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+% texmath.w
+
+% Copyright 2008-2010 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/>.
+
+@ @c
+#include "ptexlib.h"
+
+static const char _svn_version[] =
+ "$Id: texmath.w 3587 2010-04-03 14:32:25Z taco $ "
+ "$URL: http://foundry.supelec.fr/svn/luatex/tags/beta-0.60.0/source/texk/web2c/luatexdir/tex/texmath.w $";
+
+@ @c
+#define mode cur_list.mode_field
+#define head cur_list.head_field
+#define tail cur_list.tail_field
+#define prev_graf cur_list.pg_field
+#define eTeX_aux cur_list.eTeX_aux_field
+#define delim_ptr eTeX_aux
+#define space_factor cur_list.space_factor_field
+#define incompleat_noad cur_list.incompleat_noad_field
+
+#define cur_fam int_par(cur_fam_code)
+#define text_direction int_par(text_direction_code)
+
+#define var_code 7
+
+@ TODO: not sure if this is the right order
+@c
+#define back_error(A,B) do { \
+ OK_to_interrupt=false; \
+ back_input(); \
+ OK_to_interrupt=true; \
+ tex_error(A,B); \
+ } while (0)
+
+@ @c
+int scan_math(pointer, int);
+pointer fin_mlist(pointer);
+
+#define pre_display_size dimen_par(pre_display_size_code)
+#define hsize dimen_par(hsize_code)
+#define display_width dimen_par(display_width_code)
+#define display_indent dimen_par(display_indent_code)
+#define math_surround dimen_par(math_surround_code)
+#define hang_indent dimen_par(hang_indent_code)
+#define hang_after int_par(hang_after_code)
+#define every_math equiv(every_math_loc)
+#define every_display equiv(every_display_loc)
+#define par_shape_ptr equiv(par_shape_loc)
+
+
+@ When \TeX\ reads a formula that is enclosed between \.\$'s, it constructs an
+{\sl mlist}, which is essentially a tree structure representing that
+formula. An mlist is a linear sequence of items, but we can regard it as
+a tree structure because mlists can appear within mlists. For example, many
+of the entries can be subscripted or superscripted, and such ``scripts''
+are mlists in their own right.
+
+An entire formula is parsed into such a tree before any of the actual
+typesetting is done, because the current style of type is usually not
+known until the formula has been fully scanned. For example, when the
+formula `\.{\$a+b \\over c+d\$}' is being read, there is no way to tell
+that `\.{a+b}' will be in script size until `\.{\\over}' has appeared.
+
+During the scanning process, each element of the mlist being built is
+classified as a relation, a binary operator, an open parenthesis, etc.,
+or as a construct like `\.{\\sqrt}' that must be built up. This classification
+appears in the mlist data structure.
+
+After a formula has been fully scanned, the mlist is converted to an hlist
+so that it can be incorporated into the surrounding text. This conversion is
+controlled by a recursive procedure that decides all of the appropriate
+styles by a ``top-down'' process starting at the outermost level and working
+in towards the subformulas. The formula is ultimately pasted together using
+combinations of horizontal and vertical boxes, with glue and penalty nodes
+inserted as necessary.
+
+An mlist is represented internally as a linked list consisting chiefly
+of ``noads'' (pronounced ``no-adds''), to distinguish them from the somewhat
+similar ``nodes'' in hlists and vlists. Certain kinds of ordinary nodes are
+allowed to appear in mlists together with the noads; \TeX\ tells the difference
+by means of the |type| field, since a noad's |type| is always greater than
+that of a node. An mlist does not contain character nodes, hlist nodes, vlist
+nodes, math nodes or unset nodes; in particular, each mlist item appears in the
+variable-size part of |mem|, so the |type| field is always present.
+
+Each noad is five or more words long. The first word contains the
+|type| and |subtype| and |link| fields that are already so familiar to
+us; the second contains the attribute list pointer, and the third,
+fourth an fifth words are called the noad's |nucleus|, |subscr|, and
+|supscr| fields. (This use of a combined attribute list is temporary.
+Eventually, each of fields need their own list)
+
+Consider, for example, the simple formula `\.{\$x\^2\$}', which would be
+parsed into an mlist containing a single element called an |ord_noad|.
+The |nucleus| of this noad is a representation of `\.x', the |subscr| is
+empty, and the |supscr| is a representation of `\.2'.
+
+The |nucleus|, |subscr|, and |supscr| fields are further broken into
+subfields. If |p| points to a noad, and if |q| is one of its principal
+fields (e.g., |q=subscr(p)|), |q=null| indicates a field with no value (the
+corresponding attribute of noad |p| is not present). Otherwise, there are
+several possibilities for the subfields, depending on the |type| of |q|.
+
+\yskip\hang|type(q)=math_char_node| means that |math_fam(q)| refers to one of
+the sixteen font families, and |character(q)| is the number of a character
+within a font of that family, as in a character node.
+
+\yskip\hang|type(q)=math_text_char_node| is similar, but the character is
+unsubscripted and unsuperscripted and it is followed immediately by another
+character from the same font. (This |type| setting appears only
+briefly during the processing; it is used to suppress unwanted italic
+corrections.)
+
+\yskip\hang|type(q)=sub_box_node| means that |math_list(q)| points to a box
+node (either an |hlist_node| or a |vlist_node|) that should be used as the
+value of the field. The |shift_amount| in the subsidiary box node is the
+amount by which that box will be shifted downward.
+
+\yskip\hang|type(q)=sub_mlist_node| means that |math_list(q)| points to
+an mlist; the mlist must be converted to an hlist in order to obtain
+the value of this field.
+
+\yskip\noindent In the latter case, we might have |math_list(q)=null|. This
+is not the same as |q=null|; for example, `\.{\$P\_\{\}\$}'
+and `\.{\$P\$}' produce different results (the former will not have the
+``italic correction'' added to the width of |P|, but the ``script skip''
+will be added).
+
+@c
+void unsave_math(void)
+{
+ unsave();
+ decr(save_ptr);
+ flush_node_list(text_dir_ptr);
+ assert(saved_type(0) == saved_textdir);
+ text_dir_ptr = saved_value(0);
+}
+
+
+@ Sometimes it is necessary to destroy an mlist. The following
+subroutine empties the current list, assuming that |abs(mode)=mmode|.
+
+@c
+void flush_math(void)
+{
+ flush_node_list(vlink(head));
+ flush_node_list(incompleat_noad);
+ vlink(head) = null;
+ tail = head;
+ incompleat_noad = null;
+}
+
+@ Before we can do anything in math mode, we need fonts.
+
+@c
+#define MATHFONTSTACK 8
+#define MATHFONTDEFAULT 0 /* == nullfont */
+
+static sa_tree math_fam_head = NULL;
+
+@ @c
+int fam_fnt(int fam_id, int size_id)
+{
+ int n = fam_id + (256 * size_id);
+ return (int) get_sa_item(math_fam_head, n);
+}
+
+void def_fam_fnt(int fam_id, int size_id, int f, int lvl)
+{
+ int n = fam_id + (256 * size_id);
+ set_sa_item(math_fam_head, n, (sa_tree_item) f, lvl);
+ fixup_math_parameters(fam_id, size_id, f, lvl);
+ if (int_par(tracing_assigns_code) > 0) {
+ begin_diagnostic();
+ tprint("{assigning");
+ print_char(' ');
+ print_cmd_chr(def_family_cmd, size_id);
+ print_int(fam_id);
+ print_char('=');
+ print_font_identifier(fam_fnt(fam_id, size_id));
+ print_char('}');
+ end_diagnostic(false);
+ }
+}
+
+@ @c
+void unsave_math_fam_data(int gl)
+{
+ sa_stack_item st;
+ if (math_fam_head->stack == NULL)
+ return;
+ while (math_fam_head->stack_ptr > 0 &&
+ abs(math_fam_head->stack[math_fam_head->stack_ptr].level)
+ >= (int) gl) {
+ st = math_fam_head->stack[math_fam_head->stack_ptr];
+ if (st.level > 0) {
+ rawset_sa_item(math_fam_head, st.code, st.value);
+ /* now do a trace message, if requested */
+ if (int_par(tracing_restores_code) > 0) {
+ int size_id = st.code / 256;
+ int fam_id = st.code % 256;
+ begin_diagnostic();
+ tprint("{restoring");
+ print_char(' ');
+ print_cmd_chr(def_family_cmd, size_id);
+ print_int(fam_id);
+ print_char('=');
+ print_font_identifier(fam_fnt(fam_id, size_id));
+ print_char('}');
+ end_diagnostic(false);
+ }
+ }
+ (math_fam_head->stack_ptr)--;
+ }
+}
+
+
+
+@ and parameters
+
+@c
+#define MATHPARAMSTACK 8
+#define MATHPARAMDEFAULT undefined_math_parameter
+
+static sa_tree math_param_head = NULL;
+
+@ @c
+void def_math_param(int param_id, int style_id, scaled value, int lvl)
+{
+ int n = param_id + (256 * style_id);
+ set_sa_item(math_param_head, n, (sa_tree_item) value, lvl);
+ if (int_par(tracing_assigns_code) > 0) {
+ begin_diagnostic();
+ tprint("{assigning");
+ print_char(' ');
+ print_cmd_chr(set_math_param_cmd, param_id);
+ print_cmd_chr(math_style_cmd, style_id);
+ print_char('=');
+ print_int(value);
+ print_char('}');
+ end_diagnostic(false);
+ }
+}
+
+scaled get_math_param(int param_id, int style_id)
+{
+ int n = param_id + (256 * style_id);
+ return (scaled) get_sa_item(math_param_head, n);
+}
+
+
+@ @c
+void unsave_math_param_data(int gl)
+{
+ sa_stack_item st;
+ if (math_param_head->stack == NULL)
+ return;
+ while (math_param_head->stack_ptr > 0 &&
+ abs(math_param_head->stack[math_param_head->stack_ptr].level)
+ >= (int) gl) {
+ st = math_param_head->stack[math_param_head->stack_ptr];
+ if (st.level > 0) {
+ rawset_sa_item(math_param_head, st.code, st.value);
+ /* now do a trace message, if requested */
+ if (int_par(tracing_restores_code) > 0) {
+ int param_id = st.code % 256;
+ int style_id = st.code / 256;
+ begin_diagnostic();
+ tprint("{restoring");
+ print_char(' ');
+ print_cmd_chr(set_math_param_cmd, param_id);
+ print_cmd_chr(math_style_cmd, style_id);
+ print_char('=');
+ print_int(get_math_param(param_id, style_id));
+ print_char('}');
+ end_diagnostic(false);
+ }
+ }
+ (math_param_head->stack_ptr)--;
+ }
+}
+
+
+@ saving and unsaving of both
+
+@c
+void unsave_math_data(int gl)
+{
+ unsave_math_fam_data(gl);
+ unsave_math_param_data(gl);
+}
+
+@ Dumping and undumping
+@c
+void dump_math_data(void)
+{
+ if (math_fam_head == NULL)
+ math_fam_head = new_sa_tree(MATHFONTSTACK, MATHFONTDEFAULT);
+ dump_sa_tree(math_fam_head);
+ if (math_param_head == NULL)
+ math_param_head = new_sa_tree(MATHPARAMSTACK, MATHPARAMDEFAULT);
+ dump_sa_tree(math_param_head);
+}
+
+void undump_math_data(void)
+{
+ math_fam_head = undump_sa_tree();
+ math_param_head = undump_sa_tree();
+}
+
+@ @c
+void initialize_math(void)
+{
+ if (math_fam_head == NULL)
+ math_fam_head = new_sa_tree(MATHFONTSTACK, MATHFONTDEFAULT);
+ if (math_param_head == NULL) {
+ math_param_head = new_sa_tree(MATHPARAMSTACK, MATHPARAMDEFAULT);
+ initialize_math_spacing();
+ }
+ return;
+}
+
+
+
+@ Each portion of a formula is classified as Ord, Op, Bin, Rel, Ope,
+Clo, Pun, or Inn, for purposes of spacing and line breaking. An
+|ord_noad|, |op_noad|, |bin_noad|, |rel_noad|, |open_noad|, |close_noad|,
+|punct_noad|, or |inner_noad| is used to represent portions of the various
+types. For example, an `\.=' sign in a formula leads to the creation of a
+|rel_noad| whose |nucleus| field is a representation of an equals sign
+(usually |fam=0|, |character=075|). A formula preceded by \.{\\mathrel}
+also results in a |rel_noad|. When a |rel_noad| is followed by an
+|op_noad|, say, and possibly separated by one or more ordinary nodes (not
+noads), \TeX\ will insert a penalty node (with the current |rel_penalty|)
+just after the formula that corresponds to the |rel_noad|, unless there
+already was a penalty immediately following; and a ``thick space'' will be
+inserted just before the formula that corresponds to the |op_noad|.
