view doc/gendoc.py @ 29375:fcaf20175b1b

demandimport: delay loading for "from a import b" with absolute_import

Before this patch, "from a import b" doesn't delay loading module "b",
if absolute_import is enabled, even though "from . import b" does.

For example:

  - it is assumed that extension X has "from P import M" for module M
    under package P with absolute_import feature

  - if importing module M is already delayed before loading extension
    X, loading module M in extension X is delayed until actually
    referring

    util, cmdutil, scmutil or so of Mercurial itself should be
    imported by "from . import M" style before loading extension X

  - otherwise, module M is loaded immediately at loading extension X,
    even if extension X itself isn't used at that "hg" command invocation

    Some minor modules (e.g. filemerge or so) of Mercurial itself
    aren't imported by "from . import M" style before loading
    extension X. And of course, external libraries aren't, too.

This might cause startup performance problem of hg command, because
many bundled extensions already enable absolute_import feature.

To delay loading module for "from a import b" with absolute_import
feature, this patch does below in "from a (or .a) import b" with
absolute_import case:

  1. import root module of "name" by system built-in __import__
     (referred as _origimport)

  2. recurse down the module chain for hierarchical "name"

     This logic can be shared with non absolute_import
     case. Therefore, this patch also centralizes it into chainmodules().

  3. and fall through to process elements in "fromlist" for the leaf
     module of "name"

     Processing elements in "fromlist" is executed in the code path
     after "if _pypy: .... else: ..." clause. Therefore, this patch
     replaces "if _pypy:" with "elif _pypy:" to share it.

At 4f1144c3c72b introducing original "work around" for "from a import
b" case, elements in "fromlist" were imported with "level=level". But
"level" might be grater than 1 (e.g. level=2 in "from .. import b"
case) at demandimport() invocation, and importing direct sub-module in
"fromlist" with level grater than 1 causes unexpected result.

IMHO, this seems main reason of "errors for unknown reason" described
in 4f1144c3c72b, and we don't have to worry about it, because this
issue was already fixed by 78d05778907b.

This is reason why this patch removes "errors for unknown reasons"
comment.

#!/usr/bin/env python
"""usage: %s DOC ...

where DOC is the name of a document
"""

from __future__ import absolute_import

import os
import sys
import textwrap

# This script is executed during installs and may not have C extensions
# available. Relax C module requirements.
os.environ['HGMODULEPOLICY'] = 'allow'
# import from the live mercurial repo
sys.path.insert(0, "..")
from mercurial import demandimport; demandimport.enable()
from mercurial import (
    commands,
    extensions,
    help,
    minirst,
    ui as uimod,
)
from mercurial.i18n import (
    gettext,
    _,
)

table = commands.table
globalopts = commands.globalopts
helptable = help.helptable
loaddoc = help.loaddoc

def get_desc(docstr):
    if not docstr:
        return "", ""
    # sanitize
    docstr = docstr.strip("\n")
    docstr = docstr.rstrip()
    shortdesc = docstr.splitlines()[0].strip()

    i = docstr.find("\n")
    if i != -1:
        desc = docstr[i + 2:]
    else:
        desc = shortdesc

    desc = textwrap.dedent(desc)

    return (shortdesc, desc)

def get_opts(opts):
    for opt in opts:
        if len(opt) == 5:
            shortopt, longopt, default, desc, optlabel = opt
        else:
            shortopt, longopt, default, desc = opt
            optlabel = _("VALUE")
        allopts = []
        if shortopt:
            allopts.append("-%s" % shortopt)
        if longopt:
            allopts.append("--%s" % longopt)
        if isinstance(default, list):
            allopts[-1] += " <%s[+]>" % optlabel
        elif (default is not None) and not isinstance(default, bool):
            allopts[-1] += " <%s>" % optlabel
        if '\n' in desc:
            # only remove line breaks and indentation
            desc = ' '.join(l.lstrip() for l in desc.split('\n'))
        desc += default and _(" (default: %s)") % default or ""
        yield (", ".join(allopts), desc)

def get_cmd(cmd, cmdtable):
    d = {}
    attr = cmdtable[cmd]
    cmds = cmd.lstrip("^").split("|")

    d['cmd'] = cmds[0]
    d['aliases'] = cmd.split("|")[1:]
    d['desc'] = get_desc(gettext(attr[0].__doc__))
    d['opts'] = list(get_opts(attr[1]))

    s = 'hg ' + cmds[0]
    if len(attr) > 2:
        if not attr[2].startswith('hg'):
            s += ' ' + attr[2]
        else:
            s = attr[2]
    d['synopsis'] = s.strip()

    return d

def showdoc(ui):
    # print options
    ui.write(minirst.section(_("Options")))
    multioccur = False
    for optstr, desc in get_opts(globalopts):
        ui.write("%s\n    %s\n\n" % (optstr, desc))
        if optstr.endswith("[+]>"):
            multioccur = True
    if multioccur:
        ui.write(_("\n[+] marked option can be specified multiple times\n"))
        ui.write("\n")

