I'm trying to parse an array of items, using Sprache library for C# I have a working code that goes like this.
public static Parser<string> Array =
from open in OpenBrackets.Named("open bracket")
from items in Literal.Or(Identifier).Or(Array).DelimitedBy(Comma).Optional()
from close in CloseBrackets.Named("close bracket")
select open + (items.IsDefined ? string.Join(", ", items.Get()) : " ") + close;
where "Literal" is a parser for numbers or strings, "Identifier" is a parser for a variable identifier and "Comma" is a parser for a comma token. But if I want the array to allow being empty "[ ]" I need to add the Optional() property and verify if "items" is defined:
select open + (items.IsDefined ? string.Join(", ", items.Get()) : " ") + close;
Is there a better cleaner way to do this for parsing a list of items separated by a separator char, that can be empty (list). That I can reuse with other lists of items.
Sample of input data structure:
[Literal/Identifier/Array] => Value;
[Value] [,Value]* => Array
[public/private] [identifier]; => Declaration;
[public/private] [identifier] [[=] [Value]] => Initialization;
可以使用GetOrElse
方法完成一种更GetOrElse
方法。
select open + string.Join(", ", items.GetOrElse(new string[0])) + close;
Try using Regex as in code below :
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;
namespace ConsoleApplication1
{
class Program
{
const string FILENAME = @"c:\temp\test.txt";
static void Main(string[] args)
{
StreamReader reader = new StreamReader(FILENAME);
string pattern = @"\[(?'bracketData'[^\]]+)\](?'repeat'[*+])?";
string line = "";
while ((line = reader.ReadLine()) != null)
{
line = line.Trim();
if (line.Length > 0)
{
string suffix = line.Split(new string[] {"=>"}, StringSplitOptions.None).Select(x => x.Trim()).Last();
MatchCollection matches = Regex.Matches(line, pattern);
var brackets = matches.Cast<Match>().Select(x => new { bracket = x.Groups["bracketData"].Value, repeat = x.Groups["repeat"].Value }).ToArray();
Console.WriteLine("Brackets : '{0}'; Suffix : '{1}'", string.Join(",", brackets.Select(x => "(" + x.bracket + ")" + x.repeat )), suffix);
}
}
Console.ReadLine();
}
}
}
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