private bool ParseFormatSpecifier(ref StringPart result)
{
// https://en.wikipedia.org/wiki/Printf_format_string#Syntax
// %[parameter][flags][width][.precision][length]type
// text.Char() == '%'
int start = text.Position;
text.Next(); // skip %
int len = 1;
while ( true ) {
if ( text.EndOfLine || text.Char() == '\\' ) {
break;
}
len++;
if ( Char.IsLetter(text.Char()) ) {
text.Next();
break;
}
text.Next();
}
// if len == 1, then we found %"
if ( len < 2 )
return false;
result = new StringPart(start, len, StringPartType.FormatSpecifier);
return true;
}
public override bool Equals(object obj)
{
if (obj == null)
{
return(false);
}
StringPart part = (StringPart)obj;
return(part.Span == this.Span &&
part.Type == this.Type);
}
public StringPart? Next()
{
while ( !text.EndOfLine ) {
if ( text.Char() == '\\' ) {
return BasicCStringScanner.ParseEscapeSequence(text);
} else if ( text.Char() == '{' && text.NChar() == '{' ) {
text.Next(); // skip it
} else if ( text.Char() == '{' && !isInterpolated ) {
StringPart part = new StringPart();
if ( ParseFormatSpecifier(ref part) )
return part;
}
text.Next();
}
return null;
}
private bool ParseFormatSpecifier(ref StringPart result)
{
// text.Char() == '{'
int start = text.Position;
int len = 1;
text.Next();
while ( !text.EndOfLine ) {
len++;
if ( text.Char() == '}' ) {
result = new StringPart(start, len, StringPartType.FormatSpecifier);
text.Next();
return true;
}
text.Next();
}
return false;
}
public StringPart? Next()
{
while ( !text.EndOfLine ) {
if ( text.Char() == '\\' ) {
StringPart part = new StringPart();
if ( TryParseEscapeSequence(ref part) )
return part;
} else if ( text.Char() == '%' ) {
StringPart part = new StringPart();
if ( TryParseFormatSpecifier(ref part) )
return part;
} else {
text.Next();
}
}
return null;
}
public StringPart? Next()
{
while ( !text.EndOfLine ) {
if ( text.Char() == '\\' ) {
return BasicCStringScanner.ParseEscapeSequence(text);
} else if ( text.Char() == '%' ) {
// skip %%
if ( text.NChar() == '%' ) {
text.Skip(2);
continue;
}
StringPart part = new StringPart();
if ( ParseFormatSpecifier(ref part) )
return part;
}
text.Next();
}
return null;
}
private bool TryParseEscapeSequence(ref StringPart part)
{
text.Next();
if ( escapeChar.IndexOf(text.Char()) >= 0 ) {
text.Next();
part = new StringPart(new Span(text.Position - 2, 2));
return true;
}
if ( Char.IsDigit(text.Char()) && Char.IsDigit(text.NChar()) && Char.IsDigit(text.NNChar()) ) {
// a trigraph
text.Skip(3);
part = new StringPart(new Span(text.Position - 4, 4));
return true;
}
if ( text.Char() == '0' && !Char.IsDigit(text.NChar()) ) {
// \0
text.Next();
part = new StringPart(new Span(text.Position - 2, 2));
return true;
}
if ( text.Char() == 'u' ) {
text.Next();
text.Mark();
Span? span = TryParseShortUnicode();
if ( span.HasValue ) {
part = new StringPart(span.Value);
return true;
}
text.BackToMark();
}
if ( text.Char() == 'U' ) {
text.Next();
text.Mark();
Span? span = TryParseLongUnicode();
if ( span.HasValue ) {
part = new StringPart(span.Value);
return true;
}
text.BackToMark();
}
return false;
}
private bool TryParseFormatSpecifier(ref StringPart result)
{
// https://msdn.microsoft.com/en-us/library/ee370560.aspx
// %[flags][width][.precision]type
int start = text.Position;
text.Next(); // skip '%'
// ignore %%
if ( text.Char() == '%' ) {
text.Next();
return false;
}
// ignore EOF
if ( text.EndOfLine || text.Char() == '\"' )
return false;
int len = 1;
while ( !text.EndOfLine ) {
len++;
if ( Char.IsLetter(text.Char()) ) {
text.Next();
break;
}
text.Next();
}
result = new StringPart(start, len, StringPartType.FormatSpecifier);
return true;
}
