/*

Copyright 2009-2010 Taco Hoekwater <taco@luatex.org>

This file is part of LuaTeX.

LuaTeX is free software; you can redistribute it and/or modify it under the terms
of the GNU General Public License as published by the Free Software Foundation;
either version 2 of the License, or (at your option) any later version.

LuaTeX is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU General Public License along with
LuaTeX; if not, see <http://www.gnu.org/licenses/>.

*/

#include "ptexlib.h"

#define mode     mode_par
#define tail     tail_par
#define head     head_par
#define dir_save dirs_par

/*tex

    The program above includes a bunch of ``hooks'' that allow further
    capabilities to be added without upsetting \TeX's basic structure. Most of
    these hooks are concerned with ``whatsit'' nodes, which are intended to be
    used for special purposes; whenever a new extension to \TeX\ involves a new
    kind of whatsit node, a corresponding change needs to be made to the routines
    below that deal with such nodes, but it will usually be unnecessary to make
    many changes to the other parts of this program.

    In order to demonstrate how extensions can be made, we shall treat
    `\.{\\write}', `\.{\\openout}', `\.{\\closeout}', `\.{\\immediate}', and
    `\.{\\special}' as if they were extensions. These commands are actually
    primitives of \TeX, and they should appear in all implementations of the
    system; but let's try to imagine that they aren't. Then the program below
    illustrates how a person could add them.

    Sometimes, of course, an extension will require changes to \TeX\ itself; no
    system of hooks could be complete enough for all conceivable extensions. The
    features associated with `\.{\\write}' are almost all confined to the
    following paragraphs, but there are small parts of the |print_ln| and
    |print_char| procedures that were introduced specifically to \.{\\write}
    characters. Furthermore one of the token lists recognized by the scanner is a
    |write_text|; and there are a few other miscellaneous places where we have
    already provided for some aspect of \.{\\write}. The goal of a \TeX\ extender
    should be to minimize alterations to the standard parts of the program, and
    to avoid them completely if possible. He or she should also be quite sure
    that there's no easy way to accomplish the desired goals with the standard
    features that \TeX\ already has. ``Think thrice before extending,'' because
    that may save a lot of work, and it will also keep incompatible extensions of
    \TeX\ from proliferating.

    First let's consider the format of whatsit nodes that are used to represent
    the data associated with \.{\\write} and its relatives. Recall that a whatsit
    has |type=whatsit_node|, and the |subtype| is supposed to distinguish
    different kinds of whatsits. Each node occupies two or more words; the exact
    number is immaterial, as long as it is readily determined from the |subtype|
    or other data.

    We shall introduce five |subtype| values here, corresponding to the control
    sequences \.{\\openout}, \.{\\write}, \.{\\closeout}, and \.{\\special}. The
    second word of I/O whatsits has a |write_stream| field that identifies the
    write-stream number (0 to 15, or 16 for out-of-range and positive, or 17 for
    out-of-range and negative). In the case of \.{\\write} and \.{\\special},
    there is also a field that points to the reference count of a token list that
    should be sent. In the case of \.{\\openout}, we need three words and three
    auxiliary subfields to hold the string numbers for name, area, and extension.

    Extensions might introduce new command codes; but it's best to use
    |extension| with a modifier, whenever possible, so that |main_control| stays
    the same.

    The sixteen possible \.{\\write} streams are represented by the |write_file|
    array. The |j|th file is open if and only if |write_open[j]=true|. The last
    two streams are special; |write_open[16]| represents a stream number greater
    than 15, while |write_open[17]| represents a negative stream number, and both
    of these variables are always |false|.

*/

alpha_file write_file[last_file_selector+1];
halfword write_file_mode[last_file_selector+1];
halfword write_file_translation[last_file_selector+1];
boolean write_open[last_file_selector+1];

scaled neg_wd;
scaled pos_wd;
scaled neg_ht;

/*tex

    The variable |write_loc| just introduced is used to provide an appropriate
    error message in case of ``runaway'' write texts.

*/

/*tex The |eqtb| address of \.{\\write}: */

halfword write_loc;

/*tex

    When an |extension| command occurs in |main_control|, in any mode, the
    |do_extension| routine is called.

*/

int last_saved_image_index ;
int last_saved_image_pages ;
int last_saved_box_index ;
scaledpos last_position = { 0, 0 };

static void do_extension_dvi_literal(int deferred)
{
    new_whatsit(deferred ? late_special_node : special_node);
    write_stream(tail) = null;
    scan_toks(false, ! deferred);
    write_tokens(tail) = def_ref;
}

static void do_extension_dvi(int immediate, int deferred)
{
    if (scan_keyword("literal")) {
        /* immediate is the default here */
        if (scan_keyword("shipout")) { 
            deferred = 1;
        }
        do_extension_dvi_literal(deferred);
    } else if (scan_keyword("lateliteral")) {
        do_extension_dvi_literal(1);
    } else {
        tex_error("unexpected use of \\dviextension",null);
    }
}

