Extension Services

Behaviour specific to copies of the extension genre.

§1. Scanning metadata. An extension has a title and an author name, each of which is limited in length to one character less than the following constants:

define MAX_EXTENSION_TITLE_LENGTH 51
define MAX_EXTENSION_AUTHOR_LENGTH 51

typedef struct inform_extension {
    struct inbuild_copy *as_copy;
    struct wording body_text;  Body of source text supplied in extension, if any
    int body_text_unbroken;  Does this contain text waiting to be sentence-broken?
    struct wording documentation_text;  Documentation supplied in extension, if any
    int standard;  the (or perhaps just a) Standard Rules extension
    int authorial_modesty;  Do not credit in the compiled game
    struct text_stream *rubric_as_lexed;  brief description found in opening lines
    struct text_stream *extra_credit_as_lexed;
    struct source_file *read_into_file;  Which source file loaded this
    struct inbuild_requirement *must_satisfy;
    int loaded_from_built_in_area;  Located within Inform application
    struct inform_project *read_into_project;  If any
    struct parse_node_tree *syntax_tree;
    struct parse_node *inclusion_sentence;  Where the source called for this
    int auto_included;
    struct linked_list *search_list;  of inbuild_nest
    int word_count;  or 0 if this hasn't been read (yet)
    struct text_stream *last_usage_date;  perhaps on a previous run
    struct text_stream *sort_usage_date;  used temporarily when sorting
    int has_historically_been_used;
    struct linked_list *activations;  of element_activation
    struct linked_list *extensions;  of inbuild_requirement
    struct linked_list *kits;  of inbuild_requirement
    CLASS_DEFINITION
} inform_extension;

The structure inform_extension is accessed in 1/sm, 3/bg, 3/ib, 3/is3, 4/em, 5/ks, 5/ls, 5/ps, 5/ps2, 5/ts, 6/st, 6/hdn, 6/inc, 7/tm, 7/dct, 7/cns, 7/ip2 and here.

§2. This is called as soon as a new copy C of the extension genre is created. We scan the extension file for the title, author, version number and any compatibility notes given (such as "for Glulx only").

void Extensions::scan(inbuild_copy *C) {
    inform_extension *E = CREATE(inform_extension);
    E->as_copy = C;
    Copies::set_metadata(C, STORE_POINTER_inform_extension(E));
    Initialise the extension docket2.1;

    TEMPORARY_TEXT(claimed_author_name)
    TEMPORARY_TEXT(claimed_title)
    TEMPORARY_TEXT(reqs)
    semantic_version_number V = VersionNumbers::null();
    Scan the file2.2;
    Change the edition of the copy in light of the metadata found in the scan2.3;
    DISCARD_TEXT(claimed_author_name)
    DISCARD_TEXT(claimed_title)
    DISCARD_TEXT(reqs)
    if (Works::is_basic_inform(C->edition->work)) E->standard = TRUE;
    if (Works::is_standard_rules(C->edition->work)) E->standard = TRUE;

    Scan the metadata file, if there is one2.4;
    Check that the version numbers agree2.5;
}

§2.1. Initialise the extension docket2.1 =

    E->body_text = EMPTY_WORDING;
    E->body_text_unbroken = FALSE;
    E->documentation_text = EMPTY_WORDING;
    E->standard = FALSE;
    E->authorial_modesty = FALSE;
    E->read_into_file = NULL;
    E->rubric_as_lexed = Str::new();
    E->extra_credit_as_lexed = NULL;
    E->must_satisfy = NULL;
    E->loaded_from_built_in_area = FALSE;
    E->read_into_project = NULL;
    E->syntax_tree = SyntaxTree::new();
    E->inclusion_sentence = NULL;
    E->auto_included = FALSE;
    E->search_list = NEW_LINKED_LIST(inbuild_nest);
    E->has_historically_been_used = FALSE;
    E->word_count = 0;
    E->last_usage_date = Str::new();
    E->sort_usage_date = Str::new();
    E->activations = NEW_LINKED_LIST(element_activation);
    E->extensions = NEW_LINKED_LIST(inbuild_requirement);
    E->kits = NEW_LINKED_LIST(inbuild_requirement);

This code is used in §2.