+
+A noad of type |ord_noad|, |op_noad|, \dots, |inner_noad| usually
+has a |subtype=normal|. The only exception is that an |op_noad| might
+have |subtype=limits| or |no_limits|, if the normal positioning of
+limits has been overridden for this operator.
+
+A |radical_noad| also has a |left_delimiter| field, which usually
+represents a square root sign.
+
+A |fraction_noad| has a |right_delimiter| field as well as a |left_delimiter|.
+
+Delimiter fields have four subfields
+called |small_fam|, |small_char|, |large_fam|, |large_char|. These subfields
+represent variable-size delimiters by giving the ``small'' and ``large''
+starting characters, as explained in Chapter~17 of {\sl The \TeX book}.
+@:TeXbook}{\sl The \TeX book@>
+
+A |fraction_noad| is actually quite different from all other noads.
+It has |thickness|, |denominator|, and |numerator| fields instead of
+|nucleus|, |subscr|, and |supscr|. The |thickness| is a scaled value
+that tells how thick to make a fraction rule; however, the special
+value |default_code| is used to stand for the
+|default_rule_thickness| of the current size. The |numerator| and
+|denominator| point to mlists that define a fraction; we always have
+$$\hbox{|type(numerator)=type(denominator)=sub_mlist|}.$$ The
+|left_delimiter| and |right_delimiter| fields specify delimiters that will
+be placed at the left and right of the fraction. In this way, a
+|fraction_noad| is able to represent all of \TeX's operators \.{\\over},
+\.{\\atop}, \.{\\above}, \.{\\overwithdelims}, \.{\\atopwithdelims}, and
+ \.{\\abovewithdelims}.
+
+
+
+@ The |new_noad| function creates an |ord_noad| that is completely null
+
+@c
+pointer new_noad(void)
+{
+ pointer p;
+ p = new_node(simple_noad, ord_noad_type);
+ /* all noad fields are zero after this */
+ return p;
+}
+
+@ @c
+pointer new_sub_box(pointer cur_box)
+{
+ pointer p, q;
+ p = new_noad();
+ q = new_node(sub_box_node, 0);
+ nucleus(p) = q;
+ math_list(nucleus(p)) = cur_box;
+ return p;
+}
+
+
+@ A few more kinds of noads will complete the set: An |under_noad| has its
+nucleus underlined; an |over_noad| has it overlined. An |accent_noad| places
+an accent over its nucleus; the accent character appears as
+|math_fam(accent_chr(p))| and |math_character(accent_chr(p))|. A |vcenter_noad|
+centers its nucleus vertically with respect to the axis of the formula;
+in such noads we always have |type(nucleus(p))=sub_box|.
+
+And finally, we have the |fence_noad| type, to implement
+\TeX's \.{\\left} and \.{\\right} as well as eTeX's \.{\\middle}.
+The |nucleus| of such noads is
+replaced by a |delimiter| field; thus, for example, `\.{\\left(}' produces
+a |fence_noad| such that |delimiter(p)| holds the family and character
+codes for all left parentheses. A |fence_noad| of subtype |left_noad_side|
+never appears in an mlist except as the first element, and a |fence_noad|
+with subtype |right_noad_side| never appears in an mlist
+except as the last element; furthermore, we either have both a |left_noad_side|
+and a |right_noad_side|, or neither one is present.
+
+
+
+@ Math formulas can also contain instructions like \.{\\textstyle} that
+override \TeX's normal style rules. A |style_node| is inserted into the
+data structure to record such instructions; it is three words long, so it
+is considered a node instead of a noad. The |subtype| is either |display_style|
+or |text_style| or |script_style| or |script_script_style|. The
+second and third words of a |style_node| are not used, but they are
+present because a |choice_node| is converted to a |style_node|.
+
+\TeX\ uses even numbers 0, 2, 4, 6 to encode the basic styles
+|display_style|, \dots, |script_script_style|, and adds~1 to get the
+``cramped'' versions of these styles. This gives a numerical order that
+is backwards from the convention of Appendix~G in {\sl The \TeX book\/};
+i.e., a smaller style has a larger numerical value.
+@:TeXbook}{\sl The \TeX book@>
+
+@c
+const char *math_style_names[] = {
+ "display", "crampeddisplay",
+ "text", "crampedtext",
+ "script", "crampedscript",
+ "scriptscript", "crampedscriptscript",
+ NULL
+};
+
+const char *math_param_names[] = {
+ "quad", "axis", "operatorsize",
+ "overbarkern", "overbarrule", "overbarvgap",
+ "underbarkern", "underbarrule", "underbarvgap",
+ "radicalkern", "radicalrule", "radicalvgap",
+ "radicaldegreebefore", "radicaldegreeafter", "radicaldegreeraise",
+ "stackvgap", "stacknumup", "stackdenomdown",
+ "fractionrule", "fractionnumvgap", "fractionnumup",
+ "fractiondenomvgap", "fractiondenomdown", "fractiondelsize",
+ "limitabovevgap", "limitabovebgap", "limitabovekern",
+ "limitbelowvgap", "limitbelowbgap", "limitbelowkern",
+ "underdelimitervgap", "underdelimiterbgap",
+ "overdelimitervgap", "overdelimiterbgap",
+ "subshiftdrop", "supshiftdrop", "subshiftdown",
+ "subsupshiftdown", "subtopmax", "supshiftup",
+ "supbottommin", "supsubbottommax", "subsupvgap",
+ "spaceafterscript", "connectoroverlapmin",
+ "ordordspacing", "ordopspacing", "ordbinspacing", "ordrelspacing",
+ "ordopenspacing", "ordclosespacing", "ordpunctspacing", "ordinnerspacing",
+ "opordspacing", "opopspacing", "opbinspacing", "oprelspacing",
+ "opopenspacing", "opclosespacing", "oppunctspacing", "opinnerspacing",
+ "binordspacing", "binopspacing", "binbinspacing", "binrelspacing",
+ "binopenspacing", "binclosespacing", "binpunctspacing", "bininnerspacing",
+ "relordspacing", "relopspacing", "relbinspacing", "relrelspacing",
+ "relopenspacing", "relclosespacing", "relpunctspacing", "relinnerspacing",
+ "openordspacing", "openopspacing", "openbinspacing", "openrelspacing",
+ "openopenspacing", "openclosespacing", "openpunctspacing",
+ "openinnerspacing",
+ "closeordspacing", "closeopspacing", "closebinspacing", "closerelspacing",
+ "closeopenspacing", "closeclosespacing", "closepunctspacing",
+ "closeinnerspacing",
+ "punctordspacing", "punctopspacing", "punctbinspacing", "punctrelspacing",
+ "punctopenspacing", "punctclosespacing", "punctpunctspacing",
+ "punctinnerspacing",
+ "innerordspacing", "inneropspacing", "innerbinspacing", "innerrelspacing",
+ "inneropenspacing", "innerclosespacing", "innerpunctspacing",
+ "innerinnerspacing",
+ NULL
+};
+
+@ @c
+pointer new_style(small_number s)
+{ /* create a style node */
+ m_style = s;
+ return new_node(style_node, s);
+}
+
+@ Finally, the \.{\\mathchoice} primitive creates a |choice_node|, which
+has special subfields |display_mlist|, |text_mlist|, |script_mlist|,
+and |script_script_mlist| pointing to the mlists for each style.
+
+@c
+pointer new_choice(void)
+{ /* create a choice node */
+ return new_node(choice_node, 0); /* the |subtype| is not used */
+}
+
+
+@ Let's consider now the previously unwritten part of |show_node_list|
+that displays the things that can only be present in mlists; this
+program illustrates how to access the data structures just defined.
