// public static object CharacterSteam { get; private set; }
public static int HandleNumber(CharacterStream cs) {
int start = cs.Position;
if (cs.CurrentChar == '-' || cs.CurrentChar == '+') {
cs.MoveToNextChar();
}
if (cs.CurrentChar == '0' && cs.NextChar == 'x') {
cs.Advance(2);
return HandleHex(cs, start);
}
if (cs.CurrentChar == 'x' && CharacterStream.IsHex(cs.NextChar)) {
cs.MoveToNextChar();
return HandleHex(cs, start);
}
int integerPartStart = cs.Position;
int integerPartLength = 0;
int fractionPartLength = 0;
bool isDouble = false;
// collect decimals (there may be none like in .1e+20
while (cs.IsDecimal()) {
cs.MoveToNextChar();
integerPartLength++;
}
if (cs.CurrentChar == '.') {
isDouble = true;
// float/double
cs.MoveToNextChar();
// If we've seen don we need to collect factional part of any
while (cs.IsDecimal()) {
cs.MoveToNextChar();
fractionPartLength++;
}
}
if (integerPartLength + fractionPartLength == 0) {
return 0; // +e or +.e is not a number and neither is lonely + or -
}
int numberLength;
if (cs.CurrentChar == 'e' || cs.CurrentChar == 'E') {
isDouble = true;
numberLength = HandleExponent(cs, start);
} else {
numberLength = cs.Position - start;
}
// Verify double format
if (isDouble && !IsValidDouble(cs, start, cs.Position)) {
numberLength = 0;
}
if (numberLength > 0) {
// skip over trailing 'L' if any
if (cs.CurrentChar == 'L') {
cs.MoveToNextChar();
numberLength++;
}
}
return numberLength;
}
internal static int HandleExponent(CharacterStream cs, int start) {
Debug.Assert(cs.CurrentChar == 'E' || cs.CurrentChar == 'e');
bool hasSign = false;
cs.MoveToNextChar();
if (cs.IsWhiteSpace() || cs.IsEndOfStream()) {
// 0.1E or 1e
return 0;
}
if (cs.CurrentChar == '-' || cs.CurrentChar == '+') {
hasSign = true;
cs.MoveToNextChar();
}
int digitsStart = cs.Position;
// collect decimals
while (cs.IsDecimal()) {
cs.MoveToNextChar();
}
if (hasSign && digitsStart == cs.Position)
return 0; // NaN like 1.0E-
// Technically if letter or braces follows this is not
// a number but we'll leave it alone for now.
// TODO: This code is not language specific and yet it currently
// handles complex 'i' as well as R-specific 'L' suffix.
// Ideally this needs to be extended in a way so language-specific
// tokenizer can specify options or control number format.
if (char.IsLetter(cs.CurrentChar) && cs.CurrentChar != 'i' && cs.CurrentChar != 'L') {
return 0;
}
return cs.Position - start;
}