§2.2. The following scans a potential extension file. If it seems malformed, a suitable error is written to the stream error_text. If not, this is left alone, and the version number is returned.

Scan the file2.2 =

    TEMPORARY_TEXT(titling_line)
    TEMPORARY_TEXT(version_text)
    filename *F = Extensions::main_source_file(C);
    FILE *EXTF = Filenames::fopen_caseless(F, "r");
    if (EXTF == NULL) {
        Copies::attach_error(C, CopyErrors::new_F(OPEN_FAILED_CE, -1, F));
    } else {
        Read the titling line of the extension and normalise its casing2.2.1;
        Read the rubric text, if any is present2.2.2;
        Parse the version, title, author and VM requirements from the titling line2.2.3;
        fclose(EXTF);
        if (Str::len(version_text) > 0) {
            V = VersionNumbers::from_text(version_text);
            if (VersionNumbers::is_null(V)) {
                TEMPORARY_TEXT(error_text)
                WRITE_TO(error_text, "the version number '%S' is malformed", version_text);
                Copies::attach_error(C, CopyErrors::new_T(EXT_MISWORDED_CE, -1, error_text));
                DISCARD_TEXT(error_text)
            }
        }
    }
    DISCARD_TEXT(titling_line)
    DISCARD_TEXT(version_text)

This code is used in §2.

§2.2.1. The titling line is terminated by any of 0A, 0D, 0A 0D or 0D 0A, or by the local \n for good measure.

Read the titling line of the extension and normalise its casing2.2.1 =

    int c;
    while ((c = TextFiles::utf8_fgetc(EXTF, NULL, FALSE, NULL)) != EOF) {
        if (c == 0xFEFF) continue;  skip the optional Unicode BOM pseudo-character
        if ((c == '\x0a') || (c == '\x0d') || (c == '\n')) break;
        PUT_TO(titling_line, c);
    }
    Str::trim_white_space(titling_line);
    Works::normalise_casing_mixed(titling_line);

This code is used in §2.2.

§2.2.2. In the following, all possible newlines are converted to white space, and all white space before a quoted rubric text is ignored. We need to do this partly because users have probably keyed a double line break before the rubric, but also because we might have stopped reading the titling line halfway through a line division combination like 0A 0D, so that the first thing we read here is a meaningless 0D.

Read the rubric text, if any is present2.2.2 =

    int c, found_start = FALSE;
    while ((c = TextFiles::utf8_fgetc(EXTF, NULL, FALSE, NULL)) != EOF) {
        if ((c == '\x0a') || (c == '\x0d') || (c == '\n') || (c == '\t')) c = ' ';
        if ((c != ' ') && (found_start == FALSE)) {
            if (c == '"') found_start = TRUE;
            else break;
        } else {
            if (c == '"') break;
            if (found_start) PUT_TO(E->rubric_as_lexed, c);
        }
    }

This code is used in §2.2.

§2.2.3. In general, once case-normalised, a titling line looks like this:

Version 2/070423 Of Going To The Zoo (For Glulx Only) By Cary Grant Begins Here.

and the version information, the VM restriction and the full stop are all optional, but the division word "of" and the concluding "begin[s] here" are not. We break it up into pieces; for speed, we won't use the lexer to load the entire file.

Parse the version, title, author and VM requirements from the titling line2.2.3 =

    match_results mr = Regexp::create_mr();
    if (Str::get_last_char(titling_line) == '.') Str::delete_last_character(titling_line);
    if ((Regexp::match(&mr, titling_line, L"(%c*) Begin Here")) ||
        (Regexp::match(&mr, titling_line, L"(%c*) Begins Here"))) {
        Str::copy(titling_line, mr.exp[0]);
    } else {
        if ((Regexp::match(&mr, titling_line, L"(%c*) Start Here")) ||
            (Regexp::match(&mr, titling_line, L"(%c*) Starts Here"))) {
            Str::copy(titling_line, mr.exp[0]);
        }
        Copies::attach_error(C, CopyErrors::new_T(EXT_MISWORDED_CE, -1,
            I"the opening line does not end 'begin(s) here'"));
    }
    Scan the version text, if any, and advance to the position past Version... Of2.2.3.1;
    if (Regexp::match(&mr, titling_line, L"The (%c*)")) Str::copy(titling_line, mr.exp[0]);
    Divide the remaining text into a claimed author name and title, divided by By2.2.3.2;
    Extract the VM requirements text, if any, from the claimed title2.2.3.3;
    Regexp::dispose_of(&mr);

