Sort functions in doc index frames

[derek121]

The list of functions per module in the left-hand frame in the HTML docs (e.g., http://www.erlang.org/doc/man/string.html) have been sorted by their order within the associated XML doc file, which is not always alphabetically. This makes quickly finding a function within a module's function index list slower than it would be if sorted, as a full visual scan of the functions needs to be done to attempt to locate any specific function. Or, if the viewer doesn't realize that the list is not sorted, possibly missing a function that does appear in the list.

In some cases the reason for the misordering is that related functions are grouped together in the XML doc (e.g., string:chr/2 and string:rchr/2), as that makes sense when reading the body of the documentation. In other cases, there's no clear reason for the misordering.

Regardless, an index list of functions, such as this, which is sorted for most modules, but not always, is confusing. This change sorts the function index list per module alphabetically, while leaving alone the body of the page. In cases where module callbacks are included in the documentation (e.g., http://www.erlang.org/doc/man/application.html), those functions (e.g., Module:start/2) still remain at the bottom of the index list.

[OTP-Maintainer]

Patch has passed first testings and has been assigned to be reviewed

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I am a script, I am not human

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[derek121]

A few examples of unordered module function lists in the lefthand index frame:

http://www.erlang.org/doc/apps/kernel/application.html
http://www.erlang.org/doc/man/code.html
http://www.erlang.org/doc/man/filename.html
http://www.erlang.org/doc/man/gen_server.html
http://www.erlang.org/doc/man/gen_tcp.html
http://www.erlang.org/doc/man/string.html

[OTP-Maintainer]

Patch has passed first testings and has been assigned to be reviewed

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I am a script, I am not human

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[derek121]

To elaborate on this issue:

• Building the docs is done as directed at INSTALL.md:
  • make docs
  • make install-docs (not necessary to install to see the resulting .html)
• A sample doc source file that results in an unordered contents frame (as mentioned above): lib/kernel/doc/src/application.xml
• The resulting doc HTML from the make docs step: lib/kernel/doc/html/application.html

Using the modified db_html.xsl file from this PR:

• touch lib/kernel/doc/src/application.xml (to force make to rebuild it)
• make docs

Screenshot of the current contents frame for application. Note that it's mostly, but not completely, alphabetized:

Screenshot of the file built with the modified db_html.xsl from this PR:

Please let me know if there are any questions or issues with this PR.

[lthor]

Thanks for the contribution, I've rebased it to the master branch and it will be released in OTP 19.