Value.hpp

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// Copyright 2026 Daniel McGuire
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
// README
//
// Provides types for the Phasor (and Pulsar) Programming Language.
// Wraps a std::variant over null, bool, int64_t, double, string, struct, and array,
// with structs, arrays, and strings heap-allocated via std::shared_ptr. Provides arithmetic,
// comparison, and logical operators, and isTruthy() and toString().
//
// Also includes a std::formatter<Phasor::Value> implementation for use with std::format (or std::print).
// Supports four format specifiers: default (value as-is), t (type name only),
// T (type and value), ? (debug repr with quoted strings and recursive expansion), and
// q (quoted strings, default otherwise).
 
#pragma once
#include <iostream>
#include <string>
#include <variant>
#include <unordered_map>
#include <memory>
#include <vector>
#include <format>
#include <string>

namespace Phasor
{

enum class ValueType
{
    Null,
    Bool,
    Int,
    Float,
    String,
    Struct,
    Array
};

class Value
{
  public:
    struct StructInstance
    {
        std::string                            structName;
        std::unordered_map<std::string, Value> fields;
    };
    using ArrayInstance = std::vector<Value>;
 
  private:
    using DataType = std::variant<std::monostate, bool, int64_t, double, std::shared_ptr<std::string>,
                                  std::shared_ptr<StructInstance>,
                                  std::shared_ptr<ArrayInstance>>;
 
    DataType data;
 
  public:
    Value() : data(std::monostate{})
    {
    }

    Value(bool b) : data(b)
    {
    }

    Value(int64_t i) : data(i)
    {
    }

    Value(int i) : data(static_cast<int64_t>(i))
    {
    }

    Value(double d) : data(d)
    {
    }

    Value(const std::string &s) : data(std::make_shared<std::string>(s))
    {
    }

    Value(const char *s) : data(std::make_shared<std::string>(s))
    {
    }

    Value(std::shared_ptr<StructInstance> s) : data(std::move(s))
    {
    }

    Value(std::shared_ptr<ArrayInstance> a) : data(std::move(a))
    {
    }

    [[nodiscard]] ValueType getType() const noexcept {
        return static_cast<ValueType>(data.index());
    }
 
    static Value typeToString(const ValueType &type)
    {
        switch (type)
        {
        case ValueType::Null:
            return {"null"};
        case ValueType::Bool:
            return {"bool"};
        case ValueType::Int:
            return {"int"};
        case ValueType::Float:
            return {"float"};
        case ValueType::String:
            return {"string"};
        case ValueType::Struct:
            return {"struct"};
        case ValueType::Array:
            return {"array"};
        default:
            return {"unknown"};
        }
    }

    [[nodiscard]] bool isNull()   const noexcept { return data.index() == 0; }
    [[nodiscard]] bool isBool()   const noexcept { return data.index() == 1; }
    [[nodiscard]] bool isInt()    const noexcept { return data.index() == 2; }
    [[nodiscard]] bool isFloat()  const noexcept { return data.index() == 3; }
    [[nodiscard]] bool isString() const noexcept { return data.index() == 4; }
    [[nodiscard]] bool isNumber() const noexcept { return data.index() == 2 || data.index() == 3; }
    [[nodiscard]] bool isArray() const noexcept
    {
        return std::holds_alternative<std::shared_ptr<ArrayInstance>>(data);
    }

    [[nodiscard]] bool asBool() const noexcept
    {
        return std::get<bool>(data);
    }

    [[nodiscard]] int64_t asInt() const noexcept
    {
        if (isInt())
        {
            return std::get<int64_t>(data);
        }
        if (isFloat())
        {
            return static_cast<int64_t>(std::get<double>(data));
        }
        return 0;
    }

    [[nodiscard]] double asFloat() const noexcept
    {
        if (isFloat())
        {
            return std::get<double>(data);
        }
        if (isInt())
        {
            return static_cast<double>(std::get<int64_t>(data));
        }
        return 0.0;
    }

    [[nodiscard]] std::string asString() const noexcept
    {
        if (isString())
        {
            return *std::get<std::shared_ptr<std::string>>(data);
        }
        return toString();
    }

    std::shared_ptr<ArrayInstance> asArray()
    {
        return std::get<std::shared_ptr<ArrayInstance>>(data);
    }