This code is used in §2.2.

§2.2.3.1. We make no attempt to check the version number for validity: the purpose of the census is to identify extensions and reject accidentally included other files, not to syntax-check all extensions to see if they would work if used.

Scan the version text, if any, and advance to the position past Version... Of2.2.3.1 =

    if (Regexp::match(&mr, titling_line, L"Version (%c*?) Of (%c*)")) {
        Str::copy(version_text, mr.exp[0]);
        Str::copy(titling_line, mr.exp[1]);
    }

This code is used in §2.2.3.

§2.2.3.2. The earliest "by" is the divider: note that extension titles are not allowed to contain this word, so "North By Northwest By Cary Grant" is not a situation we need to contend with.

Divide the remaining text into a claimed author name and title, divided by By2.2.3.2 =

    if (Regexp::match(&mr, titling_line, L"(%c*?) By (%c*)")) {
        Str::copy(claimed_title, mr.exp[0]);
        Str::copy(claimed_author_name, mr.exp[1]);
    } else {
        Str::copy(claimed_title, titling_line);
        Copies::attach_error(C, CopyErrors::new_T(EXT_MISWORDED_CE, -1,
            I"the titling line does not give both author and title"));
    }

This code is used in §2.2.3.

§2.2.3.3. Similarly, extension titles are not allowed to contain parentheses, so this is unambiguous.

Extract the VM requirements text, if any, from the claimed title2.2.3.3 =

    if (Regexp::match(&mr, claimed_title, L"(%c*?) *(%(%c*%))")) {
        Str::copy(claimed_title, mr.exp[0]);
        Str::copy(reqs, mr.exp[1]);
    }

This code is used in §2.2.3.

§2.3. Note that we don't attempt to modify the inbuild_work structure inside the edition; we create an entirely new inbuild_work. That's because they are immutable, and need to be for the extensions dictionary to work.

Change the edition of the copy in light of the metadata found in the scan2.3 =

    if (Str::len(claimed_title) == 0) { WRITE_TO(claimed_title, "Unknown"); }
    if (Str::len(claimed_author_name) == 0) { WRITE_TO(claimed_author_name, "Anonymous"); }
    if (Str::len(claimed_title) > MAX_EXTENSION_TITLE_LENGTH)
        Copies::attach_error(C,
            CopyErrors::new_N(EXT_TITLE_TOO_LONG_CE, -1, Str::len(claimed_title)));
    if (Str::len(claimed_author_name) > MAX_EXTENSION_AUTHOR_LENGTH)
        Copies::attach_error(C,
            CopyErrors::new_N(EXT_AUTHOR_TOO_LONG_CE, -1, Str::len(claimed_author_name)));
    C->edition = Editions::new(
        Works::new_raw(extension_genre, claimed_title, claimed_author_name), V);
    if (Str::len(reqs) > 0) {
        compatibility_specification *CS = Compatibility::from_text(reqs);
        if (CS) C->edition->compatibility = CS;
        else {
            TEMPORARY_TEXT(err)
            WRITE_TO(err, "cannot read compatibility '%S'", reqs);
            Copies::attach_error(C, CopyErrors::new_T(EXT_MISWORDED_CE, -1, err));
            DISCARD_TEXT(err)
        }
    }

This code is used in §2.