+
+In the context of the following program, |p| points to a node or noad that
+should be displayed, and the current string contains the ``recursion history''
+that leads to this point. The recursion history consists of a dot for each
+outer level in which |p| is subsidiary to some node, or in which |p| is
+subsidiary to the |nucleus| field of some noad; the dot is replaced by
+`\.\_' or `\.\^' or `\./' or `\.\\' if |p| is descended from the |subscr|
+or |supscr| or |denominator| or |numerator| fields of noads. For example,
+the current string would be `\.{.\^.\_/}' if |p| points to the |ord_noad| for
+|x| in the (ridiculous) formula
+`\.{\$\\sqrt\{a\^\{\\mathinner\{b\_\{c\\over x+y\}\}\}\}\$}'.
+
+@c
+void display_normal_noad(pointer p); /* forward */
+void display_fence_noad(pointer p); /* forward */
+void display_fraction_noad(pointer p); /* forward */
+
+void show_math_node(pointer p)
+{
+ switch (type(p)) {
+ case style_node:
+ print_cmd_chr(math_style_cmd, subtype(p));
+ break;
+ case choice_node:
+ tprint_esc("mathchoice");
+ append_char('D');
+ show_node_list(display_mlist(p));
+ flush_char();
+ append_char('T');
+ show_node_list(text_mlist(p));
+ flush_char();
+ append_char('S');
+ show_node_list(script_mlist(p));
+ flush_char();
+ append_char('s');
+ show_node_list(script_script_mlist(p));
+ flush_char();
+ break;
+ case simple_noad:
+ case radical_noad:
+ case accent_noad:
+ display_normal_noad(p);
+ break;
+ case fence_noad:
+ display_fence_noad(p);
+ break;
+ case fraction_noad:
+ display_fraction_noad(p);
+ break;
+ default:
+ tprint("Unknown node type!");
+ break;
+ }
+}
+
+
+@ Here are some simple routines used in the display of noads.
+
+@c
+void print_fam_and_char(pointer p)
+{ /* prints family and character */
+ tprint_esc("fam");
+ print_int(math_fam(p));
+ print_char(' ');
+ print(math_character(p));
+}
+
+@ @c
+void print_delimiter(pointer p)
+{
+ int a;
+ if (small_fam(p) < 0) {
+ print_int(-1); /* this should never happen */
+ } else if (small_fam(p) < 16 && large_fam(p) < 16 &&
+ small_char(p) < 256 && large_char(p) < 256) {
+ /* traditional tex style */
+ a = small_fam(p) * 256 + small_char(p);
+ a = a * 0x1000 + large_fam(p) * 256 + large_char(p);
+ print_hex(a);
+ } else if ((large_fam(p) == 0 && large_char(p) == 0) ||
+ small_char(p) > 65535 || large_char(p) > 65535) {
+ /* modern xetex/luatex style */
+ print_hex(small_fam(p));
+ print_hex(small_char(p));
+ } else {
+ /* assume this is omega-style */
+ a = small_fam(p) * 65536 + small_char(p);
+ print_hex(a);
+ a = large_fam(p) * 65536 + large_char(p);
+ print_hex(a);
+ }
+}
+
+
+@ The next subroutine will descend to another level of recursion when a
+subsidiary mlist needs to be displayed. The parameter |c| indicates what
+character is to become part of the recursion history. An empty mlist is
+distinguished from a missing field, because these are not equivalent
+(as explained above).
+@^recursion@>
+
+@c
+void print_subsidiary_data(pointer p, ASCII_code c)
+{ /* display a noad field */
+ if ((int) cur_length >= depth_threshold) {
+ if (p != null)
+ tprint(" []");
+ } else {
+ append_char(c); /* include |c| in the recursion history */
+ if (p != null) {
+ switch (type(p)) {
+ case math_char_node:
+ print_ln();
+ print_current_string();
+ print_fam_and_char(p);
+ break;
+ case sub_box_node:
+ show_node_list(math_list(p));
+ break;
+ case sub_mlist_node:
+ if (math_list(p) == null) {
+ print_ln();
+ print_current_string();
+ tprint("{}");
+ } else {
+ show_node_list(math_list(p));
+ }
+ break;
+ }
+ }
+ flush_char(); /* remove |c| from the recursion history */
+ }
+}
+
+@ @c
+void display_normal_noad(pointer p)
+{
+ switch (type(p)) {
+ case simple_noad:
+ switch (subtype(p)) {
+ case ord_noad_type:
+ tprint_esc("mathord");
+ break;
+ case op_noad_type_normal:
+ case op_noad_type_limits:
+ case op_noad_type_no_limits:
+ tprint_esc("mathop");
+ if (subtype(p) == op_noad_type_limits)
+ tprint_esc("limits");
+ else if (subtype(p) == op_noad_type_no_limits)
+ tprint_esc("nolimits");
+ break;
+ case bin_noad_type:
+ tprint_esc("mathbin");
+ break;
+ case rel_noad_type:
+ tprint_esc("mathrel");
+ break;
+ case open_noad_type:
+ tprint_esc("mathopen");
+ break;
+ case close_noad_type:
+ tprint_esc("mathclose");
+ break;
+ case punct_noad_type:
+ tprint_esc("mathpunct");
+ break;
+ case inner_noad_type:
+ tprint_esc("mathinner");
+ break;
+ case over_noad_type:
+ tprint_esc("overline");
+ break;
+ case under_noad_type:
+ tprint_esc("underline");
+ break;
+ case vcenter_noad_type:
+ tprint_esc("vcenter");
+ break;
+ default:
+ tprint("<unknown noad type!>");
+ break;
+ }
+ break;
+ case radical_noad:
+ if (subtype(p) == 7)
+ tprint_esc("Udelimiterover");
+ else if (subtype(p) == 6)
+ tprint_esc("Udelimiterunder");
+ else if (subtype(p) == 5)
+ tprint_esc("Uoverdelimiter");
+ else if (subtype(p) == 4)
+ tprint_esc("Uunderdelimiter");
+ else if (subtype(p) == 3)
+ tprint_esc("Uroot");
+ else
+ tprint_esc("radical");
+ print_delimiter(left_delimiter(p));
+ if (degree(p) != null) {
+ print_subsidiary_data(degree(p), '/');
+ }
+ break;
+ case accent_noad:
+ if (accent_chr(p) != null) {
+ if (bot_accent_chr(p) != null) {
+ tprint_esc("Umathaccents");
+ print_fam_and_char(accent_chr(p));
+ print_fam_and_char(bot_accent_chr(p));
+ } else {
+ tprint_esc("accent");
+ print_fam_and_char(accent_chr(p));
+ }
+ } else {
+ tprint_esc("Umathbotaccent");
+ print_fam_and_char(bot_accent_chr(p));
+ }
+ break;
+ }
+ print_subsidiary_data(nucleus(p), '.');
+ print_subsidiary_data(supscr(p), '^');
+ print_subsidiary_data(subscr(p), '_');
+}
+
+@ @c
+void display_fence_noad(pointer p)
+{
+ if (subtype(p) == right_noad_side)
+ tprint_esc("right");
+ else if (subtype(p) == left_noad_side)
+ tprint_esc("left");
+ else
+ tprint_esc("middle");
+ print_delimiter(delimiter(p));
+}
+
+@ @c
+void display_fraction_noad(pointer p)
+{
+ tprint_esc("fraction, thickness ");
+ if (thickness(p) == default_code)
+ tprint("= default");
+ else
+ print_scaled(thickness(p));
+ if ((left_delimiter(p) != null) &&
+ ((small_fam(left_delimiter(p)) != 0) ||
+ (small_char(left_delimiter(p)) != 0) ||
+ (large_fam(left_delimiter(p)) != 0) ||
+ (large_char(left_delimiter(p)) != 0))) {
+ tprint(", left-delimiter ");
+ print_delimiter(left_delimiter(p));
+ }
+ if ((right_delimiter(p) != null) &&
+ ((small_fam(right_delimiter(p)) != 0) ||
+ (small_char(right_delimiter(p)) != 0) ||
+ (large_fam(right_delimiter(p)) != 0) ||
+ (large_char(right_delimiter(p)) != 0))) {
+ tprint(", right-delimiter ");
+ print_delimiter(right_delimiter(p));
+ }
+ print_subsidiary_data(numerator(p), '\\');
+ print_subsidiary_data(denominator(p), '/');
+}
+
+
+@ The routines that \TeX\ uses to create mlists are similar to those we have
+just seen for the generation of hlists and vlists. But it is necessary to
+make ``noads'' as well as nodes, so the reader should review the
+discussion of math mode data structures before trying to make sense out of
+the following program.
+
+Here is a little routine that needs to be done whenever a subformula
+is about to be processed. The parameter is a code like |math_group|.
+
+@c
+void new_save_level_math(group_code c)
+{
+ set_saved_record(0, saved_textdir, 0, text_dir_ptr);
+ text_dir_ptr = new_dir(math_direction);
+ incr(save_ptr);
+ new_save_level(c);
+ eq_word_define(int_base + body_direction_code, math_direction);
+ eq_word_define(int_base + par_direction_code, math_direction);
+ eq_word_define(int_base + text_direction_code, math_direction);
+}
+
+@ @c
+void push_math(group_code c, int mstyle)
+{
+ if (math_direction != text_direction)
+ dir_math_save = true;
+ push_nest();
+ mode = -mmode;
+ incompleat_noad = null;
+ m_style = mstyle;
+ new_save_level_math(c);
+}
+
+@ @c
+void enter_ordinary_math(void)
+{
+ push_math(math_shift_group, text_style);
+ eq_word_define(int_base + cur_fam_code, -1);
+ if (every_math != null)
+ begin_token_list(every_math, every_math_text);
+}
+
+@ @c
+void enter_display_math(void);
+
+@ We get into math mode from horizontal mode when a `\.\$' (i.e., a
+|math_shift| character) is scanned. We must check to see whether this
+`\.\$' is immediately followed by another, in case display math mode is
+called for.
