[groff] 17/17: [tbl]: Refactor handling of vertical lines.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 006e24c9f592304ecded205460bd075ee1f0fa44
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Mon Jan 30 13:19:36 2023 -0600

    [tbl]: Refactor handling of vertical lines.
    
    [tbl]: Refactor handling of vertical lines in table.  Validate input
    more strictly.  Add diagnostics when vertical lines are redundant with
    box borders.
    
    * src/preproc/tbl/main.cpp (process_format): Shift diagnostic about
      excess vertical lines in a sequence at the beginning of a row
      description to later, after the first proper column descriptor has
      been interpreted.  Normalize a sequence of more than two consecutive
      vertical lines to 2 when they occur at the beginning of a row
      description.  Unconditionally update `list->vline` and reset
      `vline_count` once we start looking for modifiers, since we know we've
      finished any sequence of vertical lines, and at the end of a row
      definition.  Rename and retype loop variable int `success` to Boolean
      `is_valid_modifier_sequence`.  Drop now-invalid assertion.
    
    * src/preproc/tbl/table.cpp (table::add_vlines): Throw new diagnostics
      when vertical lines are redundant with box borders.  Add assertion to
      ensure we got a valid vertical line value (0, 1, or 2) from
      `process_format`.  Throw these only once per table format, not for
      every row.
    
    Tested with:
    
