On Saturday, 17 August 2013 at 05:37:18 UTC, H. S. Teoh wrote:
On Sat, Aug 17, 2013 at 07:19:19AM +0200, Alan wrote:
On Saturday, 17 August 2013 at 05:05:12 UTC, H. S. Teoh wrote:
>On Sat, Aug 17, 2013 at 06:53:16AM +0200, Alan wrote:
>>Hello! The past few hours I've been working on some things
>>and I
>>came accross a small bug.
>>
>>I'm essentially practicing lexing and parsing by
>>implementing a
>>(very) simple language. Everything is going great so far
>>(variable
>>declarations, writing to stdout etc...) but I have a small
>>problem
>>with my string literals. I've got them working fine, quotes
>>can be
>>escaped etc... But when they include the new line character
>>(\n) for
>>example and it's written out it doesn't create a new line
>>but prints
>>out those characters raw. Does anyone have any idea why?
>>Any help
>>is very much appreciated!
>
>Which quotation marks did you use for your string literals?
>
>If you use double quotes, then it should work: "\n"
>
>But if you use the other quoting syntaxes, the \n may be
>treated
>literally rather than as an escape sequence, e.g., `\n` is a
>string
>of two characters '\' and 'n'.
>
>
>T
I don't think it matters how my string literals are
recoginized,
they can be recognized by double or single quotes.
Either way the value is stored in a string then written out,
but \n
is written out raw for some reason.
Wait, are you talking about the language that you're parsing
having
string literals that contain "\n"? If so, then you need to
manually
translate them, since in the input file, they are two literal
character
'\' and 'n', and the computer wouldn't know how you want to
interpret
them. So you have to do something like this:
auto parseStringLiteral(R)(R input)
if (is(ElementType!R : dchar))
{
auto value = appender!string();
while (!input.empty && input.front != '\"')
{
// Interpret escape sequences here
if (input.front == '\\') {
input.popFront();
if (input.empty)
throw new Exception("Unterminated escape
sequence");
switch(input.front) {
case 'n':
app.put("\n");
break;
// ... put whatever other escapes you
// want to interpret here
}
} else {
// Not an escape sequence, transcribe to
// output literally.
app.put(input.front);
}
}
return value.data;
}
In other words, none of the escape sequences are implemented
for you;
you have to implement them yourself.
T
OH! Yes that makes a lot of sense, thanks so much for the help!