+
+@c
+void init_math(void)
+{
+ if (cur_cmd == math_shift_cmd) {
+ get_token(); /* |get_x_token| would fail on \.{\\ifmmode}\thinspace! */
+ if ((cur_cmd == math_shift_cmd) && (mode > 0)) {
+ enter_display_math();
+ } else {
+ back_input();
+ enter_ordinary_math();
+ }
+ } else if (cur_cmd == math_shift_cs_cmd && cur_chr == display_style) {
+ enter_display_math();
+ } else if (cur_cmd == math_shift_cs_cmd && cur_chr == text_style) {
+ enter_ordinary_math();
+ } else {
+ you_cant();
+ }
+}
+
+
+@ We get into ordinary math mode from display math mode when `\.{\\eqno}' or
+`\.{\\leqno}' appears. In such cases |cur_chr| will be 0 or~1, respectively;
+the value of |cur_chr| is placed onto |save_stack| for safe keeping.
+
+
+@ When \TeX\ is in display math mode, |cur_group=math_shift_group|,
+so it is not necessary for the |start_eq_no| procedure to test for
+this condition.
+
+@c
+void start_eq_no(void)
+{
+ set_saved_record(0, saved_eqno, 0, cur_chr);
+ incr(save_ptr);
+ enter_ordinary_math();
+}
+
+@ Subformulas of math formulas cause a new level of math mode to be entered,
+on the semantic nest as well as the save stack. These subformulas arise in
+several ways: (1)~A left brace by itself indicates the beginning of a
+subformula that will be put into a box, thereby freezing its glue and
+preventing line breaks. (2)~A subscript or superscript is treated as a
+subformula if it is not a single character; the same applies to
+the nucleus of things like \.{\\underline}. (3)~The \.{\\left} primitive
+initiates a subformula that will be terminated by a matching \.{\\right}.
+The group codes placed on |save_stack| in these three cases are
+|math_group|, |math_group|, and |math_left_group|, respectively.
+
+Here is the code that handles case (1); the other cases are not quite as
+trivial, so we shall consider them later.
+
+@c
+void math_left_brace(void)
+{
+ pointer q;
+ tail_append(new_noad());
+ q = new_node(math_char_node, 0);
+ nucleus(tail) = q;
+ back_input();
+ (void) scan_math(nucleus(tail), m_style);
+}
+
+
+@ When we enter display math mode, we need to call |line_break| to
+process the partial paragraph that has just been interrupted by the
+display. Then we can set the proper values of |display_width| and
+|display_indent| and |pre_display_size|.
+
+@c
+void enter_display_math(void)
+{
+ scaled w; /* new or partial |pre_display_size| */
+ scaled l; /* new |display_width| */
+ scaled s; /* new |display_indent| */
+ pointer p;
+ int n; /* scope of paragraph shape specification */
+ if (head == tail || /* `\.{\\noindent\$\$}' or `\.{\$\${ }\$\$}' */
+ (vlink(head) == tail && /* the 2nd of \.{\$\${ }\$\$} \.{\$\${ }\$\$} */
+ type(tail) == whatsit_node &&
+ subtype(tail) == local_par_node && vlink(tail) == null)) {
+ if (vlink(head) == tail) {
+ /* bug \#270: |resume_after_display| inserts a |local_par_node|, but if
+ there is another display immediately following, we have to get rid
+ of that node */
+ flush_node(tail);
+ }
+ pop_nest();
+ w = -max_dimen;
+ } else {
+ line_break(true, math_shift_group);
+ w = actual_box_width(just_box, (2 * quad(get_cur_font())));
+ }
+ /* now we are in vertical mode, working on the list that will contain the display */
+ /* A displayed equation is considered to be three lines long, so we
+ calculate the length and offset of line number |prev_graf+2|. */
+ if (par_shape_ptr == null) {
+ if ((hang_indent != 0) &&
+ (((hang_after >= 0) && (prev_graf + 2 > hang_after)) ||
+ (prev_graf + 1 < -hang_after))) {
+ l = hsize - abs(hang_indent);
+ if (hang_indent > 0)
+ s = hang_indent;
+ else
+ s = 0;
+ } else {
+ l = hsize;
+ s = 0;
+ }
+ } else {
+ n = vinfo(par_shape_ptr + 1);
+ if (prev_graf + 2 >= n)
+ p = par_shape_ptr + 2 * n + 1;
+ else
+ p = par_shape_ptr + 2 * (prev_graf + 2) + 1;
+ s = varmem[(p - 1)].cint;
+ l = varmem[p].cint;
+ }
+
+ push_math(math_shift_group, display_style);
+ mode = mmode;
+ eq_word_define(int_base + cur_fam_code, -1);
+ eq_word_define(dimen_base + pre_display_size_code, w);
+ eq_word_define(dimen_base + display_width_code, l);
+ eq_word_define(dimen_base + display_indent_code, s);
+ if (every_display != null)
+ begin_token_list(every_display, every_display_text);
+ if (nest_ptr == 1) {
+ if (!output_active)
+ lua_node_filter_s(buildpage_filter_callback, "before_display");
+ build_page();
+ }
+}
+
+@ The next routine parses all variations of a delimiter code. The |extcode|
+ tells what syntax form to use (\TeX, Aleph, XeTeX, XeTeXnum, ...) , the
+ |doclass| tells whether or not read a math class also (for \.{\\delimiter} c.s.).
+ (the class is passed on for conversion to \.{\\mathchar}).
+
+@c
+#define fam_in_range ((cur_fam>=0)&&(cur_fam<256))
+
+delcodeval do_scan_extdef_del_code(int extcode, boolean doclass)
+{
+ const char *hlp[] = {
+ "I'm going to use 0 instead of that illegal code value.",
+ NULL
+ };
+ delcodeval d;
+ int cur_val1; /* and the global |cur_val| */
+ int mcls, msfam = 0, mschr = 0, mlfam = 0, mlchr = 0;
+ mcls = 0;
+ if (extcode == tex_mathcode) { /* \.{\\delcode}, this is the easiest */
+ scan_int();
+ /* "MFCCFCC or "FCCFCC */
+ if (doclass) {
+ mcls = (cur_val / 0x1000000);
+ cur_val = (cur_val & 0xFFFFFF);
+ }
+ if (cur_val > 0xFFFFFF) {
+ tex_error("Invalid delimiter code", hlp);
+ cur_val = 0;
+ }
+ msfam = (cur_val / 0x100000);
+ mschr = (cur_val % 0x100000) / 0x1000;
+ mlfam = (cur_val & 0xFFF) / 0x100;
+ mlchr = (cur_val % 0x100);
+ } else if (extcode == aleph_mathcode) { /* \.{\\odelcode} */
+ /* "MFFCCCC"FFCCCC or "FFCCCC"FFCCCC */
+ scan_int();
+ if (doclass) {
+ mcls = (cur_val / 0x1000000);
+ cur_val = (cur_val & 0xFFFFFF);
+ }
+ cur_val1 = cur_val;
+ scan_int();
+ if ((cur_val1 > 0xFFFFFF) || (cur_val > 0xFFFFFF)) {
+ tex_error("Invalid delimiter code", hlp);
+ cur_val1 = 0;
+ cur_val = 0;
+ }
+ msfam = (cur_val1 / 0x10000);
+ mschr = (cur_val1 % 0x10000);
+ mlfam = (cur_val / 0x10000);
+ mlchr = (cur_val % 0x10000);
+ } else if (extcode == xetex_mathcode) { /* \.{\\Udelcode} */
+ /* <0-7>,<0-0xFF>,<0-0x10FFFF> or <0-0xFF>,<0-0x10FFFF> */
+ if (doclass) {
+ scan_int();
+ mcls = cur_val;
+ }
+ scan_int();
+ msfam = cur_val;
+ scan_char_num();
+ mschr = cur_val;
+ if (msfam < 0 || msfam > 255) {
+ tex_error("Invalid delimiter code", hlp);
+ msfam = 0;
+ mschr = 0;
+ }
+ mlfam = 0;
+ mlchr = 0;
+ } else if (extcode == xetexnum_mathcode) { /* \.{\\Udelcodenum} */
+ /* "FF<21bits> */
+ /* the largest numeric value is $2^29-1$, but
+ the top of bit 21 can't be used as it contains invalid USV's
+ */
+ if (doclass) { /* such a primitive doesn't exist */
+ confusion("xetexnum_mathcode");
+ }
+ scan_int();
+ msfam = (cur_val / 0x200000);
+ mschr = cur_val & 0x1FFFFF;
+ if (msfam < 0 || msfam > 255 || mschr > 0x10FFFF) {
+ tex_error("Invalid delimiter code", hlp);
+ msfam = 0;
+ mschr = 0;
+ }
+ mlfam = 0;
+ mlchr = 0;
+ } else {
+ /* something's gone wrong */
+ confusion("unknown_extcode");
+ }
+ d.origin_value = extcode;
+ d.class_value = mcls;
+ d.small_family_value = msfam;
+ d.small_character_value = mschr;
+ d.large_family_value = mlfam;
+ d.large_character_value = mlchr;
+ return d;
+}
+
+@ @c
+void scan_extdef_del_code(int level, int extcode)
+{
+ delcodeval d;
+ int p;
+ scan_char_num();
+ p = cur_val;
+ scan_optional_equals();
+ d = do_scan_extdef_del_code(extcode, false);
+ set_del_code(p, extcode, d.small_family_value, d.small_character_value,
+ d.large_family_value, d.large_character_value,
+ (quarterword) (level));
+}
+
+@ @c
+mathcodeval scan_mathchar(int extcode)
+{
+ const char *hlp[] = {
+ "I'm going to use 0 instead of that illegal code value.",
+ NULL
+ };
+ mathcodeval d;
+ int mcls = 0, mfam = 0, mchr = 0;
+ if (extcode == tex_mathcode) { /* \.{\\mathcode} */
+ /* "TFCC */
+ scan_int();
+ if (cur_val > 0x8000) {
+ tex_error("Invalid math code", hlp);
+ cur_val = 0;
+ }
+ mcls = (cur_val / 0x1000);
+ mfam = ((cur_val % 0x1000) / 0x100);
+ mchr = (cur_val % 0x100);
+ } else if (extcode == aleph_mathcode) { /* \.{\\omathcode} */
+ /* "TFFCCCC */
+ scan_int();
+ if (cur_val > 0x8000000) {
