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author | Karl Berry <karl@freefriends.org> | 2021-02-25 19:22:25 +0000 |
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committer | Karl Berry <karl@freefriends.org> | 2021-02-25 19:22:25 +0000 |
commit | ad547a6b5986815fda458221149728d9d9ab1d87 (patch) | |
tree | 16296910eb3eca724371474ea9aea3994dc69614 /Build/source/texk/web2c/luatexdir/tex/align.c | |
parent | 947b43de3dd21d58ccc2ffadefc4441ea1c2a813 (diff) |
restore Build,TODO from r57911
git-svn-id: svn://tug.org/texlive/trunk@57915 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Build/source/texk/web2c/luatexdir/tex/align.c')
-rw-r--r-- | Build/source/texk/web2c/luatexdir/tex/align.c | 1299 |
1 files changed, 1299 insertions, 0 deletions
diff --git a/Build/source/texk/web2c/luatexdir/tex/align.c b/Build/source/texk/web2c/luatexdir/tex/align.c new file mode 100644 index 00000000000..bb721856fac --- /dev/null +++ b/Build/source/texk/web2c/luatexdir/tex/align.c @@ -0,0 +1,1299 @@ +/* + +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" + +void fin_align(void); +void init_row(void); +void init_col(void); + +#define noDEBUG + +/*tex + + It's sort of a miracle whenever \.{\\halign} and \.{\\valign} work, because + they cut across so many of the control structures of \TeX. Therefore the + present page is probably not the best place for a beginner to start reading + this program; it is better to master everything else first. + + Let us focus our thoughts on an example of what the input might be, in order + to get some idea about how the alignment miracle happens. The example doesn't + do anything useful, but it is sufficiently general to indicate all of the + special cases that must be dealt with; please do not be disturbed by its + apparent complexity and meaninglessness. + + \starttyping + \tabskip 2pt plus 3pt + \halign to 300pt{u1#v1& + \hskip 50pt \tabskip 1pt plus 1fil u2#v2& + \hskip 50pt u3#v3\cr + \hskip 25pt a1&\omit a2&\vrule\cr + \hskip 25pt \noalign\{\vskip 3pt} + \hskip 25pt b1\span b2\cr + \hskip 25pt \omit&c2\span\omit\cr} + \stoptyping + + Here's what happens: + + \startitemize + + \startitem + When `\.{\\halign to 300pt\{}' is scanned, the |scan_spec| routine + places the 300pt dimension onto the |save_stack|, and an + |align_group| code is placed above it. This will make it possible to + complete the alignment when the matching `\.\}' is found. + \stopitem + + \startitem + The preamble is scanned next. Macros in the preamble are not + expanded, except as part of a tabskip specification. For example, if + \.{u2} had been a macro in the preamble above, it would have been + expanded, since \TeX\ must look for `\.{minus...}' as part of the + tabskip glue. A ``preamble list'' is constructed based on the user's + preamble; in our case it contains the following seven items: + + \starttabulate + \NC \type{\glue 2pt plus 3pt} \NC the tabskip preceding column 1 \NC \NR + \NC \type{\alignrecord} of width $-\infty$ \NC preamble info for column 1 \NC \NR + \NC \type{\glue 2pt plus 3pt} \NC the tabskip between columns 1 and 2 \NC \NR + \NC \type{\alignrecord} of width $-\infty$ \NC preamble info for column 2 \NC \NR + \NC \type{\glue 1pt plus 1fil} \NC the tabskip between columns 2 and 3 \NC \NR + \NC \type{\alignrecord} of width $-\infty$ \NC preamble info for column 3 \NC \NR + \NC \type{\glue 1pt plus 1fil} \NC the tabskip following column 3 \NC \NR + \stoptabulate + + These ``alignrecord'' entries have the same size as an |unset_node|, + since they will later be converted into such nodes. These alignrecord + nodes have no |depth| field; this is split into |u_part| and + |v_part|, and they point to token lists for the templates of the + alignment. For example, the |u_part| field in the first alignrecord + points to the token list `\.{u1}', i.e., the template preceding the + `\.\#' for column~1. Furthermore, They have a |span_ptr| instead of a + |node_attr| field, and these |span_ptr| fields are initially set to + the value |end_span|, for reasons explained below. + \stopitem + + \startitem + \TeX\ now looks at what follows the \.{\\cr} that ended the preamble. + It is not `\.{\\noalign}' or `\.{\\omit}', so this input is put back + to be read again, and the template `\.{u1}' is fed to the scanner. + Just before reading `\.{u1}', \TeX\ goes into restricted horizontal + mode. Just after reading `\.{u1}', \TeX\ will see `\.{a1}', and then + (when the {\.\&} is sensed) \TeX\ will see `\.{v1}'. Then \TeX\ scans + an |endv| token, indicating the end of a column. At this point an + |unset_node| is created, containing the contents of the current hlist + (i.e., `\.{u1a1v1}'). The natural width of this unset node replaces + the |width| field of the alignrecord for column~1; in general, the + alignrecords will record the maximum natural width that has occurred + so far in a given column. + \stopitem + + \startitem + Since `\.{\\omit}' follows the `\.