§2.4. Scan the metadata file, if there is one2.4 =

    if (C->location_if_path) {
        filename *F = Filenames::in(C->location_if_path, I"extension_metadata.json");
        JSONMetadata::read_metadata_file(C, F);
        if (C->metadata_record) {
            Extract activations2.4.1;
            JSON_value *extension_details =
                JSON::look_up_object(C->metadata_record, I"extension-details");
            if (extension_details) Extract the extension details2.4.2;
            JSON_value *needs = JSON::look_up_object(C->metadata_record, I"needs");
            if (needs) {
                JSON_value *V;
                LOOP_OVER_LINKED_LIST(V, JSON_value, needs->if_list)
                    Extract this possibly conditional requirement2.4.3;
            }
        }
    }

This code is used in §2.

§2.4.1. Extract activations2.4.1 =

    JSON_value *activates = JSON::look_up_object(C->metadata_record, I"activates");
    if (activates) {
        JSON_value *V;
        LOOP_OVER_LINKED_LIST(V, JSON_value, activates->if_list)
            Extensions::activation(E, V->if_string, TRUE);
    }
    JSON_value *deactivates = JSON::look_up_object(C->metadata_record, I"deactivates");
    if (deactivates) {
        JSON_value *V;
        LOOP_OVER_LINKED_LIST(V, JSON_value, deactivates->if_list)
            Extensions::activation(E, V->if_string, FALSE);
    }

This code is used in §2.4.

§2.4.2. Extract the extension details2.4.2 =

This code is used in §2.4.

§2.4.3. Extract this possibly conditional requirement2.4.3 =

    int parity = TRUE;
    JSON_value *if_clause = JSON::look_up_object(V, I"if");
    JSON_value *unless_clause = JSON::look_up_object(V, I"unless");
    if (unless_clause) {
        if_clause = unless_clause; parity = FALSE;
    }
    if (if_clause) {
        TEMPORARY_TEXT(err)
        WRITE_TO(err, "extension dependencies must be unconditional");
        Copies::attach_error(C, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, err));
        DISCARD_TEXT(err)
    }
    JSON_value *need_clause = JSON::look_up_object(V, I"need");
    if (need_clause) {
        JSON_value *need_type = JSON::look_up_object(need_clause, I"type");
        JSON_value *need_title = JSON::look_up_object(need_clause, I"title");
        JSON_value *need_author = JSON::look_up_object(need_clause, I"author");
        JSON_value *need_version = JSON::look_up_object(need_clause, I"version");
        if (Str::eq(need_type->if_string, I"extension"))
            Deal with an extension dependency2.4.3.1
        else if (Str::eq(need_type->if_string, I"kit"))
            Deal with a kit dependency2.4.3.2
        else {
            TEMPORARY_TEXT(err)
            WRITE_TO(err, "a kit can only have extensions and kits as dependencies");
            Copies::attach_error(C, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, err));
            DISCARD_TEXT(err)
        }
    }

This code is used in §2.4.

§2.4.3.1. Deal with an extension dependency2.4.3.1 =

    text_stream *extension_title = need_title->if_string;
    text_stream *extension_author = need_author?(need_author->if_string):NULL;
    inbuild_work *work = Works::new(extension_genre, extension_title, extension_author);
    if (need_version) Add versioned extension2.4.3.1.1
    else Add unversioned extension2.4.3.1.2;

This code is used in §2.4.3.

§2.4.3.1.1. Add versioned extension2.4.3.1.1 =

    semantic_version_number V = VersionNumbers::from_text(need_version->if_string);
    if (VersionNumbers::is_null(V)) {
        TEMPORARY_TEXT(err)
        WRITE_TO(err, "cannot read version number '%S'", need_version->if_string);
        Copies::attach_error(C, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, err));
        DISCARD_TEXT(err)
    } else {
        inbuild_requirement *req = Requirements::new(work,
            VersionNumberRanges::compatibility_range(V));
        ADD_TO_LINKED_LIST(req, inbuild_requirement, E->extensions);
    }

This code is used in §2.4.3.1.

§2.4.3.1.2. Add unversioned extension2.4.3.1.2 =

    inbuild_requirement *req = Requirements::any_version_of(work);
    ADD_TO_LINKED_LIST(req, inbuild_requirement, E->extensions);

This code is used in §2.4.3.1.

