/*

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"

/*tex

    Only a dozen or so command codes |>max_command| can possibly be returned by
    |get_next|; in increasing order, they are |undefined_cs|, |expand_after|,
    |no_expand|, |input|, |if_test|, |fi_or_else|, |cs_name|, |convert|, |the|,
    |top_bot_mark|, |call|, |long_call|, |outer_call|, |long_outer_call|, and
    |end_template|.

    Sometimes, recursive calls to the following |expand| routine may cause
    exhaustion of the run-time calling stack, resulting in forced execution stops
    by the operating system. To diminish the chance of this happening, a counter
    is used to keep track of the recursion depth, in conjunction with a constant
    called |expand_depth|.

    Note that this does not catch all possible infinite recursion loops, just the
    ones that exhaust the application calling stack. The actual maximum value of
    |expand_depth| is outside of our control, but the initial setting of |100|
    should be enough to prevent problems.

*/

static int expand_depth_count = 0;

/*tex

    The |expand| subroutine is used when |cur_cmd>max_command|. It removes a
    ``call'' or a conditional or one of the other special operations just listed.
    It follows that |expand| might invoke itself recursively. In all cases,
    |expand| destroys the current token, but it sets things up so that the next
    |get_next| will deliver the appropriate next token. The value of |cur_tok|
    need not be known when |expand| is called.

    Since several of the basic scanning routines communicate via global
    variables, their values are saved as local variables of |expand| so that
    recursive calls don't invalidate them.

*/

int is_in_csname = 0;

void expand(void)
{
    /*tex token that is being ``expanded after'' */
    halfword t;
    /*tex for list manipulation */
    halfword p;
    /*tex for a local token list pointer */
    halfword cur_ptr;
    /*tex to save the global quantity |cur_val| */
    int cv_backup;
    /*tex to save |cur_val_level|, etc. */
    int cvl_backup, radix_backup, co_backup;
    /*tex to save |link(backup_head)| */
    halfword backup_backup;
    /*tex temporary storage of |scanner_status| */
    int save_scanner_status;
    incr(expand_depth_count);
    if (expand_depth_count >= expand_depth)
        overflow("expansion depth", (unsigned) expand_depth);
    cv_backup = cur_val;
    cvl_backup = cur_val_level;
    radix_backup = radix;
    co_backup = cur_order;
    backup_backup = token_link(backup_head);
  RESWITCH:
    if (cur_cmd < call_cmd) {
        /*tex Expand a nonmacro. */
        if (tracing_commands_par > 1)
            show_cur_cmd_chr();
        switch (cur_cmd) {
            case top_bot_mark_cmd:
                /*tex Insert the appropriate mark text into the scanner. */
                t = cur_chr % marks_code;
                if (cur_chr >= marks_code)
                    scan_mark_num();
                else
                    cur_val = 0;
                switch (t) {
                    case first_mark_code:
                        cur_ptr = first_mark(cur_val);
                        break;
                    case bot_mark_code:
                        cur_ptr = bot_mark(cur_val);
                        break;
                    case split_first_mark_code:
                        cur_ptr = split_first_mark(cur_val);
                        break;
                    case split_bot_mark_code:
                        cur_ptr = split_bot_mark(cur_val);
                        break;
                    default:
                        cur_ptr = top_mark(cur_val);
                        break;
                }
                if (cur_ptr != null)
                    begin_token_list(cur_ptr, mark_text);
                break;
            case expand_after_cmd:
                if (cur_chr == 0) {
                    /*tex

                        Expand the token after the next token. It takes only a
                        little shuffling to do what \TeX\ calls
                        \.{\\expandafter}.

                    */
                    get_token();
                    t = cur_tok;
                    get_token();
                    if (cur_cmd > max_command_cmd)
                        expand();
                    else
                        back_input();
                    cur_tok = t;
                    back_input();
                } else {
                    /*tex

                        Negate a boolean conditional and |goto reswitch|. The
                        result of a boolean condition is reversed when the
                        conditional is preceded by \.{\\unless}.