\&', the templates for column~2 are + now bypassed. Again \TeX\ goes into restricted horizontal mode and + makes an |unset_node| from the resulting hlist; but this time the + hlist contains simply `\.{a2}'. The natural width of the new unset + box is remembered in the |width| field of the alignrecord for + column~2. + \stopitem + + \startitem + A third |unset_node| is created for column 3, using essentially the + mechanism that worked for column~1; this unset box contains + `\.{u3\\vrule v3}'. The vertical rule in this case has running + dimensions that will later extend to the height and depth of the + whole first row, since each |unset_node| in a row will eventually + inherit the height and depth of its enclosing box. + \stopitem + + \startitem + The first row has now ended; it is made into a single unset box + comprising the following seven items: + + \starttyping + \glue 2pt plus 3pt + \unsetbox for 1 column: u1a1v1 + \glue 2pt plus 3pt + \unsetbox for 1 column: a2 + \glue 1pt plus 1fil + \unsetbox for 1 column: u3\vrule v3 + \glue 1pt plus 1fil + \stoptyping + + The width of this unset row is unimportant, but it has the correct + height and depth, so the correct baselineskip glue will be computed + as the row is inserted into a vertical list. + \stopitem + + \startitem + Since `\.{\\noalign}' follows the current \.{\\cr}, \TeX\ appends + additional material (in this case \.{\\vskip 3pt}) to the vertical + list. While processing this material, \TeX\ will be in internal + vertical mode, and |no_align_group| will be on |save_stack|. + \stopitem + + \startitem + The next row produces an unset box that looks like this: + + \starttyping + \glue 2pt plus 3pt + \unsetbox for 2 columns: u1b1v1u2b2v2 + \glue 1pt plus 1fil + \unsetbox for 1 column: {(empty)} + \glue 1pt plus 1fil + \stoptyping + + The natural width of the unset box that spans columns 1~and~2 is + stored in a ``span node,'' which we will explain later; the + |span_ptr| field of the alignrecord for column~1 now points to the + new span node, and the |span_ptr| of the span node points to + |end_span|. + \stopitem + + \startitem + + The final row produces the unset box + + \starttyping + \glue 2pt plus 3pt\cr + \unsetbox for 1 column: {(empty)} + \glue 2pt plus 3pt\cr + \unsetbox for 2 columns: u2c2v2 + \glue 1pt plus 1fil + \stoptyping + + A new span node is attached to the alignrecord for column 2. + \stopitem + + \startitem + The last step is to compute the true column widths and to change all + the unset boxes to hboxes, appending the whole works to the vertical + list that encloses the \.{\\halign}. The rules for deciding on the + final widths of each unset column box will be explained below. + \stopitem + + \stopitemize + + Note that as \.{\\halign} is being processed, we fearlessly give up control + to the rest of \TeX. At critical junctures, an alignment routine is called + upon to step in and do some little action, but most of the time these + routines just lurk in the background. It's something like post-hypnotic + suggestion. + + We have mentioned that alignrecords contain no |height| or |depth| fields. + Their |glue_sign| and |glue_order| are pre-empted as well, since it is + necessary to store information about what to do when a template ends. This + information is called the |extra_info| field. + +*/ + +/*tex The pointer to \<u_j> token list: */ + +#define u_part(A) vlink((A)+depth_offset) + +/*tex The pointer to \<v_j> token list */ + +#define v_part(A) vinfo((A)+depth_offset) + +/*tex A column spanning list */ + +#define span_ptr(A) vinfo((A)+1) + +/*tex Info to remember during template */ + +#define extra_info(A) vinfo((A)+list_offset) + +/*tex + + Alignments can occur within alignments, so a small stack is used to access + the alignrecord information. At each level we have a |preamble| pointer, + indicating the beginning of the preamble list; a |cur_align| pointer, + indicating the current position in the preamble list; a |cur_span| pointer, + indicating the value of |cur_align| at the beginning of a sequence of spanned + columns; a |cur_loop| pointer, indicating the tabskip glue before an + alignrecord that should be copied next if the current list is extended; and + the |align_state| variable, which indicates the nesting of braces so that + \.{\\cr} and \.{\\span} and tab marks are properly intercepted. There also + are pointers |cur_head| and |cur_tail| to the head and tail of a list of + adjustments being moved out from horizontal mode to vertical~mode, and alike + |cur_pre_head| and |cur_pre_tail| for pre-adjust lists. + + The current values of these nine quantities appear in global variables; when + they have to be pushed down, they are stored in 6-word nodes, and |align_ptr| + points to the topmost such node. + +*/ + +/*tex This could be in |texnodes.h| but it's documented here. */ + +/*tex The current preamble list: */ + +#define preamble vlink(align_head) + +/*tex The current position in the preamble list: */ + +pointer cur_align = null; + +/*tex The start of the currently spanned columns in the preamble list: */ + +pointer cur_span = null; + +/*tex A place to copy when extending a periodic preamble: */ + +pointer cur_loop = null; + +/*tex The most recently pushed-down alignment stack node: */ + +pointer align_ptr = null; + +/*tex Adjustment list pointers: */ + +pointer cur_head = null, cur_tail = null; + +/*tex Pre-adjustment list pointers: */ + +pointer cur_pre_head = null, cur_pre_tail = null; + +/*tex + + The |align_state| and |preamble| variables are initialized elsewhere. + + Alignment stack maintenance is handled by a pair of trivial routines called + |push_alignment| and |pop_alignment|. + + (HH:) It makes not much sense to add support for an \.