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namespace System.Web.ModelBinding {
using System;
using System.Collections.Generic;
using System.Linq;
/// <summary>
/// This is a container for prefix values. It normalizes all the values into dotted-form and then stores
/// them in a sorted array. All queries for prefixes are also normalized to dotted-form, and searches
/// for ContainsPrefix are done with a binary search.
/// </summary>
internal sealed class PrefixContainer {
private readonly string[] _sortedValues;
internal PrefixContainer(IEnumerable<string> values) {
if (values == null) {
throw new ArgumentNullException("values");
}
_sortedValues = values.Where(val => val != null).ToArray();
Array.Sort(_sortedValues, StringComparer.OrdinalIgnoreCase);
}
internal bool ContainsPrefix(string prefix) {
if (prefix == null) {
throw new ArgumentNullException("prefix");
}
if (prefix.Length == 0) {
return _sortedValues.Length > 0; // only match empty string when we have some value
}
return Array.BinarySearch(_sortedValues, prefix, new PrefixComparer(prefix)) > -1;
}
internal static bool IsPrefixMatch(string prefix, string testString) {
if (testString == null) {
return false;
}
if (prefix.Length == 0) {
return true; // shortcut - non-null testString matches empty prefix
}
if (prefix.Length > testString.Length) {
return false; // not long enough
}
if (!testString.StartsWith(prefix, StringComparison.OrdinalIgnoreCase)) {
return false; // prefix doesn't match
}
if (testString.Length == prefix.Length) {
return true; // exact match
}
// invariant: testString.Length > prefix.Length
switch (testString[prefix.Length]) {
case '.':
case '[':
return true; // known delimiters
default:
return false; // not known delimiter
}
}
private sealed class PrefixComparer : IComparer<String> {
private string _prefix;
public PrefixComparer(string prefix) {
_prefix = prefix;
}
public int Compare(string x, string y) {
string testString = Object.ReferenceEquals(x, _prefix) ? y : x;
if (IsPrefixMatch(_prefix, testString)) {
return 0;
}
return StringComparer.OrdinalIgnoreCase.Compare(x, y);
}
}
}
}
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