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import core.interpolation;
alias AliasSeq(T...) = T;
string simpleToString(T...)(T thing) {
string s;
foreach(item; thing)
// all the items provided by core.interpolation have
// toString to return an appropriate value
//
// then this particular example only has embedded strings
// and chars, to we can append them directly
static if(__traits(hasMember, item, "toString"))
s ~= item.toString();
else
s ~= item;
return s;
}
void main() {
int a = 1;
string b = "one";
// parser won't permit alias = i".." directly; i"..." is meant to
// be used as a function/template parameter at this time.
alias expr = AliasSeq!i"$(a) $(b)";
// elements from the source code are available at compile time, so
// we static assert those, but the values, of course, are different
static assert(expr[0] == InterpolationHeader());
static assert(expr[1] == InterpolatedExpression!"a"());
assert(expr[2] == a); // actual value not available at compile time
static assert(expr[3] == InterpolatedLiteral!" "());
// the parens around the expression are not included
static assert(expr[4] == InterpolatedExpression!"b"());
assert(expr[5] == b); // actual value not available at compile time
static assert(expr[6] == InterpolationFooter());
// it does currently allow `auto` to be used, it creates a value tuple
// you can embed any D expressions inside the parenthesis, and the
// token is not ended until you get the *outer* ) and ".
auto thing = i"$(b) $("$" ~ ')' ~ `"`)";
assert(simpleToString(thing) == "one $)\"");
assert(simpleToString(i"$b") == "$b"); // support for $ident removed by popular demand
// i`` and iq{} should also work
assert(simpleToString(i` $(b) is $(b)!`) == " one is one!");
assert(simpleToString(iq{ $(b) is $(b)!}) == " one is one!");
assert(simpleToString(i`\$('$')`) == "\\$"); // no \ escape there
assert(simpleToString(iq{{$('$')}}) == "{$}"); // {} needs to work
}
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