{attr} keyword to + \.{\\halign} and \.{\\valign} because then we need to decide if we tag rows + or cells or both or come up with \.{cellattr} and \.{rowattr} and such. But + then it even makes sense to have explicit commands (in addition to the + seperator) to tags individual cells. Too muss hassle for now and the + advantages are not that large. + +*/ + +static void push_alignment(void) +{ + /*tex The new alignment stack node: */ + pointer p; + p = new_node(align_stack_node, 0); + vinfo(p + 1) = align_ptr; + vlink(p + 1) = cur_align; + vinfo(p + 2) = preamble; + vlink(p + 2) = cur_span; + vinfo(p + 3) = cur_loop; + vlink(p + 3) = align_state; + vinfo(p + 4) = cur_head; + vlink(p + 4) = cur_tail; + vinfo(p + 5) = cur_pre_head; + vlink(p + 5) = cur_pre_tail; + align_ptr = p; + cur_head = new_node(temp_node, 0); + cur_pre_head = new_node(temp_node, 0); +} + +static void pop_alignment(void) +{ + /*tex The top alignment stack node: */ + pointer p; + flush_node(cur_head); + flush_node(cur_pre_head); + p = align_ptr; + cur_pre_tail = vlink(p + 5); + cur_pre_head = vinfo(p + 5); + cur_tail = vlink(p + 4); + cur_head = vinfo(p + 4); + align_state = vlink(p + 3); + cur_loop = vinfo(p + 3); + cur_span = vlink(p + 2); + preamble = vinfo(p + 2); + cur_align = vlink(p + 1); + align_ptr = vinfo(p + 1); + flush_node(p); +} + +/*tex + + \TeX\ has eight procedures that govern alignments: |init_align| and + |fin_align| are used at the very beginning and the very end; |init_row| and + |fin_row| are used at the beginning and end of individual rows; |init_span| + is used at the beginning of a sequence of spanned columns (possibly involving + only one column); |init_col| and |fin_col| are used at the beginning and end + of individual columns; and |align_peek| is used after \.{\\cr} to see whether + the next item is \.{\\noalign}. + + We shall consider these routines in the order they are first used during the + course of a complete \.{\\halign}, namely |init_align|, |align_peek|, + |init_row|, |init_span|, |init_col|, |fin_col|, |fin_row|, |fin_align|. + + The preamble is copied directly, except that \.{\\tabskip} causes a change to + the tabskip glue, thereby possibly expanding macros that immediately follow + it. An appearance of \.{\\span} also causes such an expansion. + + Note that if the preamble contains `\.{\\global\\tabskip}', the + `\.{\\global}' token survives in the preamble and the `\.{\\tabskip}' defines + new tabskip glue (locally). + +*/ + +static void get_preamble_token(void) +{ + RESTART: + get_token(); + while ((cur_chr == span_code) && (cur_cmd == tab_mark_cmd)) { + /*tex This token will be expanded once. */ + get_token(); + if (cur_cmd > max_command_cmd) { + expand(); + get_token(); + } + } + if (cur_cmd == endv_cmd) + fatal_error("(interwoven alignment preambles are not allowed)"); + if ((cur_cmd == assign_glue_cmd) + && (cur_chr == glue_base + tab_skip_code)) { + scan_optional_equals(); + scan_glue(glue_val_level); + if (global_defs_par > 0) + geq_define(glue_base + tab_skip_code, glue_ref_cmd, cur_val); + else + eq_define(glue_base + tab_skip_code, glue_ref_cmd, cur_val); + goto RESTART; + } +} + +/*tex + + When \.{\\halign} or \.{\\valign} has been scanned in an appropriate mode, + \TeX\ calls |init_align|, whose task is to get everything off to a good + start. This mostly involves scanning the preamble and putting its information + into the preamble list. + +*/ + +void init_align(void) +{ + /*tex |warning_index| value for error messages */ + pointer save_cs_ptr; + /*tex for short-term temporary use */ + pointer p, r; + /*tex \.{\\halign} or \.{\\valign}, usually */ + save_cs_ptr = cur_cs; + push_alignment(); + /*tex enter a new alignment level */ + align_state = -1000000; + /*tex + + When \.