LocalsLocator.cpp

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#include <Ark/Compiler/Lowerer/LocalsLocator.hpp>
 
#include <ranges>
 
namespace Ark::internal
{
    LocalsLocator::LocalsLocator()
    {
        // create a default scope
        m_scopes.emplace_back();
    }
 
    void LocalsLocator::addLocal(const std::string& name)
    {
        auto& scope = m_scopes.back();
        if (std::ranges::find_if(
                scope.data,
                [&name](const Scope::Var& v) {
                    return name == v.name;
                }) == scope.data.end())
            scope.data.push_back(Scope::Var { .name = name, .unreachable = false });
    }
 
    std::optional<std::size_t> LocalsLocator::lookupLastScopeByName(const std::string& name)
    {
        auto& [data, type] = m_scopes.back();
 
        if (type != ScopeType::Closure)
        {
            // Compute the index of the variable in the active scope from the end.
            for (auto it = data.rbegin(); it != data.rend(); ++it)
            {
                // If a variable is marked unreachable, then anything before it can not be accessed as well
                if (it->unreachable)
                    return std::nullopt;
                if (it->name == name)
                    return static_cast<std::size_t>(std::distance(data.rbegin(), it));
            }
        }
 
        return std::nullopt;
    }
 
    void LocalsLocator::createScope(const ScopeType type)
    {
        m_scopes.emplace_back(Scope {
            .data = {},
            .type = type });
    }
 
    void LocalsLocator::deleteScope()
    {
        m_scopes.pop_back();
    }
 
    void LocalsLocator::saveScopeLengthForBranch()
    {
        m_drop_for_conds.push_back(m_scopes.back().data.size());
    }
 
    bool LocalsLocator::dropVarsForBranch()
    {
        const auto old_length = m_drop_for_conds.back();
        m_drop_for_conds.pop_back();
 
        auto& back = m_scopes.back();
        if (back.data.size() > old_length)
        {
            back.data.erase(
                back.data.begin() + static_cast<decltype(back.data)::difference_type>(old_length),
                back.data.end());
            return true;
        }
        return false;
    }
 
    void LocalsLocator::markLastLocalAsUnreachable()
    {
        if (!m_scopes.back().data.empty())
            m_scopes.back().data.back().unreachable = true;
    }
}