                    */
                    get_token();
                    if ((cur_cmd == if_test_cmd) && (cur_chr != if_case_code)) {
                        cur_chr = cur_chr + unless_code;
                        goto RESWITCH;
                    }
                    print_err("You can't use `\\unless' before `");
                    print_cmd_chr((quarterword) cur_cmd, cur_chr);
                    print_char('\'');
                    help1("Continue, and I'll forget that it ever happened.");
                    back_error();
                }
                break;
            case no_expand_cmd:
                if (cur_chr == 0) {
                    /*tex

                        Suppress expansion of the next token. The implementation
                        of \.{\\noexpand} is a bit trickier, because it is
                        necessary to insert a special `|dont_expand|' marker into
                        \TeX's reading mechanism. This special marker is
                        processed by |get_next|, but it does not slow down the
                        inner loop.

                        Since \.{\\outer} macros might arise here, we must also
                        clear the |scanner_status| temporarily.

                    */
                    save_scanner_status = scanner_status;
                    scanner_status = normal;
                    get_token();
                    scanner_status = save_scanner_status;
                    t = cur_tok;
                    back_input();
                    /*tex Now |start| and |loc| point to the backed-up token |t|. */
                    if (t >= cs_token_flag) {
                        p = get_avail();
                        set_token_info(p, cs_token_flag + frozen_dont_expand);
                        set_token_link(p, iloc);
                        istart = p;
                        iloc = p;
                    }

                } else {
                    /*tex

                        The \.{\\primitive} handling. If the primitive meaning of
                        the next token is an expandable command, it suffices to
                        replace the current token with the primitive one and
                        restart |expand|.

                        Otherwise, the token we just read has to be pushed back,
                        as well as a token matching the internal form of
                        \.{\\primitive}, that is sneaked in as an alternate form
                        of |ignore_spaces|.

                        An implementation problem surfaces: There really is no
                        |cur_cs| attached to the inserted primitive command, so
                        it is safer to set |cur_cs| to zero. |cur_tok| has a
                        similar problem. And for the non-expanded branch, simply
                        pushing back a token that matches the correct internal
                        command does not work, because that approach would not
                        survive roundtripping to a temporary file or even a token
                        list.

                        It would be smart to create |frozen_| versions of all the
                        primitives. Then, this problem would not happen, at the
                        expense of a few hundred extra control sequences.

                    */
                    save_scanner_status = scanner_status;
                    scanner_status = normal;
                    get_token();
                    scanner_status = save_scanner_status;
                    cur_cs = prim_lookup(cs_text(cur_cs));
                    if (cur_cs != undefined_primitive) {
                        t = get_prim_eq_type(cur_cs);
                        if (t > max_command_cmd) {
                            cur_cmd = t;
                            cur_chr = get_prim_equiv(cur_cs);
                            cur_tok = token_val(cur_cmd, cur_chr);
                            cur_cs = 0;
                            goto RESWITCH;
                        } else {
                            back_input();
                            /*tex  Now |loc| and |start| point to a one-item list. */
                            p = get_avail();
                            set_token_info(p, cs_token_flag + frozen_primitive);
                            set_token_link(p, iloc);
                            iloc = p;
                            istart = p;
                        }
                    } else if (suppress_primitive_error_par == 0) {
                        print_err("Missing primitive name");
                        help2(
                            "The control sequence marked <to be read again> does not",
                            "represent any known primitive."
                        );
                        back_error();
                    }
                }
                break;
            case cs_name_cmd:
                /*tex Manufacture a control sequence name. */
                if (cur_chr == 0) {
                    manufacture_csname(0);
                } else if (cur_chr == 1) {
                    inject_last_tested_cs();
                } else {
                    manufacture_csname(1);
                }
                break;
            case convert_cmd:
                conv_toks();
                break;
            case the_cmd:
                ins_the_toks();
                break;
            case if_test_cmd:
                /*tex An experiment. */
                if (cur_chr == if_condition_code) {
                    break;
                }
                /*tex End of experiment. */
                conditional();
                break;
            case fi_or_else_cmd:
                /*tex

                    Terminate the current conditional and skip to \.{\\fi} The
                    processing of conditionals is complete except for the
                    following code, which is actually part of |expand|. It comes
                    into play when \.{\\or}, \.{\\else}, or \.{\\fi} is scanned.