{\\halign} is used as a displayed formula, there should be no + other pieces of mlists present. + + */ + if ((cur_list.mode_field == mmode) && ((cur_list.tail_field != cur_list.head_field) || (incompleat_noad_par != null))) { + const char *hlp[] = { + "Displays can use special alignments (like \\eqalignno)", + "only if nothing but the alignment itself is between $$'s.", + "So I've deleted the formulas that preceded this alignment.", + NULL + }; + tex_error("Improper \\halign inside $$'s", hlp); + flush_math(); + } + /*tex Enter a new semantic level. */ + push_nest(); + /*tex + + In vertical modes, |prev_depth| already has the correct value. But if we + are in |mmode| (displayed formula mode), we reach out to the enclosing + vertical mode for the |prev_depth| value that produces the correct + baseline calculations. + */ + if (cur_list.mode_field == mmode) { + cur_list.mode_field = -vmode; + prev_depth_par = nest[nest_ptr - 2].prev_depth_field; + } else if (cur_list.mode_field > 0) { + cur_list.mode_field = -(cur_list.mode_field); + } + scan_spec(align_group); + /*tex Scan the preamble. */ + preamble = null; + cur_align = align_head; + cur_loop = null; + scanner_status = aligning; + warning_index = save_cs_ptr; + align_state = -1000000; + /*tex At this point, |cur_cmd=left_brace|. */ + while (true) { + /*tex Append the current tabskip glue to the preamble list. */ + r = new_param_glue(tab_skip_code); + vlink(cur_align) = r; + cur_align = vlink(cur_align); + if (cur_cmd == car_ret_cmd) { + /*tex \.{\\cr} ends the preamble. */ + break; + } + /*tex + + Scan preamble text until |cur_cmd| is |tab_mark| or |car_ret| and + then scan the template \<u_j>, putting the resulting token list in + |hold_token_head|. Spaces are eliminated from the beginning of a + template. + + */ + p = hold_token_head; + token_link(p) = null; + while (1) { + get_preamble_token(); + if (cur_cmd == mac_param_cmd) + break; + if ((cur_cmd <= car_ret_cmd) && (cur_cmd >= tab_mark_cmd) + && (align_state == -1000000)) { + if ((p == hold_token_head) && (cur_loop == null) && (cur_cmd == tab_mark_cmd)) { + cur_loop = cur_align; + } else { + const char *hlp[] = { + "There should be exactly one # between &'s, when an", + "\\halign or \\valign is being set up. In this case you had", + "none, so I've put one in; maybe that will work.", + NULL + }; + back_input(); + tex_error("Missing # inserted in alignment preamble", hlp); + break; + } + } else if ((cur_cmd != spacer_cmd) || (p != hold_token_head)) { + r = get_avail(); + token_link(p) = r; + p = token_link(p); + token_info(p) = cur_tok; + } + } + r = new_node(align_record_node, 0); + vlink(cur_align) = r; + /*tex A new align record: */ + cur_align = vlink(cur_align); + span_ptr(cur_align) = end_span; + width(cur_align) = null_flag; + u_part(cur_align) = token_link(hold_token_head); + /*tex + + Scan the template \<v_j>, putting the resulting token list in + |hold_token_head|. + + */ + p = hold_token_head; + token_link(p) = null; + while (1) { + CONTINUE: + get_preamble_token(); + if ((cur_cmd <= car_ret_cmd) && (cur_cmd >= tab_mark_cmd) && (align_state == -1000000)) + break; + if (cur_cmd == mac_param_cmd) { + const char *hlp[] = { + "There should be exactly one # between &'s, when an", + "\\halign or \\valign is being set up. In this case you had", + "more than one, so I'm ignoring all but the first.", + NULL + }; + tex_error("Only one # is allowed per tab", hlp); + goto CONTINUE; + } + r = get_avail(); + token_link(p) = r; + p = token_link(p); + token_info(p) = cur_tok; + } + r = get_avail(); + token_link(p) = r; + p = token_link(p); + /*tex Put \.{\\endtemplate} at the end: */ + token_info(p) = end_template_token; + v_part(cur_align) = token_link(hold_token_head); + } + scanner_status = normal; + new_save_level(align_group); + if (every_cr_par != null) + begin_token_list(every_cr_par, every_cr_text); + /*tex Look for \.{\\noalign} or \.{\\omit}. */ + align_peek(); +} + +/*tex + + The tricky part about alignments is getting the templates into the scanner at + the right time, and recovering control when a row or column is finished. + + We usually begin a row after each \.{\\cr} has been sensed, unless that + \.{\\cr} is followed by \.{\\noalign} or by the right brace that terminates + the alignment. The |align_peek| routine is used to look ahead and do the + right thing; it either gets a new row started, or gets a \.{\\noalign} + started, or finishes off the alignment. + +*/ + +void align_peek(void) +{ + RESTART: + align_state = 1000000; + do { + get_x_or_protected(); + } while (cur_cmd == spacer_cmd); + if (cur_cmd == no_align_cmd) { + scan_left_brace(); + new_save_level(no_align_group); + if (cur_list.mode_field == -vmode) + normal_paragraph(); + } else if (cur_cmd == right_brace_cmd) { + fin_align(); + } else if ((cur_cmd == car_ret_cmd) && (cur_chr == cr_cr_code)) { + /*tex Ignore \.{\\crcr}. */ + goto RESTART; + } else { + /*tex Start a new row. */ + init_row(); + /*tex Start a new column and replace what we peeked at. */ + init_col(); + } +} + + +/*tex + + The parameter to |init_span| is a pointer to the alignrecord where the next + column or group of columns will begin. A new semantic level is entered, so + that the columns will generate a list for subsequent packaging. + +*/ + +static void init_span(pointer p) +{ + push_nest(); + if (cur_list.mode_field == -hmode) { + space_factor_par = 1000; + } else { + prev_depth_par = ignore_depth; + normal_paragraph(); + } + cur_span = p; +} + +/*tex + + To start a row (i.e., a `row' that rhymes with `dough' but not with `bough'), + we enter a new semantic level, copy the first tabskip glue, and change from + internal