+ tex_error("Invalid math code", hlp);
+ cur_val = 0;
+ }
+ mcls = (cur_val / 0x1000000);
+ mfam = ((cur_val % 0x1000000) / 0x10000);
+ mchr = (cur_val % 0x10000);
+ } else if (extcode == xetex_mathcode) {
+ /* <0-0x7> <0-0xFF> <0-0x10FFFF> */
+ scan_int();
+ mcls = cur_val;
+ scan_int();
+ mfam = cur_val;
+ scan_char_num();
+ mchr = cur_val;
+ if (mcls < 0 || mcls > 7 || mfam > 255) {
+ tex_error("Invalid math code", hlp);
+ mchr = 0;
+ mfam = 0;
+ mcls = 0;
+ }
+ } else if (extcode == xetexnum_mathcode) {
+ /* "FFT<21bits> */
+ /* the largest numeric value is $2^32-1$, but
+ the top of bit 21 can't be used as it contains invalid USV's
+ */
+ /* Note: |scan_int| won't accept families 128-255 because these use bit 32 */
+ scan_int();
+ mfam = (cur_val / 0x200000) & 0x7FF;
+ mcls = mfam % 0x08;
+ mfam = mfam / 0x08;
+ mchr = cur_val & 0x1FFFFF;
+ if (mchr > 0x10FFFF) {
+ tex_error("Invalid math code", hlp);
+ mcls = 0;
+ mfam = 0;
+ mchr = 0;
+ }
+ } else {
+ /* something's gone wrong */
+ confusion("unknown_extcode");
+ }
+ d.class_value = mcls;
+ d.family_value = mfam;
+ d.origin_value = extcode;
+ d.character_value = mchr;
+ return d;
+}
+
+@ @c
+void scan_extdef_math_code(int level, int extcode)
+{
+ mathcodeval d;
+ int p;
+ scan_char_num();
+ p = cur_val;
+ scan_optional_equals();
+ d = scan_mathchar(extcode);
+ set_math_code(p, extcode, d.class_value,
+ d.family_value, d.character_value, (quarterword) (level));
+}
+
+
+@ this reads in a delcode when actually a mathcode is needed
+@c
+mathcodeval scan_delimiter_as_mathchar(int extcode)
+{
+ delcodeval dval;
+ mathcodeval mval;
+ dval = do_scan_extdef_del_code(extcode, true);
+ mval.origin_value = 0;
+ mval.class_value = dval.class_value;
+ mval.family_value = dval.small_family_value;
+ mval.character_value = dval.small_character_value;
+ return mval;
+}
+
+@ this has to match the inverse routine in the pascal code
+ where the \.{\\Umathchardef} is executed
+
+@c
+mathcodeval mathchar_from_integer(int value, int extcode)
+{
+ mathcodeval mval;
+ mval.origin_value = extcode;
+ if (extcode == tex_mathcode) {
+ mval.class_value = (value / 0x1000);
+ mval.family_value = ((value % 0x1000) / 0x100);
+ mval.character_value = (value % 0x100);
+ } else if (extcode == aleph_mathcode) {
+ mval.class_value = (value / 0x1000000);
+ mval.family_value = ((value % 0x1000000) / 0x10000);
+ mval.character_value = (value % 0x10000);
+ } else { /* some xetexended xetex thing */
+ int mfam = (value / 0x200000) & 0x7FF;
+ mval.class_value = mfam % 0x08;
+ mval.family_value = mfam / 0x08;
+ mval.character_value = value & 0x1FFFFF;
+ }
+ return mval;
+}
+
+@ Recall that the |nucleus|, |subscr|, and |supscr| fields in a noad
+are broken down into subfields called |type| and either |math_list| or
+|(math_fam,math_character)|. The job of |scan_math| is to figure out
+what to place in one of these principal fields; it looks at the
+subformula that comes next in the input, and places an encoding of
+that subformula into a given word of |mem|.
+
+@c
+#define get_next_nb_nr() do { get_x_token(); } while (cur_cmd==spacer_cmd||cur_cmd==relax_cmd)
+
+
+int scan_math(pointer p, int mstyle)
+{
+ /* label restart,reswitch,exit; */
+ mathcodeval mval = { 0, 0, 0, 0 };
+ assert(p != null);
+ RESTART:
+ get_next_nb_nr();
+ RESWITCH:
+ switch (cur_cmd) {
+ case letter_cmd:
+ case other_char_cmd:
+ case char_given_cmd:
+ mval = get_math_code(cur_chr);
+ if (mval.class_value == 8) {
+ /* An active character that is an |outer_call| is allowed here */
+ cur_cs = active_to_cs(cur_chr, true);
+ cur_cmd = eq_type(cur_cs);
+ cur_chr = equiv(cur_cs);
+ x_token();
+ back_input();
+ goto RESTART;
+ }
+ break;
+ case char_num_cmd:
+ scan_char_num();
+ cur_chr = cur_val;
+ cur_cmd = char_given_cmd;
+ goto RESWITCH;
+ break;
+ case math_char_num_cmd:
+ if (cur_chr == 0)
+ mval = scan_mathchar(tex_mathcode);
+ else if (cur_chr == 1)
+ mval = scan_mathchar(aleph_mathcode);
+ else if (cur_chr == 2)
+ mval = scan_mathchar(xetex_mathcode);
+ else if (cur_chr == 3)
+ mval = scan_mathchar(xetexnum_mathcode);
+ else
+ confusion("scan_math");
+ break;
+ case math_given_cmd:
+ mval = mathchar_from_integer(cur_chr, tex_mathcode);
+ break;
+ case omath_given_cmd:
+ mval = mathchar_from_integer(cur_chr, aleph_mathcode);
+ break;
+ case xmath_given_cmd:
+ mval = mathchar_from_integer(cur_chr, xetex_mathcode);
+ break;
+ case delim_num_cmd:
+ if (cur_chr == 0)
+ mval = scan_delimiter_as_mathchar(tex_mathcode);
+ else if (cur_chr == 1)
+ mval = scan_delimiter_as_mathchar(aleph_mathcode);
+ else if (cur_chr == 2)
+ mval = scan_delimiter_as_mathchar(xetex_mathcode);
+ else
+ confusion("scan_math");
+ break;
+ default:
+ /* The pointer |p| is placed on |save_stack| while a complex subformula
+ is being scanned. */
+ back_input();
+ scan_left_brace();
+ set_saved_record(0, saved_math, 0, p);
+ incr(save_ptr);
+ push_math(math_group, mstyle);
+ return 1;
+ }
+ type(p) = math_char_node;
+ math_character(p) = mval.character_value;
+ if ((mval.class_value == var_code) && fam_in_range)
+ math_fam(p) = cur_fam;
+ else
+ math_fam(p) = mval.family_value;
+ return 0;
+}
+
+
+
+@ The |set_math_char| procedure creates a new noad appropriate to a given
+math code, and appends it to the current mlist. However, if the math code
+is sufficiently large, the |cur_chr| is treated as an active character and
+nothing is appended.
+
+@c
+void set_math_char(mathcodeval mval)
+{
+ pointer p; /* the new noad */
+ if (mval.class_value == 8) {
+ /* An active character that is an |outer_call| is allowed here */
+ cur_cs = active_to_cs(cur_chr, true);
+ cur_cmd = eq_type(cur_cs);
+ cur_chr = equiv(cur_cs);
+ x_token();
+ back_input();
+ } else {
+ pointer q;
+ p = new_noad();
+ q = new_node(math_char_node, 0);
+ nucleus(p) = q;
+ math_character(nucleus(p)) = mval.character_value;
+ math_fam(nucleus(p)) = mval.family_value;
+ if (mval.class_value == var_code) {
+ if (fam_in_range)
+ math_fam(nucleus(p)) = cur_fam;
+ subtype(p) = ord_noad_type;
+ } else {
+ switch (mval.class_value) {
+ /* *INDENT-OFF* */
+ case 0: subtype(p) = ord_noad_type; break;
+ case 1: subtype(p) = op_noad_type_normal; break;
+ case 2: subtype(p) = bin_noad_type; break;
+ case 3: subtype(p) = rel_noad_type; break;
+ case 4: subtype(p) = open_noad_type; break;
+ case 5: subtype(p) = close_noad_type; break;
+ case 6: subtype(p) = punct_noad_type; break;
+ /* *INDENT-ON* */
+ }
+ }
+ vlink(tail) = p;
+ tail = p;
+ }
+}
+
+
+
+@ The |math_char_in_text| procedure creates a new node representing a math char
+in text code, and appends it to the current list. However, if the math code
+is sufficiently large, the |cur_chr| is treated as an active character and
+nothing is appended.
+
+@c
+void math_char_in_text(mathcodeval mval)
+{
+ pointer p; /* the new node */
+ if (mval.class_value == 8) {
+ /* An active character that is an |outer_call| is allowed here */
+ cur_cs = active_to_cs(cur_chr, true);
+ cur_cmd = eq_type(cur_cs);
+ cur_chr = equiv(cur_cs);
+ x_token();
+ back_input();
+ } else {
+ p = new_char(fam_fnt(mval.family_value, text_size),
+ mval.character_value);
+ vlink(tail) = p;
+ tail = p;
+ }
+}
+
+
+@ @c
+void math_math_comp(void)
+{
+ pointer q;
+ tail_append(new_noad());
+ subtype(tail) = (quarterword) cur_chr;
+ q = new_node(math_char_node, 0);
+ nucleus(tail) = q;
+ if (cur_chr == over_noad_type)
+ (void) scan_math(nucleus(tail), cramped_style(m_style));
+ else
+ (void) scan_math(nucleus(tail), m_style);
+}
+
+
+@ @c
+void math_limit_switch(void)
+{
+ const char *hlp[] = {
+ "I'm ignoring this misplaced \\limits or \\nolimits command.",
+ NULL
+ };
+ if (head != tail) {
+ if (type(tail) == simple_noad) {
+ subtype(tail) = (quarterword) cur_chr;
+ return;
+ }
+ }
+ tex_error("Limit controls must follow a math operator", hlp);
+}
+
+
+@ Delimiter fields of noads are filled in by the |scan_delimiter| routine.
+The first parameter of this procedure is the |mem| address where the
+delimiter is to be placed; the second tells if this delimiter follows
+\.{\\radical} or not.