                */
                if (tracing_ifs_par > 0)
                    if (tracing_commands_par <= 1)
                        show_cur_cmd_chr();
                if (cur_chr > if_limit) {
                    if (if_limit == if_code) {
                        /*tex Condition is not yet evaluated. */
                        insert_relax();
                    } else {
                        print_err("Extra ");
                        print_cmd_chr(fi_or_else_cmd, cur_chr);
                        help1("I'm ignoring this; it doesn't match any \\if.");
                        error();
                    }
                } else {
                    while (cur_chr != fi_code) {
                        /*tex Skip to \.{\\fi}. */
                        pass_text();
                    }
                    pop_condition_stack();
                }
                break;
            case input_cmd:
                /*tex Initiate or terminate input from a file */
                if (cur_chr == 1)
                    force_eof = true;
                else if (cur_chr == 2)
                    pseudo_start();
                else if (cur_chr == 3) {
                    pseudo_start();
                    iname = 19;
                } else if (name_in_progress)
                    insert_relax();
                else
                    start_input();
                break;
            case lua_expandable_call_cmd:
                if (cur_chr <= 0) {
                    normal_error("luacall", "invalid number");
                } else {
                    str_number u = save_cur_string();
                    luacstrings = 0;
                    luafunctioncall(cur_chr);
                    restore_cur_string(u);
                    if (luacstrings > 0)
                        lua_string_start();
                }
                break;
            case lua_local_call_cmd:
                if (cur_chr <= 0) {
                    normal_error("luacall", "invalid number");
                } else {
                    str_number u = save_cur_string();
                    luacstrings = 0;
                    lua_rawgeti(Luas, LUA_REGISTRYINDEX, cur_chr);
                    lua_call(Luas,0,0);
                    restore_cur_string(u);
                    if (luacstrings > 0)
                        lua_string_start();
                }
                break;
            case variable_cmd:
                do_variable();
                break;
            case feedback_cmd:
                do_feedback();
                break;
            default:
                /*tex Complain about an undefined macro */
                print_err("Undefined control sequence");
                help5(
                    "The control sequence at the end of the top line",
                    "of your error message was never \\def'ed. If you have",
                    "misspelled it (e.g., `\\hobx'), type `I' and the correct",
                    "spelling (e.g., `I\\hbox'). Otherwise just continue,",
                    "and I'll forget about whatever was undefined."
                );
                error();
                break;
        }
    } else if (cur_cmd < end_template_cmd) {
        macro_call();
    } else {
        /*tex

            Insert a token containing |frozen_endv|. An |end_template| command is
            effectively changed to an |endv| command by the following code. (The
            reason for this is discussed below; the |frozen_end_template| at the
            end of the template has passed the |check_outer_validity| test, so
            its mission of error detection has been accomplished.)

        */
        cur_tok = cs_token_flag + frozen_endv;
        back_input();
    }
    cur_val = cv_backup;
    cur_val_level = cvl_backup;
    radix = radix_backup;
    cur_order = co_backup;
    set_token_link(backup_head, backup_backup);
    decr(expand_depth_count);
}

void complain_missing_csname(void)
{
    print_err("Missing \\endcsname inserted");
    help2(
        "The control sequence marked <to be read again> should",
        "not appear between \\csname and \\endcsname."
    );
    back_error();
}

void manufacture_csname(boolean use)
{
    halfword p, q, r;
    lstring *ss;
    r = get_avail();
    p = r;
    is_in_csname += 1;
    do {
        get_x_token();
        if (cur_cs == 0)
            store_new_token(cur_tok);
    } while (cur_cs == 0);
    if (cur_cmd != end_cs_name_cmd) {
        /*tex Complain about missing \.{\\endcsname}. */
        complain_missing_csname();
    }
    /*tex Look up the characters of list |r| in the hash table, and set |cur_cs|. */
    ss = tokenlist_to_lstring(r, true);
    is_in_csname -= 1;
    if (use) {
        if (ss->l > 0) {
            cur_cs = string_lookup((char *) ss->s, ss->l);
        } else {
            cur_cs = null_cs;
        }
        last_cs_name = cur_cs ;
        free_lstring(ss);
        flush_list(r);
        if (cur_cs == null_cs) {
            /*tex skip */
        } else if (eq_type(cur_cs) == undefined_cs_cmd) {
            /*tex skip */
        } else {
            cur_tok = cur_cs + cs_token_flag;
            back_input();
        }
    } else {
        if (ss->l > 0) {
            no_new_control_sequence = false;
            cur_cs = string_lookup((char *) ss->s, ss->l);
            no_new_control_sequence = true;
        } else {
            /*tex the list is empty */
            cur_cs = null_cs;
        }
        last_cs_name = cur_cs ;
        free_lstring(ss);
        flush_list(r);
        if (eq_type(cur_cs) == undefined_cs_cmd) {
            /*tex The |save_stack| might change! */
            eq_define(cur_cs, relax_cmd, too_big_char);
        };
        /*tex The control sequence will now match \.{\\relax} */
        cur_tok = cur_cs + cs_token_flag;
        back_input();
    }
}