vertical mode to restricted horizontal mode or vice versa. The + |space_factor| and |prev_depth| are not used on this semantic level, but we + clear them to zero just to be tidy. + +*/ + +void init_row(void) +{ + push_nest(); + cur_list.mode_field = (-hmode - vmode) - cur_list.mode_field; + if (cur_list.mode_field == -hmode) + space_factor_par = 0; + else + prev_depth_par = 0; + tail_append(new_glue(preamble)); + subtype(cur_list.tail_field) = tab_skip_code + 1; + cur_align = vlink(preamble); + cur_tail = cur_head; + cur_pre_tail = cur_pre_head; + init_span(cur_align); +} + +/*tex + + When a column begins, we assume that |cur_cmd| is either |omit| or else the + current token should be put back into the input until the \<u_j> template has + been scanned. (Note that |cur_cmd| might be |tab_mark| or |car_ret|.) We also + assume that |align_state| is approximately 1000000 at this time. We remain in + the same mode, and start the template if it is called for. + +*/ + +void init_col(void) +{ + extra_info(cur_align) = cur_cmd; + if (cur_cmd == omit_cmd) + align_state = 0; + else { + back_input(); + begin_token_list(u_part(cur_align), u_template); + } + /*tex now |align_state=1000000| */ +} + + +/*tex + + The scanner sets |align_state| to zero when the \<u_j> template ends. When a + subsequent \.{\\cr} or \.{\\span} or tab mark occurs with |align_state=0|, + the scanner activates the following code, which fires up the \<v_j> template. + We need to remember the |cur_chr|, which is either |cr_cr_code|, |cr_code|, + |span_code|, or a character code, depending on how the column text has ended. + + This part of the program had better not be activated when the preamble to + another alignment is being scanned, or when no alignment preamble is active. + +*/ + +void insert_vj_template(void) +{ + if ((scanner_status == aligning) || (cur_align == null)) + fatal_error("(interwoven alignment preambles are not allowed)"); + cur_cmd = extra_info(cur_align); + extra_info(cur_align) = cur_chr; + if (cur_cmd == omit_cmd) + begin_token_list(omit_template, v_template); + else + begin_token_list(v_part(cur_align), v_template); + align_state = 1000000; +} + +/*tex Determine the stretch order */ + +#define determine_stretch_order() do { \ + if (total_stretch[filll]!= 0) o = filll; \ + else if (total_stretch[fill] != 0) o = fill; \ + else if (total_stretch[fil] != 0) o = fil; \ + else if (total_stretch[sfi] != 0) o = sfi; \ + else o=normal; \ +} while (0) + +/*tex Determine the shrink order */ + +#define determine_shrink_order() do { \ + if (total_shrink[filll] != 0) o = filll; \ + else if (total_shrink[fill] != 0) o = fill; \ + else if (total_shrink[fil] != 0) o = fil; \ + else if (total_shrink[sfi] != 0) o = sfi; \ + else o=normal; \ +} while (0) + +/*tex + + When the |endv| command at the end of a \<v_j> template comes through the + scanner, things really start to happen; and it is the |fin_col| routine that + makes them happen. This routine returns |true| if a row as well as a column + has been finished. + +*/ + +boolean fin_col(void) +{ + /*tex the alignrecord after the current one */ + pointer p; + /*tex temporary pointers for list manipulation */ + pointer q, r; + /*tex a new span node */ + pointer s; + /*tex a new unset box */ + pointer u; + /*tex natural width */ + scaled w; + /*tex order of infinity */ + unsigned char o; + /*tex span counter */ + halfword n; + if (cur_align == null) + confusion("endv"); + q = vlink(cur_align); + if (q == null) + confusion("endv"); + if (align_state < 500000) + fatal_error("(interwoven alignment preambles are not allowed)"); + p = vlink(q); + /*tex If the preamble list has been traversed, check that the row has ended. */ + if ((p == null) && (extra_info(cur_align) < cr_code)) { + if (cur_loop != null) { + /*tex Lengthen the preamble periodically: */ + r = new_node(align_record_node, 0); + vlink(q) = r; + /*tex A new align record: */ + p = vlink(q); + span_ptr(p) = end_span; + width(p) = null_flag; + cur_loop = vlink(cur_loop); + /*tex Copy the templates from node |cur_loop| into node |p|. */ + q = hold_token_head; + r = u_part(cur_loop); + while (r != null) { + s = get_avail(); + token_link(q) = s; + q = token_link(q); + token_info(q) = token_info(r); + r = token_link(r); + } + token_link(q) = null; + u_part(p) = token_link(hold_token_head); + q = hold_token_head; + r = v_part(cur_loop); + while (r != null) { + s = get_avail(); + token_link(q) = s; + q = token_link(q); + token_info(q) = token_info(r); + r = token_link(r); + } + token_link(q) = null; + v_part(p) = token_link(hold_token_head); + cur_loop = vlink(cur_loop); + r = new_glue(cur_loop); + vlink(p) = r; + } else { + const char *hlp[] = { + "You have given more \\span or & marks than there were", + "in the preamble to the \\halign or \\valign now in progress.", + "So I'll assume that you meant to type \\cr instead.", + NULL + }; + extra_info(cur_align) = cr_code; + tex_error("Extra alignment tab has been changed to \\cr", hlp); + } + } + if (extra_info(cur_align) != span_code) { + unsave(); + new_save_level(align_group); + /*tex Package an unset box for the current column and record its width. */ + if (cur_list.mode_field == -hmode) { + adjust_tail = cur_tail; + pre_adjust_tail = cur_pre_tail; + u = filtered_hpack(cur_list.head_field, cur_list.tail_field, 0, additional, align_set_group, -1, 0, 0); + w = width(u); + cur_tail = adjust_tail; + adjust_tail = null; + cur_pre_tail = pre_adjust_tail; + pre_adjust_tail = null; + } else { + u = filtered_vpackage(vlink(cur_list.head_field), 0, additional, 0, align_set_group, -1, 0, 0); + w = height(u); + } + /*tex This represents a span count of 1: */ + n = min_quarterword; + if (cur_span != cur_align) { + /*tex Update width entry for spanned columns. */ + q = cur_span; + do { + incr(n); + q = vlink(vlink(q)); + } while (q != cur_align); + if (n > max_quarterword) { + /*tex This can happen, but won't. */ + confusion("too many spans"); + } + q = cur_span; + while (span_span(span_ptr(q)) < n) { + q = span_ptr(q); + } + if (span_span(span_ptr(q)) > n) { + s = new_span_node(span_ptr(q), n, w); + span_ptr(q) = s; + } else if (width(span_ptr(q)) < w) { + width(span_ptr(q)) = w; + } + } else if (w > width(cur_align)) { + width(cur_align) = w; + } + type(u) = unset_node; + span_count(u) = (quarterword) n; + determine_stretch_order(); + glue_order(u) = o; + glue_stretch(u) = total_stretch[o]; + determine_shrink_order(); + glue_sign(u) = o; + glue_shrink(u) = total_shrink[o]; + pop_nest(); + vlink(cur_list.tail_field) = u; + cur_list.tail_field = u; + /*tex Copy the tabskip glue between columns. */ + tail_append(new_glue(vlink(cur_align))); + subtype(cur_list.tail_field) = tab_skip_code + 1; + if (extra_info(cur_align) >= cr_code) { + return true; + } + init_span(p); + } + align_state = 1000000; + do { + get_x_or_protected(); + } while (cur_cmd == spacer_cmd); + cur_align = p; + init_col(); + return false; +} + +/*tex + + A span node is a 3-word record containing |width|, |span_span|, and + |span_ptr| fields. The |span_span| field indicates the number of spanned + columns; the |span_ptr| field points to a span node for the same starting + column, having a greater extent of spanning, or to |end_span|, which has the + largest possible |span_span| field; the |width| field holds the largest + natural width corresponding to a particular set of spanned columns. + + A list of the maximum widths so far, for spanned columns starting at a given + column, begins with the |span_ptr| field of the alignrecord for that column. + The code has to make sure that there is room for |span_ptr| in both the + alignrecord and the span nodes, which is why |span_ptr| replaces |node_attr|. + + The |new_span_node| function is defined in |texnodes.c|. + +*/ + +/*tex This is normally |alink|: */ + +#ifndef span_span +# define span_span(A) vlink((A)+1) +#endif + +/*tex + + At the end of a row, we append an unset box to the current vlist (for + \.{\\halign}) or the current hlist (for \.{\\valign}). This unset box + contains the unset boxes for the columns, separated by the tabskip glue. + Everything will be set later. + +*/ + +void fin_row(void) +{ + /*tex The new unset box: */ + pointer p; + if (cur_list.mode_field == -hmode) { + p = filtered_hpack(cur_list.head_field, cur_list.tail_field, 0, + additional, fin_row_group, -1, 0, 0); + pop_nest(); + if (cur_pre_head != cur_pre_tail) + append_list(cur_pre_head, cur_pre_tail); + append_to_vlist(p,lua_key_index(alignment)); + if (cur_head != cur_tail) + append_list(cur_head, cur_tail); + } else { + p = filtered_vpackage(vlink(cur_list.head_field), + 0, additional, max_depth_par, fin_row_group, -1, 0, 0); + pop_nest(); + vlink(cur_list.tail_field) = p; + cur_list.tail_field = p; + space_factor_par = 1000; + } + type(p) = unset_node; + glue_stretch(p) = 0; + if (every_cr_par != null) + begin_token_list(every_cr_par, every_cr_text); + align_peek(); + /*tex Note that |glue_shrink(p)=0| since |glue_shrink==shift_amount|. */ +} + +/*tex + + Finally, we will reach the end of the alignment, and we can breathe a sigh of + relief that memory hasn't overflowed. All the unset boxes will now be set so + that the columns line up, taking due account of spanned columns. + +*/ + +void fin_align(void) +{ + /*tex registers for the list operations */ + pointer p, q, r, s, u, rr; + /*tex width of column */ + scaled t, w; + /*tex shift offset for unset boxes */ + scaled o; + /*tex matching span amount */ + halfword n; + /*tex temporary storage for |overfull_rule| */ + scaled rule_save; + /*tex temporary storage for |prev_depth| */ + halfword pd; + /*tex temporary storage for |new_glue| */ + halfword ng; + /*tex The |align_group| was for individual entries: */ + if (cur_group != align_group) + confusion("align1"); + unsave(); + /*tex The |align_group| was for the whole alignment: */ + if (cur_group != align_group) + confusion("align0"); + unsave(); + if (nest[nest_ptr - 1].mode_field == mmode) { + o = display_indent_par; + } else { + o = 0; + } + /*tex + + Go through the preamble list, determining