+
+@c
+void scan_delimiter(pointer p, int r)
+{
+ delcodeval dval = { 0, 0, 0, 0, 0, 0 };
+ if (r == tex_mathcode) { /* \.{\\radical} */
+ dval = do_scan_extdef_del_code(tex_mathcode, true);
+ } else if (r == aleph_mathcode) { /* \.{\\oradical} */
+ dval = do_scan_extdef_del_code(aleph_mathcode, true);
+ } else if (r == xetex_mathcode) { /* \.{\\Uradical} */
+ dval = do_scan_extdef_del_code(xetex_mathcode, false);
+ } else if (r == no_mathcode) {
+ get_next_nb_nr();
+ switch (cur_cmd) {
+ case letter_cmd:
+ case other_char_cmd:
+ dval = get_del_code(cur_chr);
+ break;
+ case delim_num_cmd:
+ if (cur_chr == 0) /* \.{\\delimiter} */
+ dval = do_scan_extdef_del_code(tex_mathcode, true);
+ else if (cur_chr == 1) /* \.{\\odelimiter} */
+ dval = do_scan_extdef_del_code(aleph_mathcode, true);
+ else if (cur_chr == 2) /* \.{\\Udelimiter} */
+ dval = do_scan_extdef_del_code(xetex_mathcode, true);
+ else
+ confusion("scan_delimiter1");
+ break;
+ default:
+ dval.small_family_value = -1;
+ break;
+ }
+ } else {
+ confusion("scan_delimiter2");
+ }
+ if (p == null)
+ return;
+ if (dval.small_family_value < 0) {
+ const char *hlp[] = {
+ "I was expecting to see something like `(' or `\\{' or",
+ "`\\}' here. If you typed, e.g., `{' instead of `\\{', you",
+ "should probably delete the `{' by typing `1' now, so that",
+ "braces don't get unbalanced. Otherwise just proceed",
+ "Acceptable delimiters are characters whose \\delcode is",
+ "nonnegative, or you can use `\\delimiter <delimiter code>'.",
+ NULL
+ };
+ back_error("Missing delimiter (. inserted)", hlp);
+ small_fam(p) = 0;
+ small_char(p) = 0;
+ large_fam(p) = 0;
+ large_char(p) = 0;
+ } else {
+ small_fam(p) = dval.small_family_value;
+ small_char(p) = dval.small_character_value;
+ large_fam(p) = dval.large_family_value;
+ large_char(p) = dval.large_character_value;
+ }
+ return;
+}
+
+
+@ @c
+void math_radical(void)
+{
+ halfword q;
+ int chr_code = cur_chr;
+ tail_append(new_node(radical_noad, chr_code));
+ q = new_node(delim_node, 0);
+ left_delimiter(tail) = q;
+ if (chr_code == 0) /* \.{\\radical} */
+ scan_delimiter(left_delimiter(tail), tex_mathcode);
+ else if (chr_code == 1) /* \.{\\oradical} */
+ scan_delimiter(left_delimiter(tail), aleph_mathcode);
+ else if (chr_code == 2) /* \.{\\Uradical} */
+ scan_delimiter(left_delimiter(tail), xetex_mathcode);
+ else if (chr_code == 3) /* \.{\\Uroot} */
+ scan_delimiter(left_delimiter(tail), xetex_mathcode);
+ else if (chr_code == 4) /* \.{\\Uunderdelimiter} */
+ scan_delimiter(left_delimiter(tail), xetex_mathcode);
+ else if (chr_code == 5) /* \.{\\Uoverdelimiter} */
+ scan_delimiter(left_delimiter(tail), xetex_mathcode);
+ else if (chr_code == 6) /* \.{\\Udelimiterunder} */
+ scan_delimiter(left_delimiter(tail), xetex_mathcode);
+ else if (chr_code == 7) /* \.{\\Udelimiterover} */
+ scan_delimiter(left_delimiter(tail), xetex_mathcode);
+ else
+ confusion("math_radical");
+ if (chr_code == 3) {
+ /* the trick with the |vlink(q)| is used by |scan_math|
+ to decide whether it needs to go on */
+ q = new_node(math_char_node, 0);
+ vlink(q) = tail;
+ degree(tail) = q;
+ if (!scan_math(degree(tail), sup_sup_style(m_style))) {
+ vlink(degree(tail)) = null;
+ q = new_node(math_char_node, 0);
+ nucleus(tail) = q;
+ (void) scan_math(nucleus(tail), cramped_style(m_style));
+ }
+ } else {
+ q = new_node(math_char_node, 0);
+ nucleus(tail) = q;
+ (void) scan_math(nucleus(tail), cramped_style(m_style));
+ }
+}
+
+@ @c
+void math_ac(void)
+{
+ halfword q;
+ mathcodeval t = { 0, 0, 0, 0 }, b = {
+ 0, 0, 0, 0};
+ if (cur_cmd == accent_cmd) {
+ const char *hlp[] = {
+ "I'm changing \\accent to \\mathaccent here; wish me luck.",
+ "(Accents are not the same in formulas as they are in text.)",
+ NULL
+ };
+ tex_error("Please use \\mathaccent for accents in math mode", hlp);
+ }
+ tail_append(new_node(accent_noad, 0));
+ if (cur_chr == 0) { /* \.{\\mathaccent} */
+ t = scan_mathchar(tex_mathcode);
+ } else if (cur_chr == 1) { /* \.{\\omathaccent} */
+ t = scan_mathchar(aleph_mathcode);
+ } else if (cur_chr == 2) { /* \.{\\Umathaccent} */
+ t = scan_mathchar(xetex_mathcode);
+ } else if (cur_chr == 3) { /* \.{\\Umathbotaccent} */
+ b = scan_mathchar(xetex_mathcode);
+ } else if (cur_chr == 4) { /* \.{\\Umathaccents} */
+ t = scan_mathchar(xetex_mathcode);
+ b = scan_mathchar(xetex_mathcode);
+ } else {
+ confusion("math_ac");
+ }
+ if (!(t.character_value == 0 && t.family_value == 0)) {
+ q = new_node(math_char_node, 0);
+ accent_chr(tail) = q;
+ math_character(accent_chr(tail)) = t.character_value;
+ if ((t.class_value == var_code) && fam_in_range)
+ math_fam(accent_chr(tail)) = cur_fam;
+ else
+ math_fam(accent_chr(tail)) = t.family_value;
+ }
+ if (!(b.character_value == 0 && b.family_value == 0)) {
+ q = new_node(math_char_node, 0);
+ bot_accent_chr(tail) = q;
+ math_character(bot_accent_chr(tail)) = b.character_value;
+ if ((b.class_value == var_code) && fam_in_range)
+ math_fam(bot_accent_chr(tail)) = cur_fam;
+ else
+ math_fam(bot_accent_chr(tail)) = b.family_value;
+ }
+ q = new_node(math_char_node, 0);
+ nucleus(tail) = q;
+ (void) scan_math(nucleus(tail), cramped_style(m_style));
+}
+
+@ @c
+pointer math_vcenter_group(pointer p)
+{
+ pointer q, r;
+ q = new_noad();
+ subtype(q) = vcenter_noad_type;
+ r = new_node(sub_box_node, 0);
+ nucleus(q) = r;
+ math_list(nucleus(q)) = p;
+ return q;
+}
+
+
+@ The routine that scans the four mlists of a \.{\\mathchoice} is very
+much like the routine that builds discretionary nodes.
+
+@c
+void append_choices(void)
+{
+ tail_append(new_choice());
+ incr(save_ptr);
+ set_saved_record(-1, saved_choices, 0, 0);
+ push_math(math_choice_group, display_style);
+ scan_left_brace();
+}
+
+@ @c
+void build_choices(void)
+{
+ pointer p; /* the current mlist */
+ int prev_style;
+ prev_style = m_style;
+ unsave_math();
+ p = fin_mlist(null);
+ assert(saved_type(-1) == saved_choices);
+ switch (saved_value(-1)) {
+ case 0:
+ display_mlist(tail) = p;
+ break;
+ case 1:
+ text_mlist(tail) = p;
+ break;
+ case 2:
+ script_mlist(tail) = p;
+ break;
+ case 3:
+ script_script_mlist(tail) = p;
+ decr(save_ptr);
+ return;
+ break;
+ } /* there are no other cases */
+ set_saved_record(-1, saved_choices, 0, (saved_value(-1) + 1));
+ push_math(math_choice_group, (prev_style + 2));
+ scan_left_brace();
+}
+
+
+@ Subscripts and superscripts are attached to the previous nucleus by the
+action procedure called |sub_sup|.
+
+@c
+void sub_sup(void)
+{
+ pointer q;
+ if (tail == head || (!scripts_allowed(tail))) {
+ tail_append(new_noad());
+ q = new_node(sub_mlist_node, 0);
+ nucleus(tail) = q;
+ }
+ if (cur_cmd == sup_mark_cmd || cur_chr == sup_mark_cmd) { /* |super_sub_script| */
+ if (supscr(tail) != null) {
+ const char *hlp[] = {
+ "I treat `x^1^2' essentially like `x^1{}^2'.", NULL
+ };
+ tail_append(new_noad());
+ q = new_node(sub_mlist_node, 0);
+ nucleus(tail) = q;
+ tex_error("Double superscript", hlp);
+ }
+ q = new_node(math_char_node, 0);
+ supscr(tail) = q;
+ (void) scan_math(supscr(tail), sup_style(m_style));
+ } else if (cur_cmd == sub_mark_cmd || cur_chr == sub_mark_cmd) {
+ if (subscr(tail) != null) {
+ const char *hlp[] = {
+ "I treat `x_1_2' essentially like `x_1{}_2'.", NULL
+ };
+ tail_append(new_noad());
+ q = new_node(sub_mlist_node, 0);
+ nucleus(tail) = q;
+ tex_error("Double subscript", hlp);
+ }
+ q = new_node(math_char_node, 0);
+ subscr(tail) = q;
+ (void) scan_math(subscr(tail), sub_style(m_style));
+ }
+}
+
+
+@ An operation like `\.{\\over}' causes the current mlist to go into a
+state of suspended animation: |incompleat_noad| points to a |fraction_noad|
+that contains the mlist-so-far as its numerator, while the denominator
+is yet to come. Finally when the mlist is finished, the denominator will
+go into the incompleat fraction noad, and that noad will become the
+whole formula, unless it is surrounded by `\.{\\left}' and `\.{\\right}'
+delimiters.
