gendoc: automatically create help for default extensions.

Adds a section in the hg.1 manpage and corresponding hg.1.html
file. Each extension is listed with its module docstring, followed by
the commands defined by that extendsion.

Creates help for extensions by extracting doc strings from the extension modules
and its commands.

doc/gendoc.py

@@ -8,6 +8,7 b' from mercurial import encoding'
 from mercurial.commands import table, globalopts
 from mercurial.i18n import _
 from mercurial.help import helptable
+from mercurial import extensions
 
 def get_desc(docstr):
     if not docstr:
@@ -67,6 +68,12 b' def section(ui, s):'
 def subsection(ui, s):
     ui.write("%s\n%s\n\n" % (s, '"' * encoding.colwidth(s)))
 
+def subsubsection(ui, s):
+    ui.write("%s\n%s\n\n" % (s, "." * encoding.colwidth(s)))
+
+def subsubsubsection(ui, s):
+    ui.write("%s\n%s\n\n" % (s, "#" * encoding.colwidth(s)))
+
 
 def show_doc(ui):
     # print options
@@ -76,7 +83,7 b' def show_doc(ui):'
 
     # print cmds
     section(ui, _("Commands"))
-    commandprinter(ui, table)
+    commandprinter(ui, table, subsection)
 
     # print topics
     for names, sec, doc in helptable:
@@ -89,7 +96,26 b' def show_doc(ui):'
         ui.write(doc)
         ui.write("\n")
 
-def commandprinter(ui, cmdtable):
+    section(ui, _("Extensions"))
+    ui.write(_("This section contains help for extensions that is distributed "
+               "together with Mercurial. Help for other extensions is available "
+               "in the help system."))
+    ui.write("\n\n"
+             ".. contents::\n"
+             "   :class: htmlonly\n"
+             "   :local:\n"
+             "   :depth: 1\n\n")
+
+    for extensionname in sorted(allextensionnames()):
+        mod = extensions.load(None, extensionname, None)
+        subsection(ui, extensionname)
+        ui.write("%s\n\n" % mod.__doc__)
+        cmdtable = getattr(mod, 'cmdtable', None)
+        if cmdtable:
+            subsubsection(ui, _('Commands'))
+            commandprinter(ui, cmdtable, subsubsubsection)
+
+def commandprinter(ui, cmdtable, sectionfunc):
     h = {}
     for c, attr in cmdtable.items():
         f = c.split("|")[0]
@@ -102,7 +128,7 b' def commandprinter(ui, cmdtable):'
         if f.startswith("debug"):
             continue
         d = get_cmd(h[f], cmdtable)
-        subsection(ui, d['cmd'])
+        sectionfunc(ui, d['cmd'])
         # synopsis
         ui.write("``%s``\n" % d['synopsis'].replace("hg ","", 1))
         ui.write("\n")
@@ -125,5 +151,17 b' def commandprinter(ui, cmdtable):'
             ui.write(_("    aliases: %s\n\n") % " ".join(d['aliases']))
 
 
+def allextensionnames():
+    extensionnames = []
+
+    extensionsdictionary = extensions.enabled()[0]
+    extensionnames.extend(extensionsdictionary.keys())
+
+    extensionsdictionary = extensions.disabled()[0]
+    extensionnames.extend(extensionsdictionary.keys())
+
+    return extensionnames
+
+
 if __name__ == "__main__":
     show_doc(sys.stdout)