using System;
using System.Text;

namespace ServiceStack.Text;

/// <summary>
/// Reusable StringBuilder ThreadStatic Cache
/// </summary>
public static class StringBuilderCache
{
    [ThreadStatic]
    static StringBuilder cache;

    public static StringBuilder Allocate()
    {
        var ret = cache;
        if (ret == null)
            return new StringBuilder();

        ret.Length = 0;
        cache = null;  //don't re-issue cached instance until it's freed
        return ret;
    }

    public static void Free(StringBuilder sb)
    {
        cache = sb;
    }

    public static string ReturnAndFree(StringBuilder sb)
    {
        var ret = sb.ToString();
        cache = sb;
        return ret;
    }
}

/// <summary>
/// Alternative Reusable StringBuilder ThreadStatic Cache
/// </summary>
public static class StringBuilderCacheAlt
{
    [ThreadStatic]
    static StringBuilder cache;

    public static StringBuilder Allocate()
    {
        var ret = cache;
        if (ret == null)
            return new StringBuilder();

        ret.Length = 0;
        cache = null;  //don't re-issue cached instance until it's freed
        return ret;
    }

    public static void Free(StringBuilder sb)
    {
        cache = sb;
    }

    public static string ReturnAndFree(StringBuilder sb)
    {
        var ret = sb.ToString();
        cache = sb;
        return ret;
    }
}

//Use separate cache internally to avoid re-allocations and cache misses
internal static class StringBuilderThreadStatic
{
    [ThreadStatic]
    static StringBuilder cache;

    public static StringBuilder Allocate()
    {
        var ret = cache;
        if (ret == null)
            return new StringBuilder();

        ret.Length = 0;
        cache = null;  //don't re-issue cached instance until it's freed
        return ret;
    }

    public static void Free(StringBuilder sb)
    {
        cache = sb;
    }

    public static string ReturnAndFree(StringBuilder sb)
    {
        var ret = sb.ToString();
        cache = sb;
        return ret;
    }
}