void inject_last_tested_cs(void)
{
    if (last_cs_name != null_cs) {
        cur_cs = last_cs_name;
        cur_tok = last_cs_name + cs_token_flag;
        back_input();
    }
}

/*tex

    Sometimes the expansion looks too far ahead, so we want to insert a harmless
    \.{\\relax} into the user's input.

*/

void insert_relax(void)
{
    cur_tok = cs_token_flag + cur_cs;
    back_input();
    cur_tok = cs_token_flag + frozen_relax;
    back_input();
    token_type = inserted;
}


/*tex

    Here is a recursive procedure that is \TeX's usual way to get the next token
    of input. It has been slightly optimized to take account of common cases.

*/

void get_x_token(void)
{
    /*tex This code sets |cur_cmd|, |cur_chr|, |cur_tok|, and expands macros. */
  RESTART:
    get_next();
    if (cur_cmd <= max_command_cmd)
        goto DONE;
    if (cur_cmd >= call_cmd) {
        if (cur_cmd < end_template_cmd) {
            macro_call();
        } else {
            cur_cs = frozen_endv;
            cur_cmd = endv_cmd;
            /*tex Now |cur_chr=null_list|. */
            goto DONE;
        }
    } else {
        expand();
    }
    goto RESTART;
  DONE:
    if (cur_cs == 0)
        cur_tok = token_val(cur_cmd, cur_chr);
    else
        cur_tok = cs_token_flag + cur_cs;
}

/*tex

    The |get_x_token| procedure is equivalent to two consecutive procedure calls:
    |get_next; x_token|. It's |get_x_token| without the initial |get_next|.

*/

void x_token(void)
{
    while (cur_cmd > max_command_cmd) {
        expand();
        get_next();
   }
    if (cur_cs == 0)
        cur_tok = token_val(cur_cmd, cur_chr);
    else
        cur_tok = cs_token_flag + cur_cs;
}

/*tex

    A control sequence that has been \.{\\def}'ed by the user is expanded by
    \TeX's |macro_call| procedure.

    Before we get into the details of |macro_call|, however, let's consider the
    treatment of primitives like \.{\\topmark}, since they are essentially macros
    without parameters. The token lists for such marks are kept in five global
    arrays of pointers; we refer to the individual entries of these arrays by
    symbolic macros |top_mark|, etc. The value of |top_mark(x)|, etc. is either
    |null| or a pointer to the reference count of a token list.

    The variable |biggest_used_mark| is an aid to try and keep the code somehwat
    efficient without too much extra work: it registers the highest mark class
    ever instantiated by the user, so the loops in |fire_up| and |vsplit| do not
    have to traverse the full range |0..biggest_mark|.

*/

halfword top_marks_array[(biggest_mark + 1)];
halfword first_marks_array[(biggest_mark + 1)];
halfword bot_marks_array[(biggest_mark + 1)];
halfword split_first_marks_array[(biggest_mark + 1)];
halfword split_bot_marks_array[(biggest_mark + 1)];
halfword biggest_used_mark;

void initialize_marks(void)
{
    int i;
    biggest_used_mark = 0;
    for (i = 0; i <= biggest_mark; i++) {
        top_mark(i) = null;
        first_mark(i) = null;
        bot_mark(i) = null;
        split_first_mark(i) = null;
        split_bot_mark(i) = null;
    }
}

/*tex

    Now let's consider |macro_call| itself, which is invoked when \TeX\ is
    scanning a control sequence whose |cur_cmd| is either |call|, |long_call|,
    |outer_call|, or |long_outer_call|. The control sequence definition appears
    in the token list whose reference count is in location |cur_chr| of |mem|.