    [[nodiscard]] std::shared_ptr<const ArrayInstance> asArray() const noexcept
    {
        return std::get<std::shared_ptr<ArrayInstance>>(data);
    }

    Value operator+(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            return {asInt() + other.asInt()};
        }
        if (isNumber() && other.isNumber())
        {
            return {asFloat() + other.asFloat()};
        }
        if (isString() && other.isString())
        {
            return Value(asString() + other.asString());
        }
        throw std::runtime_error("Cannot add these value types");
    }

    Value operator-(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            return {asInt() - other.asInt()};
        }
        if (isNumber() && other.isNumber())
        {
            return {asFloat() - other.asFloat()};
        }
        throw std::runtime_error("Cannot subtract these value types");
    }
 
    Value &operator--()
    {
        if (isInt())
        {
            data = asInt() - 1;
            return *this;
        }
        if (isFloat())
        {
            data = asFloat() - 1.0;
            return *this;
        }
        throw std::runtime_error("Cannot decrement this value type");
    }
 
    Value &operator++()
    {
        if (isInt())
        {
            data = asInt() + 1;
            return *this;
        }
        if (isFloat())
        {
            data = asFloat() + 1.0;
            return *this;
        }
        throw std::runtime_error("Cannot increment this value type");
    }

    Value operator*(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            return {asInt() * other.asInt()};
        }
        if (isNumber() && other.isNumber())
        {
            return {asFloat() * other.asFloat()};
        }
        throw std::runtime_error("Cannot multiply these value types");
    }

    Value operator/(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            if (other.asInt() == 0)
            {
                throw std::runtime_error("Division by zero");
            }
            return {asInt() / other.asInt()};
        }
        if (isNumber() && other.isNumber())
        {
            if (other.asFloat() == 0.0)
            {
                throw std::runtime_error("Division by zero");
            }
            return {asFloat() / other.asFloat()};
        }
        throw std::runtime_error("Cannot divide these value types");
    }

    Value operator%(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            if (other.asInt() == 0)
            {
                throw std::runtime_error("Modulo by zero");
            }
            return {asInt() % other.asInt()};
        }
        throw std::runtime_error("Modulo requires integer operands");
    }

    Value operator!() const noexcept
    {
        return {!isTruthy()};
    }

    [[nodiscard]] Value logicalAnd(const Value &other) const noexcept
    {
        return {isTruthy() && other.isTruthy()};
    }

    [[nodiscard]] Value logicalOr(const Value &other) const noexcept
    {
        return {isTruthy() || other.isTruthy()};
    }

    [[nodiscard]] bool isTruthy() const noexcept
    {
        if (isNull())
        {
            return false;
        }
        if (isBool())
        {
            return asBool();
        }
        if (isInt())
        {
            return asInt() != 0;
        }
        if (isFloat())
        {
            return asFloat() != 0.0;
        }
        if (isString())
        {
            return !asString().empty();
        }
        return false;
    }

    bool operator==(const Value &other) const noexcept
    {
        if (getType() != other.getType())
        {
            return false;
        }
        if (isNull())
        {
            return true;
        }
        if (isBool())
        {
            return asBool() == other.asBool();
        }
        if (isInt())
        {
            return asInt() == other.asInt();
        }
        if (isFloat())
        {
            return asFloat() == other.asFloat();
        }
        if (isString())
        {
            return asString() == other.asString();
        }
        if (isArray())
        {
            if (!other.isArray())
            {
                return false;
            }
            const auto &self_arr = *asArray();
            const auto &other_arr = *other.asArray();
            return self_arr == other_arr;
        }
        return false;
    }

    bool operator!=(const Value &other) const noexcept
    {
        return !(*this == other);
    }

    bool operator<(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            return asInt() < other.asInt();
        }
        if (isNumber() && other.isNumber())
        {
            return asFloat() < other.asFloat();
        }
        if (isString() && other.isString())
        {
            return asString() < other.asString();
        }
        throw std::runtime_error("Cannot compare these value types ");
    }

    bool operator>(const Value &other) const
    {
        if (isInt() && other.isInt())
        {
            return asInt() > other.asInt();
        }
        if (isNumber() && other.isNumber())
        {
            return asFloat() > other.asFloat();
        }
        if (isString() && other.isString())
        {
            return asString() > other.asString();
        }
        throw std::runtime_error("Cannot compare these value types ");
    }

    bool operator<=(const Value &other) const noexcept
    {
        return !(*this > other);
    }

    bool operator>=(const Value &other) const noexcept
    {
        return !(*this < other);
    }