the column widths and + changing the alignrecords to dummy unset boxes. + + It's time now to dismantle the preamble list and to compute the + column widths. Let $w_{ij}$ be the maximum of the natural widths of + all entries that span columns $i$ through $j$, inclusive. The + alignrecord for column~$i$ contains $w_{ii}$ in its |width| field, + and there is also a linked list of the nonzero $w_{ij}$ for + increasing $j$, accessible via the |info| field; these span nodes + contain the value $j-i+|min_quarterword|$ in their |link| fields. The + values of $w_{ii}$ were initialized to |null_flag|, which we regard + as $-\infty$. + + The final column widths are defined by the formula $$w_j=\max_{1\L + i\L j}\biggl( w_{ij}-\sum_{i\L k<j}(t_k+w_k)\biggr),$$ where $t_k$ is + the natural width of the tabskip glue between columns $k$ and~$k+1$. + However, if $w_{ij}=-\infty$ for all |i| in the range |1<=i<=j| + (i.e., if every entry that involved column~|j| also involved + column~|j+1|), we let $w_j=0$, and we zero out the tabskip glue after + column~|j|. + + \TeX\ computes these values by using the following scheme: First + $w_1=w_{11}$. Then replace $w_{2j}$ by $\max(w_{2j},w_{1j}-t_1-w_1)$, + for all $j>1$. Then $w_2=w_{22}$. Then replace $w_{3j}$ by + $\max(w_{3j},w_{2j}-t_2-w_2)$ for all $j>2$; and so on. If any $w_j$ + turns out to be $-\infty$, its value is changed to zero and so is the + next tabskip. + + */ + q = vlink(preamble); + do { + flush_list(u_part(q)); + flush_list(v_part(q)); + p = vlink(vlink(q)); + if (width(q) == null_flag) { + /*tex Nullify |width(q)| and the tabskip glue following this column. */ + width(q) = 0; + r = vlink(q); + reset_glue_to_zero(r); + } + if (span_ptr(q) != end_span) { + /*tex + + Merge the widths in the span nodes of |q| with those of |p|, + destroying the span nodes of |q|. + + Merging of two span-node lists is a typical exercise in the + manipulation of linearly linked data structures. The essential + invariant in the following |repeat| loop is that we want to + dispense with node |r|, in |q|'s list, and |u| is its successor; + all nodes of |p|'s list up to and including |s| have been + processed, and the successor of |s| matches |r| or precedes |r| + or follows |r|, according as |link(r)=n| or |link(r)>n| or + |link(r)<n|. + + */ + t = width(q) + width(vlink(q)); + r = span_ptr(q); + s = end_span; + span_ptr(s) = p; + n = min_quarterword + 1; + do { + width(r) = width(r) - t; + u = span_ptr(r); + while (span_span(r) > n) { + s = span_ptr(s); + n = span_span(span_ptr(s)) + 1; + } + if (span_span(r) < n) { + span_ptr(r) = span_ptr(s); + span_ptr(s) = r; + decr(span_span(r)); + s = r; + } else { + if (width(r) > width(span_ptr(s))) + width(span_ptr(s)) = width(r); + flush_node(r); + } + r = u; + } while (r != end_span); + } + type(q) = unset_node; + span_count(q) = min_quarterword; + height(q) = 0; + depth(q) = 0; + glue_order(q) = normal; + glue_sign(q) = normal; + glue_stretch(q) = 0; + glue_shrink(q) = 0; + q = p; + } while (q != null); + /*tex + + Package the preamble list, to determine the actual tabskip glue amounts, + and let |p| point to this prototype box. + + Now the preamble list has been converted to a list of alternating unset + boxes and tabskip glue, where the box widths are equal to the final + column sizes. In case of \.{\\valign}, we change the widths to heights, + so that a correct error message will be produced if the alignment is + overfull or underfull. + + */ + decr(save_ptr); + pack_begin_line = -cur_list.ml_field; + if (cur_list.mode_field == -vmode) { + rule_save = overfull_rule_par; + /*tex Prevent the rule from being packaged. */ + overfull_rule_par = 0; + p = hpack(preamble, saved_value(0), saved_level(0), -1); + overfull_rule_par = rule_save; + } else { + q = vlink(preamble); + do { + height(q) = width(q); + width(q) = 0; + q = vlink(vlink(q)); + } while (q != null); + p = filtered_vpackage(preamble, + saved_value(0), saved_level(0), max_depth_par, preamble_group, -1, 0, 0); + q = vlink(preamble); + do { + width(q) = height(q); + height(q) = 0; + q = vlink(vlink(q)); + } while (q != null); + } + pack_begin_line = 0; + /*tex Set the glue in all the unset boxes of the current list. */ + q = vlink(cur_list.head_field); + s = cur_list.head_field; + while (q != null) { + if (!is_char_node(q)) { + if (type(q) == unset_node) { + /*tex + + We set the unset box |q| and the unset boxes in it. The unset + box |q| represents a row that contains one or more unset + boxes, depending on how soon \.