static void do_extension_pdf_literal(int deferred)
{
    new_whatsit(deferred ? pdf_late_literal_node : pdf_literal_node);
    if (scan_keyword("direct"))
        set_pdf_literal_mode(tail, direct_always);
    else if (scan_keyword("page"))
        set_pdf_literal_mode(tail, direct_page);
    else if (scan_keyword("text"))
        set_pdf_literal_mode(tail, direct_text);
    else if (scan_keyword("raw"))
        set_pdf_literal_mode(tail, direct_raw);
    else if (scan_keyword("origin"))
        set_pdf_literal_mode(tail, set_origin);
    else
        set_pdf_literal_mode(tail, set_origin);
    scan_toks(false, ! deferred);
    set_pdf_literal_type(tail, normal);
    set_pdf_literal_data(tail, def_ref);
}

static void do_extension_pdf(int immediate, int deferred)
{
    int i;
    if (scan_keyword("literal")) {
        /* immediate is the default here */
        if (scan_keyword("shipout")) { 
            deferred = 1;
        }
        do_extension_pdf_literal(deferred);
    } else if (scan_keyword("lateliteral")) {
        do_extension_pdf_literal(1);
    } else if (scan_keyword("dest")) {
        scan_pdfdest(static_pdf);
    } else if (scan_keyword("annot")) {
        scan_annot(static_pdf);
    } else if (scan_keyword("save")) {
        new_whatsit(pdf_save_node);
    } else if (scan_keyword("restore")) {
        new_whatsit(pdf_restore_node);
    } else if (scan_keyword("linkstate")) {
        new_whatsit(pdf_link_state_node);
        scan_int();
        pdf_link_state(tail) = cur_val;
    } else if (scan_keyword("setmatrix")) {
        new_whatsit(pdf_setmatrix_node);
        scan_toks(false, true);
        set_pdf_setmatrix_data(tail, def_ref);
    } else if (scan_keyword("obj")) {
        scan_obj(static_pdf);
        if (immediate) {
            if (obj_data_ptr(static_pdf, pdf_last_obj) == 0) {
                /*tex This object has not been initialized yet. */
                normal_error("pdf backend","\\pdfextension obj 'reserveobjnum' cannot be used with \\immediate");
            }
            pdf_write_obj(static_pdf, pdf_last_obj);
        }
    } else if (scan_keyword("refobj")) {
        scan_refobj(static_pdf);
    } else if (scan_keyword("colorstack")) {
        scan_int();
        if (cur_val >= colorstackused()) {
            print_err("Unknown color stack number ");
            print_int(cur_val);
            help3(
                "Allocate and initialize a color stack with \\pdfextension colorstackinit.",
                "I'll use default color stack 0 here.",
                "Proceed, with fingers crossed."
            );
            error();
            cur_val = 0;
        }
        if (cur_val < 0) {
            print_err("Invalid negative color stack number");
            help2(
                "I'll use default color stack 0 here.",
                "Proceed, with fingers crossed."
            );
            error();
            cur_val = 0;
        }
        if (scan_keyword("set"))
            i = colorstack_set;
        else if (scan_keyword("push"))
            i = colorstack_push;
        else if (scan_keyword("pop"))
            i = colorstack_pop;
        else if (scan_keyword("current"))
            i = colorstack_current;
        else
            i = -1;
        if (i >= 0) {
            new_whatsit(pdf_colorstack_node);
            set_pdf_colorstack_stack(tail, cur_val);
            set_pdf_colorstack_cmd(tail, i);
            set_pdf_colorstack_data(tail, null);
            if (i <= colorstack_data) {
                scan_toks(false, true);
                set_pdf_colorstack_data(tail, def_ref);
            }
        } else {
            print_err("Color stack action is missing");
            help3(
                "The expected actions for \\pdfextension colorstack:",
                "    set, push, pop, current",
                "I'll ignore the color stack command."
            );
            error();
        }
    } else if (scan_keyword("startlink")) {
        scan_startlink(static_pdf);
    } else if (scan_keyword("endlink")) {
        if (abs(mode) == vmode)
            normal_error("pdf backend", "\\pdfextension endlink cannot be used in vertical mode");
        new_whatsit(pdf_end_link_node);
    } else if (scan_keyword("startthread")) {
        new_annot_whatsit(pdf_start_thread_node);
        scan_thread_id();
    } else if (scan_keyword("endthread")) {
        new_whatsit(pdf_end_thread_node);
    } else if (scan_keyword("thread")) {
        new_annot_whatsit(pdf_thread_node);
        scan_thread_id();
    } else if (scan_keyword("outline")) {
        scan_pdfoutline(static_pdf);
    } else if (scan_keyword("glyphtounicode")) {
        glyph_to_unicode();
    } else if (scan_keyword("catalog")) {
        scan_pdfcatalog(static_pdf);
    } else if (scan_keyword("fontattr")) {
        /*tex

            The font attributes are simply initialized to zero now, this is
            easier to deal with from C than an empty \TeX{} string, and surely
            nobody will want to set font attr to a string containing a single
            zero, as that would be nonsensical in the PDF output.

