private static SqlTokenInfo ReadLiteral(char[] peekBuffer, int peekLength, SqlCharReader reader)
{
Debug.Assert(peekBuffer != null);
Debug.Assert(peekBuffer.Length >= 1);
Debug.Assert(peekLength >= 1);
Debug.Assert(reader != null);
// Sql literals are generally short
var cap = peekLength + 32;
var buffer = new char[cap];
var sb = new StringBuilder(cap);
// We already know the incoming data is "<literal>", so keep it
sb.Append(peekBuffer, 0, 1);
// Undo any extraneous data
if (peekLength >= 2)
{
reader.Undo(peekBuffer, 1, peekLength - 1);
}
while (true)
{
reader.FillRemaining(buffer, 0, out var count);
if (count <= 0)
{
break;
}
for (var i = 0; i < count; i++)
{
switch (buffer[i])
{
// Math
case '+':
case '-':
case '*':
case '/':
case '%':
// Logical
case '&':
case '|':
case '^':
case '~':
// Comparison
case '>':
case '<':
case '!':
case '=':
// Quote
case '\'':
case '"':
// Symbol
case ',':
case '.':
case ';':
case ':':
case '(':
case ')':
// Exit if delimiter
break;
default:
// Exit if whitespace
if (char.IsWhiteSpace(buffer[i]))
{
break;
}
// Loop if not whitespace
continue;
}
if (i >= 1)
{
sb.Append(buffer, 0, i);
}
reader.Undo(buffer, i, count - i);
var t1 = new SqlTokenInfo(SqlTokenKind.Literal, sb);
return(t1);
}
sb.Append(buffer, 0, count);
}
var token = new SqlTokenInfo(SqlTokenKind.Literal, sb);
return(token);
}
/// <summary>
///
/// </summary>
/// <param name="peekBuffer"></param>
/// <param name="peekLength"></param>
/// <param name="reader"></param>
/// <param name="skipSundry">Do not emit sundry tokens (such as comments and whitespace) in the output.</param>
/// <returns></returns>
private static SqlTokenInfo ReadWhitespace(char[] peekBuffer, int peekLength, SqlCharReader reader, bool skipSundry)
{
Debug.Assert(peekBuffer != null);
Debug.Assert(peekBuffer.Length >= 1);
Debug.Assert(peekLength >= 1);
Debug.Assert(reader != null);
// Fast path for single whitespace
if (peekLength >= 2 &&
!char.IsWhiteSpace(peekBuffer[1]))
{
// Undo any extraneous data
reader.Undo(peekBuffer, 1, peekLength - 1);
var t0 = new SqlTokenInfo(SqlTokenKind.Whitespace, peekBuffer[0]);
return(t0);
}
// Perf: Assume whitespace is N chars
const int averageLen = 10;
var cap = peekLength + averageLen;
var buffer = new char[cap];
var sb = skipSundry ? null : new StringBuilder(cap);
// We already know the incoming data is "<whitespace>", so keep it
if (!skipSundry)
{
sb.Append(peekBuffer, 0, peekLength);
}
while (true)
{
reader.FillRemaining(buffer, 0, out var count);
if (count <= 0)
{
break;
}
// Try find any non-whitespace in current batch
var idx = -1;
for (var i = 0; i < count; i++)
{
if (!char.IsWhiteSpace(buffer[i]))
{
idx = i;
break;
}
}
// If we found any non-whitespace
if (idx >= 0)
{
// Undo any extraneous data and exit the loop
if (!skipSundry)
{
sb.Append(buffer, 0, idx);
}
reader.Undo(buffer, idx, count - idx);
break;
}
// Else keep the whitespace and check next batch
if (!skipSundry)
{
sb.Append(buffer, 0, count);
}
}
var token = new SqlTokenInfo(SqlTokenKind.Whitespace, sb);
return(token);
}