python2ruby/src/indent_stack.hpp

#pragma once
#include <stack>
enum class IndentAction
{
    Indent,
    Dedent,
    None
};

constexpr int TAB_WIDTH = 8;
constexpr char TAB = '\t';

class IndentStack
{
    std::stack<int> indent_stack;
    int dedent_queue = 0;

public:
    IndentStack() { indent_stack.push(0); }

    IndentAction updateIndentation(int spaces)
    {
        int current = indent_stack.top();

        if (spaces == current)
        {
            return IndentAction::None;
        }

        if (spaces > current)
        {
            indent_stack.push(spaces);
            return IndentAction::Indent;
        }

        while (!indent_stack.empty() && indent_stack.top() > spaces)
        {
            indent_stack.pop();
            dedent_queue++;
        }

        if (dedent_queue > 0)
        {
            dedent_queue--;
            return IndentAction::Dedent;
        }

        return IndentAction::None;
    }

    bool popDedent()
    {
        if (dedent_queue <= 0)
        {
            return false;
        }
        dedent_queue--;
        return true;
    }

    static int calculateColumn(const char *text, int length)
    {
        int spaces = 0;
        for (int i = 0; i < length; i++)
        {
            if (text[i] == TAB)
            {
                spaces += TAB_WIDTH - (spaces % TAB_WIDTH);
                continue;
            }
            spaces++;
        }
        return spaces;
    }

    bool hasRemainingDedents()
    {
        return dedent_queue > 0;
    }

    IndentAction closeBlock()
    {
        // Force indentation reset at EOF
        return updateIndentation(0);
    }
};