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Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 86 |
1 files changed, 86 insertions, 0 deletions
@@ -1,3 +1,14 @@ +2007-02-05 Werner LEMBERG <wl@gnu.org> + + * src/preproc/eqn/eqn.man: Revised. + + * src/preproc/eqn/text.cpp (map, special_char_boc::output): Use + `const'. + (spacing_type): Fix typo. + (special_to_entity): Use `const'. + Remove unused variable. + * src/preproc/eqn/other.cpp (font_box::output): Use `const'. + 2007-02-05 Eric S. Raymond <esr@snark.thyrsus.com> * src/devices/grotty/grotty.man: \m[] and \M[] aren't portable, @@ -23,6 +34,79 @@ * MORE.STUFF: More-stuff entries for doclifter and pic2plot. + + Add support for MathML output to eqn. + + The strategy used is very simple and relies on the fact that the box + models of eqn and Presentation MathML differ in only trivial ways. + It leaves the grammar and existing internal object structures + unchanged. A new global, `output_format', is defined as an + enumerated type with values {troff, mathml}. Most of the functions + and methods that emit actual output acquire a top-level conditional, + dispatching on this global, which has one arm for troff mode and one + for MathML mode. In most cases the MathML arm is drastically + simpler. + + (This strategy could be easily generalized to support other output + formats. TeX is a possibility that leaps to mind.) + + The only even moderately tricky changes are in the lexer. Some of + the predefined macros used constructs like `up', `down', `fwd', + `back', and `vcenter' that have no equivalents in MathML. I + attacked this problem in these ways: + + 1. I eliminated three uses of `back' to compose characters in favor + of using equivalent groff specials `\(<<', `\(>>', and `\(<>' + that did not exist when these macros were written. (This will be + a quality improvement for troff users.) + + 2. I eliminated one use of `vcenter' by using \\(md. (Likewise...) + + 3. I then split the table of pre-definitions in three; one large + common table and two small troff-specific and MathML-specific + tables. Use of troff-only operations (up, down, back, fwd, + vcenter) is now confined to the former. The latter now uses + `size big' and drops out the explicit positioning operations, + counting on MathML processors to do them. + + POTENTIAL TROUBLE SPOTS: + + Here are notes for reviewers on places I'm not 100% sure I've done + the right thing: + + * In the process of preparing the troff table, I translated three + definitions (dot_def, dotdot_def, and utilde def) that previously + used explicit \v escapes to use `up' and `down' instead. I + modeled the new definitions on the way `vec' and `dyad' work, but + it's possible I got something subtle wrong. + + * I'm not certain the MathML implementation of font_box::output() is + right, because I don't quite get what the switcheroo between + `current_roman_font' and `old_roman_font' is supposed to + accomplish. It does seem to generare good MathML, though. + + Finally, I made one purely cosmetic change in `text.cpp'; I replaced + with an enum some magic numbers for spacing types that I thought + were too ugly to live. + + REMAINING ISSUES: + + The entirety of eqn is translated when `-TMathML' is specified, + with the following exceptions... + + Limitations that cannot be fixed include non-support for special, + up/down/fwd/back, and vcenter. + + Limitations that might be fixable include non-support for mark and + lineup. I will investigate further, but if these can be implemented + at all it's going to be in a very complicated and nasty way. + + The way character boxes are output means that each digit of a + multi-digit number gets its own <mn></mn> tag pair in the MathHTML. + While this is not technically wrong for Presentation MathML, it is + ugly and inefficient. Fixing this will require implementing a + little state machine in the `text.cpp' output method. + * src/preproc/eqn/box.cpp, src/preproc/eqn/delim.cpp, src/preproc/eqn/eqn.h, src/preproc/eqn/eqn.man, src/preproc/eqn/lex.cpp, src/preproc/eqn/limit.cpp, @@ -32,6 +116,8 @@ src/preproc/eqn/sqrt.cpp, src/preproc/eqn/text.cpp, src/preproc/eqn/eqn.man: MathML output mode. + * NEWS: Document it. + 2007-02-02 Eric S. Raymond <esr@snark.thyrsus.com> * src/roff/groff/groff.man: Converted to use .SY/.OP/.YS |