private static StringSlice ParseString(ref StringSlice text)
{
ConsumeWhitespace(ref text);
if (text.Length == 0)
{
throw new QueryParseException("string", text);
}
char start = text[0];
if (start == '\'' || start == '"')
{
char terminator = start;
// Keep a StringBuilder for unescaping (only if needed) and track what we've copied to it already
StringBuilder unescapedForm = null;
int nextCopyFrom = 1;
int terminatorIndex = 1;
for (; terminatorIndex < text.Length - 1; ++terminatorIndex)
{
if (text[terminatorIndex] == terminator)
{
// If this wasn't a doubled quote, the string is done
if (text[terminatorIndex + 1] != terminator)
{
break;
}
// Copy to the StringBuilder without either quote
if (unescapedForm == null)
{
unescapedForm = new StringBuilder();
}
text.Substring(nextCopyFrom, terminatorIndex - nextCopyFrom).AppendTo(unescapedForm);
// Include the second quote next time
nextCopyFrom = terminatorIndex + 1;
// Skip to look after the second quote next iteration
terminatorIndex += 1;
}
}
// Ensure the string is terminated
if (terminatorIndex == text.Length || text[terminatorIndex] != terminator)
{
throw new QueryParseException("string terminator", text);
}
if (unescapedForm != null)
{
if (nextCopyFrom < terminatorIndex)
{
text.Substring(nextCopyFrom, terminatorIndex - nextCopyFrom).AppendTo(unescapedForm);
}
text = text.Substring(terminatorIndex + 1);
return(unescapedForm.ToString());
}
else
{
StringSlice resultSlice = text.Substring(1, terminatorIndex - 1);
text = text.Substring(terminatorIndex + 1);
return(resultSlice);
}
}
else
{
// Read until whitespace or ')' (so closing a subexpression doesn't require a space)
int terminatorIndex = 0;
for (; terminatorIndex < text.Length; ++terminatorIndex)
{
char c = text[terminatorIndex];
if (c == ')' || IsWhitespace(c))
{
break;
}
}
// Consume and return the string
StringSlice result = text.Substring(0, terminatorIndex);
text = text.Substring(terminatorIndex);
return(result);
}
}
public Literal(StringSlice text, T value)
{
Text = text;
Value = value;
}
internal QueryParseException(string categoryExpected, StringSlice text)
: this($"Expected {categoryExpected} but found {(text.Length == 0 ? "<End>" : text)}")
{
}
