220 lines
8.1 KiB
C#
220 lines
8.1 KiB
C#
#region Apache License 2.0
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/*
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Nuclex .NET Framework
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Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#endregion // Apache License 2.0
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using System;
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using System.Runtime.InteropServices;
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namespace Nuclex.Support {
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/// <summary>View into a section of a string without copying said string</summary>
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/// <remarks>
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/// <para>
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/// The design of this class pretty much mirrors that of the
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/// <see cref="T:System.ArraySegment" /> class found in the .NET framework, but is
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/// specialized to be used for strings, which can not be expressed as arrays but
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/// share a lot of the characteristics of an array.
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/// </para>
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/// <para>
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/// In certain situations, passing a StringSegment instead of the actual copied
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/// substring is useful. For example, the caller might want to know from which
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/// index of the original string the substring was taken. Used internally in parsers,
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/// it can also prevent needless string copying and garbage generation.
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/// </para>
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/// </remarks>
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#if !NO_SERIALIZATION
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[Serializable, StructLayout(LayoutKind.Sequential)]
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#endif
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public struct StringSegment {
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/// <summary>
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/// Initializes a new instance of the <see cref="StringSegment" /> class that delimits
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/// all the elements in the specified string
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/// </summary>
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/// <param name="text">String that will be wrapped</param>
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/// <exception cref="System.ArgumentNullException">String is null</exception>
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public StringSegment(string text) {
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if(text == null) { // questionable, but matches behavior of ArraySegment class
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throw new ArgumentNullException("text", "Text must not be null");
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}
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this.text = text;
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this.offset = 0;
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this.count = text.Length;
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="StringSegment" /> class that delimits
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/// the specified range of the elements in the specified string
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/// </summary>
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/// <param name="text">The string containing the range of elements to delimit</param>
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/// <param name="offset">The zero-based index of the first element in the range</param>
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/// <param name="count">The number of elements in the range</param>
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/// <exception cref="System.ArgumentOutOfRangeException">
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/// Offset or count is less than 0
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/// </exception>
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/// <exception cref="System.ArgumentException">
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/// Offset and count do not specify a valid range in array
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/// </exception>
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/// <exception cref="System.ArgumentNullException">String is null</exception>
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public StringSegment(string text, int offset, int count) {
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if(text == null) { // questionable, but matches behavior of ArraySegment class
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throw new ArgumentNullException("text");
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}
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if(offset < 0) {
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throw new ArgumentOutOfRangeException(
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"offset", "Argument out of range, non-negative number required"
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);
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}
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if(count < 0) {
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throw new ArgumentOutOfRangeException(
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"count", "Argument out of range, non-negative number required"
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);
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}
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if(count > (text.Length - offset)) {
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throw new ArgumentException(
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"Invalid argument, specified offset and count exceed string length"
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);
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}
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this.text = text;
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this.offset = offset;
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this.count = count;
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}
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/// <summary>
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/// Gets the original string containing the range of elements that the string
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/// segment delimits
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/// </summary>
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/// <returns>
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/// The original string that was passed to the constructor, and that contains the range
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/// delimited by the <see cref="StringSegment" />
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/// </returns>
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public string Text {
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get { return this.text; }
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}
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/// <summary>
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/// Gets the position of the first element in the range delimited by the string segment,
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/// relative to the start of the original string
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/// </summary>
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/// <returns>
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/// The position of the first element in the range delimited by the
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/// <see cref="StringSegment" />, relative to the start of the original string
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/// </returns>
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public int Offset {
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get { return this.offset; }
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}
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/// <summary>
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/// Gets the number of elements in the range delimited by the string segment
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/// </summary>
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/// <returns>
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/// The number of elements in the range delimited by the <see cref="StringSegment" />
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/// </returns>
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public int Count {
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get { return this.count; }
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}
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/// <summary>Returns the hash code for the current instance</summary>
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/// <returns>A 32-bit signed integer hash code</returns>
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public override int GetHashCode() {
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return this.text.GetHashCode() ^ this.offset ^ this.count;
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}
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/// <summary>
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/// Determines whether the specified object is equal to the current instance
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/// </summary>
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/// <returns>
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/// True if the specified object is a <see cref="StringSegment" /> structure and is
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/// equal to the current instance; otherwise, false
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/// </returns>
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/// <param name="other">The object to be compared with the current instance</param>
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public override bool Equals(object other) {
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return
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(other is StringSegment) &&
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this.Equals((StringSegment)other);
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}
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/// <summary>
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/// Determines whether the specified <see cref="StringSegment" /> structure is equal
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/// to the current instance
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/// </summary>
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/// <returns>
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/// True if the specified <see cref="StringSegment" /> structure is equal to the
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/// current instance; otherwise, false
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/// </returns>
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/// <param name="other">
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/// The <see cref="StringSegment" /> structure to be compared with the current instance
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/// </param>
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public bool Equals(StringSegment other) {
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return
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(other.text == this.text) &&
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(other.offset == this.offset) &&
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(other.count == this.count);
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}
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/// <summary>
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/// Indicates whether two <see cref="StringSegment" /> structures are equal
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/// </summary>
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/// <returns>True if a is equal to b; otherwise, false</returns>
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/// <param name="left">
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/// The <see cref="StringSegment" /> structure on the left side of the
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/// equality operator
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/// </param>
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/// <param name="right">
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/// The <see cref="StringSegment" /> structure on the right side of the
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/// equality operator
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/// </param>
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public static bool operator ==(StringSegment left, StringSegment right) {
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return left.Equals(right);
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}
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/// <summary>
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/// Indicates whether two <see cref="StringSegment" /> structures are unequal
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/// </summary>
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/// <returns>True if a is not equal to b; otherwise, false</returns>
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/// <param name="left">
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/// The <see cref="StringSegment" /> structure on the left side of the
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/// inequality operator
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/// </param>
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/// <param name="right">
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/// The <see cref="StringSegment" /> structure on the right side of the
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/// inequality operator
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/// </param>
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public static bool operator !=(StringSegment left, StringSegment right) {
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return !(left == right);
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}
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/// <summary>Returns a string representation of the string segment</summary>
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/// <returns>The string representation of the string segment</returns>
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public override string ToString() {
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return this.text.Substring(this.offset, this.count);
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}
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/// <summary>String wrapped by the string segment</summary>
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private string text;
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/// <summary>Offset in the original string the segment begins at</summary>
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private int offset;
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/// <summary>Number of characters in the segment</summary>
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private int count;
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}
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} // namespace Nuclex.Support
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