        */
        scan_font_ident();
        i = cur_val;
        if (i == null_font)
            normal_error("pdf backend", "invalid font identifier");
        scan_toks(false, true);
        set_pdf_font_attr(i, tokens_to_string(def_ref));
        if (str_length(pdf_font_attr(i)) == 0) {
            /*tex From |tokens_to_string|. */
            flush_str((str_ptr - 1));
            set_pdf_font_attr(i, 0);
        }
    } else if (scan_keyword("mapfile")) {
        scan_toks(false, true);
        pdfmapfile(def_ref);
        delete_token_ref(def_ref);
    } else if (scan_keyword("mapline")) {
        scan_toks(false, true);
        pdfmapline(def_ref);
        delete_token_ref(def_ref);
    } else if (scan_keyword("includechars")) {
        pdf_include_chars(static_pdf);
    } else if (scan_keyword("info")) {
        scan_toks(false, true);
        pdf_info_toks = concat_tokens(pdf_info_toks, def_ref);
    } else if (scan_keyword("names")) {
        scan_toks(false, true);
        pdf_names_toks = concat_tokens(pdf_names_toks, def_ref);
    } else if (scan_keyword("trailer")) {
        scan_toks(false, true);
        pdf_trailer_toks = concat_tokens(pdf_trailer_toks, def_ref);
    } else {
        tex_error("unexpected use of \\pdfextension",null);
    }
}

static void do_resource_dvi(int immediate, int code)
{
    /*tex Nothing is done here. */
}

static void do_resource_pdf(int immediate, int code)
{
    switch (code) {
        case use_box_resource_code:
            scan_pdfrefxform(static_pdf);
            break;
        case use_image_resource_code:
            scan_pdfrefximage(static_pdf);
            break;
        case save_box_resource_code:
            scan_pdfxform(static_pdf);
            if (immediate) {
                pdf_cur_form = last_saved_box_index;
                ship_out(static_pdf, obj_xform_box(static_pdf, last_saved_box_index), SHIPPING_FORM);
            }
            break;
        case save_image_resource_code:
            scan_pdfximage(static_pdf);
            if (immediate) {
                pdf_write_image(static_pdf, last_saved_image_index);
            }
            break;
    }
}

/*tex

    Ad immediate:

    To write a token list, we must run it through \TeX's scanner, expanding
    macros and \.{\\the} and \.{\\number}, etc. This might cause runaways, if a
    delimited macro parameter isn't matched, and runaways would be extremely
    confusing since we are calling on \TeX's scanner in the middle of a
    \.{\\shipout} command. Therefore we will put a dummy control sequence as a
    ``stopper,'' right after the token list. This control sequence is
    artificially defined to be \.{\\outer}.

    The presence of `\.{\\immediate}' causes the |do_extension| procedure to
    descend to one level of recursion. Nothing happens unless \.{\\immediate} is
    followed by `\.{\\openout}', `\.{\\write}', or `\.{\\closeout}'.

*/

/*tex

    The extensions are backend related. The next subroutine uses |cur_chr| to
    decide what sort of whatsit is involved, and also inserts a |write_stream|
    number. 

*/

static void new_write_whatsit(int w, int check)
{
    new_whatsit(cur_chr);
    if (check) {
        /*tex So we check with open and close. */
        scan_limited_int(last_file_selector,NULL);
    } else {
        /*tex But we're tolerant with the rest. */
        scan_int();
        if (cur_val < 0)
            cur_val = term_only;
        else if (cur_val > last_file_selector) {
            cur_val = term_and_log;
        }
    }
    write_stream(tail) = cur_val;
}

/* 
    Specials and literals are immediate by default but can be deferred as well. We have two prefixes that 
    don't accumulate but trigger a next token pickup. Writes and resources are deferred by default. The 
    (wish for a) shipout key scanner comes from similar features in the other engines. So, we're 
    compatible but also conceptually a bit more consistent by introducing a |\deferred| prefix. 
*/

void do_extension(int immediate, int deferred)
{
    /*tex All-purpose pointers. */
    halfword k, p;
    if (cur_cmd == extension_cmd) {
        /*tex These have their own range starting at 0. */
        switch (cur_chr) {
            case open_code:
                p = tail;
                new_write_whatsit(open_node_size,1);
                scan_optional_equals();
                /* scan_file_name(); */
                do {
                    get_x_token();
                } while ((cur_cmd == spacer_cmd) || (cur_cmd == relax_cmd));
                back_input();
                if (cur_cmd != left_brace_cmd) {
                    scan_file_name();
                } else {
                    scan_file_name_toks();
                }
                /* */
                open_name(tail) = cur_name;
                open_area(tail) = cur_area;
                open_ext(tail) = cur_ext;
                if (immediate) {
                    wrapup_leader(tail);
                    flush_node_list(tail);
                    tail = p;
                    vlink(p) = null;
                }
                break;
            case write_code:
                /*tex

                    When `\.{\\write 12\{...\}}' appears, we scan the token list
                    `\.{\{...\}}' without expanding its macros; the macros will
                    be expanded later when this token list is rescanned.

                */
                k = cur_cs;
                p = tail;
                new_write_whatsit(write_node_size,0); // this can modify cur_cs
                cur_cs = k;                           // so we restore the prev. cur_cs, as in pdftex
                scan_toks(false, false);
                write_tokens(tail) = def_ref;
                if (immediate) {
                    wrapup_leader(tail);
                    flush_node_list(tail);
                    tail = p;
                    vlink(p) = null;
                }
                break;
            case close_code:
                p = tail;
                new_write_whatsit(close_node_size,1);
                write_tokens(tail) = null;
                if (immediate) {
                    wrapup_leader(tail);
                    flush_node_list(tail);
                    tail = p;
                    vlink(p) = null;
                }
                break;
            case special_code:
                /*tex

                    When `\.{\\special\{...\}}' appears, we expand the macros in
                    the token list as in \.{\\xdef} and \.{\\mark}.  When marked with \.{shipout}, we keep
                    tokens unexpanded for now.

