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d8dcb940ab
This implements the Enhanced Interpolated Expression Sequence proposal:
i"" or iq{} or q`` with a $(expression) in the middle are converted to a tuple of druntime types for future processing by library code.
51 lines
2 KiB
D
51 lines
2 KiB
D
import core.interpolation;
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alias AliasSeq(T...) = T;
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string simpleToString(T...)(T thing) {
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string s;
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foreach(item; thing)
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// all the items provided by core.interpolation have
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// toString to return an appropriate value
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//
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// then this particular example only has embedded strings
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// and chars, to we can append them directly
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static if(__traits(hasMember, item, "toString"))
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s ~= item.toString();
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else
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s ~= item;
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return s;
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}
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void main() {
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int a = 1;
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string b = "one";
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// parser won't permit alias = i".." directly; i"..." is meant to
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// be used as a function/template parameter at this time.
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alias expr = AliasSeq!i"$(a) $(b)";
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// elements from the source code are available at compile time, so
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// we static assert those, but the values, of course, are different
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static assert(expr[0] == InterpolationHeader());
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static assert(expr[1] == InterpolatedExpression!"a"());
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assert(expr[2] == a); // actual value not available at compile time
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static assert(expr[3] == InterpolatedLiteral!" "());
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// the parens around the expression are not included
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static assert(expr[4] == InterpolatedExpression!"b"());
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assert(expr[5] == b); // actual value not available at compile time
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static assert(expr[6] == InterpolationFooter());
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// it does currently allow `auto` to be used, it creates a value tuple
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// you can embed any D expressions inside the parenthesis, and the
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// token is not ended until you get the *outer* ) and ".
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auto thing = i"$(b) $("$" ~ ')' ~ `"`)";
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assert(simpleToString(thing) == "one $)\"");
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assert(simpleToString(i"$b") == "$b"); // support for $ident removed by popular demand
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// i`` and iq{} should also work
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assert(simpleToString(i` $(b) is $(b)!`) == " one is one!");
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assert(simpleToString(iq{ $(b) is $(b)!}) == " one is one!");
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assert(simpleToString(i`\$('$')`) == "\\$"); // no \ escape there
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assert(simpleToString(iq{{$('$')}}) == "{$}"); // {} needs to work
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}
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