ast or Error
/// using Parser structure internally
static Result<Ast> parse(std::string_view source, std::string_view filename, unsigned line_number = 0);
/// Parse sequence, collection of expressions
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Result<Ast> parse_sequence();
/// Parse either infix expression or variable declaration
Result<Ast> parse_expression();
/// Parse infix expression
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Result<Ast> parse_infix_expression();
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/// Parse right hand size of infix expression
Result<Ast> parse_rhs_of_infix_expression(Ast lhs);
/// Parse either index expression or atomic expression
Result<Ast> parse_index_expression();
/// Parse function call, literal etc
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Result<Ast> parse_atomic_expression();
/// Parse variable declaration
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Result<Ast> parse_variable_declaration();
/// Utility function for identifier parsing
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Result<Ast> parse_identifier_with_trailing_separators();
/// Utility function for identifier parsing
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Result<Ast> parse_identifier();
/// Peek current token
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Result<Token> peek() const;
/// Peek type of the current token
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Result<Token::Type> peek_type() const;
/// Consume current token
Token consume();
/// Tests if current token has given type
bool expect(Token::Type type) const;
/// Tests if current token has given type and source
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bool expect(Token::Type type, std::string_view lexeme) const;
};
/// Number type supporting integer and fractional constants
///
/// \invariant gcd(num, den) == 1, after any operation
struct Number
{
/// Type that represents numerator and denominator values
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using value_type = i64;
value_type num = 0; ///< Numerator of a fraction beeing represented
value_type den = 1; ///< Denominator of a fraction beeing represented
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constexpr Number() = default;
constexpr Number(Number const&) = default;
constexpr Number(Number &&) = default;
constexpr Number& operator=(Number const&) = default;
constexpr Number& operator=(Number &&) = default;
explicit Number(value_type v); ///< Creates Number as fraction v / 1
Number(value_type num, value_type den); ///< Creates Number as fraction num / den
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auto as_int() const -> value_type; ///< Returns self as int
auto simplify() const -> Number; ///< Returns self, but with gcd(num, den) == 1
void simplify_inplace(); ///< Update self, to have gcd(num, den) == 1
bool operator==(Number const&) const;
bool operator!=(Number const&) const;
std::strong_ordering operator<=>(Number const&) const;
Number operator+(Number const& rhs) const;
Number& operator+=(Number const& rhs);
Number operator-(Number const& rhs) const;
Number& operator-=(Number const& rhs);
Number operator*(Number const& rhs) const;
Number& operator*=(Number const& rhs);
Result<Number> operator/(Number const& rhs) const;
Result<Number> operator%(Number const& rhs) const;
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Number floor() const; ///< Return number rounded down to nearest integer
Number ceil() const; ///< Return number rounded up to nearest integer
Number round() const; ///< Return number rounded to nearest integer
Result<Number> inverse() const; ///< Return number raised to power -1
Result<Number> pow(Number n) const; ///< Return number raised to power `n`.
/// Parses source contained by token into a Number instance
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static Result<Number> from(Token token);
};
std::ostream& operator<<(std::ostream& os, Number const& num);
struct Env;
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struct Interpreter;
struct Value;
using Intrinsic = Result<Value>(*)(Interpreter &i, std::vector<Value>);
/// Lazy Array / Continuation / Closure type thingy
struct Block
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{
/// Location of definition / creation
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Location location;
/// Names of expected parameters
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std::vector<std::string> parameters;
/// Body that will be executed
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Ast body;
/// Context from which block was created. Used for closures
std::shared_ptr<Env> context;
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/// Calling block
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Result<Value> operator()(Interpreter &i, std::vector<Value> params);
/// Indexing block
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Result<Value> index(Interpreter &i, unsigned position);
/// Count of elements in block
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usize size() const;
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};
/// Representation of musical note or musical pause
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struct Note
{
/// Base of a note, like `c` (=0), `c#` (=1) `d` (=2)
/// Or nullopt where there is no note - case when we have pause
std::optional<i32> base = std::nullopt;
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/// Octave in MIDI acceptable range (from -1 to 9 inclusive)
std::optional<i8> octave = std::nullopt;
/// Length of playing note
std::optional<Number> length = std::nullopt;
/// Create Note from string
static std::optional<Note> from(std::string_view note);
/// Extract midi note number
std::optional<u8> into_midi_note() const;
/// Extract midi note number, but when octave is not present use provided default
u8 into_midi_note(i8 default_octave) const;
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bool operator==(Note const&) const;
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std::partial_ordering operator<=>(Note const&) const;