                */
                if (scan_keyword("shipout")) {
                    deferred = 1;
                } 
                new_whatsit(deferred ? late_special_node : special_node);
                write_stream(tail) = null;
                p = scan_toks(false, ! deferred);
                write_tokens(tail) = def_ref;
                break;
            case reserved_immediate_code:
                get_x_token();
                do_extension(1, 0);
                break;
            case reserved_deferred_code:
                get_x_token();
                do_extension(0, 1);
                break;
            case end_local_code:
                if (tracing_nesting_par > 2) {
                    local_control_message("leaving token scanner");
                }
                end_local_control();
                break;
            case use_box_resource_code:
            case use_image_resource_code:
            case save_box_resource_code:
            case save_image_resource_code:
                switch (get_o_mode()) {
                    case OMODE_DVI:
                        do_resource_dvi(immediate,cur_chr);
                        break;
                    case OMODE_PDF:
                        do_resource_pdf(immediate,cur_chr);
                        break;
                    default:
                        break;
                }
                break;
            /*tex Backend extensions have their own range starting at 32. */
            case dvi_extension_code:
                if (get_o_mode() == OMODE_DVI)
                    do_extension_dvi(immediate, deferred);
                break;
            case pdf_extension_code:
                if (get_o_mode() == OMODE_PDF)
                    do_extension_pdf(immediate, deferred);
                break;
            /*tex Done. */
            default:
                if (immediate) {
                    back_input();
                } else {
                    confusion("invalid extension");
                }
                break;
        }
    } else {
        /*tex No extension command, quite certainly following |\immediate|. */
        back_input();
    }
}

/*tex

    Here is a subroutine that creates a whatsit node having a given |subtype| and
    a given number of words. It initializes only the first word of the whatsit,
    and appends it to the current list.

*/

void new_whatsit(int s)
{
    halfword p = new_node(whatsit_node, s);
    couple_nodes(tail, p);
    tail = p;
}

/*tex

    The final line of this routine is slightly subtle; at least, the author
    didn't think about it until getting burnt! There is a used-up token list on
    the stack, namely the one that contained |end_write_token|. (We insert this
    artificial `\.{\\endwrite}' to prevent runaways, as explained above.) If it
    were not removed, and if there were numerous writes on a single page, the
    stack would overflow.

*/

void expand_macros_in_tokenlist(halfword p)
{
    int old_mode;
    pointer q = get_avail();
    pointer r = get_avail();
    token_info(q) = right_brace_token + '}';
    token_link(q) = r;
    token_info(r) = end_write_token;
    begin_token_list(q, inserted);
    begin_token_list(p, write_text);
    q = get_avail();
    token_info(q) = left_brace_token + '{';
    begin_token_list(q, inserted);
    /*tex

        Now we're ready to scan `\.\{$\langle\,$token list$\,\rangle$\.{\}
        \\endwrite}'.

    */
    old_mode = mode;
    mode = 0;
    /*tex

        Disable \.{\\prevdepth}, \.{\\spacefactor}, \.{\\lastskip},
        \.{\\prevgraf}.

    */
    cur_cs = write_loc;
    /*tex Expand macros, etc. */
    q = scan_toks(false, true);
    get_token();
    if (cur_tok != end_write_token) {
        /*tex Recover from an unbalanced write command */
        const char *hlp[] = {
            "On this page there's a \\write with fewer real {'s than }'s.",
            "I can't handle that very well; good luck.",
            NULL
        };
        tex_error("Unbalanced write command", hlp);
        do {
            get_token();
        } while (cur_tok != end_write_token);
    }
    mode = old_mode;
    /*tex Conserve stack space. */
    end_token_list();
}

void write_out(halfword p)
{
    /*tex holds print |selector| */
    int old_setting;
    /*tex write stream number */
    int j;
    /*tex line to be written, as a Lua string */
    lstring *ss = NULL;
    lstring *s = NULL;
    int callback_id;
    int lua_retval;
    expand_macros_in_tokenlist(write_tokens(p));
    old_setting = selector;
    j = write_stream(p);
    if (file_can_be_written(j)) {
        selector = j;
    } else if ((j == term_only) && (selector == term_and_log)) {
        /*tex write to the terminal if file isn't open */
        selector = log_only;
        tprint_nl("");
    } else {
        tprint_nl("");
    }
    s = tokenlist_to_lstring(def_ref, false);
    if (selector < no_print) {
        /*tex selector is a file */
        callback_id = callback_defined(process_output_buffer_callback);
        if (callback_id > 0) {
            /*tex fix up the output buffer using callbacks */
            lua_retval = run_callback(callback_id, "L->L", s, &ss);
            if ((lua_retval == true) && (ss != NULL)) {
                free_lstring(s);
                s = ss;
            }
        }
    }
    lprint(s);
    free_lstring(s);
    print_ln();
    flush_list(def_ref);
    selector = old_setting;
}

