debian-packages/taggedalgebraic
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Let errors in generic visitors through.

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Avoids the visit!() instantiation failing early and hiding the concrete source of the error.
This commit is contained in:
Sönke Ludwig 2021-01-05 10:43:43 +01:00
parent d4a55ea4c0
commit 8166b54b12
1 changed files with 13 additions and 8 deletions
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21
source/taggedalgebraic/visit.d
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@ -215,10 +215,13 @@ private template validateHandlers(TU, VISITORS...)
alias Types = TU.FieldTypes;
static foreach (int i; 0 .. VISITORS.length) {
static assert(!is(VISITORS[i]) || isSomeFunction!(VISITORS[i]),
"Visitor at index "~i.stringof~" must be a function/delegate literal: "~VISITORS[i].stringof);
static assert(anySatisfy!(matchesType!(VISITORS[i]), Types),
"Visitor at index "~i.stringof~" does not match any type of "~TU.FieldTypes.stringof);
static if (isSomeFunction!(VISITORS[i])) {
static assert(anySatisfy!(matchesType!(VISITORS[i]), Types),
"Visitor at index "~i.stringof~" does not match any type of "~TU.FieldTypes.stringof);
} else {
static assert(__traits(isTemplate, VISITORS[i]),
"Visitor at index "~i.stringof~" must be a function/delegate literal: "~VISITORS[i].stringof);
}
}
}
@ -273,22 +276,24 @@ private template selectHandler(T, VISITORS...)
static if (i < VISITORS.length) {
alias fun = VISITORS[i];
static if (!isSomeFunction!fun) {
static if (__traits(compiles, fun!T) && isSomeFunction!(fun!T)) {
static if (!__traits(isTemplate, fun)) enum genericIndex = "Visitor at index " ~ i.stringof ~ " is neither a function, nor a template.";
else static if (__traits(compiles, fun!T) && isSomeFunction!(fun!T)) {
static if (ParameterTypeTuple!(fun!T).length == 1) {
static if (matched_index >= 0) enum genericIndex = "Only one generic visitor allowed";
else enum genericIndex = genericIndex!(i+1, i);
} else enum genericIndex = "Generic visitor at index "~i.stringof~" must have a single parameter.";
} else enum genericIndex = "Visitor at index "~i.stringof~" (or its template instantiation with type "~T.stringof~") must be a valid function or delegate.";
} else enum genericIndex = genericIndex!(i+1, i); // let this fail within the template instantiation instead of here
} else enum genericIndex = genericIndex!(i+1, matched_index);
} else enum genericIndex = matched_index;
}
enum typed_index = typedIndex!0;
static if (is(T == void)) enum generic_index = -1;
static if (is(T == void) || (is(typeof(typed_index) == string) && typed_index != -1))
enum generic_index = -1;
else enum generic_index = genericIndex!0;
static if (is(typeof(typed_index) == string)) enum selectHandler = typed_index;
else static if (is(typeof(generic_index == string))) enum selectHandler = generic_index;
else static if (is(typeof(generic_index) == string)) enum selectHandler = generic_index;
else static if (typed_index >= 0) alias selectHandler = VISITORS[typed_index];
else static if (generic_index >= 0) alias selectHandler = VISITORS[generic_index];
else enum selectHandler = null;