mercurial/parser.py

url: refactor util.drop_scheme() and hg.localpath() into url.localpath()

This replaces util.drop_scheme() with url.localpath(), using url.url for
parsing instead of doing it on its own. The function is moved from
util to url to avoid an import cycle.

hg.localpath() is removed in favor of using url.localpath(). This
provides more consistent behavior between "hg clone" and other
commands.

To preserve backwards compatibility, URLs like bundle://../foo still
refer to ../foo, not /foo.

If a URL contains a scheme, percent-encoded entities are decoded. When
there's no scheme, all characters are left untouched.

Comparison of old and new behaviors:

URL                      drop_scheme()   hg.localpath()    url.localpath()
===                      =============   ==============    ===============
file://foo/foo           /foo            foo/foo           /foo
file://localhost:80/foo  /foo            localhost:80/foo  /foo
file://localhost:/foo    /foo            localhost:/foo    /foo
file://localhost/foo     /foo            /foo              /foo
file:///foo              /foo            /foo              /foo
file://foo               (empty string)  foo               /
file:/foo                /foo            /foo              /foo
file:foo                 foo             foo               foo
file:foo%23bar           foo%23bar       foo%23bar         foo#bar
foo%23bar                foo%23bar       foo%23bar         foo%23bar
/foo                     /foo            /foo              /foo

Windows-related paths on Windows:

URL                      drop_scheme()   hg.localpath()    url.localpath()
===                      =============   ==============    ===============
file:///C:/foo           C:/C:/foo       /C:/foo           C:/foo
file:///D:/foo           C:/D:/foo       /D:/foo           D:/foo
file://C:/foo            C:/foo          C:/foo            C:/foo
file://D:/foo            C:/foo          D:/foo            D:/foo
file:////foo/bar         //foo/bar       //foo/bar         //foo/bar
//foo/bar                //foo/bar       //foo/bar         //foo/bar
\\foo\bar                //foo/bar       //foo/bar         \\foo\bar

Windows-related paths on other platforms:

file:///C:/foo           C:/C:/foo       /C:/foo           C:/foo
file:///D:/foo           C:/D:/foo       /D:/foo           D:/foo
file://C:/foo            C:/foo          C:/foo            C:/foo
file://D:/foo            C:/foo          D:/foo            D:/foo
file:////foo/bar         //foo/bar       //foo/bar         //foo/bar
//foo/bar                //foo/bar       //foo/bar         //foo/bar
\\foo\bar                //foo/bar       //foo/bar         \\foo\bar

For more information about file:// URL handling, see:
http://www-archive.mozilla.org/quality/networking/testing/filetests.html

Related issues:

- issue1153: File URIs aren't handled correctly in windows

  This patch should preserve the fix implemented in
  2770d03ae49f. However, it goes a step further and "promotes"
  Windows-style drive letters from being interpreted as host names to
  being part of the path.

- issue2154: Cannot escape '#' in Mercurial URLs (#1172 in THG)

  The fragment is still interpreted as a revision or a branch, even in
  paths to bundles. However, when file: is used, percent-encoded
  entities are decoded, so file:test%23bundle.hg can refer to
  test#bundle.hg ond isk.

# parser.py - simple top-down operator precedence parser for mercurial
#
# Copyright 2010 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

# see http://effbot.org/zone/simple-top-down-parsing.htm and
# http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/
# for background

# takes a tokenizer and elements
# tokenizer is an iterator that returns type, value pairs
# elements is a mapping of types to binding strength, prefix and infix actions
# an action is a tree node name, a tree label, and an optional match
# __call__(program) parses program into a labelled tree

import error

class parser(object):
    def __init__(self, tokenizer, elements, methods=None):
        self._tokenizer = tokenizer
        self._elements = elements
        self._methods = methods
        self.current = None
    def _advance(self):
        'advance the tokenizer'
        t = self.current
        try:
            self.current = self._iter.next()
        except StopIteration:
            pass
        return t
    def _match(self, m, pos):
        'make sure the tokenizer matches an end condition'
        if self.current[0] != m:
            raise error.ParseError("unexpected token: %s" % self.current[0],
                                   self.current[2])
        self._advance()
    def _parse(self, bind=0):
        token, value, pos = self._advance()
        # handle prefix rules on current token
        prefix = self._elements[token][1]
        if not prefix:
            raise error.ParseError("not a prefix: %s" % token, pos)
        if len(prefix) == 1:
            expr = (prefix[0], value)
        else:
            if len(prefix) > 2 and prefix[2] == self.current[0]:
                self._match(prefix[2], pos)
                expr = (prefix[0], None)
            else:
                expr = (prefix[0], self._parse(prefix[1]))
                if len(prefix) > 2:
                    self._match(prefix[2], pos)
        # gather tokens until we meet a lower binding strength
        while bind < self._elements[self.current[0]][0]:
            token, value, pos = self._advance()
            e = self._elements[token]
            # check for suffix - next token isn't a valid prefix
            if len(e) == 4 and not self._elements[self.current[0]][1]:
                suffix = e[3]
                expr = (suffix[0], expr)
            else:
                # handle infix rules
                if len(e) < 3 or not e[2]:
                    raise error.ParseError("not an infix: %s" % token, pos)
                infix = e[2]
                if len(infix) == 3 and infix[2] == self.current[0]:
                    self._match(infix[2], pos)
                    expr = (infix[0], expr, (None))
                else:
                    expr = (infix[0], expr, self._parse(infix[1]))
                    if len(infix) == 3:
                        self._match(infix[2], pos)
        return expr
    def parse(self, message):
        'generate a parse tree from a message'
        self._iter = self._tokenizer(message)
        self._advance()
        res = self._parse()
        token, value, pos = self.current
        return res, pos
    def eval(self, tree):
        'recursively evaluate a parse tree using node methods'
        if not isinstance(tree, tuple):
            return tree
        return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]])
    def __call__(self, message):
        'parse a message into a parse tree and evaluate if methods given'
        t = self.parse(message)
        if self._methods:
            return self.eval(t)
        return t