/// Simplify note by adding base to octave if octave is present
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void simplify_inplace();
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};
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std::ostream& operator<<(std::ostream& os, Note note);
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/// Represantation of simultaneously played notes, aka musical chord
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struct Chord
{
std::vector<Note> notes; ///< Notes composing a chord
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/// Parse chord literal from provided source
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static Chord from(std::string_view source);
bool operator==(Chord const&) const = default;
};
std::ostream& operator<<(std::ostream& os, Chord const& chord);
/// Eager Array
struct Array
{
/// Elements that are stored in array
std::vector<Value> elements;
/// Index element of an array
Result<Value> index(Interpreter &i, unsigned position);
/// Count of elements
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usize size() const;
bool operator==(Array const&) const = default;
};
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std::ostream& operator<<(std::ostream& os, Array const& v);
/// Representation of any value in language
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struct Value
{
/// Creates value from literal contained in Token
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static Result<Value> from(Token t);
/// Create value holding provided boolean
///
/// Using Explicit_Bool to prevent from implicit casts
static Value from(Explicit_Bool b);
static Value from(Array &&array); ///< Create value of type array holding provided array
static Value from(Block &&l); ///< Create value of type block holding provided block
static Value from(Chord chord); ///< Create value of type music holding provided chord
static Value from(Note n); ///< Create value of type music holding provided note
static Value from(Number n); ///< Create value of type number holding provided number
static Value from(char const* s); ///< Create value of type symbol holding provided symbol
static Value from(std::string s); ///< Create value of type symbol holding provided symbol
static Value from(std::string_view s); ///< Create value of type symbol holding provided symbol
static Value from(std::vector<Value> &&array); ///< Create value of type array holding provided array
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enum class Type
{
Nil, ///< Unit type, used for denoting emptiness and result of some side effect only functions
Bool, ///< Boolean type, used for logic computations
Number, ///< Number type, representing only rational numbers
Symbol, ///< Symbol type, used to represent identifiers
Intrinsic, ///< Intrinsic functions that are implemented in C++
Block, ///< Block type, containing block value (lazy array/closure/lambda like)
Array, ///< Array type, eager array
Music, ///< Music type,
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};
Value() = default;
Value(Value const&) = default;
Value(Value &&) = default;
Value& operator=(Value const&) = default;
Value& operator=(Value &&) = default;
/// Contructs Intrinsic, used to simplify definition of intrinsics
inline Value(Intrinsic intr) : type{Type::Intrinsic}, intr(intr)
{
}
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Type type = Type::Nil;
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bool b;
Number n;
Intrinsic intr;
Block blk;
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Chord chord;
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Array array;
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// TODO Most strings should not be allocated by Value, but reference to string allocated previously
// Wrapper for std::string is needed that will allocate only when needed, middle ground between:
// std::string - always owning string type
// std::string_view - not-owning string type
std::string s{};
/// Returns truth judgment for current type, used primarly for if function
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bool truthy() const;
/// Returns false judgment for current type, used primarly for if function
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bool falsy() const;
/// Calls contained value if it can be called
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Result<Value> operator()(Interpreter &i, std::vector<Value> args);
/// Index contained value if it can be called
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Result<Value> index(Interpreter &i, unsigned position);
/// Return elements count of contained value if it can be measured
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usize size() const;
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bool operator==(Value const& other) const;
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std::partial_ordering operator<=>(Value const& other) const;
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};
template<Value::Type>
struct Member_For_Value_Type {};
template<> struct Member_For_Value_Type<Value::Type::Bool>
{ static constexpr auto value = &Value::b; };
template<> struct Member_For_Value_Type<Value::Type::Number>
{ static constexpr auto value = &Value::n; };
template<> struct Member_For_Value_Type<Value::Type::Symbol>
{ static constexpr auto value = &Value::s; };
template<> struct Member_For_Value_Type<Value::Type::Intrinsic>
{ static constexpr auto value = &Value::intr; };
template<> struct Member_For_Value_Type<Value::Type::Block>
{ static constexpr auto value = &Value::blk; };
template<> struct Member_For_Value_Type<Value::Type::Array>
{ static constexpr auto value = &Value::array; };
template<> struct Member_For_Value_Type<Value::Type::Music>
{ static constexpr auto value = &Value::chord; };
/// Returns type name of Value type
std::string_view type_name(Value::Type t);
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std::ostream& operator<<(std::ostream& os, Value const& v);
/// Collection holding all variables in given scope.
