/// <summary>
/// returns a substring of specified <paramref name="str"/> in the range
/// [<paramref name="startIndex"/>, <paramref name="endIndex"/>).
/// </summary>
/// <param name="str"></param>
/// <param name="startIndex"></param>
/// <param name="endIndex"></param>
/// <returns>
/// substring of specified <paramref name="str"/> in the range
/// [<paramref name="startIndex"/>, <paramref name="endIndex"/>)
/// </returns>
/// <exception cref="IndexOutOfRangeException">
/// <seealso cref="StringUtils.AssertValidRangeIndicesInString(int, int, string)"/>
/// </exception>
public static string SubstringByIndex(this string str, int startIndex, int endIndex)
{
StringUtils.AssertValidRangeIndicesInString(startIndex, endIndex, str);
int substringLength = endIndex - startIndex;
StringUtils.AssertValidStringLengths(substringLength);
return(str.Substring(startIndex, substringLength));
}
/// <summary>
/// returns a substring of <paramref name="str"/> in range
/// [<paramref name="startIndex"/>, <paramref name="endIndex"/>),
/// omitting all occurrences of any expression contained in specified
/// <paramref name="expressionsToOmit"/>.
/// </summary>
/// <param name="str"></param>
/// <param name="startIndex"></param>
/// <param name="endIndex"></param>
/// <param name="expressionsToOmit"></param>
/// <returns>
/// substring of <paramref name="str"/> in range
/// [<paramref name="startIndex"/>, <paramref name="endIndex"/>),
/// omitting all occurrences of any expression contained in specified
/// <paramref name="expressionsToOmit"/>
/// </returns>
/// <exception cref="IndexOutOfRangeException">
/// <seealso cref="StringUtils.AssertValidRangeIndicesInString(int, int, string)"/>
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <seealso cref="StringUtils.AssertValidStringLengths(int[])"/>
/// </exception>
public static string SubstringByIndexWithout(
this string str,
int startIndex,
int endIndex,
params string[] expressionsToOmit)
{
StringUtils.AssertValidRangeIndicesInString(startIndex, endIndex, str);
StringUtils.AssertValidStringLengths(endIndex - startIndex);
StringBuilder substringBuilder = new StringBuilder();
// current index in str, starting at startIndex
int curStringIndex = startIndex;
// index of the first occurrence of any of the specified expressionsToOmit,
// starting at curStringIndex
int indexOfFirstOccurrenceOfChosenExpressionToOmit;
// expression whose occurrence is the first to appear, starting at curStringIndex
string chosenExpressionToOmit;
// get index of first occurrence of any of the specified expressionsToOmit,
// starting at beginning of str
indexOfFirstOccurrenceOfChosenExpressionToOmit = str.IndexOfAny(
curStringIndex,
expressionsToOmit,
out chosenExpressionToOmit);
// occurrence of an expression to omit, starting at index in range
// [curStringIndex, endIndex), was found
while (
indexOfFirstOccurrenceOfChosenExpressionToOmit != -1 &&
indexOfFirstOccurrenceOfChosenExpressionToOmit < endIndex)
{
// append all characters from str, upto first occurrence of expressionToOmit,
// to substringBuilder
while (curStringIndex < indexOfFirstOccurrenceOfChosenExpressionToOmit)
{
substringBuilder.Append(str[curStringIndex]);
curStringIndex++;
}
// skip over expressionToOmit
curStringIndex += chosenExpressionToOmit.Length;
if (curStringIndex < endIndex) // endIndex not yet reached
{
// get index of first occurrence of any of the specified expressionsToOmit,
// starting at curStringIndex
indexOfFirstOccurrenceOfChosenExpressionToOmit = str.IndexOfAny(
curStringIndex,
expressionsToOmit,
out chosenExpressionToOmit);
}
else // endIndex reached - no next occurrence available
{
indexOfFirstOccurrenceOfChosenExpressionToOmit = -1;
}
}
// append the remainder of str (after last occurrence of an expression to omit)
// to substringBuilder
while (curStringIndex < endIndex)
{
substringBuilder.Append(str[curStringIndex]);
curStringIndex++;
}
return(substringBuilder.ToString());
}