+
+@c
+void math_fraction(void)
+{
+ halfword c; /* the type of generalized fraction we are scanning */
+ pointer q;
+ c = cur_chr;
+ if (incompleat_noad != null) {
+ const char *hlp[] = {
+ "I'm ignoring this fraction specification, since I don't",
+ "know whether a construction like `x \\over y \\over z'",
+ "means `{x \\over y} \\over z' or `x \\over {y \\over z}'.",
+ NULL
+ };
+ if (c >= delimited_code) {
+ scan_delimiter(null, no_mathcode);
+ scan_delimiter(null, no_mathcode);
+ }
+ if ((c % delimited_code) == above_code)
+ scan_normal_dimen();
+ tex_error("Ambiguous; you need another { and }", hlp);
+ } else {
+ incompleat_noad = new_node(fraction_noad, 0);
+ numerator(incompleat_noad) = new_node(sub_mlist_node, 0);
+ math_list(numerator(incompleat_noad)) = vlink(head);
+ vlink(head) = null;
+ tail = head;
+ m_style = cramped_style(m_style);
+
+ if (c >= delimited_code) {
+ q = new_node(delim_node, 0);
+ left_delimiter(incompleat_noad) = q;
+ q = new_node(delim_node, 0);
+ right_delimiter(incompleat_noad) = q;
+ scan_delimiter(left_delimiter(incompleat_noad), no_mathcode);
+ scan_delimiter(right_delimiter(incompleat_noad), no_mathcode);
+ }
+ switch (c % delimited_code) {
+ case above_code:
+ scan_normal_dimen();
+ thickness(incompleat_noad) = cur_val;
+ break;
+ case over_code:
+ thickness(incompleat_noad) = default_code;
+ break;
+ case atop_code:
+ thickness(incompleat_noad) = 0;
+ break;
+ } /* there are no other cases */
+ }
+}
+
+
+
+@ At the end of a math formula or subformula, the |fin_mlist| routine is
+called upon to return a pointer to the newly completed mlist, and to
+pop the nest back to the enclosing semantic level. The parameter to
+|fin_mlist|, if not null, points to a |fence_noad| that ends the
+current mlist; this |fence_noad| has not yet been appended.
+
+@c
+pointer fin_mlist(pointer p)
+{
+ pointer q; /* the mlist to return */
+ if (incompleat_noad != null) {
+ if (denominator(incompleat_noad) != null) {
+ type(denominator(incompleat_noad)) = sub_mlist_node;
+ } else {
+ q = new_node(sub_mlist_node, 0);
+ denominator(incompleat_noad) = q;
+ }
+ math_list(denominator(incompleat_noad)) = vlink(head);
+ if (p == null) {
+ q = incompleat_noad;
+ } else {
+ q = math_list(numerator(incompleat_noad));
+ if ((type(q) != fence_noad) || (subtype(q) != left_noad_side)
+ || (delim_ptr == null))
+ confusion("right"); /* this can't happen */
+ math_list(numerator(incompleat_noad)) = vlink(delim_ptr);
+ vlink(delim_ptr) = incompleat_noad;
+ vlink(incompleat_noad) = p;
+ }
+ } else {
+ vlink(tail) = p;
+ q = vlink(head);
+ }
+ pop_nest();
+ return q;
+}
+
+
+@ Now at last we're ready to see what happens when a right brace occurs
+in a math formula. Two special cases are simplified here: Braces are effectively
+removed when they surround a single Ord without sub/superscripts, or when they
+surround an accent that is the nucleus of an Ord atom.
+
+@c
+void close_math_group(pointer p)
+{
+ pointer q;
+ int old_style = m_style;
+ unsave_math();
+
+ decr(save_ptr);
+ assert(saved_type(0) == saved_math);
+ type(saved_value(0)) = sub_mlist_node;
+ p = fin_mlist(null);
+ math_list(saved_value(0)) = p;
+ if (p != null) {
+ if (vlink(p) == null) {
+ if (type(p) == simple_noad && subtype(p) == ord_noad_type) {
+ if (subscr(p) == null && supscr(p) == null) {
+ type(saved_value(0)) = type(nucleus(p));
+ if (type(nucleus(p)) == math_char_node) {
+ math_fam(saved_value(0)) = math_fam(nucleus(p));
+ math_character(saved_value(0)) =
+ math_character(nucleus(p));
+ } else {
+ math_list(saved_value(0)) = math_list(nucleus(p));
+ math_list(nucleus(p)) = null;
+ }
+ delete_attribute_ref(node_attr(saved_value(0)));
+ node_attr(saved_value(0)) = node_attr(nucleus(p));
+ node_attr(nucleus(p)) = null;
+ flush_node(p);
+ }
+ } else if (type(p) == accent_noad) {
+ if (saved_value(0) == nucleus(tail)) {
+ if (type(tail) == simple_noad
+ && subtype(tail) == ord_noad_type) {
+ q = head;
+ while (vlink(q) != tail)
+ q = vlink(q);
+ vlink(q) = p;
+ nucleus(tail) = null;
+ subscr(tail) = null;
+ supscr(tail) = null;
+ delete_attribute_ref(node_attr(p));
+ node_attr(p) = node_attr(tail);
+ node_attr(tail) = null;
+ flush_node(tail);
+ tail = p;
+ }
+ }
+ }
+ }
+ }
+ if (vlink(saved_value(0)) > 0) {
+ pointer q;
+ q = new_node(math_char_node, 0);
+ nucleus(vlink(saved_value(0))) = q;
+ vlink(saved_value(0)) = null;
+ saved_value(0) = q;
+ (void) scan_math(saved_value(0), old_style);
+ /* restart */
+ }
+}
+
+
+@ We have dealt with all constructions of math mode except `\.{\\left}' and
+`\.{\\right}', so the picture is completed by the following sections of
+the program. The |middle| feature of eTeX allows one ore several \.{\\middle}
+delimiters to appear between \.{\\left} and \.{\\right}.
+
+@c
+void math_left_right(void)
+{
+ halfword t; /* |left_noad_side| .. |right_noad_side| */
+ pointer p; /* new noad */
+ pointer q; /* resulting mlist */
+ pointer r; /* temporary */
+ t = cur_chr;
+ if ((t != left_noad_side) && (cur_group != math_left_group)) {
+ if (cur_group == math_shift_group) {
+ scan_delimiter(null, no_mathcode);
+ if (t == middle_noad_side) {
+ const char *hlp[] = {
+ "I'm ignoring a \\middle that had no matching \\left.",
+ NULL
+ };
+ tex_error("Extra \\middle", hlp);
+ } else {
+ const char *hlp[] = {
+ "I'm ignoring a \\right that had no matching \\left.",
+ NULL
+ };
+ tex_error("Extra \\right", hlp);
+ }
+ } else {
+ off_save();
+ }
+ } else {
+ p = new_noad();
+ type(p) = fence_noad;
+ subtype(p) = (quarterword) t;
+ r = new_node(delim_node, 0);
+ delimiter(p) = r;
+ scan_delimiter(delimiter(p), no_mathcode);
+ if (t == left_noad_side) {
+ q = p;
+ } else {
+ q = fin_mlist(p);
+ unsave_math();
+ }
+ if (t != right_noad_side) {
+ push_math(math_left_group, m_style);
+ vlink(head) = q;
+ tail = p;
+ delim_ptr = p;
+ } else {
+ tail_append(new_noad());
+ subtype(tail) = inner_noad_type;
+ r = new_node(sub_mlist_node, 0);
+ nucleus(tail) = r;
+ math_list(nucleus(tail)) = q;
+ }
+ }
+}
+
+
+@ \TeX\ gets to the following part of the program when
+the first `\.\$' ending a display has been scanned.
+
+@c
+static void check_second_math_shift(void)
+{
+ get_x_token();
+ if (cur_cmd != math_shift_cmd) {
+ const char *hlp[] = {
+ "The `$' that I just saw supposedly matches a previous `$$'.",
+ "So I shall assume that you typed `$$' both times.",
+ NULL
+ };
+ back_error("Display math should end with $$", hlp);
+ }
+}
+
+static void check_display_math_end(void)
+{
+ if (cur_chr != cramped_display_style) {
+ const char *hlp[] = {
+ "I shall assume that you typed that.",
+ NULL
+ };
+ tex_error("Display math should end with \\Ustopdisplaymath", hlp);
+ }
+}
+
+static void check_inline_math_end(void)
+{
+ if (cur_chr != cramped_text_style) {
+ const char *hlp[] = {
+ "I shall assume that you typed that.",
+ NULL
+ };
+ tex_error("Inline math should end with \\Ustopmath", hlp);
+ }
+}
+
+@ @c
+void resume_after_display(void)
+{
+ if (cur_group != math_shift_group)
+ confusion("display");
+ unsave_math();
+ prev_graf = prev_graf + 3;
+ push_nest();
+ mode = hmode;
+ space_factor = 1000;
+ tail_append(make_local_par_node()); /* this needs to be intercepted in
+ the display math start ! */
+ get_x_token();
+ if (cur_cmd != spacer_cmd)
+ back_input();
+ if (nest_ptr == 1) {
+ lua_node_filter_s(buildpage_filter_callback, "after_display");
+ build_page();
+ }
+}
+
+
+@ If the inline directions of \.{\\pardir} and \.{\\mathdir} are
+opposite, then this function will return true. Discovering that fact
+is somewhat odd because it needs traversal of the |save_stack|.
+The occurance of displayed equations is weird enough that this is
+probably still better than having yet another field in the |input_stack|
+structures.
+
+None of this makes much sense if the inline direction of either one of
+\.{\\pardir} or \.{\\mathdir} is vertical, but in that case the current
+math machinery is ill suited anyway so I do not bother to test that.
+
+@c
+static boolean math_and_text_reversed_p(void)
+{
+ int i = save_ptr - 1;
+ while (save_type(i) != level_boundary)
+ i--;
+ while (i < save_ptr) {
+ if (save_type(i) == restore_old_value &&
+ save_value(i) == int_base + par_direction_code) {
+ if (textdir_opposite(math_direction, save_value(i - 1)))
+ return true;
+ }
+ i++;
+ }
+ return false;
+}
+
+
+
+@ The fussiest part of math mode processing occurs when a displayed formula is
+being centered and placed with an optional equation number.