{\\cr} occurred in that row. + + */ + if (cur_list.mode_field == -vmode) { + type(q) = hlist_node; + subtype(q) = align_row_list; + width(q) = width(p); + } else { + type(q) = vlist_node; + subtype(q) = align_row_list; + height(q) = height(p); + } + glue_order(q) = glue_order(p); + glue_sign(q) = glue_sign(p); + glue_set(q) = glue_set(p); + shift_amount(q) = o; + r = vlink(list_ptr(q)); + if (type(r) != unset_node) { + formatted_error("alignment","bad box"); + } + s = vlink(list_ptr(p)); + do { + /*tex + + We set the glue in node |r| and change it from an unset + node. A box made from spanned columns will be followed by + tabskip glue nodes and by empty boxes as if there were no + spanning. This permits perfect alignment of subsequent + entries, and it prevents values that depend on floating + point arithmetic from entering into the dimensions of any + boxes. + + */ + n = span_count(r); + t = width(s); + w = t; + u = hold_head; + while (n > min_quarterword) { + decr(n); + /*tex + + Append tabskip glue and an empty box to list |u|, and + update |s| and |t| as the prototype nodes are passed. + + */ + s = vlink(s); + ng = new_glue(s); + vlink(u) = ng; + u = vlink(u); + subtype(u) = tab_skip_code + 1; + t = t + width(s); + if (glue_sign(p) == stretching) { + if (stretch_order(s) == glue_order(p)) + t = t + round(float_cast(glue_set(p)) * float_cast(stretch(s))); + } else if (glue_sign(p) == shrinking) { + if (shrink_order(s) == glue_order(p)) + t = t - round(float_cast(glue_set(p)) * float_cast(shrink(s))); + } + s = vlink(s); + rr = new_null_box(); + vlink(u) = rr; + u = vlink(u); + t = t + width(s); + subtype(u) = align_cell_list; + if (cur_list.mode_field == -vmode) { + width(u) = width(s); + } else { + type(u) = vlist_node; + height(u) = width(s); + } + } + if (cur_list.mode_field == -vmode) { + /*tex + + Make the unset node |r| into an |hlist_node| of width + |w|, setting the glue as if the width were |t|. + + */ + height(r) = height(q); + depth(r) = depth(q); + if (t == width(r)) { + glue_sign(r) = normal; + glue_order(r) = normal; + set_glue_ratio_zero(glue_set(r)); + } else if (t > width(r)) { + glue_sign(r) = stretching; + if (glue_stretch(r) == 0) + set_glue_ratio_zero(glue_set(r)); + else + glue_set(r) = unfloat((double) (t - width(r)) / glue_stretch(r)); + } else { + glue_order(r) = glue_sign(r); + glue_sign(r) = shrinking; + if (glue_shrink(r) == 0) + set_glue_ratio_zero(glue_set(r)); + else if ((glue_order(r) == normal) && (width(r) - t > glue_shrink(r))) + set_glue_ratio_one(glue_set(r)); + else + glue_set(r) = unfloat((double) (width(r) - t) / glue_shrink(r)); + } + width(r) = w; + type(r) = hlist_node; + subtype(r) = align_cell_list; + + } else { + /*tex + + Make the unset node |r| into a |vlist_node| of height + |w|, setting the glue as if the height were |t|. + + */ + width(r) = width(q); + if (t == height(r)) { + glue_sign(r) = normal; + glue_order(r) = normal; + set_glue_ratio_zero(glue_set(r)); + } else if (t > height(r)) { + glue_sign(r) = stretching; + if (glue_stretch(r) == 0) + set_glue_ratio_zero(glue_set(r)); + else + glue_set(r) = unfloat((t - height(r)) / glue_stretch(r)); + } else { + glue_order(r) = glue_sign(r); + glue_sign(r) = shrinking; + if (glue_shrink(r) == 0) + set_glue_ratio_zero(glue_set(r)); + else if ((glue_order(r) == normal) && (height(r) - t > glue_shrink(r))) + set_glue_ratio_one(glue_set(r)); + else + glue_set(r) = unfloat((height(r) - t) / glue_shrink(r)); + } + height(r) = w; + type(r) = vlist_node; + subtype(r) = align_cell_list; + } + shift_amount(r) = 0; + if (u != hold_head) { + /*tex Append blank boxes to account for spanned nodes. */ + vlink(u) = vlink(r); + vlink(r) = vlink(hold_head); + r = u; + } + + r = vlink(vlink(r)); + s = vlink(vlink(s)); + } while (r != null); + + } else if (type(q) == rule_node) { + /*tex + + Make the running dimensions in rule |q| extend to the + boundaries of the alignment. + + */ + if (is_running(width(q))) + width(q) = width(p); + if (is_running(height(q))) + height(q) = height(p); + if (is_running(depth(q))) + depth(q) = depth(p); + if (o != 0) { + r = vlink(q); + vlink(q) = null; + q = hpack(q, 0, additional, -1); + shift_amount(q) = o; + subtype(q) = align_cell_list; + vlink(q) = r; + vlink(s) = q; + } + } + } + s = q; + q = vlink(q); + } + flush_node_list(p); + pop_alignment(); + /*tex + + We now have a completed alignment, in the list that starts at + |cur_list.head_field| and ends at |cur_list.tail_field|. This list will + be merged with the one that encloses it. (In case the enclosing mode is + |mmode|, for displayed formulas, we will need to insert glue before and + after the display; that part of the program will be deferred until we're + more familiar with such operations.) + + */ + pd = prev_depth_par; + p = vlink(cur_list.head_field); + q = cur_list.tail_field; + pop_nest(); + if (cur_list.mode_field == mmode) { + finish_display_alignment(p, q, pd); + } else { + prev_depth_par = pd; + vlink(cur_list.tail_field) = p; + if (p != null) + cur_list.tail_field = q; + if (cur_list.mode_field == vmode) { + if (!output_active) + lua_node_filter_s(buildpage_filter_callback,lua_key_index(alignment)); + build_page(); + } + } +} + +/*tex + + The token list |omit_template| just referred to is a constant token list that + contains the special control sequence \.{\\endtemplate} only. + +*/ + +void initialize_alignments(void) +{ + token_info(omit_template) = end_template_token; + span_span(end_span) = max_quarterword + 1; + span_ptr(end_span) = null; +} |