§2.4.3.2. Deal with a kit dependency2.4.3.2 =

    text_stream *kit_title = need_title->if_string;
    text_stream *kit_author = need_author?(need_author->if_string):NULL;
    inbuild_work *work = Works::new(kit_genre, kit_title, kit_author);
    if (need_version) Add versioned kit2.4.3.2.1
    else Add unversioned kit2.4.3.2.2;

This code is used in §2.4.3.

§2.4.3.2.1. Add versioned kit2.4.3.2.1 =

    semantic_version_number V = VersionNumbers::from_text(need_version->if_string);
    if (VersionNumbers::is_null(V)) {
        TEMPORARY_TEXT(err)
        WRITE_TO(err, "cannot read version number '%S'", need_version->if_string);
        Copies::attach_error(C, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, err));
        DISCARD_TEXT(err)
    } else {
        inbuild_requirement *req = Requirements::new(work,
            VersionNumberRanges::compatibility_range(V));
        ADD_TO_LINKED_LIST(req, inbuild_requirement, E->kits);
    }

This code is used in §2.4.3.2.

§2.4.3.2.2. Add unversioned kit2.4.3.2.2 =

    inbuild_requirement *req = Requirements::any_version_of(work);
    ADD_TO_LINKED_LIST(req, inbuild_requirement, E->kits);

This code is used in §2.4.3.2.

§2.5. Check that the version numbers agree2.5 =

    semantic_version_number V2 = C->edition->version;
    if (VersionNumbers::ne(V, V2)) {
        TEMPORARY_TEXT(error_text)
        WRITE_TO(error_text, "the extension itself gives version number '%v', "
            "but the metadata file says '%v': these need to match", &V, &V2);
        Copies::attach_error(C, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, error_text));
        DISCARD_TEXT(error_text)
    }

This code is used in §2.

§3. Language elements can be activated or deactivated:

void Extensions::activation(inform_extension *E, text_stream *name, int act) {
    element_activation *EA = CREATE(element_activation);
    EA->element_name = Str::duplicate(name);
    EA->activate = act;
    ADD_TO_LINKED_LIST(EA, element_activation, E->activations);
}

§4. Since there are two ways extensions can be stored:

inform_extension *Extensions::from_copy(inbuild_copy *C) {
    inform_extension *ext = ExtensionBundleManager::from_copy(C);
    if (ext == NULL) ext = ExtensionManager::from_copy(C);
    return ext;
}

filename *Extensions::main_source_file(inbuild_copy *C) {
    filename *F = C->location_if_file;
    if (F == NULL) {
        pathname *P = C->location_if_path;
        if (P) {
            TEMPORARY_TEXT(leaf)
            WRITE_TO(leaf, "%S.i7x", Pathnames::directory_name(P));
            F = Filenames::in(Pathnames::down(P, I"Source"), leaf);
            DISCARD_TEXT(leaf)
        }
    }
    return F;
}

§5. Cached metadata. The following data hides between runs in the Dictionary.

void Extensions::set_usage_date(inform_extension *E, text_stream *date) {
    Str::clear(E->last_usage_date);
    Str::copy(E->last_usage_date, date);
}

void Extensions::set_sort_date(inform_extension *E, text_stream *date) {
    Str::clear(E->sort_usage_date);
    Str::copy(E->sort_usage_date, date);
}

text_stream *Extensions::get_usage_date(inform_extension *E) {
    return E->last_usage_date;
}

text_stream *Extensions::get_sort_date(inform_extension *E) {
    return E->sort_usage_date;
}

void Extensions::set_word_count(inform_extension *E, int wc) {
    E->word_count = wc;
}

int Extensions::get_word_count(inform_extension *E) {
    return E->word_count;
}

text_stream *Extensions::get_sort_word_count(inform_extension *E) {
    text_stream *T = Str::new();
    WRITE_TO(T, "%8d", E->word_count);
    return T;
}