struct Env : std::enable_shared_from_this<Env>
{
/// Constructor of Env class
static std::shared_ptr<Env> make();
/// Global scope that is beeing set by Interpreter
static std::shared_ptr<Env> global;
/// Variables in current scope
std::unordered_map<std::string, Value> variables;
/// Parent scope
std::shared_ptr<Env> parent;
Env(Env const&) = delete;
Env(Env &&) = default;
Env& operator=(Env const&) = delete;
Env& operator=(Env &&) = default;
/// Defines new variable regardless of it's current existance
Env& force_define(std::string name, Value new_value);
/// Finds variable in current or parent scopes
Value* find(std::string const& name);
/// Create new scope with self as parent
std::shared_ptr<Env> enter();
/// Leave current scope returning parent
std::shared_ptr<Env> leave();
private:
/// Ensure that all values of this class are behind shared_ptr
Env() = default;
};
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/// Context holds default values for music related actions
struct Context
{
/// Default note octave
i8 octave = 4;
/// Default note length
Number length = Number(1, 4);
/// Default BPM
unsigned bpm = 120;
/// Fills empty places in Note like octave and length with default values from context
Note fill(Note) const;
/// Converts length to seconds with current bpm
std::chrono::duration<float> length_to_duration(std::optional<Number> length) const;
};
/// Given program tree evaluates it into Value
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struct Interpreter
{
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/// MIDI connection that is used to play music.
/// It's optional for simple interpreter testing.
midi::Connection *midi_connection = nullptr;
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/// Operators defined for language
std::unordered_map<std::string, Intrinsic> operators;
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/// Current environment (current scope)
std::shared_ptr<Env> env;
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/// Context stack. `constext_stack.back()` is a current context.
/// There is always at least one context
std::vector<Context> context_stack;
std::function<Result<void>(Interpreter&, Value)> default_action;
struct Incoming_Midi_Callbacks;
std::unique_ptr<Incoming_Midi_Callbacks> callbacks;
void register_callbacks();
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Interpreter();
~Interpreter();
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Interpreter(Interpreter const&) = delete;
Interpreter(Interpreter &&) = default;
/// Try to evaluate given program tree
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Result<Value> eval(Ast &&ast);
// Enter scope by changing current environment
void enter_scope();
// Leave scope by changing current environment
void leave_scope();
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/// Play note resolving any missing parameters with context via `midi_connection` member.
Result<void> play(Chord);
/// Add to global interpreter scope all builtin function definitions
///
/// Invoked during construction
void register_builtin_functions();
/// Add to interpreter operators table all operators
///
/// Invoked during construction
void register_builtin_operators();
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};
namespace errors
{
[[noreturn]]
void all_tokens_were_not_parsed(std::span<Token>);
}
/// Intrinsic implementation primitive providing a short way to check if arguments match required type signature
static inline bool typecheck(std::vector<Value> const& args, auto const& ...expected_types)
{
return (args.size() == sizeof...(expected_types)) &&
[&args, expected_types...]<std::size_t ...I>(std::index_sequence<I...>) {
return ((expected_types == args[I].type) && ...);
} (std::make_index_sequence<sizeof...(expected_types)>{});
}
/// Intrinsic implementation primitive providing a short way to move values based on matched type signature
static inline bool typecheck_front(std::vector<Value> const& args, auto const& ...expected_types)
{
return (args.size() >= sizeof...(expected_types)) &&
[&args, expected_types...]<std::size_t ...I>(std::index_sequence<I...>) {
return ((expected_types == args[I].type) && ...);
} (std::make_index_sequence<sizeof...(expected_types)>{});
}
/// Intrinsic implementation primitive providing a short way to move values based on matched type signature
template<auto ...Types>
static inline auto move_from(std::vector<Value>& args)
{
return [&args]<std::size_t ...I>(std::index_sequence<I...>) {
return std::tuple { (std::move(args[I]).*(Member_For_Value_Type<Types>::value)) ... };
} (std::make_index_sequence<sizeof...(Types)>{});
}
/// Shape abstraction to define what types are required once
template<auto ...Types>
struct Shape
{
static inline auto move_from(std::vector<Value>& args) { return ::move_from<Types...>(args); }
static inline auto typecheck(std::vector<Value>& args) { return ::typecheck(args, Types...); }
static inline auto typecheck_front(std::vector<Value>& args) { return ::typecheck_front(args, Types...); }
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static inline auto typecheck_and_move(std::vector<Value>& args)
{
return typecheck(args) ? std::optional { move_from(args) } : std::nullopt;
}
};
/// Returns if type can be indexed
static constexpr bool is_indexable(Value::Type type)
{
return type == Value::Type::Array || type == Value::Type::Block;
}
/// Returns if type can be called
static constexpr bool is_callable(Value::Type type)
{
return type == Value::Type::Block || type == Value::Type::Intrinsic;
}
/// Flattens one layer: `[[[1], 2], 3]` becomes `[[1], 2, 3]`
Result<std::vector<Value>> flatten(Interpreter &i, std::span<Value>);
Result<std::vector<Value>> flatten(Interpreter &i, std::vector<Value>);
template<> struct std::hash<Token> { std::size_t operator()(Token const&) const; };
template<> struct std::hash<Ast> { std::size_t operator()(Ast const&) const; };
template<> struct std::hash<Number> { std::size_t operator()(Number const&) const; };
template<> struct std::hash<Value> { std::size_t operator()(Value const&) const; };
#endif