用括号中的嵌套子项拆分逗号分隔的字符串

Question

I have a string formatted something like this: "a, b(c,d(e,f),g),h, i(j, k, l)" where each letter represents one or more words.

I need to split this string up in to a list of objects:

public class Item
{
    public string Name { get; set; }
    public IEnumerable<Item> Children { get; set; }

    public Ingredient()
    {
        Children = new List<Item>();
    }
}

The desired result represented in an outline format:

1. a
2. b
   2.1. c
   2.2. d
   2.2.1. e
   2.2.2. f
   2.3. g
3. h
4. i
   4.1. j
   4.2. k
   4.2. l

What would be the most efficient way to do so?

Answer 1

You can use a stack like this:

static public List<Item> Parse(string str)
{
    Stack<Item> stack = new Stack<Item>();

    Item root = new Item();

    stack.Push(root);

    foreach (char c in str)
    {
        if (char.IsLetter(c))
        {
            Item item = new Item();

            item.Name = c.ToString();

            stack.Peek().Children.Add(item);

            stack.Push(item);
        }
        else if (c == ')' || c == ',')
        {
            stack.Pop();
        }
    }

    return root.Children;
}

Please note that the Children property needs to be a List like this:

public class Item
{
    public string Name { get; set; }
    public List<Item> Children { get; set; }

    public Item()
    {
        Children = new List<Item>();
    }
}

Answer 2

You can use a recursive algorithm to parse your string like this:

static IEnumerable<Item> Parse(string source)
{
    var root = new Item() { Name = "Root", Children = new List<Item>() };
    AddChildrenTo(root, source);
    return root.Children;
}

static int AddChildrenTo(Item item, string source)
{
    Item node = null;
    var word = new List<char>();
    for (int i = 0; i < source.Length; i++)
    {
        var c = source[i];
        if (new[] { ',', '(', ')' }.Contains(c))
        {
            if (word.Count > 0)
            {
                node = new Item { Name = new string(word.ToArray()), Children = new List<Item>() };
                (item.Children as List<Item>).Add(node);
                word.Clear();
            }

            if (c == '(')
            {
                i += AddChildrenTo(node, source.Substring(i + 1)) + 1;
            }
            else if (c == ')')
            {
                return i;
            }
        }
        else if (char.IsLetter(c)) // add other valid characters to if condition 
        {
            word.Add(c);
        }
    }

    return source.Length;
}

Then you can simply call Parse() (For better demonstration I've changed the letters (a, b, ..) in your string to words (ark, book, ...)):

string source = "ark,book(cook,door(euro,fun),good),hello,ink(jack,kill,loop)";
var res = Parse(source);

Please note that for a very large string recursive approach wouldn't be the best solution. And for simplicity I didn't do the error checkings.

Answer 3

If you don't care about unbalanced bracket type:

static string[] SplitString(string input)
{
    bool nSingleQuote = false;
    bool nDubbleQuote = false;

    int nBracket = 0;
    int start = 0;
    List<String> result = new List<String>();
    for (int i = 0; i < input.Length; i++)
    {
        char c = input[i];
        if (c == '\'')
        {
            if(!nDubbleQuote) nSingleQuote = !nSingleQuote;
        }
        else if (c == '"')
        {
            if(!nSingleQuote) nDubbleQuote = !nDubbleQuote;
        }

        if (!nSingleQuote && !nDubbleQuote)
        {
            if (c == ',')
            {
                if (nBracket == 0)
                {
                    result.Add(input.Substring(start, i - start).Trim());
                    start = i + 1;
                }
            }
            else if (c == '(' || c == '[' || c == '{')
            {
                nBracket++;
            }
            else if (c == ')' || c == ']' || c == '}')
            {
                nBracket--;
                if (nBracket < 0)
                    throw new Exception("Unbalanced parenthesis, square bracket or curly bracket at offset #" + i);
            }
        }
    }
    if (nBracket > 0)
        throw new Exception("Missing closing parenthesis, square bracket or curly bracket");
    if (nSingleQuote || nDubbleQuote)
        throw new Exception("Missing end quotation mark");
    result.Add(input.Substring(start).Trim());
    return result.ToArray();
}