void finalize_write_files(void) {
    int k;
    for (k = 0; k <= last_file_selector; k++) {
        if (write_open[k]) {
            lua_a_close_out(write_file[k]);
        }
    }
}

void initialize_write_files(void) {
    int k;
    for (k = 0; k <= last_file_selector; k++) {
        write_open[k] = false;
    }
}

void close_write_file(int id) {
    if (write_open[id]) {
        lua_a_close_out(write_file[id]);
        write_open[id] = false;
    }
}

boolean open_write_file(int id, char *fn) {
    if (lua_a_open_out(&(write_file[id]), fn, (id + 1))) {
        write_open[id] = true;
        return true;
    } else {
        return false;
    }
}

/*tex

    To implement primitives as \.{\\pdfextension info}, \.{\\pdfextension
    catalog} or \.{\\pdfextension names} we need to concatenate tokens lists.

*/

halfword concat_tokens(halfword q, halfword r)
{
    /*tex concat |q| and |r| and returns the result tokens list */
    halfword p;
    if (q == null)
        return r;
    p = q;
    while (token_link(p) != null)
        p = token_link(p);
    set_token_link(p, token_link(r));
    free_avail(r);
    return q;
}

/*tex

    The \eTeX\ features available in extended mode are grouped into two
    categories: (1)~Some of them are permanently enabled and have no semantic
    effect as long as none of the additional primitives are executed. (2)~The
    remaining \eTeX\ features are optional and can be individually enabled and
    disabled. For each optional feature there is an \eTeX\ state variable named
    \.{\\...state}; the feature is enabled, resp.\ disabled by assigning a
    positive, resp.\ non-positive value to that integer.

    In order to handle \.{\\everyeof} we need an array |eof_seen| of boolean
    variables.

*/

boolean *eof_seen;

/*tex

    The |print_group| procedure prints the current level of grouping and the name
    corresponding to |cur_group|.

*/

void print_group(boolean e)
{
    switch (cur_group) {
        case bottom_level:
            tprint("bottom level");
            return;
            break;
        case simple_group:
        case semi_simple_group:
            if (cur_group == semi_simple_group)
                tprint("semi ");
            tprint("simple");
            break;;
        case hbox_group:
        case adjusted_hbox_group:
            if (cur_group == adjusted_hbox_group)
                tprint("adjusted ");
            tprint("hbox");
            break;
        case vbox_group:
            tprint("vbox");
            break;
        case vtop_group:
            tprint("vtop");
            break;
        case align_group:
        case no_align_group:
            if (cur_group == no_align_group)
                tprint("no ");
            tprint("align");
            break;
        case output_group:
            tprint("output");
            break;
        case disc_group:
            tprint("disc");
            break;
        case insert_group:
            tprint("insert");
            break;
        case vcenter_group:
            tprint("vcenter");
            break;
        case math_group:
        case math_choice_group:
        case math_shift_group:
        case math_left_group:
            tprint("math");
            if (cur_group == math_choice_group)
                tprint(" choice");
            else if (cur_group == math_shift_group)
                tprint(" shift");
            else if (cur_group == math_left_group)
                tprint(" left");
            break;
    }
    tprint(" group (level ");
    print_int(cur_level);
    print_char(')');
    if (saved_value(-1) != 0) {
        /*tex |saved_line| */
        if (e)
            tprint(" entered at line ");
        else
            tprint(" at line ");
        print_int(saved_value(-1));
    }
}

/*tex

    The |group_trace| procedure is called when a new level of grouping begins
    (|e=false|) or ends (|e=true|) with |saved_value(-1)| containing the line
    number.

*/

void group_trace(boolean e)
{
    begin_diagnostic();
    print_char('{');
    if (e)
        tprint("leaving ");
    else
        tprint("entering ");
    print_group(e);
    print_char('}');
    end_diagnostic(false);
}

/*tex

    A group entered (or a conditional started) in one file may end in a different
    file. Such slight anomalies, although perfectly legitimate, may cause errors
    that are difficult to locate. In order to be able to give a warning message
    when such anomalies occur, \eTeX\ uses the |grp_stack| and |if_stack| arrays
    to record the initial |cur_boundary| and |cond_ptr| values for each input
    file.

*/

/*tex initial |cur_boundary| */

save_pointer *grp_stack;

/*tex initial |cond_ptr| */

halfword *if_stack;

/*tex

    When a group ends that was apparently entered in a different input file, the
    |group_warning| procedure is invoked in order to update the |grp_stack|. If
    moreover \.{\\tracingnesting} is positive we want to give a warning message.
    The situation is, however, somewhat complicated by two facts: (1)~There may
    be |grp_stack| elements without a corresponding \.{\\input} file or
    \.{\\scantokens} pseudo file (e.g., error insertions from the terminal); and
    (2)~the relevant information is recorded in the |name_field| of the
    |input_stack| only loosely synchronized with the |in_open| variable indexing
    |grp_stack|.