    # print cmds
    ui.write(minirst.section(_("Commands")))
    commandprinter(ui, table, minirst.subsection)

    # print help topics
    # The config help topic is included in the hgrc.5 man page.
    helpprinter(ui, helptable, minirst.section, exclude=['config'])

    ui.write(minirst.section(_("Extensions")))
    ui.write(_("This section contains help for extensions that are "
               "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(ui, extensionname, None)
        ui.write(minirst.subsection(extensionname))
        ui.write("%s\n\n" % gettext(mod.__doc__))
        cmdtable = getattr(mod, 'cmdtable', None)
        if cmdtable:
            ui.write(minirst.subsubsection(_('Commands')))
            commandprinter(ui, cmdtable, minirst.subsubsubsection)

def showtopic(ui, topic):
    extrahelptable = [
        (["common"], '', loaddoc('common')),
        (["hg.1"], '', loaddoc('hg.1')),
        (["hg-ssh.8"], '', loaddoc('hg-ssh.8')),
        (["hgignore.5"], '', loaddoc('hgignore.5')),
        (["hgrc.5"], '', loaddoc('hgrc.5')),
        (["hgignore.5.gendoc"], '', loaddoc('hgignore')),
        (["hgrc.5.gendoc"], '', loaddoc('config')),
    ]
    helpprinter(ui, helptable + extrahelptable, None, include=[topic])

def helpprinter(ui, helptable, sectionfunc, include=[], exclude=[]):
    for names, sec, doc in helptable:
        if exclude and names[0] in exclude:
            continue
        if include and names[0] not in include:
            continue
        for name in names:
            ui.write(".. _%s:\n" % name)
        ui.write("\n")
        if sectionfunc:
            ui.write(sectionfunc(sec))
        if callable(doc):
            doc = doc(ui)
        ui.write(doc)
        ui.write("\n")

def commandprinter(ui, cmdtable, sectionfunc):
    h = {}
    for c, attr in cmdtable.items():
        f = c.split("|")[0]
        f = f.lstrip("^")
        h[f] = c
    cmds = h.keys()
    cmds.sort()

    for f in cmds:
        if f.startswith("debug"):
            continue
        d = get_cmd(h[f], cmdtable)
        ui.write(sectionfunc(d['cmd']))
        # short description
        ui.write(d['desc'][0])
        # synopsis
        ui.write("::\n\n")
        synopsislines = d['synopsis'].splitlines()
        for line in synopsislines:
            # some commands (such as rebase) have a multi-line
            # synopsis
            ui.write("   %s\n" % line)
        ui.write('\n')
        # description
        ui.write("%s\n\n" % d['desc'][1])
        # options
        opt_output = list(d['opts'])
        if opt_output:
            opts_len = max([len(line[0]) for line in opt_output])
            ui.write(_("Options:\n\n"))
            multioccur = False
            for optstr, desc in opt_output:
                if desc:
                    s = "%-*s  %s" % (opts_len, optstr, desc)
                else:
                    s = optstr
                ui.write("%s\n" % s)
                if optstr.endswith("[+]>"):
                    multioccur = True
            if multioccur:
                ui.write(_("\n[+] marked option can be specified"
                           " multiple times\n"))
            ui.write("\n")
        # aliases
        if d['aliases']:
            ui.write(_("    aliases: %s\n\n") % " ".join(d['aliases']))


def allextensionnames():
    return extensions.enabled().keys() + extensions.disabled().keys()

if __name__ == "__main__":
    doc = 'hg.1.gendoc'
    if len(sys.argv) > 1:
        doc = sys.argv[1]

    ui = uimod.ui()
    if doc == 'hg.1.gendoc':
        showdoc(ui)
    else:
        showtopic(ui, sys.argv[1])