int Extensions::compare_by_edition(inform_extension *E1, inform_extension *E2) {
    if ((E1 == NULL) || (E2 == NULL)) internal_error("bad work match");
    int d = Works::cmp(E1->as_copy->edition->work, E2->as_copy->edition->work);
    if (d != 0) return d;
    return VersionNumbers::cmp(
        E1->as_copy->edition->version, E2->as_copy->edition->version);
}

int Extensions::compare_by_date(inform_extension *E1, inform_extension *E2) {
    if ((E1 == NULL) || (E2 == NULL)) internal_error("bad work match");
    int d = Str::cmp(Extensions::get_sort_date(E2), Extensions::get_sort_date(E1));
    if (d != 0) return d;
    return Extensions::compare_by_edition(E1, E2);
}

int Extensions::compare_by_author(inform_extension *E1, inform_extension *E2) {
    if ((E1 == NULL) || (E2 == NULL)) internal_error("bad work match");
    int d = Str::cmp(E2->as_copy->edition->work->author_name,
        E1->as_copy->edition->work->author_name);
    if (d != 0) return d;
    return Extensions::compare_by_edition(E1, E2);
}

int Extensions::compare_by_title(inform_extension *E1, inform_extension *E2) {
    if ((E1 == NULL) || (E2 == NULL)) internal_error("bad work match");
    int d = Str::cmp(E2->as_copy->edition->work->title,
        E1->as_copy->edition->work->title);
    if (d != 0) return d;
    return Extensions::compare_by_edition(E1, E2);
}

int Extensions::compare_by_length(inform_extension *E1, inform_extension *E2) {
    if ((E1 == NULL) || (E2 == NULL)) internal_error("bad work match");
    int d = Str::cmp(
        Extensions::get_sort_word_count(E2), Extensions::get_sort_word_count(E1));
    if (d != 0) return d;
    return Extensions::compare_by_edition(E1, E2);
}

§6. Search list. Sometimes ane extension is being looked at in isolation, and then read_into_project will be NULL; but if it is being loaded to be included in the source text of a project, then...

void Extensions::set_associated_project(inform_extension *E, inform_project *P) {
    E->read_into_project = P;
}

§7. ...and this affects its search list, because now its own inclusions can see the Materials folder of the project in question:

linked_list *Extensions::nest_list(inform_extension *E) {
    if (E == NULL) return Supervisor::shared_nest_list();
    RUN_ONLY_FROM_PHASE(NESTED_INBUILD_PHASE)
    if (LinkedLists::len(E->search_list) == 0) {
        inform_project *proj = E->read_into_project;
        if (proj) ADD_TO_LINKED_LIST(proj->materials_nest, inbuild_nest, E->search_list);
        inbuild_nest *N;
        linked_list *L = Supervisor::shared_nest_list();
        LOOP_OVER_LINKED_LIST(N, inbuild_nest, L)
            ADD_TO_LINKED_LIST(N, inbuild_nest, E->search_list);
    }
    return E->search_list;
}

§8. Language element activation. Note that this function is meaningful only when this module is part of the inform7 executable, and it invites us to activate or deactivate language features as E would like.

void Extensions::activate_elements(inform_extension *E) {
    element_activation *EA;
    LOOP_OVER_LINKED_LIST(EA, element_activation, E->activations) {
        compiler_feature *P = Features::from_name(EA->element_name);
        if (P == NULL) {
            TEMPORARY_TEXT(err)
            WRITE_TO(err, "extension metadata refers to unknown compiler feature '%S'", EA->element_name);
            Copies::attach_error(E->as_copy, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, err));
            DISCARD_TEXT(err)
        } else {
            if (EA->activate) Features::activate(P);
            else if (Features::deactivate(P) == FALSE) {
                TEMPORARY_TEXT(err)
                WRITE_TO(err, "extension metadata asks to deactivate mandatory compiler feature '%S'",
                    EA->element_name);
                Copies::attach_error(E->as_copy, CopyErrors::new_T(METADATA_MALFORMED_CE, -1, err));
                DISCARD_TEXT(err)
            }
        }
    }
}

§9. Graph. The dependency graph is not so much constructed as discovered; dependencies are made to each other extension as it's Included in this one, during the course of reading in the text.