    The global variable |long_state| will be set to |call| or to |long_call|,
    depending on whether or not the control sequence disallows \.{\\par} in its
    parameters. The |get_next| routine will set |long_state| to |outer_call| and
    emit \.{\\par}, if a file ends or if an \.{\\outer} control sequence occurs
    in the midst of an argument.

*/

/*tex Governs the acceptance of \.{\\par}: */

int long_state;

/*tex

    The parameters, if any, must be scanned before the macro is expanded.
    Parameters are token lists without reference counts. They are placed on an
    auxiliary stack called |pstack| while they are being scanned, since the
    |param_stack| may be losing entries during the matching process. (Note that
    |param_stack| can't be gaining entries, since |macro_call| is the only
    routine that puts anything onto |param_stack|, and it is not recursive.)

*/

/*tex The arguments supplied to a macro: */

halfword pstack[9];

/*tex

    After parameter scanning is complete, the parameters are moved to the
    |param_stack|. Then the macro body is fed to the scanner; in other words,
    |macro_call| places the defined text of the control sequence at the top of\/
    \TeX's input stack, so that |get_next| will proceed to read it next.

    The global variable |cur_cs| contains the |eqtb| address of the control
    sequence being expanded, when |macro_call| begins. If this control sequence
    has not been declared \.{\\long}, i.e., if its command code in the |eq_type|
    field is not |long_call| or |long_outer_call|, its parameters are not allowed
    to contain the control sequence \.{\\par}. If an illegal \.{\\par} appears,
    the macro call is aborted, and the \.{\\par} will be rescanned.

*/

/*tex This invokes a user-defined control sequence. */

void macro_call(void)
{
    /*tex current node in the macro's token list */
    halfword r;
    /*tex current node in parameter token list being built */
    halfword p = null;
    /*tex new node being put into the token list */
    halfword q;
    /*tex backup pointer for parameter matching */
    halfword s;
    /*tex cycle pointer for backup recovery */
    halfword t;
    /*tex auxiliary pointers for backup recovery */
    halfword u, v;
    /*tex one step before the last |right_brace| token */
    halfword rbrace_ptr = null;
    /*tex the number of parameters scanned */
    int n = 0;
    /*tex unmatched left braces in current parameter */
    halfword unbalance;
    /*tex the number of tokens or groups (usually) */
    halfword m = 0;
    /*tex start of the token list */
    halfword ref_count;
    /*tex |scanner_status| upon entry */
    int save_scanner_status = scanner_status;
    /*tex |warning_index| upon entry */
    halfword save_warning_index = warning_index;
    /*tex character used in parameter */
    int match_chr = 0;
    warning_index = cur_cs;
    ref_count = cur_chr;
    r = token_link(ref_count);
    if (tracing_macros_par > 0) {
        /*tex Show the text of the macro being expanded. */
        begin_diagnostic();
        print_input_level();
     // print_ln();
        print_cs(warning_index);
        token_show(ref_count);
        end_diagnostic(false);
    }
    if (token_info(r) == protected_token)
        r = token_link(r);
    if (token_info(r) != end_match_token) {
        /*tex

            Scan the parameters and make |link(r)| point to the macro body; but
            |return| if an illegal \.{\\par} is detected.

            At this point, the reader will find it advisable to review the
            explanation of token list format that was presented earlier, since
            many aspects of that format are of importance chiefly in the
            |macro_call| routine.

            The token list might begin with a string of compulsory tokens before
            the first |match| or |end_match|. In that case the macro name is
            supposed to be followed by those tokens; the following program will
            set |s=null| to represent this restriction. Otherwise |s| will be set
            to the first token of a string that will delimit the next parameter.

        */
        scanner_status = matching;
        unbalance = 0;
        long_state = eq_type(cur_cs);
        if (long_state >= outer_call_cmd)
            long_state = long_state - 2;
        do {
            set_token_link(temp_token_head, null);
            if ((token_info(r) >= end_match_token)
                || (token_info(r) < match_token)) {
                s = null;
            } else {
                match_chr = token_info(r) - match_token;
                s = token_link(r);
                r = s;
                p = temp_token_head;
                m = 0;
            }
            /*tex

                Scan a parameter until its delimiter string has been found; or,
                if |s=null|, simply scan the delimiter string.

