Rework tbl(7) layout parsing:

* Continue parsing even if part of the input is invalid.
* Do not require whitespace between cell specifications.
* Allow tabs as well as blanks between modifiers.
* Mark the 'm' modifier as unsupported.
* Parse and ignore the 'p' and 'v' modifiers.
* Better warning and error messages.
* Get rid of a static buffer.
Improved functionality but minus 50 lines of code.

1 files changed, 40 insertions, 2 deletions

diff --git a/mandoc.1 b/mandoc.1
index c0ec8d12..7c3c2950 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -1273,6 +1273,24 @@ its value is implicitly set to the empty string.
 However, defining strings explicitly before use
 keeps the code more readable.
 .El
+.Ss "Warnings related to tables"
+.Bl -ohang
+.It Sy "tbl line starts with span"
+.Pq tbl
+The first cell in a table layout line is a horizontal span
+.Pq Sq Cm s .
+Data provided for this cell is ignored, and nothing is printed in the cell.
+.It Sy "tbl column starts with span"
+.Pq tbl
+The first line of a table layout specification
+requests a vertical span
+.Pq Sq Cm ^ .
+Data provided for this cell is ignored, and nothing is printed in the cell.
+.It Sy "skipping vertical bar in tbl layout"
+.Pq tbl
+A table layout specification contains more than two consecutive vertical bars.
+A double bar is printed, all additional bars are discarded.
+.El
 .Ss "Errors related to equations"
 .Bl -inset -compact
 .It "unexpected equation scope closure"
@@ -1302,10 +1320,25 @@ The option is ignored.
 .Pq tbl
 A table option argument contains an invalid number of characters.
 Both the option and the argument are ignored.
+.It Sy "empty tbl layout"
+.Pq tbl
+A table layout specification is completely empty,
+specifying zero lines and zero columns.
+As a fallback, a single left-justified column is used.
+.It Sy "invalid character in tbl layout"
+.Pq tbl
+A table layout specification contains a character that can neither
+be interpreted as a layout key character nor as a layout modifier,
+or a modifier precedes the first key.
+The invalid character is discarded.
+.It Sy "unmatched parenthesis in tbl layout"
+.Pq tbl
+A table layout specification contains an opening parenthesis,
+but no matching closing parenthesis.
+The rest of the input line, starting from the parenthesis, has no effect.
 .El
 .Pp
 .Bl -inset -compact
-.It Sy "no table layout cells specified"
 .It Sy "no table data cells specified"
 .It Sy "ignore data in cell"
 .It Sy "data block still open"
@@ -1607,7 +1640,12 @@ request supported by GNU troff or Heirloom troff but not by
 .Nm ,
 and it is likely that this will cause information loss
 or considerable misformatting.
-.It Sy "unsupported table layout"
+.It Sy "unsupported table layout modfier"
+.Pq tbl
+A table layout specification contains an
+.Sq Cm m
+modifier.
+The modifier is discarded.
 .It Sy "ignoring macro in table"
 .It Sy "eqn in tbl"
 .Pq eqn , tbl