Suppose we have an identifier name which we think refers to some symbol in an Inter tree. Where do we look for it?

§1. The answer must depend on context, so the question really has to be "with the conventions given by this identifier_finder, what inter_symbol does this name correspond to?".

define MAX_IDENTIFIER_PRIORITIES 3

typedef struct identifier_finder {
    int no_priorities;
    struct inter_symbols_table *priorities[MAX_IDENTIFIER_PRIORITIES];
    struct text_stream *from_namespace;
} identifier_finder;

• The structure identifier_finder is private to this section.

§2. The most basic set of conventions only allows us to see names visible everywhere:

identifier_finder IdentifierFinders::common_names_only(void) {
    identifier_finder finder;
    finder.no_priorities = 0;
    finder.from_namespace = NULL;
    return finder;
}

§3. But we can add to that by providing up to three symbols tables to search in preference order (first match wins):

void IdentifierFinders::next_priority?Usage of IdentifierFinders::next_priority:
Emitting Inter Schemas - §2.1.3(identifier_finder *finder,
    inter_symbols_table *where) {
    if (finder->no_priorities >= MAX_IDENTIFIER_PRIORITIES)
        internal_error("too many identifier finder priorities");
    finder->priorities[finder->no_priorities++] = where;
}

§4. And we can similarly specify the namespace we're coming from:

void IdentifierFinders::set_namespace(identifier_finder *finder,
    text_stream *namespace) {
    if (Str::len(namespace) > 0) {
        if (Str::len(finder->from_namespace) > 0) internal_error("namespace twice");
        finder->from_namespace = Str::duplicate(namespace);
    }
}

§5. And here goes.

inter_symbol *IdentifierFinders::find?Usage of IdentifierFinders::find:
§6
Emitting Inter Schemas - §2.1.3, §3.1.10.2, §3.1.11.1(inter_tree *I, text_stream *name,
    identifier_finder finder) {
    if (Str::get_at(name, 0) == 0x00A7)
        Interpret this as an absolute URL5.1
    else
        Interpret this as an identifier5.2;
    LOG("Defeated on %S\n", name);
    internal_error("unable to find identifier");
    return NULL;
}

§5.1. If the name begins with this magic character, we interpret it as an absolute URL within the tree — the conventions are then unimportant: either the symbol exists where we said it is, or nothing is found. And in that case we will halt with an internal error: so this must be done speculatively.

Interpret this as an absolute URL5.1 =

    TEMPORARY_TEXT(SR)
    Str::copy(SR, name);
    Str::delete_first_character(SR);
    Str::delete_last_character(SR);
    inter_symbol *S = InterSymbolsTable::URL_to_symbol(I, SR);
    DISCARD_TEXT(SR)
    if (S) return S;

• This code is used in §5.

§5.2. Here, though, if all attempts to find the identifier fail, we in effect force it to exist by creating a plug with this name, and then returning that. So the above internal error cannot occur.

Interpret this as an identifier5.2 =

    text_stream *seek = name;
    TEMPORARY_TEXT(N)
    int add_namespace = FALSE;
    if (Str::len(finder.from_namespace) > 0) {
        add_namespace = TRUE;
        for (int i=0; i<Str::len(name); i++)
            if (Str::get_at(name, i) == '`')
                add_namespace = FALSE;
        if (add_namespace) {
            WRITE_TO(N, "%S`%S", finder.from_namespace, name);
            seek = N;
        }
    }
    inter_symbol *S = NULL;
    for (int i = 0; i < finder.no_priorities; i++) {
        S = InterSymbolsTable::symbol_from_name(finder.priorities[i], seek);
        if (S) goto Exit;
    }
    S = LargeScale::find_architectural_symbol(I, name);
    if (S) goto Exit;
    S = InterSymbolsTable::symbol_from_name(LargeScale::connectors_scope(I), seek);
    if (S) goto Exit;
    S = InterSymbolsTable::symbol_from_name(LargeScale::main_scope(I), name);
    if (S) goto Exit;
    if (add_namespace)
        S = InterNames::to_symbol(HierarchyLocations::find_by_implied_name(I, name, finder.from_namespace));
    else
        S = InterNames::to_symbol(HierarchyLocations::find_by_name(I, seek));
    Exit: ;
    DISCARD_TEXT(N)
    return S;

• This code is used in §5.

§6. A small variation. Note that a token can be marked explicitly with an iname to which it corresponds; if it has been, then this overrides the finding process, because the symbol which that iname incarnates as must be the right one.

inter_symbol *IdentifierFinders::find_token?Usage of IdentifierFinders::find_token:
Emitting Inter Schemas - §3.1.2.1, §3.1.7.2(inter_tree *I, inter_schema_token *t,
    identifier_finder finder) {
    if (t->as_quoted) return InterNames::to_symbol(t->as_quoted);
    #ifdef CORE_MODULE
    local_variable *lvar = LocalVariables::by_identifier(t->material);
    if (lvar) return LocalVariables::declare(lvar);
    #endif
    LOGIF(INTER_CONNECTORS, "Finding token %S from namespace '%S'\n",
        t->material, finder.from_namespace);
    return IdentifierFinders::find(I, t->material, finder);
}