                If |info(r)| is a |match| or |end_match| command, it cannot be
                equal to any token found by |get_token|. Therefore an undelimited
                parameter---i.e., a |match| that is immediately followed by
                |match| or |end_match|---will always fail the test
                `|cur_tok=info(r)|' in the following algorithm.

            */
          CONTINUE:
            /*tex Set |cur_tok| to the next token of input: */
            get_token();
            if (cur_tok == token_info(r)) {
                /*tex

                    Advance |r|; |goto found| if the parameter delimiter has been
                    fully matched, otherwise |goto continue|.

                    A slightly subtle point arises here: When the parameter
                    delimiter ends with `\.{\#\{}', the token list will have a
                    left brace both before and after the |end_match|\kern-.4pt.
                    Only one of these should affect the |align_state|, but both
                    will be scanned, so we must make a correction.

                */
                r = token_link(r);
                if ((token_info(r) >= match_token)
                    && (token_info(r) <= end_match_token)) {
                    if (cur_tok < left_brace_limit)
                        decr(align_state);
                    goto FOUND;
                } else {
                    goto CONTINUE;
                }

            }
            /*tex

                Contribute the recently matched tokens to the current parameter,
                and |goto continue| if a partial match is still in effect; but
                abort if |s=null|.

                When the following code becomes active, we have matched tokens
                from |s| to the predecessor of |r|, and we have found that
                |cur_tok<>info(r)|. An interesting situation now presents itself:
                If the parameter is to be delimited by a string such as `\.{ab}',
                and if we have scanned `\.{aa}', we want to contribute one `\.a'
                to the current parameter and resume looking for a `\.b'. The
                program must account for such partial matches and for others that
                can be quite complex. But most of the time we have |s=r| and
                nothing needs to be done.

                Incidentally, it is possible for \.{\\par} tokens to sneak in to
                certain parameters of non-\.{\\long} macros. For example,
                consider a case like `\.{\\def\\a\#1\\par!\{...\}}' where the
                first \.{\\par} is not followed by an exclamation point. In such
                situations it does not seem appropriate to prohibit the
                \.{\\par}, so \TeX\ keeps quiet about this bending of the rules.

            */
            if (s != r) {
                if (s == null) {
                    /*tex Report an improper use of the macro and abort. */
                    print_err("Use of ");
                    sprint_cs(warning_index);
                    tprint(" doesn't match its definition");
                    help4(
                        "If you say, e.g., `\\def\\a1{...}', then you must always",
                        "put `1' after `\\a', since control sequence names are",
                        "made up of letters only. The macro here has not been",
                        "followed by the required stuff, so I'm ignoring it."
                    );
                    error();
                    goto EXIT;

                } else {
                    t = s;
                    do {
                        store_new_token(token_info(t));
                        incr(m);
                        u = token_link(t);
                        v = s;
                        while (1) {
                            if (u == r) {
                                if (cur_tok != token_info(v)) {
                                    goto DONE;
                                } else {
                                    r = token_link(v);
                                    goto CONTINUE;
                                }
                            }
                            if (token_info(u) != token_info(v))
                                goto DONE;
                            u = token_link(u);
                            v = token_link(v);
                        }
                      DONE:
                        t = token_link(t);
                    } while (t != r);
                    r = s;
                    /*tex At this point, no tokens are recently matched. */
                }
            }
            if (cur_tok == par_token)
                if (long_state != long_call_cmd)
                    if (!suppress_long_error_par) {
                        goto RUNAWAY;
                    }
            if (cur_tok < right_brace_limit) {
                if (cur_tok < left_brace_limit) {
                    /*tex Contribute an entire group to the current parameter. */
                    unbalance = 1;
                    while (1) {
                        fast_store_new_token(cur_tok);
                        get_token();
                        if (cur_tok == par_token) {
                            if (long_state != long_call_cmd) {
                                if (!suppress_long_error_par) {
                                    goto RUNAWAY;

