Shaman.ValueString

Allocation-free methods for string manipulation.

ValueString is a struct type that represents a portion of a string.

Supported features:

• Concat, IndexOf, LastIndexOf, Equals, StartsWith, EndsWith, Substring, Trim
• ParseInt32, ParseInt64, ParseUInt32, ParseUInt64 and their TryParseXxxx equivalents.
• Allocation-free Split(char). You can optionally pass a ref array to be recycled
• SubstringCached/ToStringCached for strings and StringBuilders: uses a cache of recently-allocated strings, useful when parsing many possibly repeated strings.
• Specialized versions of AppendFast and Write for StringBuilders and TextWriters with numeric inputs.
• MultiValueStringBuilder, creates ValueString from arbitrary char[] data. A large string is internally used to batch writes.
• ValueStringStreamReader, useful for reading text or CSV files without allocating a new string for every line.

Example usage

using Shaman.Runtime;

int num = ValueString.ParseInt32("example-12".AsValueString().Substring(8)) // No allocations

var mv = new MultiValueStringBuilder(4096);
ValueString a = mv.CreateValueString(new char[] { 'h', 'e', 'l', 'l', 'o'});
ValueString b = mv.CreateValueString(new StringBuilder("world"));
// ValueString a == "hello"
// ValueString b == "world"
// Now, mv contains an internal string "helloworld\0\0\0\0\0\0\0\0…".
// Further ValueString creations will be appended to this physical string (using unsafe code).
mv.DestroyPreviousValueStrings(); // Reuses the same string, overwriting old values.
                                  // Make sure you haven't stored old ValueStrings.

using (var csv = new ValueStringStreamReader(stream, Encoding.UTF8, mv))
{
    ValueString[] arr = null;
    while (true)
    {
        mv.DestroyPreviousValueStrings();
        var line = csv.ReadLine();
        if (line == null) break;
        line.Value.Split('\t', StringSplitOptions.None, ref arr);

        ulong id;
        Utils.TryParseUInt64(arr[0], out id);
        // Process the remaining fields
    }
}