• BCS <f d.c> Dec 16 2006
• Kevin Bealer <kevinbealer gmail.com> Dec 17 2006
• Bill Baxter <dnewsgroup billbaxter.com> Dec 17 2006
• BCS <BCS pathlink.com> Dec 18 2006

BCS <f d.c> writes:

I'm about ready to pull my hair out!!!
I'm trying to write a template that will split a string based on a character:

 char[][] foo = SplitString!("hello|world|this|is|a|test",'|');
 // foo == ["hello","world","this","is","a","test"];


I keep getting an error about this being non-const:

 null[0..0] ~ "hello" ~ "world" ~ "this" ~ "is" ~ "a" ~ "test"


I'm doing something like this:

template SplitString(char[] string, char c)
{
	static if(string == "")
		char[][] SplitString = (char[][]).init;
	else
		char[][] SplitString = SplitString!(BeforLast!(string,c),c) ~
AfterLast!(string,c);
}


Any ideas??



Better yet would be a template that evaluates to a tuple

template SplitString(char[] string, char c, V...)
{
	static if(string == "")
		auto SplitString = V;
	else
		auto SplitString = SplitString!(BeforLast!(string,c),c, V,
AfterLast!(string,c));
}


that would allow this:

void foo(char[] string)
{
	// static foreach
	foreach(s;SplitString!("hello|world|this|is|a|test",'|'))
	{
		//use s as const
	}
}

Kevin Bealer <kevinbealer gmail.com> writes:

I've never done this myself, but there is an example of a metaprogramming regex
parser at the bottom of this page:

http://www.digitalmars.com/d/templates-revisited.html

Kevin

Bill Baxter <dnewsgroup billbaxter.com> writes:

Kevin Bealer wrote:
 I've never done this myself, but there is an example of a metaprogramming regex
 parser at the bottom of this page:
 
 http://www.digitalmars.com/d/templates-revisited.html
 
 Kevin


If actually splitting the string doesn't work then maybe you can manage 
to have it generate a tuple of ints that represent the split points.


--bb

BCS <BCS pathlink.com> writes:

Bill Baxter wrote:
 Kevin Bealer wrote:
 
 I've never done this myself, but there is an example of a 
 metaprogramming regex
 parser at the bottom of this page:

 http://www.digitalmars.com/d/templates-revisited.html

 Kevin


 
 If actually splitting the string doesn't work then maybe you can manage 
 to have it generate a tuple of ints that represent the split points.
 
 
 --bb


This is what I ended up using (and it actually does a better job for 
what I was trying to do) it returns a tuple.

/************
	Return a slice up-to but not including the first instance of t.
*/
template UseTill(char[] string, char t)
{
	static if(string == "" || string[0] == t)
		const char[] UseTill = "";
	else
		const char[] UseTill = string[0..1] ~ UseTill!(string[1..$],t);
}

/***********
	Return a slice starting after the first instance of t and containing 
the rest of the string.
*/
template DiscardTill(char[] string, char t)
{
	static if(string == "")
		const char[] DiscardTill = "";
	else static if(string[0] == t)
		const char[] DiscardTill = string[1..$];
	else
		const char[] DiscardTill = DiscardTill!(string[1..$],t);
}

/***********
	mixin temp with {V + 'string' broken up by 'c'}
*/
template BreakBy(char[] string, char d, V...)
{
	static if(string == "")
		alias V BreakBy;
	else static
		alias BreakBy!(DiscardTill!(string,d), d, V, UseTill!(string,d)) BreakBy;
}