    [[nodiscard]] std::string toString() const noexcept
    {
        if (isNull())
        {
            return "null";
        }
        if (isBool())
        {
            return asBool() ? "true" : "false";
        }
        if (isInt())
        {
            return std::to_string(asInt());
        }
        if (isFloat())
        {
            return std::to_string(asFloat());
        }
        if (isString())
        {
            [[likely]] return asString();
        }
        if (isArray())
        {
            std::string result = "[";
            const auto &arr = *asArray();
            for (size_t i = 0; i < arr.size(); ++i)
            {
                result += arr[i].toString();
                if (i < arr.size() - 1)
                {
                    result += ", ";
                }
            }
            result += "]";
            return result;
        }
        return "unknown";
    }

    [[nodiscard]] const char *c_str() const
    {
        if (!isString())
        {
            [[unlikely]] throw std::runtime_error("c_str() can only be called on string values");
        }
        return std::get<std::shared_ptr<std::string>>(data)->c_str();
    }

    friend std::ostream &operator<<(std::ostream &os, const Value &v)
    {
        os << v.toString();
        return os;
    }
 
    [[nodiscard]] bool isStruct() const
    {
        return std::holds_alternative<std::shared_ptr<StructInstance>>(data);
    }
 
    std::shared_ptr<StructInstance> asStruct()
    {
        return std::get<std::shared_ptr<StructInstance>>(data);
    }
 
    [[nodiscard]] std::shared_ptr<const StructInstance> asStruct() const noexcept
    {
        return std::get<std::shared_ptr<StructInstance>>(data);
    }
 
    static Value createStruct(const std::string &name)
    {
        return Value(std::make_shared<StructInstance>(StructInstance{.structName = name, .fields = {}}));
    }
 
    static Value createArray(std::vector<Value> elements = {})
    {
        return {std::make_shared<ArrayInstance>(std::move(elements))};
    }
 
    [[nodiscard]] Value getField(const std::string &name) const
    {
        if (!std::holds_alternative<std::shared_ptr<StructInstance>>(data))
        {
            [[unlikely]] throw std::runtime_error("getField() called on non-struct value");
        }
        auto s = std::get<std::shared_ptr<StructInstance>>(data);
        auto it = s->fields.find(name);
        if (it == s->fields.end())
        {
            return {};
        }
        return it->second;
    }
 
    void setField(const std::string &name, Value value)
    {
        if (!std::holds_alternative<std::shared_ptr<StructInstance>>(data))
        {
            [[unlikely]] throw std::runtime_error("setField() called on non-struct value");
        }
        auto s = std::get<std::shared_ptr<StructInstance>>(data);
        s->fields[name] = std::move(value);
    }
 
    [[nodiscard]] bool hasField(const std::string &name) const noexcept
    {
        if (!std::holds_alternative<std::shared_ptr<StructInstance>>(data))
        {
            return false;
        }
        auto s = std::get<std::shared_ptr<StructInstance>>(data);
        return s->fields.contains(name);
    }
};
} // namespace Phasor
 
template <> struct std::formatter<Phasor::Value>
{
    enum class Style
    {
        Value,
        TypeOnly,
        TypeValue,
        Debug,
        Quoted
    };
    Style            style = Style::Value;
    std::string_view passthrough;
 
    constexpr auto parse(std::format_parse_context &ctx)
    {
        auto it = ctx.begin();
        auto end = ctx.end();
 
        auto close = it;
        while (close != end && *close != '}')
        {
            ++close;
        }
 
        std::string_view full(&*it, static_cast<size_t>(close - it));
        std::string_view inner = full;
 