                                }
                            }
                        }
                        if (cur_tok < right_brace_limit) {
                            if (cur_tok < left_brace_limit) {
                                incr(unbalance);
                            } else {
                                decr(unbalance);
                                if (unbalance == 0)
                                    break;
                            }
                        }
                    }
                    rbrace_ptr = p;
                    store_new_token(cur_tok);
                } else {
                    /*tex Report an extra right brace and |goto continue|. */
                    back_input();
                    print_err("Argument of ");
                    sprint_cs(warning_index);
                    tprint(" has an extra }");
                    help6(
                        "I've run across a `}' that doesn't seem to match anything.",
                        "For example, `\\def\\a#1{...}' and `\\a}' would produce",
                        "this error. If you simply proceed now, the `\\par' that",
                        "I've just inserted will cause me to report a runaway",
                        "argument that might be the root of the problem. But if",
                        "your `}' was spurious, just type `2' and it will go away."
                    );
                    incr(align_state);
                    long_state = call_cmd;
                    cur_tok = par_token;
                    ins_error();
                    goto CONTINUE;
                    /*tex A white lie; the \.{\\par} won't always trigger a runaway. */
                }
            } else {
                /*tex

                    Store the current token, but |goto continue| if it is a blank
                    space that would become an undelimited parameter.

                */
                if (cur_tok == space_token && token_info(r) <= end_match_token && token_info(r) >= match_token)
                    goto CONTINUE;
                store_new_token(cur_tok);
            }
            incr(m);
            if (token_info(r) > end_match_token)
                goto CONTINUE;
            if (token_info(r) < match_token)
                goto CONTINUE;
          FOUND:
            if (s != null) {
                /*

                    Tidy up the parameter just scanned, and tuck it away. If the
                    parameter consists of a single group enclosed in braces, we
                    must strip off the enclosing braces. That's why |rbrace_ptr|
                    was introduced.

                */
                if ((m == 1) && (token_info(p) < right_brace_limit)
                    && (p != temp_token_head)) {
                    set_token_link(rbrace_ptr, null);
                    free_avail(p);
                    p = token_link(temp_token_head);
                    pstack[n] = token_link(p);
                    free_avail(p);
                } else {
                    pstack[n] = token_link(temp_token_head);
                }
                incr(n);
                if (tracing_macros_par > 0) {
                    begin_diagnostic();
                    print_input_level();
                 // print_nl(match_chr);
                    print(match_chr);
                    print_int(n);
                    tprint("<-");
                    show_token_list(pstack[n - 1], null, 1000);
                    end_diagnostic(false);
                }
            }
            /*tex

                Now |info(r)| is a token whose command code is either |match| or
                |end_match|.

            */
        } while (token_info(r) != end_match_token);
    }
    /*tex

        Feed the macro body and its parameters to the scanner Before we put a new
        token list on the input stack, it is wise to clean off all token lists
        that have recently been depleted. Then a user macro that ends with a call
        to itself will not require unbounded stack space.

    */
    while ((istate == token_list) && (iloc == null) && (token_type != v_template)) {
        /*tex Conserve stack space. */
        end_token_list();
    }
    begin_token_list(ref_count, macro);
    iname = warning_index;
    iloc = token_link(r);
    if (n > 0) {
        if (param_ptr + n > max_param_stack) {
            max_param_stack = param_ptr + n;
            if (max_param_stack > param_size)
                overflow("parameter stack size", (unsigned) param_size);
        }
        for (m = 0; m <= n - 1; m++)
            param_stack[param_ptr + m] = pstack[m];
        param_ptr = param_ptr + n;
    }
    goto EXIT;
  RUNAWAY:
    /*tex

        Report a runaway argument and abort. If |long_state=outer_call|, a
        runaway argument has already been reported.

    */
    if (long_state == call_cmd) {
        runaway();
        print_err("Paragraph ended before ");
        sprint_cs(warning_index);
        tprint(" was complete");
        help3(
            "I suspect you've forgotten a `}', causing me to apply this",
            "control sequence to too much text. How can we recover?",
            "My plan is to forget the whole thing and hope for the best."
        );
        back_error();
    }
    pstack[n] = token_link(temp_token_head);
    align_state = align_state - unbalance;
    for (m = 0; m <= n; m++)
        flush_list(pstack[m]);
  EXIT:
    scanner_status = save_scanner_status;
    warning_index = save_warning_index;
}