*/

void group_warning(void)
{
    /*tex do we need a warning? */
    boolean w = false;
    /*tex index into |grp_stack| */
    int i = in_open;
    base_ptr = input_ptr;
    /*tex store current state */
    input_stack[base_ptr] = cur_input;
    while ((grp_stack[i] == cur_boundary) && (i > 0)) {
        /*tex

            Set variable |w| to indicate if this case should be reported. This
            code scans the input stack in order to determine the type of the
            current input file.

        */
        if (tracing_nesting_par > 0) {
            while ((input_stack[base_ptr].state_field == token_list) || (input_stack[base_ptr].index_field > i))
                decr(base_ptr);
            if (input_stack[base_ptr].name_field > 17)
                w = true;
        }
        grp_stack[i] = save_value(save_ptr);
        decr(i);
    }
    if (w) {
        tprint_nl("Warning: end of ");
        print_group(true);
        tprint(" of a different file");
        print_ln();
        if (tracing_nesting_par > 1)
            show_context();
        if (history == spotless)
            history = warning_issued;
    }
}

/*tex

    When a conditional ends that was apparently started in a different input
    file, the |if_warning| procedure is invoked in order to update the
    |if_stack|. If moreover \.{\\tracingnesting} is positive we want to give a
    warning message (with the same complications as above).

*/

void if_warning(void)
{
    /*tex Do we need a warning? */
    boolean w = false;
    int i = in_open;
    base_ptr = input_ptr;
    /*tex Store current state. */
    input_stack[base_ptr] = cur_input;
    while (if_stack[i] == cond_ptr) {
        /*tex Set variable |w| to. */
        if (tracing_nesting_par > 0) {
            while ((input_stack[base_ptr].state_field == token_list) || (input_stack[base_ptr].index_field > i))
                decr(base_ptr);
            if (input_stack[base_ptr].name_field > 17)
                w = true;
        }
        if_stack[i] = vlink(cond_ptr);
        decr(i);
    }
    if (w) {
        tprint_nl("Warning: end of ");
        print_cmd_chr(if_test_cmd, cur_if);
        print_if_line(if_line);
        tprint(" of a different file");
        print_ln();
        if (tracing_nesting_par > 1)
            show_context();
        if (history == spotless)
            history = warning_issued;
    }
}

/*tex

    Conversely, the |file_warning| procedure is invoked when a file ends and some
    groups entered or conditionals started while reading from that file are still
    incomplete.

*/

void file_warning(void)
{
    /*tex saved value of |save_ptr| or |cond_ptr| */
    halfword p = save_ptr;
    /*tex saved value of |cur_level| or |if_limit| */
    int l = cur_level;
    /*tex saved value of |cur_group| or |cur_if| */
    int c = cur_group;
    /*tex saved value of |if_line| */
    int i;
    save_ptr = cur_boundary;
    while (grp_stack[in_open] != save_ptr) {
        decr(cur_level);
        tprint_nl("Warning: end of file when ");
        print_group(true);
        tprint(" is incomplete");
        cur_group = save_level(save_ptr);
        save_ptr = save_value(save_ptr);
    }
    save_ptr = p;
    cur_level = (quarterword) l;
    /*tex Restore old values. */
    cur_group = (group_code) c;
    p = cond_ptr;
    l = if_limit;
    c = cur_if;
    i = if_line;
    while (if_stack[in_open] != cond_ptr) {
        tprint_nl("Warning: end of file when ");
        print_cmd_chr(if_test_cmd, cur_if);
        if (if_limit == fi_code)
            tprint_esc("else");
        print_if_line(if_line);
        tprint(" is incomplete");
        if_line = if_line_field(cond_ptr);
        cur_if = if_limit_subtype(cond_ptr);
        if_limit = if_limit_type(cond_ptr);
        cond_ptr = vlink(cond_ptr);
    }
    /*tex restore old values */
    cond_ptr = p;
    if_limit = l;
    cur_if = c;
    if_line = i;
    print_ln();
    if (tracing_nesting_par > 1)
        show_context();
    if (history == spotless)
        history = warning_issued;
}

/*tex The |par_fill_skip| glue node of the new paragraph. */

halfword last_line_fill;

/*tex

    The lua interface needs some extra functions. The functions themselves are
    quite boring, but they are handy because otherwise this internal stuff has to
    be accessed from C directly, where lots of the defines are not available.

*/

#define get_tex_dimen_register(j) dimen(j)
#define get_tex_skip_register(j) skip(j)
#define get_tex_mu_skip_register(j) mu_skip(j)
#define get_tex_count_register(j) count(j)
#define get_tex_attribute_register(j) attribute(j)
#define get_tex_box_register(j) box(j)

