// delimitiers: ' " ( [ { ) ] } space
// two continuous splitter can form a word boundary without presence of space
// result of Bracketed or Quoted may not balanced or matched
public static IEnumerable <(BalancedTermType termType, StringView termStr)> EachTerm(this StringView str)
{
int n = str.Length;
int p, i;
i = p = str.NextNonSpace(0);
while (i != n)
{
char c = str[i];
if (c == ' ')
{
yield return(BalancedTermType.Spaced, str.GetSubView(p, i));
i = p = str.NextNonSpace(i);
}
else if (c.IsOpeningBracket())
{
if (p != i)
{
yield return(BalancedTermType.Spaced, str.GetSubView(p, i));
p = i;
}
if ((i = str.BalanceBracket(i)) == str.Length)
{
throw new Exception("bracket are not balanced");
}
yield return(BalancedTermType.Bracketed, str.GetSubView(p, i + 1));
i = p = str.NextNonSpace(i + 1);
}
else if (c.IsQuote())
{
if (p != i)
{
yield return(BalancedTermType.Spaced, str.GetSubView(p, i));
p = i;
}
if ((i = str.BalanceQuote(i)) == str.Length)
{
throw new Exception("quote are not balanced");
}
yield return(BalancedTermType.Quoted, str.GetSubView(p, i + 1));
i = p = str.NextNonSpace(i + 1);
}
else
{
++i;
}
}
if (i != p)
{
yield return(BalancedTermType.Spaced, str.GetSubView(p, i));
}
}