Simplify the usage of print_otag() by making it accept a variable

number of arguments.

Delete struct htmlpair and all the PAIR_*() macros.
Delete enum htmlattr, handle that in print_otag() instead.

Minus 190 lines of code; no functional change except better ordering
of attributes (class before style) in three cases.

1 files changed, 112 insertions, 17 deletions

diff --git a/mandoc_html.3 b/mandoc_html.3
index 54273da1..5e132979 100644
--- a/mandoc_html.3
+++ b/mandoc_html.3
@@ -30,8 +30,8 @@
 .Fo print_otag
 .Fa "struct html *h"
 .Fa "enum htmltag tag"
-.Fa "int sz"
-.Fa "const struct htmlpair *p"
+.Fa "const char *fmt"
+.Fa ...
 .Fc
 .Ft void
 .Fo print_tagq
@@ -84,15 +84,6 @@ These structures are declared in
 .Bl -tag -width Ds
 .It Vt struct html
 Internal state of the HTML formatter.
-.It Vt struct htmlpair
-Holds one HTML attribute.
-Members are
-.Fa "enum htmlattr key"
-and
-.Fa "const char *val" .
-Helper macros
-.Fn PAIR_*
-are provided to support initialization of such structures.
 .It Vt struct tag
 One entry for the LIFO stack of HTML elements.
 Members are
@@ -134,12 +125,116 @@ The function
 .Fn print_otag
 prints the start tag of an HTML element with the name
 .Fa tag ,
-including the
-.Fa sz
-attributes that can optionally be provided in the
-.Fa p
-array.
-It uses the private function
+optionally including the attributes specified by
+.Fa fmt .
+If
+.Fa fmt
+is the empty string, no attributes are written.
+Each letter of
+.Fa fmt
+specifies one attribute to write.
+Most attributes require one
+.Va char *
+argument which becomes the value of the attribute.
+The arguments have to be given in the same order as the attribute letters.
+.Bl -tag -width 1n -offset indent
+.It Cm c
+Print a
+.Cm class
+attribute.
+.It Cm h
+Print a
+.Cm href
+attribute.
+.It Cm i
+Print an
+.Cm id
+attribute.
+.It Cm \&?
+Print an arbitrary attribute.
+This format letter requires two
+.Vt char *
+arguments, the attribute name and the value.
+.It Cm s
+Print a
+.Cm style
+attribute.
+If present, it must be the last format letter.
+In contrast to the other format letters, this one does not yet
+print the value and does not require an argument.
+Instead, the rest of the format string consists of pairs of
+argument type letters and style name letters.
+.El
+.Pp
+Argument type letters each require on argument as follows:
+.Bl -tag -width 1n -offset indent
+.It Cm h
+Requires one
+.Vt int
+argument, interpreted as a horizontal length in units of
+.Dv SCALE_EN .
+.It Cm s
+Requires one
+.Vt char *
+argument, used as a style value.
+.It Cm u
+Requires one
+.Vt struct roffsu *
+argument, used as a length.
+.It Cm v
+Requires one
+.Vt int
+argument, interpreted as a vertical length in units of
+.Dv SCALE_VS .
+.It Cm w
+Requires one
+.Vt char *
+argument, interpreted as an
+.Xr mdoc 7 Ns -style
+width specifier.
+.El
+.Pp
+Style name letters decide what to do with the preceding argument:
+.Bl -tag -width 1n -offset indent
+.It Cm b
+Set
+.Cm margin-bottom
+to the given length.
+.It Cm h
+Set
+.Cm height
+to the given length.
+.It Cm i
+Set
+.Cm text-indent
+to the given length.
+.It Cm l
+Set
+.Cm margin-left
+to the given length.
+.It Cm t
+Set
+.Cm margin-top
+to the given length.
+.It Cm w
+Set
+.Cm width
+to the given length.
+.It Cm W
+Set
+.Cm min-width
+to the given length.
+.It Cm \&?
+The special pair
+.Cm s?
+requires two
+.Vt char *
+arguments.
+The first is the style name, the second its value.
+.El
+.Pp
+.Fn print_otag
+uses the private function
 .Fn print_attr
 which in turn uses the private function
 .Fn print_encode