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Diffstat (limited to 'Build/source/texk/web2c/luatexdir/tex/align.w')
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diff --git a/Build/source/texk/web2c/luatexdir/tex/align.w b/Build/source/texk/web2c/luatexdir/tex/align.w deleted file mode 100644 index dd0ed10338e..00000000000 --- a/Build/source/texk/web2c/luatexdir/tex/align.w +++ /dev/null @@ -1,1144 +0,0 @@ -% align.w -% -% 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/>. - -\def\<#1>{$#1$} - -@ @c - - -#include "ptexlib.h" - -@ @c -void fin_align(void); -void init_row(void); -void init_col(void); - -#define noDEBUG - -@ 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. -$$\vbox{\halign{\.{#}\hfil\cr -{}\\tabskip 2pt plus 3pt\cr -{}\\halign to 300pt\{u1\#v1\&\cr -\hskip 50pt\\tabskip 1pt plus 1fil u2\#v2\&\cr -\hskip 50pt u3\#v3\\cr\cr -\hskip 25pt a1\&\\omit a2\&\\vrule\\cr\cr -\hskip 25pt \\noalign\{\\vskip 3pt\}\cr -\hskip 25pt b1\\span b2\\cr\cr -\hskip 25pt \\omit\&c2\\span\\omit\\cr\}\cr}}$$ -Here's what happens: - -\yskip -(0) 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. - -(1) The preamble is scanned next. Macros in the preamble are not expanded, -@^preamble@> -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: -$$\vbox{\halign{\.{#}\hfil\qquad&(#)\hfil\cr -{}\\glue 2pt plus 3pt&the tabskip preceding column 1\cr -{}\\alignrecord, width $-\infty$&preamble info for column 1\cr -{}\\glue 2pt plus 3pt&the tabskip between columns 1 and 2\cr -{}\\alignrecord, width $-\infty$&preamble info for column 2\cr -{}\\glue 1pt plus 1fil&the tabskip between columns 2 and 3\cr -{}\\alignrecord, width $-\infty$&preamble info for column 3\cr -{}\\glue 1pt plus 1fil&the tabskip following column 3\cr}}$$ -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. - -(2) \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. - -(3) 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. - -(4) 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. - -(5) The first row has now ended; it is made into a single unset box -comprising the following seven items: -$$\vbox{\halign{\hbox to 325pt{\qquad\.{#}\hfil}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 1 column: u1a1v1\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 1 column: a2\cr -{}\\glue 1pt plus 1fil\cr -{}\\unsetbox for 1 column: u3\\vrule v3\cr -{}\\glue 1pt plus 1fil\cr}}$$ -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. - -(6) 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|. - -(7) The next row produces an unset box that looks like this: -$$\vbox{\halign{\hbox to 325pt{\qquad\.{#}\hfil}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 2 columns: u1b1v1u2b2v2\cr -{}\\glue 1pt plus 1fil\cr -{}\\unsetbox for 1 column: {\rm(empty)}\cr -{}\\glue 1pt plus 1fil\cr}}$$ -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|. - -(8) The final row produces the unset box -$$\vbox{\halign{\hbox to 325pt{\qquad\.{#}\hfil}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 1 column: {\rm(empty)}\cr -{}\\glue 2pt plus 3pt\cr -{}\\unsetbox for 2 columns: u2c2v2\cr -{}\\glue 1pt plus 1fil\cr}}$$ -A new span node is attached to the alignrecord for column 2. - -(9) 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. - -\yskip\noindent -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. - -@c -/* could be in texnodes.h, but documented here*/ - -#define u_part(A) vlink((A)+depth_offset) /* pointer to \<u_j> token list */ -#define v_part(A) vinfo((A)+depth_offset) /* pointer to \<v_j> token list */ -#define span_ptr(A) vinfo((A)+1) /* column spanning list */ -#define extra_info(A) vinfo((A)+list_offset) /* info to remember during template */ - -@ 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. - -@c -/* could be in texnodes.h but documented here*/ - -#define preamble vlink(align_head) /* the current preamble list */ - -pointer cur_align = null; /* current position in preamble list */ -pointer cur_span = null; /* start of currently spanned columns in preamble list */ -pointer cur_loop = null; /* place to copy when extending a periodic preamble */ -pointer align_ptr = null; /* most recently pushed-down alignment stack node */ -pointer cur_head = null, cur_tail = null; /* adjustment list pointers */ -pointer cur_pre_head = null, cur_pre_tail = null; /* pre-adjustment list pointers */ - -/* 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. - -@c -static void push_alignment(void) -{ - pointer p; /* the new alignment stack node */ - 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) -{ - pointer p; /* the top alignment stack node */ - 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\ 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). - -@c -static void get_preamble_token(void) -{ - RESTART: - get_token(); - while ((cur_chr == span_code) && (cur_cmd == tab_mark_cmd)) { - get_token(); /* this token will be expanded once */ - 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; - } -} - - - -@ 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. -@^preamble@> - -@c -void init_align(void) -{ - /* label done, done1, done2, continue; */ - pointer save_cs_ptr; /* |warning_index| value for error messages */ - pointer p, r; /* for short-term temporary use */ - save_cs_ptr = cur_cs; /* \.{\\halign} or \.{\\valign}, usually */ - push_alignment(); - align_state = -1000000; /* enter a new alignment level */ - - /* 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(); - } - push_nest(); /* enter a new semantic level */ - /* 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); - /* Scan the preamble */ - preamble = null; - cur_align = align_head; - cur_loop = null; - scanner_status = aligning; - warning_index = save_cs_ptr; - align_state = -1000000; - /* at this point, |cur_cmd=left_brace| */ - while (true) { - /* 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) - break; /* \.