/*tex These can now be macros (todo). */

int get_tex_extension_count_register(int i)
{
    return (int) int_par(backend_int_base-int_base+i);
}

void set_tex_extension_count_register(int i, int d)
{
    int_par(backend_int_base-int_base+i) = d;
}

int get_tex_extension_dimen_register(int i)
{
    return (int) dimen_par(backend_dimen_base-dimen_base+i);
}

void set_tex_extension_dimen_register(int i, int d)
{
    dimen_par(backend_dimen_base-dimen_base+i) = d;
}

int get_tex_extension_toks_register(int i)
{
    return equiv(backend_toks_base+i);
}

int set_tex_dimen_register(int j, scaled v)
{
    int a;
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    word_define(j + scaled_base, v);
    return 0;
}

int set_tex_skip_register(int j, halfword v)
{
    int a;
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    if (type(v) != glue_spec_node)
        return 1;
    word_define(j + skip_base, v);
    return 0;
}

int set_tex_mu_skip_register(int j, halfword v)
{
    int a;
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    if (type(v) != glue_spec_node)
        return 1;
    word_define(j + mu_skip_base, v);
    return 0;
}

int set_tex_count_register(int j, scaled v)
{
    int a;
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    word_define(j + count_base, v);
    return 0;
}

int set_tex_box_register(int j, scaled v)
{
    int a;
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    define(j + box_base, box_ref_cmd, v);
    return 0;
}

int set_tex_attribute_register(int j, scaled v)
{
    int a;
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    if (j > max_used_attr)
        max_used_attr = j;
    attr_list_cache = cache_disabled;
    word_define(j + attribute_base, v);
    return 0;
}

int get_tex_toks_register(int j)
{
    str_number s = get_nullstr();
    if (toks(j) != null) {
        s = tokens_to_string(toks(j));
    }
    return s;
}

int set_tex_toks_register(int j, lstring s)
{
    int a;
    halfword ref = get_avail();
    (void) str_toks(s);
    set_token_ref_count(ref, 0);
    set_token_link(ref, token_link(temp_token_head));
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    define(j + toks_base, call_cmd, ref);
    return 0;
}

int scan_tex_toks_register(int j, int c, lstring s)
{
    int a;
    halfword ref = get_avail();
    (void) str_scan_toks(c,s);
    set_token_ref_count(ref, 0);
    set_token_link(ref, token_link(temp_token_head));
    if (global_defs_par > 0)
        a = 4;
    else
        a = 0;
    define(j + toks_base, call_cmd, ref);
    return 0;
}

scaled get_tex_box_width(int j)
{
    halfword q = box(j);
    if (q != null)
        return width(q);
    return 0;
}

int set_tex_box_width(int j, scaled v)
{
    halfword q = box(j);
    if (q == null)
        return 1;
    width(q) = v;
    return 0;
}

scaled get_tex_box_height(int j)
{
    halfword q = box(j);
    if (q != null)
        return height(q);
    return 0;
}

int set_tex_box_height(int j, scaled v)
{
    halfword q = box(j);
    if (q == null)
        return 1;
    height(q) = v;
    return 0;
}

scaled get_tex_box_depth(int j)
{
    halfword q = box(j);
    if (q != null)
        return depth(q);
    return 0;
}

int set_tex_box_depth(int j, scaled v)
{
    halfword q = box(j);
    if (q == null)
        return 1;
    depth(q) = v;
    return 0;
}

/*tex

    This section is devoted to the {\sl Synchronize \TeX nology} - or simply {\sl
    Sync\TeX} - used to synchronize between input and output. This section
    explains how synchronization basics are implemented. Before we enter into
    more technical details, let us recall in a few words what is synchronization.

    \TeX\ typesetting system clearly separates the input and the output material,
    and synchronization will provide a new link between both that can help text
    editors and viewers to work together. More precisely, forwards
    synchronization is the ability, given a location in the input source file, to
    find what is the corresponding place in the output. Backwards synchronization
    just performs the opposite: given a location in the output, retrieve the
    corresponding material in the input source file.

    For better code management and maintainance, we adopt a naming convention.
    Throughout this program, code related to the {\sl Synchronize \TeX nology} is
    tagged with the ``{\sl synctex}'' key word. Any code extract where {\sl
    Sync\TeX} plays its part, either explicitly or implicitly, (should) contain
    the string ``{\sl synctex}''. This naming convention also holds for external
    files. Moreover, all the code related to {\sl Sync\TeX} is gathered in this
    section, except the definitions.

    Enabling synchronization should be performed from the command line,
    |synctexoption| is used for that purpose. This global integer variable is
    declared here but it is not used here. This is just a placeholder where the
    command line controller will put the {\sl Sync\TeX} related options, and the
    {\sl Sync\TeX} controller will read them.

*/

int synctexoption;

/*tex

    A convenient primitive is provided: \.{\\synctex=1} in the input source file
    enables synchronization whereas \.{\\synctex=0} disables it. Its memory
    address is |synctex_code|. It is initialized by the {\sl Sync\TeX} controller
    to the command-line option if given. The controller may filter some reserved
    bits.

    In order to give the {\sl Sync\TeX} controller read and write access to the
    contents of the \.{\\synctex} primitive, we declare |synctexoffset|, such
    that |mem[synctexoffset]| and \.{\\synctex} correspond to the same memory
    storage. |synctexoffset| is initialized to the correct value when quite
    everything is initialized.

*/

/*tex Holds the true value of |synctex_code|: */

int synctexoffset;

/*tex

    Synchronization is achieved with the help of an auxiliary file named `\.{{\sl
    jobname}.synctex}' ({\sl jobname} is the contents of the \.{\\jobname}
    macro), where a {\sl Sync\TeX} controller implemented in the external
    |synctex.c| file will store geometrical information. This {\sl Sync\TeX}
    controller will take care of every technical details concerning the {\sl
    Sync\TeX} file, we will only focus on the messages the controller will
    receive from the \TeX\ program.

