[Rd] Rdconv --type=Ssgm drops singleton keywords (PR#9051)

[maechler at stat.math.ethz.ch]

Thank you Bill,

particularly for not only reporting the bug but also diagnose
and patch it.

I've committed the fix for both R-devel and R-patched.

With regards,
Martin

>> If an Rd file has only one keyword entry then
>> the Splus sgm file made with Rdconv --type=SSgm
>> has no keyword entries.
>> 
>> To reproduce:
>>    Use prompt() to make a skeleton help file
>>       R> f<-function(x)log(1+x)-log1p(x)
>>       R> prompt(f)
>>       Created file named 'f.Rd'.
>>       Edit the file and move it to the appropriate directory.
>>       R> q()
>>    It has 2 \keyword entries in it
>>       % grep keyword f.Rd
>>       \keyword{ ~kwd1 }% at least one, from doc/KEYWORDS
>>       \keyword{ ~kwd2 }% __ONLY ONE__ keyword per line
>>    If you convert it to the Splus sgm format you get 2
>>    <s-keyword> entries, in a <s-keywords> section:
>>       % R CMD Rdconv --type=Ssgm f.Rd | grep 'keyword'
>>       <s-keywords>
>>       <s-keyword>~kwd1</s-keyword>
>>       <s-keyword>~kwd2</s-keyword>
>>       </s-keywords>
>>       %
>>    That is good.
>> 
>>    If you remove one keyword entry from the Rd file so it has one left
>>    then the sgm file has no <s-keyword> entries (and no <s-keywords>
>>    section):
>>       % grep -v '~kwd2' < f.Rd > f1kw.Rd
>>       % grep keyword f1kw.Rd
>>       \keyword{ ~kwd1 }% at least one, from doc/KEYWORDS
>>       % R CMD Rdconv --type=Ssgm f1kw.Rd | grep s-keyword
>>       %
>> 
>> The fix:
>>    The problem is that the line
>>       if ($#keywords > 0) {
>>    should use >= 0 to tell if the list @keywords is non-empty.
>> 
>> *** share/perl/R/Rdconv.pm	2006-05-23 08:51:16.000000000 -0700
>> --- /tmp/Rdconv.pm	2006-06-30 11:51:53.000000000 -0700
>> ***************
>> *** 2965,2971 ****
>>       Ssgm_print_block_named("references", "References");
>>       Ssgm_print_seealso();
>>       Ssgm_print_examples();
>> !     if ($#keywords > 0) {
>>   	print $sgmlout "<s-keywords>\n";
>>   	while ($#keywords >= 0) {
>>   	    print $sgmlout "<s-keyword>", shift( @keywords ),
>> --- 2965,2971 ----
>>       Ssgm_print_block_named("references", "References");
>>       Ssgm_print_seealso();
>>       Ssgm_print_examples();
>> !     if ($#keywords >= 0) {
>>   	print $sgmlout "<s-keywords>\n";
>>   	while ($#keywords >= 0) {
>>   	    print $sgmlout "<s-keyword>", shift( @keywords ),
>> 
>> 
>> --please do not edit the information below--
>> 
>> Version:
>>  platform = i686-pc-linux-gnu
>>  arch = i686
>>  os = linux-gnu
>>  system = i686, linux-gnu
>>  status = Under development (unstable)
>>  major = 2
>>  minor = 4.0
>>  year = 2006
>>  month = 06
>>  day = 29
>>  svn rev = 38459
>>  language = R
>>  version.string = R version 2.4.0 Under development (unstable) (2006-06-29 r38459)
>> 
>> Locale:
>> LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=en_US.UTF-8;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
>> 
>> Search Path:
>>  .GlobalEnv, package:methods, package:stats, package:graphics, package:grDevices, package:utils, package:datasets, Autoloads, package:base
>> 
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