pgLab/pglablib/CaseChangingCharStream.h

#pragma once

#include "antlr4-runtime.h"
#include <QChar>

/// Helper stream for antlr, the lexer does not need to base case sensitive
/// this is achieved by changing the case of the chars in LA how ever
/// when the text of a recognized token is captured the getText function
/// is used which does no case conversion so the parse will receive the original
/// case.
class CaseChangingCharStream: public antlr4::CharStream
{
public:
    CaseChangingCharStream(antlr4::CharStream *stream, bool upper)
        : stream(stream)
        , upper(upper)
    {}

    virtual ~CaseChangingCharStream()
    {}

    virtual void consume() override
    {
        stream->consume();
    }

    virtual size_t LA(ssize_t i) override
    {
        int c = stream->LA(i);
        if (c <= 0)
            return c;

        if (upper)
            return QChar::toUpper(c);

        return QChar::toLower(c);
    }

    virtual std::string getText(const antlr4::misc::Interval &interval) override
    {
        return stream->getText(interval);
    }

    virtual std::string toString() const override
    {
        return stream->toString();
    }

    virtual ssize_t mark() override
    {
        return stream->mark();
    }

    virtual void release(ssize_t marker) override
    {
        stream->release(marker);
    }

    virtual size_t index() override
    {
        return stream->index();
    }

    virtual void seek(size_t index) override
    {
        stream->seek(index);
    }

    virtual size_t size() override
    {
        return stream->size();
    }

    virtual std::string getSourceName() const  override
    {
        return stream->getSourceName();
    }

private:
    antlr4::CharStream *stream;
    bool upper;

};