    The most accurate synchronization information should allow to map any
    character of the input source file to the corresponding location in the
    output, if relevant. Ideally, the synchronization information of the input
    material consists of the file name, the line and column numbers of every
    character. The synchronization information in the output is simply the page
    number and either point coordinates, or box dimensions and position. The
    problem is that the mapping between these informations is only known at ship
    out time, which means that we must keep track of the input synchronization
    information until the pages ship out.

    As \TeX\ only knows about file names and line numbers, but forgets the column
    numbers, we only consider a restricted input synchronization information
    called {\sl Sync\TeX\ information}. It consists of a unique file name
    identifier, the {\sl Sync\TeX\ file tag}, and the line number.

    Keeping track of such information, should be different whether characters or
    nodes are involved. Actually, only certain nodes are involved in {\sl
    Sync\TeX}, we call them {\sl synchronized nodes}. Synchronized nodes store
    the {\sl Sync\TeX} information in their last two words: the first one
    contains a {\sl Sync\TeX\ file tag} uniquely identifying the input file, and
    the second one contains the current line number, as returned by the
    \.{\\inputlineno} primitive. The |synctex_field_size| macro contains the
    necessary size to store the {\sl Sync\TeX} information in a node.

    When declaring the size of a new node, it is recommanded to use the following
    convention: if the node is synchronized, use a definition similar to
    |my_synchronized_node_size|={\sl xxx}+|synctex_field_size|. Moreover, one
    should expect that the {\sl Sync\TeX} information is always stored in the
    last two words of a synchronized node.

    By default, every node with a sufficiently big size is initialized at
    creation time in the |get_node| routine with the current {\sl Sync\TeX}
    information, whether or not the node is synchronized. One purpose is to set
    this information very early in order to minimize code dependencies, including
    forthcoming extensions. Another purpose is to avoid the assumption that every
    node type has a dedicated getter, where initialization should take place.
    Actually, it appears that some nodes are created using directly the
    |get_node| routine and not the dedicated constructor. And finally,
    initializing the node at only one place is less error prone.

    Instead of storing the input file name, it is better to store just an
    identifier. Each time \TeX\ opens a new file, it notifies the {\sl Sync\TeX}
    controller with a |synctex_start_input| message. This controller will create
    a new {\sl Sync\TeX} file tag and will update the current input state record
    accordingly. If the input comes from the terminal or a pseudo file, the
    |synctex_tag| is set to 0. It results in automatically disabling
    synchronization for material input from the terminal or pseudo files.

    Synchronized nodes are boxes, math, kern and glue nodes. Other nodes should
    be synchronized too, in particular math noads. \TeX\ assumes that math, kern
    and glue nodes have the same size, this is why both are synchronized. {\sl In
    fine}, only horizontal lists are really used in {\sl Sync\TeX}, but all box
    nodes are considered the same with respect to synchronization, because a box
    node type is allowed to change at execution time.

    {\em Nota Bene:} The {\sl Sync\TeX} code is very close to the memory model.
    It is not connected to any other part of the code, except for memory
    management. It is possible to neutralize the {\sl Sync\TeX} code rather
    simply. The first step is to define a null |synctex_field_size|. The second
    step is to comment out the code in ``Initialize bigger nodes...'' and every
    ``Copy ... {\sl Sync\TeX} information''. The last step will be to comment out
    the |synctex_tag_field| related code in the definition of |synctex_tag| and
    the various ``Prepare ... {\sl Sync\TeX} information''. Then all the
    remaining code should be just harmless. The resulting program would behave
    exactly the same as if absolutely no {\sl Sync\TeX} related code was there,
    including memory management. Of course, all this assumes that {\sl Sync\TeX}
    is turned off from the command line.

    Here are extra variables for Web2c. (This numbering of the system-dependent
    section allows easy integration of Web2c and e-\TeX, etc.)

*/

/*tex where the filename to switch to starts */

pool_pointer edit_name_start;

/*tex what line to start editing at */

int edit_name_length, edit_line;

/*tex whether |more_name| returns false for space */

boolean stop_at_space;

/*tex

    The |edit_name_start| will be set to point into |str_pool| somewhere after
    its beginning if \TeX\ is supposed to switch to an editor on exit.

*/

int shellenabledp;
int restrictedshell;
char *output_comment;

/*tex

    Are we printing extra info as we read the format file?

*/

boolean debug_format_file;

void wrapup_leader(halfword p)
{
    /*tex Do some work that has been queued up for \.{\\write}. */
    if (!doing_leaders) {
        int j = write_stream(p);
        if (subtype(p) == write_node) {
            write_out(p);
        } else if (subtype(p) == close_node) {
            close_write_file(j);
        } else if (valid_write_file(j)) {
            char *fn;
            close_write_file(j);
            cur_name = open_name(p);
            cur_area = open_area(p);
            cur_ext = open_ext(p);
            if (cur_ext == get_nullstr())
                cur_ext = maketexstring(".tex");
            fn = pack_file_name(cur_name, cur_area, cur_ext);
            while (! open_write_file(j,fn)) {
                fn = prompt_file_name("output file name", ".tex");
            }
        }
    }
}
