JUCE/modules/juce_graphics/unicode/juce_Unicode.cpp

/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

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   Or:

   You may also use this code under the terms of the AGPLv3:
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   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
/*
    A collection of methods and types for breaking down text into a unicode representation.
*/
class Unicode
{
    using Key = String;

public:
    Unicode() = delete;

    //==============================================================================
    /*  A unicode Codepoint, from this you can infer various Unicode properties such
        as direction, logical string index and breaking type, etc.
    */
    struct Codepoint
    {
        uint32_t codepoint;

        TextBreakType breaking;  // Breaking characteristics of this codepoint

        TextScript script;       // Script class for this codepoint
    };

    template <typename Value>
    static auto prefix (Span<Value> v, size_t num)
    {
        return Span { v.data(), std::min (v.size(), num) };
    }

    template <typename Value>
    static auto removePrefix (Span<Value> v, size_t num)
    {
        const auto increment = std::min (v.size(), num);
        return Span { v.data() + increment, v.size() - increment };
    }

    //==============================================================================
    /*  Performs unicode analysis on a piece of text and returns an array of Codepoints
        in logical order.
    */
    static Array<Codepoint> performAnalysis (const String& string)
    {
        if (string.isEmpty())
            return {};

        thread_local LruCache<Key, Array<Unicode::Codepoint>> cache;

        return cache.get (string, analysisCallback);
    }

    //==============================================================================
    template <typename Traits>
    struct Iterator
    {
        using ValueType = typename Traits::ValueType;

        Iterator() = default;
        explicit Iterator (Span<ValueType> s) : data (s) {}

        std::optional<Span<ValueType>> next()
        {
            if (data.empty())
                return {};

            const auto breakpoint = std::find_if (data.begin(), data.end(), [&] (const auto& i)
            {
                return ! Traits::compare (i, data.front());
            });
            const auto lengthToBreak = (size_t) std::distance (data.begin(), breakpoint) + (Traits::includeBreakingIndex() ? 1 : 0);
            const ScopeGuard scope { [&] { data = removePrefix (data, lengthToBreak); } };
            return prefix (data, lengthToBreak);
        }

    private:
        Span<ValueType> data;
    };

    struct LineTraits
    {
        using ValueType = const Codepoint;

        static bool compare (const Codepoint& t1, const Codepoint&)
        {
            return t1.breaking != TextBreakType::hard;
        }

        static bool includeBreakingIndex() { return true; }
    };

    using LineBreakIterator = Iterator<LineTraits>;

    struct WordTraits
    {
        using ValueType = const Codepoint;

        static bool compare (const Codepoint& t1, const Codepoint&)
        {
            return t1.breaking != TextBreakType::soft;
        }

        static bool includeBreakingIndex() { return false; }
    };

    using WordBreakIterator = Iterator<WordTraits>;

    struct ScriptTraits
    {
        using ValueType = const Codepoint;

        static bool compare (const Codepoint& t1, const Codepoint& t2)
        {
            return t1.script == t2.script;
        }

        static bool includeBreakingIndex() { return false; }
    };

    using ScriptRunIterator = Iterator<ScriptTraits>;

private:
    static Array<Unicode::Codepoint> analysisCallback (const Key& key)
    {
        auto analysisBuffer = [&key]
        {
            std::vector<UnicodeAnalysisPoint> points;

            const auto data   = key.toUTF32();
            const auto length = data.length();

            points.reserve (length);

            std::transform (data.getAddress(), data.getAddress() + length, std::back_inserter (points), [] (uint32_t cp)
            {
                UnicodeAnalysisPoint p { cp, UnicodeDataTable::getDataForCodepoint (cp) };

                // Define this to enable TR9 debugging. All upper case
                // characters will be interpreted as right-to-left.
               #if defined (JUCE_TR9_UPPERCASE_IS_RTL)
                if (65 <= cp && cp <= 90)
                    p.data.bidi = BidiType::al;
               #endif

                return p;
            });

            return points;
        }();

        Array<Unicode::Codepoint> result;
        result.resize ((int) analysisBuffer.size());

        for (size_t i = 0; i < analysisBuffer.size(); i++)
            result.getReference ((int) i).codepoint = analysisBuffer[i].character;

        TR24::analyseScripts (analysisBuffer, [&result] (int index, TextScript script)
        {
            result.getReference (index).script = script;
        });

        TR14::analyseLineBreaks (analysisBuffer, [&result] (int index, TextBreakType type)
        {
            result.getReference (index).breaking = type;
        });

        return result;
    }
};

namespace detail
{

std::vector<int> UnicodeHelpers::getLineBreaks (const String& data)
{
    std::vector<int> lineBreaks;
    const auto analysis = Unicode::performAnalysis (data);

    for (const auto [index, codepoint] : enumerate (analysis, int{}))
    {
        if (codepoint.breaking == TextBreakType::hard)
            lineBreaks.push_back (index);
    }

    return lineBreaks;
}

} // namespace detail

} // namespace juce