To manage key-value pairs of bibliographic data, metadata if you like, associated with a given web.

• §1. Storing data
• §4. Initialising a web
• §6. Reading bibliographic data
• §7. Writing bibliographic data
• §8. Parsing bibliographic data

§1. Storing data.There are never more than a dozen or so key-value pairs, and it's more convenient to store them directly here than to use a dictionary.

typedef struct web_bibliographic_datum {
    struct text_stream *key;
    struct text_stream *value;
    int declaration_permitted;  is the contents page of the web allowed to set this?
    int declaration_mandatory;  is it positively required to?
    int on_or_off;  boolean: which we handle as the string "On" or "Off"
    struct web_bibliographic_datum *alias;
    CLASS_DEFINITION
} web_bibliographic_datum;

• The structure web_bibliographic_datum is accessed in 2/dl, 2/dct, 4/prp, 4/jsn, 5/mrk, 5/ee and here.

§2. We keep these in linked lists, and here's a convenient way to scan them:

define LOOP_OVER_BIBLIOGRAPHIC_DATA(bd, W)
    LOOP_OVER_LINKED_LIST(bd, web_bibliographic_datum, W->bibliographic_data)

§3. The following check the rules:

int Bibliographic::datum_can_be_declared?Usage of Bibliographic::datum_can_be_declared:
§8.1(ls_web *W, text_stream *key) {
    web_bibliographic_datum *bd = Bibliographic::look_up_datum(W, key);
    if (bd == NULL) return FALSE;
    return bd->declaration_permitted;
}

int Bibliographic::datum_on_or_off?Usage of Bibliographic::datum_on_or_off:
§8.1(ls_web *W, text_stream *key) {
    web_bibliographic_datum *bd = Bibliographic::look_up_datum(W, key);
    if (bd == NULL) return FALSE;
    return bd->on_or_off;
}

§4. Initialising a web.Each web has the following slate of data:

void Bibliographic::initialise_data?Usage of Bibliographic::initialise_data:
Web Structure - §1(ls_web *W) {
    web_bibliographic_datum *bd;

    bd = Bibliographic::set_datum(W, I"Title", I"Untitled");
    bd = Bibliographic::set_datum(W, I"Author", I"Anonymous");
    bd = Bibliographic::set_datum(W, I"Language", I"None");
    bd = Bibliographic::set_datum(W, I"Purpose", I"");

    bd = Bibliographic::set_datum(W, I"License", NULL);
    bd->alias = Bibliographic::set_datum(W, I"Licence", NULL);  alias US to UK spelling

    Bibliographic::set_datum(W, I"Short Title", NULL);
    Bibliographic::set_datum(W, I"Capitalized Title", NULL);
    Bibliographic::set_datum(W, I"Build Date", NULL);
    Bibliographic::set_datum(W, I"Build Number", NULL);
    Bibliographic::set_datum(W, I"Prerelease", NULL);
    Bibliographic::set_datum(W, I"Semantic Version Number", NULL);
    Bibliographic::set_datum(W, I"Version Number", I"1");
    Bibliographic::set_datum(W, I"Version Name", NULL);
    Bibliographic::set_datum(W, I"Index Template", NULL);
    Bibliographic::set_datum(W, I"Preform Language", NULL);

    bd = Bibliographic::set_datum(W, I"Declare Section Usage", I"Off"); bd->on_or_off = TRUE;
    bd = Bibliographic::set_datum(W, I"Namespaces", I"Off"); bd->on_or_off = TRUE;
    bd = Bibliographic::set_datum(W, I"Sequential Section Ranges", I"Off"); bd->on_or_off = TRUE;
    bd = Bibliographic::set_datum(W, I"Strict Usage Rules", I"Off"); bd->on_or_off = TRUE;
    bd = Bibliographic::set_datum(W, I"TeX Mathematics Notation", I"$");
    bd = Bibliographic::set_datum(W, I"TeX Mathematics Displayed Notation", I"$$");
    bd = Bibliographic::set_datum(W, I"Footnote Begins Notation", I"[");
    bd = Bibliographic::set_datum(W, I"Footnote Ends Notation", I"]");
    bd = Bibliographic::set_datum(W, I"Code In Commentary Notation", I"|");
    bd = Bibliographic::set_datum(W, I"Code In Code Comments Notation", I"|");
    bd = Bibliographic::set_datum(W, I"Cross-References Notation", I"//");
    bd = Bibliographic::set_datum(W, I"Web Syntax Version", NULL);
    bd = Bibliographic::set_datum(W, I"Paragraph Numbers Visibility", I"On");
}

§5. Once the declarations for a web have been processed, the following is called to check that all the mandatory declarations have indeed been made:

void Bibliographic::check_required_data?Usage of Bibliographic::check_required_data:
Web Structure - §10(ls_web *W) {
    web_bibliographic_datum *bd;
    LOOP_OVER_BIBLIOGRAPHIC_DATA(bd, W)
        if ((bd->declaration_mandatory) &&
            (Str::len(bd->value) == 0))
                Errors::fatal_with_text(
                    "The web does not specify '%S: ...'", bd->key);
}

§6. Reading bibliographic data.Key names are case-sensitive.