{\\cr} ends the preamble */ - - /* Scan preamble text until |cur_cmd| is |tab_mark| or |car_ret| */ - /* 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; - cur_align = vlink(cur_align); /* a new alignrecord */ - span_ptr(cur_align) = end_span; - width(cur_align) = null_flag; - u_part(cur_align) = token_link(hold_token_head); - /* 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); - token_info(p) = end_template_token; /* put \.{\\endtemplate} at the end */ - - 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); - align_peek(); /* look for \.{\\noalign} or \.{\\omit} */ -} - - -@ 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. - -@c -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)) { - goto RESTART; /* ignore \.{\\crcr} */ - } else { - init_row(); /* start a new row */ - init_col(); /* start a new column and replace what we peeked at */ - } -} - - -@ 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. - -@c -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; -} - - -@ 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. - -@c -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); -} - - -@ 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. - -@c -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); - } /* now |align_state=1000000| */ -} - - -@ 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. - -@c -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; -} - -/* 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) - - -/* 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) - - - -@ 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. - -@c -boolean fin_col(void) -{ - pointer p; /* the alignrecord after the current one */ - pointer q, r; /* temporary pointers for list manipulation */ - pointer s; /* a new span node */ - pointer u; /* a new unset box */ - scaled w; /* natural width */ - unsigned char o; /* order of infinity */ - halfword n; /* span counter */ - 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); - /* 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) { - /* Lengthen the preamble periodically */ - r = new_node(align_record_node, 0); - vlink(q) = r; - p = vlink(q); /* a new alignrecord */ - span_ptr(p) = end_span; - width(p) = null_flag; - cur_loop = vlink(cur_loop); - - /* 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); - /* 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); - } - n = min_quarterword; /* this represents a span count of 1 */ - if (cur_span != cur_align) { - /* Update width entry for spanned columns */ - q = cur_span; - do { - incr(n); - q = vlink(vlink(q)); - } while (q != cur_align); - if (n > max_quarterword) - confusion("too many spans"); /* this can happen, but won't */ - 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; - - /* 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; -} - - - -@ 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|. -@^data structure assumptions@> - -The |new_span_node| function is defined in |texnodes.c|. - -@c -#ifndef span_span -# define span_span(A) vlink((A)+1) /* that is normally |alink| */ -#endif - - -@ 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. - -@c -void fin_row(void) -{ - pointer p; /* the new unset box */ - 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(); - /* note that |glue_shrink(p)=0| since |glue_shrink==shift_amount| */ -} - - -@ 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. - -@c -void fin_align(void) -{ - pointer p, q, r, s, u, rr; /* registers for the list operations */ - scaled t, w; /* width of column */ - scaled o; /* shift offset for unset boxes */ - halfword n; /* matching span amount */ - scaled rule_save; /* temporary storage for |overfull_rule| */ - halfword pd; /* temporary storage for |prev_depth| */ - halfword ng; /* temporary storage for |new_glue| */ - if (cur_group != align_group) - confusion("align1"); - unsave(); /* that |align_group| was for individual entries */ - if (cur_group != align_group) - confusion("align0"); - unsave(); /* that |align_group| was for the whole alignment */ - if (nest[nest_ptr - 1].mode_field == mmode) - o = display_indent_par; - else - o = 0; - /* 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) { - /* Nullify |width(q)| and the tabskip glue following this column */ - width(q) = 0; - r = vlink(q); - reset_glue_to_zero(r); /* is a lready copy */ - } - if (span_ptr(q) != end_span) { - /* 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); - - /* 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; - overfull_rule_par = 0; /* prevent rule from being packaged */ - 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; - - /* 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) { - /* 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)); - assert (type(r) == unset_node); - s = vlink(list_ptr(p)); - do { - /* 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); - /* 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) { - /* 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 { - /* 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; - - } - /* subtype(r) = 0; */ - shift_amount(r) = 0; - if (u != hold_head) { /* 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) { - /* 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(); - /* Insert the current list into its environment */ - /* 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; /* aux:=aux_save; */ - 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(); - } - } -} - -@ The token list |omit_template| just referred to is a constant token -list that contains the special control sequence \.{\\endtemplate} only. - -@c -void initialize_alignments(void) -{ - token_info(omit_template) = end_template_token; /* |link(omit_template)=null| */ - span_span(end_span) = max_quarterword + 1; - span_ptr(end_span) = null; -} |