Note that this function is not called when graphing a project which Includes this extension: this is called only when inbuild wants to see the graph of an extension in isolation from projects. (That's why we must perform the Inclusion traverse: for a project this traverse would come later, but with no project involved, we must take action ourselves.)

void Extensions::construct_graph(inform_extension *E) {
    Copies::get_source_text(E->as_copy);
    Sentences::set_start_of_source(sfsm, -1);
    Inclusions::traverse(E->as_copy, E->syntax_tree);
}

§10. Read source text. The scan only skimmed the surface of the file, and didn't try to parse it as natural language text with Preform. But if the extension turns out to be one that we need to use for something, we'll need to read its full text eventually. This is that time.

At present all extensions are assumed to have English as the language of syntax.

void Extensions::read_source_text_for(inform_extension *E) {
    inform_language *L = Languages::find_for(I"English", Extensions::nest_list(E));
    Languages::read_Preform_definition(L, Extensions::nest_list(E));
    filename *F = Extensions::main_source_file(E->as_copy);
    int doc_only = FALSE;
    if (census_mode) doc_only = TRUE;
    TEMPORARY_TEXT(synopsis)
    Concoct a synopsis for the extension to be read10.1;
    E->read_into_file = SourceText::read_file(E->as_copy, F, synopsis, doc_only, FALSE);
    DISCARD_TEXT(synopsis)
    if (E->read_into_file) {
        E->read_into_file->your_ref = STORE_POINTER_inbuild_copy(E->as_copy);
        Break the text into sentences10.2;
        E->body_text_unbroken = FALSE;
    }
}

§10.1. We concoct a textual synopsis in the form

    "Pantomime Sausages by Mr Punch"

to be used by SourceFiles::read_extension_source_text for printing to stdout. Since we dare not assume stdout can manage characters outside the basic ASCII range, we flatten them from general ISO to plain ASCII.

Concoct a synopsis for the extension to be read10.1 =

    WRITE_TO(synopsis, "%S by %S",
        E->as_copy->edition->work->title,
        E->as_copy->edition->work->author_name);
    LOOP_THROUGH_TEXT(pos, synopsis)
        Str::put(pos,
            Characters::make_wchar_t_filename_safe(
                Str::get(pos)));

This code is used in §10.

§10.2. Note that if there is an active project, then we are reading the extension in order to include it in that, and so we send it to the project's syntax tree, rather than to the extension's own one. But if we are simply examining the extension by running -graph on it in the Inbuild command line, for example, then its sentences will go to the extension's own tree.

Break the text into sentences10.2 =

    wording EXW = E->read_into_file->text_read;
    if (Wordings::nonempty(EXW))
        Break the extension's text into body and documentation10.2.2;
    inform_project *project = E->read_into_project;
    if (project) E->syntax_tree = project->syntax_tree;
    Sentences::break_into_extension_copy(E->syntax_tree,
        E->body_text, E->as_copy, project);
    E->body_text_unbroken = FALSE;

This code is used in §10.

§10.2.1. If an extension file contains the special text (outside literal mode) of ---- Documentation ---- then this is taken as the end of the Inform source, and the beginning of a snippet of documentation about the extension; text from that point on is saved until later, but not broken into sentences for the parse tree, and it is therefore invisible to the rest of Inform. If this division line is not present then the extension contains only body source and no documentation.

<extension-body> ::=
    *** ---- documentation ---- ... |  ==> { TRUE, - }
    ...                                ==> { FALSE, - }

This is Preform grammar, not regular C code.

§10.2.2. Break the extension's text into body and documentation10.2.2 =

    <extension-body>(EXW);
    E->body_text = GET_RW(<extension-body>, 1);
    if (<<r>>) E->documentation_text = GET_RW(<extension-body>, 2);
    E->body_text_unbroken = TRUE;  mark this to be sentence-broken

This code is used in §10.2.