        if (!full.empty())
        {
            switch (full.back())
            {
            case 't':
                style = Style::TypeOnly;
                inner = full.substr(0, full.size() - 1);
                break;
            case 'T':
                style = Style::TypeValue;
                inner = full.substr(0, full.size() - 1);
                break;
            case '?':
                style = Style::Debug;
                inner = full.substr(0, full.size() - 1);
                break;
            case 'q':
                style = Style::Quoted;
                inner = full.substr(0, full.size() - 1);
                break;
            default:
                break;
            }
        }
 
        passthrough = inner;
        return close;
    }
 
    template <typename FormatContext> auto format(const Phasor::Value &v, FormatContext &ctx) const
    {
        std::string fmtstr;
        fmtstr.reserve(passthrough.size() + 3);
        fmtstr += "{:";
        fmtstr += passthrough;
        fmtstr += '}';
 
        auto fwd = [&]<typename T>(const T &val) {
            return std::vformat_to(ctx.out(), fmtstr, std::make_format_args(val));
        };
 
        using namespace Phasor;
 
        switch (style)
        {
        case Style::TypeOnly:
            return fwd(Value::typeToString(v.getType()).asString());
 
        case Style::TypeValue:
            return fwd(Value::typeToString(v.getType()).asString() + "(" + escapeString(v.toString()) + ")");
 
        case Style::Debug:
            return fwd(debug_repr(v));
 
        case Style::Quoted:
            if (v.isString())
            {
                return fwd("\"" + escapeString(v.asString()) + "\"");
            }
            [[fallthrough]];
 
        case Style::Value:
        default:
            switch (v.getType())
            {
            case ValueType::Null:
                return std::format_to(ctx.out(), "null");
            case ValueType::Bool:
                return fwd(v.asBool());
            case ValueType::Int:
                return fwd(v.asInt());
            case ValueType::Float:
                return fwd(v.asFloat());
            case ValueType::String:
                return fwd(debug_repr(escapeString(v.asString())));
            case ValueType::Array:
                return fwd(v.toString());
            case ValueType::Struct:
                return fwd(v.toString());
            }
        }
        return ctx.out();
    }
 
  private:
    static std::string escapeString(const std::string &input)
    {
        std::string output;
        output.reserve(input.size());
        for (char c : input)
        {
            switch (c)
            {
            case '\n':
                output += "\\n";
                break;
            case '\t':
                output += "\\t";
                break;
            case '\r':
                output += "\\r";
                break;
            case '\0':
                output += "\\0";
                break;
            case '\\':
                output += "\\\\";
                break;
            case '\"':
                output += "\\\"";
                break;
            case '\'':
                output += "\\'";
                break;
            case '\a':
                output += "\\a";
                break;
            case '\b':
                output += "\\b";
                break;
            case '\f':
                output += "\\f";
                break;
            case '\v':
                output += "\\v";
                break;
            default:
                if (c < 0x20 || c == 0x7F)
                {
                    char buf[5];
                    snprintf(buf, sizeof(buf), "\\x%02X", (unsigned char)c);
                    output += buf;
                }
                else
                {
                    output += c;
                }
                break;
            }
        }
        return output;
    }
 
    static std::string debug_repr(const Phasor::Value &v)
    {
        using Phasor::ValueType;
        switch (v.getType())
        {
        case ValueType::Null:
            return "null";
        case ValueType::String:
            return "\"" + escapeString(v.asString()) + "\"";
        case ValueType::Array: {
            const auto &arr = *v.asArray();
            std::string out = "[";
            for (std::size_t i = 0; i < arr.size(); ++i)
            {
                out += debug_repr(arr[i]);
                if (i + 1 < arr.size())
                {
                    out += ", ";
                }
            }
            return out + "]";
        }
        case ValueType::Struct: {
            const auto &s = *v.asStruct();
            std::string out = s.structName + " { ";
            bool        first = true;
            for (const auto &[k, val] : s.fields)
            {
                if (!first)
                {
                    out += ", ";
                }
                out += k + ": " + debug_repr(val);
                first = false;
            }
            return out + " }";
        }
        default:
            return v.toString();
        }
    }
};