    .ll 64n
    .nf
    1234567890123456789012345678901234567890123456789012345678901234
    .fi
    .TS
    L L L L L.
    abandoning      babysitter      cablecasts      dachshunds      earmarkingX
    .TE
    .
    .TS
    | L L L L L.
    abandoning      babysitter      cablecasts      dachshunds      earmarkingX
    .TE
    .
    .TS
    L L L L L |.
    abandoning      babysitter      cablecasts      dachshunds      earmarkingX
    .TE
    .
    .TS
    | L L L L L |.
    abandoning      babysitter      cablecasts      dachshunds      earmarkingX
    .TE
    .
    .TS
    doublebox;
    L L L L L.
    abandoning      babysitter      cablecasts      dachshunds      earmarkingX
    .TE
    .
    .TS
    box;
    | L L L L L |.
    abandoning      babysitter      cablecasts      dachshunds      earmarkingX
    .TE
    .
    .TS
    box tab(:);
    Lz  S | Rt
    Ld| Cb| ^
    ^ | Rz  S.
    left:r
    l:center:
    :right
    .TE
    .TS
    L,|||R.
    foo
    bar
    .TE
    .TS
    L||R.
    foo     bar
    .TE
    .pl \n(nlu
---
 ChangeLog                 | 23 +++++++++++++++++++++++
 src/preproc/tbl/main.cpp  | 33 +++++++++++++++++----------------
 src/preproc/tbl/table.cpp | 19 +++++++++++++++++--
 3 files changed, 57 insertions(+), 18 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 7294c63f3..760efe9a9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,26 @@
+2023-02-02  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       [tbl]: Refactor handling of vertical lines in format.  Validate
+       input more strictly.  Add diagnostics when vertical lines are
+       redundant with box borders.
+
+       * src/preproc/tbl/main.cpp (process_format): Shift diagnostic
+       about excess vertical lines in a sequence at the beginning of a
+       row description to later, after the first proper column
+       descriptor has been interpreted.  Normalize a sequence of more
+       than two consecutive vertical lines to 2 when they occur at the
+       beginning of a row description.  Unconditionally update
+       `list->vline` and reset `vline_count` once we start looking for
+       modifiers, since we know we've finished any sequence of vertical
+       lines, and at the end of a row definition.  Rename and retype
+       loop variable int `success` to Boolean
+       `is_valid_modifier_sequence`.  Drop now-invalid assertion.
+       * src/preproc/tbl/table.cpp (table::add_vlines): Throw new
+       diagnostics when vertical lines are redundant with box borders.
+       Add assertion to ensure we got a valid vertical line value (0,
+       1, or 2) from `process_format`.  Throw these only once per table
+       format, not for every row.
+
 2023-01-30  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        * src/preproc/tbl/main.cpp (process_table): Trivially refactor.
diff --git a/src/preproc/tbl/main.cpp b/src/preproc/tbl/main.cpp
index a868b4238..467c19f86 100644
--- a/src/preproc/tbl/main.cpp
+++ b/src/preproc/tbl/main.cpp
@@ -841,11 +841,7 @@ format *process_format(table_input &in, options *opt,
        // leading vertical line in row
        opt->flags |= table::HAS_TOP_VLINE;
        vline_count++;
-       if (vline_count > 2) {
-         vline_count = 2;
-         error("more than 2 vertical lines at beginning of row"
-               " description");
-       }
+       // list->vline_count is updated later
        break;
       case ' ':
       case '\t':
@@ -868,9 +864,14 @@ format *process_format(table_input &in, options *opt,
     if (got_period)
       break;
     list = new input_entry_format(t, list);
-    if (vline_count)
-      list->vline_count = vline_count;
-    int success = 1;
+    if (vline_count > 2) {
+      vline_count = 2;
+      error("more than 2 vertical lines at beginning of row description");
+    }
+    list->vline_count = vline_count;
+    // Now handle modifiers.
+    vline_count = 0;
+    bool is_valid_modifier_sequence = true;
     do {
       switch (c) {
       case '0':
@@ -1115,7 +1116,7 @@ format *process_format(table_input &in, options *opt,
        if (is_first_row)
          opt->flags |= table::HAS_TOP_VLINE;
        c = in.get();
-       list->vline++;
+       vline_count++;
        break;
       case ' ':
       case '\t':
@@ -1125,15 +1126,17 @@ format *process_format(table_input &in, options *opt,
        if (c == opt->tab_char)
          c = in.get();
        else
-         success = 0;
+         is_valid_modifier_sequence = false;
        break;
       }
-    } while (success);
-    if (list->vline > 2) {
-      list->vline = 2;
+    } while (is_valid_modifier_sequence);
+    if (vline_count > 2) {
+      vline_count = 2;
       error("more than 2 vertical lines after column descriptor");
     }
+    list->vline += vline_count;
     if (c == '\n' || c == ',') {
+      vline_count = 0;
       is_first_row = false;
       c = in.get();
       list->is_last_column = true;
@@ -1238,10 +1241,8 @@ format *process_format(table_input &in, options *opt,
        error("multiple widths for column %1", col + 1);
       f->width[col] = tem->width;
     }
-    if (tem->vline_count) {
-      assert(col == 0);
+    if (tem->vline_count)
       f->vline[row][col] = tem->vline_count;
-    }
     f->vline[row][col + 1] = tem->vline;
     if (tem->is_last_column) {
       row++;
diff --git a/src/preproc/tbl/table.cpp b/src/preproc/tbl/table.cpp
index 97b0845d1..d815bbf13 100644
--- a/src/preproc/tbl/table.cpp
+++ b/src/preproc/tbl/table.cpp
@@ -1675,8 +1675,23 @@ void table::add_entry(int r, int c, const string &str,
 void table::add_vlines(int r, const char *v)
 {
   allocate(r);
-  for (int i = 0; i < ncolumns+1; i++)
-    vline[r][i] = v[i];
+  bool lwarned = false;
+  bool twarned = false;
+  for (int i = 0; i < ncolumns+1; i++) {
+    assert(v[i] < 3);
+    if (v[i] && (flags & (BOX | ALLBOX | DOUBLEBOX)) && (i == 0)
+       && (!lwarned)) {
+      error("ignoring vertical line at leading edge of boxed table");
+      lwarned = true;
+    }
+    else if (v[i] && (flags & (BOX | ALLBOX | DOUBLEBOX))
+            && (i == ncolumns) && (!twarned)) {
+      error("ignoring vertical line at trailing edge of boxed table");
+      twarned = true;
+    }
+    else
+      vline[r][i] = v[i];
+  }
 }
 
 void table::check()