§11. When the extension source text was read from its source_file, we attached a reference to say which inform_extension it was, and here we make use of that:

inform_extension *Extensions::corresponding_to(source_file *sf) {
    if (sf == NULL) return NULL;
    inbuild_copy *C = RETRIEVE_POINTER_inbuild_copy(sf->your_ref);
    if (C == NULL) return NULL;
    if (C->edition->work->genre != extension_genre) return NULL;
    return Extensions::from_copy(C);
}

§12. Miscellaneous.

void Extensions::write(OUTPUT_STREAM, inform_extension *E) {
    if (E == NULL) WRITE("none");
    else WRITE("%X", E->as_copy->edition->work);
}

void Extensions::write_name_to_file(inform_extension *E, OUTPUT_STREAM) {
    WRITE("%S", E->as_copy->edition->work->raw_title);
}

void Extensions::write_author_to_file(inform_extension *E, OUTPUT_STREAM) {
    WRITE("%S", E->as_copy->edition->work->raw_author_name);
}

§13. Three pieces of information will be set later on, by other parts of Inform calling the routines below.

The rubric text for an extension, which is double-quoted matter just below its "begins here" line, is parsed as a sentence and will be read as an assertion in the usual way when the material from this extension is being worked through (quite a long time after the EF structure was created). When that happens, the following function will be called to set the rubric.

void Extensions::set_rubric(inform_extension *E, text_stream *text) {
    if (E == NULL) internal_error("no extension");
    E->rubric_as_lexed = Str::duplicate(text);
    LOGIF(EXTENSIONS_CENSUS, "Extension rubric: %S\n", E->rubric_as_lexed);
}

text_stream *Extensions::get_rubric(inform_extension *E) {
    if (E == NULL) return NULL;
    return E->rubric_as_lexed;
}

§14. The optional extra credit line is used to acknowledge I6 sources, collaborators, translators and so on.

void Extensions::set_extra_credit(inform_extension *E, text_stream *text) {
    if (E == NULL) internal_error("no extension");
    E->extra_credit_as_lexed = Str::duplicate(text);
    LOGIF(EXTENSIONS_CENSUS, "Extension extra credit: %S\n", E->extra_credit_as_lexed);
}

§15. The use option "authorial modesty" is unusual in applying to the extension it is found in, not the whole source text. When we read it, we call one of the following routines, depending on whether it was in an extension or in the main source text:

int general_authorial_modesty = FALSE;
void Extensions::set_authorial_modesty(inform_extension *E) {
    if (E == NULL) internal_error("no extension");
    E->authorial_modesty = TRUE;
}
void Extensions::set_general_authorial_modesty(void) {
    general_authorial_modesty = TRUE;
}

§16. The inclusion sentence for an extension is where it was Included in a project's syntax tree (if it was). It isn't used in compilation, only for problem messages and the index.

void Extensions::set_inclusion_sentence(inform_extension *E, parse_node *N) {
    E->inclusion_sentence = N;
}
parse_node *Extensions::get_inclusion_sentence(inform_extension *E) {
    if (E == NULL) return NULL;
    return E->inclusion_sentence;
}

§17. An extension is "standard" if it's either the Standard Rules or Basic Inform.

int Extensions::is_standard(inform_extension *E) {
    if (E == NULL) return FALSE;
    return E->standard;
}

§18. Version requirements. When it's known that an extension must satisfy a given version requirement — say, being version 7.2.1 or better — the following is called. Note that if incompatible requirements are placed on it, the range in E->must_satisfy becomes empty and stays that way.

void Extensions::must_satisfy(inform_extension *E, inbuild_requirement *req) {
    if (E->must_satisfy == NULL) E->must_satisfy = req;
    else VersionNumberRanges::intersect_range(E->must_satisfy->version_range, req->version_range);
}

§19. And it is certainly possible, if an extension is loaded for multiple reasons with different versioning needs, that the extension no longer meets its requirements (even though it did when first loaded). This tests for that:

int Extensions::satisfies(inform_extension *E) {
    if (E == NULL) return FALSE;
    return Requirements::meets(E->as_copy->edition, E->must_satisfy);
}