通过解析库探究函数式抽象代价 ( ini 解析示例补充)
上一篇 用 HexColor 作为示例，可能过于简单
这里再补充一个 ini 解析的示例
由于实在写不动用其他库解析 ini 了, 春节都要过完了，累了，写不动了，
所以随意找了一份解析ini的库， 仅供参考，对比不准确，毕竟完整库包含了更多功能
先看看结果
BenchmarkDotNet v0.13.12, Windows 11 (10.0.22631.3085/23H2/2023Update/SunValley3)
Intel Core i7-9750H CPU 2.60GHz, 1 CPU, 12 logical and 6 physical cores
.NET SDK 8.0.200
[Host] : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2
DefaultJob : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2
| Method | Mean | Error | StdDev | Gen0 | Gen1 | Allocated |
|---|---|---|---|---|---|---|
| Hande_Ini | 567.9 ns | 11.24 ns | 21.66 ns | 0.2851 | - | 1.75 KB |
| RuQu_Ini | 1,691.4 ns | 33.48 ns | 64.51 ns | 0.4177 | - | 2.56 KB |
| IniDataParser | 4,836.3 ns | 94.44 ns | 167.87 ns | 1.1215 | 0.0076 | 6.91 KB |
// * Legends *
Mean : Arithmetic mean of all measurements
Error : Half of 99.9% confidence interval
StdDev : Standard deviation of all measurements
Gen0 : GC Generation 0 collects per 1000 operations
Gen1 : GC Generation 1 collects per 1000 operations
Allocated : Allocated memory per single operation (managed only, inclusive, 1KB = 1024B)
1 ns : 1 Nanosecond (0.000000001 sec)
总结
delegate肯定会有调用消耗，ini 场景使用的函数远多于 HexColor ，可以看到消耗大了很多
先看来自 dotnet Microsoft.Extensions.Configuration 中解析 ini 的代码
public static IDictionary<string, string?> Read(string content)
{
var data = new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
using (var reader = new StringReader(content))
{
string sectionPrefix = string.Empty;
while (reader.Peek() != -1)
{
string rawLine = reader.ReadLine()!; // Since Peak didn't return -1, stream hasn't ended.
string line = rawLine.Trim();
// Ignore blank lines
if (string.IsNullOrWhiteSpace(line))
{
continue;
}
// Ignore comments
if (line[0] is ';' or '#' or '/')
{
continue;
}
// [Section:header]
if (line[0] == '[' && line[line.Length - 1] == ']')
{
// remove the brackets
sectionPrefix = string.Concat(line.AsSpan(1, line.Length - 2).Trim(), ConfigurationPath.KeyDelimiter);
continue;
}
// key = value OR "value"
int separator = line.IndexOf('=');
if (separator < 0)
{
throw new FormatException(rawLine);
}
string key = sectionPrefix + line.Substring(0, separator).Trim();
string value = line.Substring(separator + 1).Trim();
// Remove quotes
if (value.Length > 1 && value[0] == '"' && value[value.Length - 1] == '"')
{
value = value.Substring(1, value.Length - 2);
}
if (data.ContainsKey(key))
{
throw new FormatException(key);
}
data[key] = value;
}
}
return data;
}
再来看看部分函数语义优化的代码
public class Ini
{
private static Ini instance = new Ini();
public Func<IPeeker<char>, bool> WhiteSpace = Chars.IngoreWhiteSpace.Map(i => i > 0);
public Func<IPeeker<char>, bool> Comment = Chars.In(";#/").Delimited(Chars.NotCRLF.ToSlice().Opt(), Chars.IsCRLF, "Comment not right").Map((c, x, y, z) => c);
public Func<IPeeker<char>, string> SectionName = Chars.Is('[').Delimited(Chars.Not(']').ToSlice().Once("Section name is required."), Chars.Is(']'), "Section name must end with ']'").Map((c, x, y, z) => y?.ToString());
public Func<IPeeker<char>, string> Key = Chars.Not('=').ToSlice().Once("key is required.").Map(i => i.ToString());
public Func<IPeeker<char>, char> Separater = Chars.Is('=').Once("Section name is required.");
public Func<IPeeker<char>, string> Value = Chars.NotCRLF.ToSlice().Once("value is required.").Map(i =>
{
var v = i.ToString().Trim();
return v.StartsWith('"') ? v[1..^1] : v;
});
public IDictionary<string, string> ParseString(string content)
{
var input = Input.From(content);
var dict = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
while (input.TryPeek(out var v))
{
if (!(WhiteSpace(input) || Comment(input) || Section(input, dict)))
{
throw new NotSupportedException(v.ToString());
}
}
return dict;
}
public bool SectionContentEnd(IPeeker<char> input)
{
return !input.TryPeek(out var v) || v is '[';
}
public bool Section(StringPeeker input, Dictionary<string, string> dict)
{
var name = SectionName(input);
if (name == null) return false;
while (!SectionContentEnd(input))
{
if (WhiteSpace(input) || Comment(input))
{
continue;
}
SectionKV(input, dict, name);
}
return true;
}
public void SectionKV(StringPeeker input, Dictionary<string, string> dict, string name)
{
var k = Key(input);
Separater(input);
var v = Value(input);
k = $"{name}:{k.Trim()}";
dict.Add(k, v.Trim());
}
public static IDictionary<string, string> Parse(string content)
{
return instance.ParseString(content);
}
}
最后截取 部分 ini 解析库的代码 仅供参考
public IniData Parse(string iniDataString)
{
IniData iniData = (Configuration.CaseInsensitive ? new IniDataCaseInsensitive() : new IniData());
iniData.Configuration = Configuration.Clone();
if (string.IsNullOrEmpty(iniDataString))
{
return iniData;
}
_errorExceptions.Clear();
_currentCommentListTemp.Clear();
_currentSectionNameTemp = null;
try
{
string[] array = iniDataString.Split(new string[2] { "\n", "\r\n" }, StringSplitOptions.None);
for (int i = 0; i < array.Length; i++)
{
string text = array[i];
if (text.Trim() == string.Empty)
{
continue;
}
try
{
ProcessLine(text, iniData);
}
catch (Exception ex)
{
ParsingException ex2 = new ParsingException(ex.Message, i + 1, text, ex);
if (Configuration.ThrowExceptionsOnError)
{
throw ex2;
}
_errorExceptions.Add(ex2);
}
}
if (_currentCommentListTemp.Count > 0)
{
if (iniData.Sections.Count > 0)
{
iniData.Sections.GetSectionData(_currentSectionNameTemp).TrailingComments.AddRange(_currentCommentListTemp);
}
else if (iniData.Global.Count > 0)
{
iniData.Global.GetLast().Comments.AddRange(_currentCommentListTemp);
}
_currentCommentListTemp.Clear();
}
}
catch (Exception item)
{
_errorExceptions.Add(item);
if (Configuration.ThrowExceptionsOnError)
{
throw;
}
}
if (HasError)
{
return null;
}
return (IniData)iniData.Clone();
}