text_stream *Bibliographic::get_datum?Usage of Bibliographic::get_datum:
Web Structure - §3, §11.1, §11.1.1
Web Contents Pages - §3.2.1.2.1, §3.2.1.3.1.1
Single-File Webs - §3.2
Web Ranges - §1
Tangle Targets - §5
The Tangler - §10.1.2
Build Files - §6
ACME Support - §6
InC Support - §14
The Swarm - §8.1.1
The Collater - §5.1.9.1
The Weaver of Text - §1, §4
HTML Formats - §5.2, §5.3, §11
Readme Writeme - §2, §3(ls_web *W, text_stream *key) {
    web_bibliographic_datum *bd = Bibliographic::look_up_datum(W, key);
    if (bd) return bd->value;
    return NULL;
}

int Bibliographic::data_exists?Usage of Bibliographic::data_exists:
InC Support - §14
The Swarm - §11
The Collater - §5.1.9(ls_web *W, text_stream *key) {
    web_bibliographic_datum *bd = Bibliographic::look_up_datum(W, key);
    if ((bd) && (Str::len(bd->value) > 0)) return TRUE;
    return FALSE;
}

web_bibliographic_datum *Bibliographic::look_up_datum?Usage of Bibliographic::look_up_datum:
§3, §7
The Tangler - §10.1.2(ls_web *W, text_stream *key) {
    web_bibliographic_datum *bd;
    LOOP_OVER_BIBLIOGRAPHIC_DATA(bd, W)
        if (Str::eq(key, bd->key)) {
            if (bd->alias) return bd->alias;
            return bd;
        }
    return NULL;
}

§7. Writing bibliographic data.Note that a key-value pair is created if the key doesn't exist at present, so this routine never fails.

web_bibliographic_datum *Bibliographic::set_datum?Usage of Bibliographic::set_datum:
§4, §7.2, §8.1
Web Structure - §11.1
Web Contents Pages - §3
Single-File Webs - §3.1
Web Syntax - §7
Tangle Targets - §5
Build Files - §5, §6
The Swarm - §8.1.1, §11
Patterns - §3
Format Methods - §6
HTML Formats - §5.14, §5.16(ls_web *W, text_stream *key, text_stream *val) {
    web_bibliographic_datum *bd = Bibliographic::look_up_datum(W, key);
    if (bd == NULL) Create a new datum, then7.1
    else Str::copy(bd->value, val);
    if (Str::eq_wide_string(key, U"Title")) Also set a capitalized form7.2;
    return bd;
}

§7.1. Create a new datum, then7.1 =

    bd = CREATE(web_bibliographic_datum);
    bd->key = Str::duplicate(key);
    bd->value = Str::duplicate(val);
    bd->declaration_mandatory = FALSE;
    bd->declaration_permitted = TRUE;
    bd->on_or_off = FALSE;
    bd->alias = NULL;
    ADD_TO_LINKED_LIST(bd, web_bibliographic_datum, W->bibliographic_data);

• This code is used in §7.

§7.2. A slightly foolish feature, this; if text like "Wuthering Heights" is written to the "Title" key, then a full-caps "WUTHERING HEIGHTS" is written to a "Capitalized Title" key. (This enables cover sheets which want to typeset the title in full caps to do so.)

Also set a capitalized form7.2 =

    TEMPORARY_TEXT(recapped)
    Str::copy(recapped, val);
    LOOP_THROUGH_TEXT(P, recapped)
        Str::put(P, Characters::toupper(Str::get(P)));
    Bibliographic::set_datum(W, I"Capitalized Title", recapped);
    DISCARD_TEXT(recapped)

• This code is used in §7.

§8. Parsing bibliographic data.The following attempts to parse line as a key-value pair, i.e., as text reading Key: Value, and returns TRUE or FALSE according to whether the text syntactically looks that way.

If set is TRUE then the setting is made in the web W: or, it that's not possible, an error is issued (but the function still returns TRUE).

int Bibliographic::parse_kvp?Usage of Bibliographic::parse_kvp:
Web Contents Pages - §3.2
Single-File Webs - §3.2
Web Syntax - §7(ls_web *W, text_stream *line, int set, text_file_position *tfp, text_stream *k) {
    int rv = FALSE;
    match_results mr = Regexp::create_mr();
    if (Regexp::match(&mr, line, U"(%c+?): (%c+?) *")) {
        TEMPORARY_TEXT(key)
        Str::copy(key, mr.exp[0]);
        TEMPORARY_TEXT(value)
        Str::copy(value, mr.exp[1]);
        if (set) Set bibliographic key-value pair8.1;
        if (k) {
            Str::clear(k);
            Str::copy(k, key);
        }
        DISCARD_TEXT(key)
        DISCARD_TEXT(value)
        rv = TRUE;
    }
    Regexp::dispose_of(&mr);
    return rv;
}

§8.1. Set bibliographic key-value pair8.1 =

    if (Bibliographic::datum_can_be_declared(W, key)) {
        if (Bibliographic::datum_on_or_off(W, key)) {
            if ((Str::ne_wide_string(value, U"On")) && (Str::ne_wide_string(value, U"Off"))) {
                TEMPORARY_TEXT(err)
                WRITE_TO(err, "this setting must be 'On' or 'Off': %S", key);
                Errors::in_text_file_S(err, tfp);
                DISCARD_TEXT(err)
                Str::clear(value);
                WRITE_TO(value, "Off");
            }
        }
        Bibliographic::set_datum(W, key, value);
    } else {
        TEMPORARY_TEXT(err)
        WRITE_TO(err, "no such bibliographic datum: %S", key);
        Errors::in_text_file_S(err, tfp);
        DISCARD_TEXT(err)
    }

• This code is used in §8.