+
+
+At this time we are in vertical mode (or internal vertical mode).
+
+ |p| points to the mlist for the formula.
+ |a| is either |null| or it points to a box containing the equation number.
+ |l| is true if there was an \.{\\leqno}/ (so |a| is a horizontal box).
+
+
+@c
+static void finish_displayed_math(boolean l, pointer a, pointer p)
+{
+ pointer eq_box; /* box containing the equation */
+ scaled eq_w; /* width of the equation */
+ scaled line_w; /* width of the line */
+ scaled eqno_w; /* width of equation number */
+ scaled eqno_w2; /* width of equation number plus space to separate from equation */
+ scaled line_s; /* move the line right this much */
+ scaled d; /* displacement of equation in the line */
+ small_number g1, g2; /* glue parameter codes for before and after */
+ pointer r; /* kern node used to position the display */
+ pointer t; /* tail of adjustment list */
+ pointer pre_t; /* tail of pre-adjustment list */
+ boolean swap_dir; /* true if the math and surrounding text dirs are opposed */
+ swap_dir = math_and_text_reversed_p();
+
+ adjust_tail = adjust_head;
+ pre_adjust_tail = pre_adjust_head;
+ eq_box = hpack(p, 0, additional, -1);
+ p = list_ptr(eq_box);
+ t = adjust_tail;
+ adjust_tail = null;
+ pre_t = pre_adjust_tail;
+ pre_adjust_tail = null;
+ eq_w = width(eq_box);
+ line_w = display_width;
+ line_s = display_indent;
+ if (a == null) {
+ eqno_w = 0;
+ eqno_w2 = 0;
+ } else {
+ eqno_w = width(a);
+ eqno_w2 = eqno_w + get_math_quad(text_size);
+ }
+ if (eq_w + eqno_w2 > line_w) {
+ /* The user can force the equation number to go on a separate line
+ by causing its width to be zero. */
+ if ((eqno_w != 0)
+ && ((eq_w - total_shrink[normal] + eqno_w2 <= line_w)
+ || (total_shrink[sfi] != 0) || (total_shrink[fil] != 0)
+ || (total_shrink[fill] != 0)
+ || (total_shrink[filll] != 0))) {
+ list_ptr(eq_box) = null;
+ flush_node(eq_box);
+ eq_box = hpack(p, line_w - eqno_w2, exactly, -1);
+ } else {
+ eqno_w = 0;
+ if (eq_w > line_w) {
+ list_ptr(eq_box) = null;
+ flush_node(eq_box);
+ eq_box = hpack(p, line_w, exactly, -1);
+ }
+ }
+ eq_w = width(eq_box);
+ }
+ /* We try first to center the display without regard to the existence of
+ the equation number. If that would make it too close (where ``too close''
+ means that the space between display and equation number is less than the
+ width of the equation number), we either center it in the remaining space
+ or move it as far from the equation number as possible. The latter alternative
+ is taken only if the display begins with glue, since we assume that the
+ user put glue there to control the spacing precisely.
+ */
+ d = half(line_w - eq_w);
+ if ((eqno_w > 0) && (d < 2 * eqno_w)) { /* too close */
+ d = half(line_w - eq_w - eqno_w);
+ if (p != null)
+ if (!is_char_node(p))
+ if (type(p) == glue_node)
+ d = 0;
+ }
+
+ /* If the equation number is set on a line by itself, either before or
+ after the formula, we append an infinite penalty so that no page break will
+ separate the display from its number; and we use the same size and
+ displacement for all three potential lines of the display, even though
+ `\.{\\parshape}' may specify them differently.
+ */
+ tail_append(new_penalty(int_par(pre_display_penalty_code)));
+ if ((d + line_s <= pre_display_size) || l) { /* not enough clearance */
+ g1 = above_display_skip_code;
+ g2 = below_display_skip_code;
+ } else {
+ g1 = above_display_short_skip_code;
+ g2 = below_display_short_skip_code;
+ }
+
+ if (l && (eqno_w == 0)) { /* \.{\\leqno} on a forced single line due to |width=0| */
+ /* it follows that |type(a)=hlist_node| */
+ if (swap_dir) {
+ shift_amount(a) = line_w + line_s;
+ } else {
+ shift_amount(a) = line_s;
+ }
+ append_to_vlist(a);
+ tail_append(new_penalty(inf_penalty));
+ } else {
+ tail_append(new_param_glue(g1));
+ }
+
+ if (eqno_w != 0) {
+ r = new_kern(line_w - eq_w - eqno_w - d);
+ if (l) {
+ vlink(a) = r;
+ vlink(r) = eq_box;
+ eq_box = a;
+ d = 0;
+ } else {
+ vlink(eq_box) = r;
+ vlink(r) = a;
+ }
+ eq_box = hpack(eq_box, 0, additional, -1);
+ }
+ if (swap_dir) {
+ /* |d = line_w - d;| */
+ if (eqno_w != 0) {
+ if (l)
+ d = line_w - width(eq_box);
+ else
+ d = 0;
+ } else {
+ d = line_w - eq_w - eqno_w - d;
+ }
+ }
+ shift_amount(eq_box) = line_s + d;
+ append_to_vlist(eq_box);
+
+ if ((a != null) && (eqno_w == 0) && !l) {
+ tail_append(new_penalty(inf_penalty));
+ if (!swap_dir) {
+ shift_amount(a) = line_s + line_w - width(a);
+ } else {
+ shift_amount(a) = line_s;
+ }
+ append_to_vlist(a);
+ g2 = 0;
+ }
+ if (t != adjust_head) { /* migrating material comes after equation number */
+ vlink(tail) = vlink(adjust_head);
+ tail = t;
+ }
+ if (pre_t != pre_adjust_head) {
+ vlink(tail) = vlink(pre_adjust_head);
+ tail = pre_t;
+ }
+ tail_append(new_penalty(int_par(post_display_penalty_code)));
+ if (g2 > 0)
+ tail_append(new_param_glue(g2));
+
+ resume_after_display();
+}
+
+@ @c
+void after_math(void)
+{
+ int m; /* |mmode| or |-mmode| */
+ pointer p; /* the formula */
+ pointer a = null; /* box containing equation number */
+ boolean l = false; /* `\.{\\leqno}' instead of `\.{\\eqno}' */
+ m = mode;
+ p = fin_mlist(null); /* this pops the nest */
+ if (cur_cmd == math_shift_cs_cmd &&
+ (cur_chr == text_style || cur_chr == display_style)) {
+ you_cant();
+ }
+ if (mode == -m) { /* end of equation number */
+ if (cur_cmd == math_shift_cmd) {
+ check_second_math_shift();
+ } else {
+ check_display_math_end();
+ }
+ run_mlist_to_hlist(p, text_style, false);
+ a = hpack(vlink(temp_head), 0, additional, -1);
+ unsave_math();
+ decr(save_ptr); /* now |cur_group=math_shift_group| */
+ assert(saved_type(0) == saved_eqno);
+ if (saved_value(0) == 1)
+ l = true;
+ m = mode;
+ p = fin_mlist(null);
+ }
+ if (m < 0) {
+ /* The |unsave| is done after everything else here; hence an appearance of
+ `\.{\\mathsurround}' inside of `\.{\$...\$}' affects the spacing at these
+ particular \.\$'s. This is consistent with the conventions of
+ `\.{\$\$...\$\$}', since `\.{\\abovedisplayskip}' inside a display affects the
+ space above that display.
+ */
+ if (cur_cmd == math_shift_cs_cmd) {
+ check_inline_math_end();
+ }
+ tail_append(new_math(math_surround, before));
+ if (dir_math_save) {
+ tail_append(new_dir(math_direction));
+ }
+ run_mlist_to_hlist(p, text_style, (mode > 0));
+ vlink(tail) = vlink(temp_head);
+ while (vlink(tail) != null)
+ tail = vlink(tail);
+ if (dir_math_save) {
+ tail_append(new_dir(math_direction - 64));
+ }
+ dir_math_save = false;
+ tail_append(new_math(math_surround, after));
+ space_factor = 1000;
+ unsave_math();
+ } else {
+ if (a == null) {
+ if (cur_cmd == math_shift_cmd) {
+ check_second_math_shift();
+ } else {
+ check_display_math_end();
+ }
+ }
+ run_mlist_to_hlist(p, display_style, false);
+ finish_displayed_math(l, a, vlink(temp_head));
+ }
+}
+
+
+@ When \.{\\halign} appears in a display, the alignment routines operate
+essentially as they do in vertical mode. Then the following program is
+activated, with |p| and |q| pointing to the beginning and end of the
+resulting list, and with |aux_save| holding the |prev_depth| value.
+
+@c
+void finish_display_alignment(pointer p, pointer q, halfword saved_prevdepth)
+{
+ do_assignments();
+ if (cur_cmd != math_shift_cmd) {
+ const char *hlp[] = {
+ "Displays can use special alignments (like \\eqalignno)",
+ "only if nothing but the alignment itself is between $$'s.",
+ NULL
+ };
+ back_error("Missing $$ inserted", hlp);
+ } else {
+ check_second_math_shift();
+ }
+ pop_nest();
+ tail_append(new_penalty(int_par(pre_display_penalty_code)));
+ tail_append(new_param_glue(above_display_skip_code));
+ vlink(tail) = p;
+ if (p != null)
+ tail = q;
+ tail_append(new_penalty(int_par(post_display_penalty_code)));
+ tail_append(new_param_glue(below_display_skip_code));
+ cur_list.prev_depth_field = saved_prevdepth;
+ resume_after_display();
+}
+
+@ Interface to \.{\\Umath} and \.{\\mathstyle}
+
+@c
+void setup_math_style(void)
+{
+ pointer q;
+ tail_append(new_noad());
+ q = new_node(math_char_node, 0);
+ nucleus(tail) = q;
+ (void) scan_math(nucleus(tail), num_style(m_style));
+}
+
+
+@ @c
+void print_math_style(void)
+{
+ if (abs(mode) == mmode)
+ print_int(m_style);
+ else
+ print_int(-1);
+}