view mercurial/mdiff.py @ 35218:d61f2a3d5e53

hgweb: only include graph-related data in jsdata variable on /graph pages (BC)

Historically, client-side graph code was not only rendering the graph itself,
but it was also adding all of the changeset information to the page as well.
It meant that JavaScript code needed to construct valid HTML as a string
(although proper escaping was done server-side). It wasn't too clunky, even
though it meant that a lot of server-side things were duplicated client-side
for no good reason, but the worst thing about it was the data format it used.
It was somewhat future-proof, but not human-friendly, because it was just a
tuple: it was possible to append things to it (as was done in e.g.
270f57d35525), but you'd then have to remember the indices and reading the
resulting JS code wasn't easy, because cur[8] is not descriptive at all.

So what would need to happen for graph to have more features, such as more
changeset information or a different vertex style (branch-closing, obsolete)?
First you'd need to take some property, process it (e.g. escape and pass
through templatefilters function, and mind the encoding too), append it to
jsdata and remember its index, then go add nearly identical JavaScript code to
4 different hgweb themes that use jsdata to render HTML, and finally try and
forget how brittle it all felt. Oh yeah, and the indices go to double digits if
we add 2 more items, say phase and obsolescence, and there are more to come.
Rendering vertex in a different style would need another property (say,
character "o", "_", or "x"), except if you want to be backwards-compatible, it
would need to go after tags and bookmarks, and that just doesn't feel right.

So here I'm trying to fix both the duplication of code and the data format:

- changesets will be rendered by hgweb templates the same way as changelog and
  other such pages, so jsdata won't need any information that's not needed for
  rendering the graph itself

- jsdata will be a dict, or an Object in JS, which is a lot nicer to humans and
  is a lot more future-proof in the long run, because it doesn't use numeric
  indices

What about hgweb themes? Obviously, this will break all hgweb themes that
render graph in JavaScript, including 3rd-party custom ones. But this will also
reduce the size of client-side code and make it more uniform, so that it can be
shared across hgweb themes, further reducing its size. The next few patches
demonstrate that it's not hard to adapt a theme to these changes. And in a
later series, I'm planning to move duplicate JS code from */graph.tmpl to
mercurial.js and leave only 4 lines of code embedded in those <script>
elements, and even that would be just to allow redefining graph.vertex
function. So adapting a custom 3rd-party theme to these changes would mean:

- creating or copying graphnode.tmpl and adding it to the map file (if a theme
  doesn't already use __base__)

- modifying one line in graph.tmpl and simply removing the bigger part of
  JavaScript code from there

Making these changes in this patch and not updating every hgweb theme that uses
jsdata at the same time is a bit of a cheat to make this series more
manageable: /graph pages that use jsdata are broken by this patch, but since
there are no tests that would detect this, bisect works fine; and themes are
updated separately, in the next 4 patches of this series to ease reviewing.

# mdiff.py - diff and patch routines for mercurial
#
# Copyright 2005, 2006 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.

from __future__ import absolute_import

import re
import struct
import zlib

from .i18n import _
from . import (
    error,
    policy,
    pycompat,
    util,
)

bdiff = policy.importmod(r'bdiff')
mpatch = policy.importmod(r'mpatch')

blocks = bdiff.blocks
fixws = bdiff.fixws
patches = mpatch.patches
patchedsize = mpatch.patchedsize
textdiff = bdiff.bdiff

def splitnewlines(text):
    '''like str.splitlines, but only split on newlines.'''
    lines = [l + '\n' for l in text.split('\n')]
    if lines:
        if lines[-1] == '\n':
            lines.pop()
        else:
            lines[-1] = lines[-1][:-1]
    return lines

class diffopts(object):
    '''context is the number of context lines
    text treats all files as text
    showfunc enables diff -p output
    git enables the git extended patch format
    nodates removes dates from diff headers
    nobinary ignores binary files
    noprefix disables the 'a/' and 'b/' prefixes (ignored in plain mode)
    ignorews ignores all whitespace changes in the diff
    ignorewsamount ignores changes in the amount of whitespace
    ignoreblanklines ignores changes whose lines are all blank
    upgrade generates git diffs to avoid data loss
    '''

    defaults = {
        'context': 3,
        'text': False,
        'showfunc': False,
        'git': False,
        'nodates': False,
        'nobinary': False,
        'noprefix': False,
        'index': 0,
        'ignorews': False,
        'ignorewsamount': False,
        'ignorewseol': False,
        'ignoreblanklines': False,
        'upgrade': False,
        'showsimilarity': False,
        }

    def __init__(self, **opts):
        opts = pycompat.byteskwargs(opts)
        for k in self.defaults.keys():
            v = opts.get(k)
            if v is None:
                v = self.defaults[k]
            setattr(self, k, v)

        try:
            self.context = int(self.context)
        except ValueError:
            raise error.Abort(_('diff context lines count must be '
                               'an integer, not %r') % self.context)

    def copy(self, **kwargs):
        opts = dict((k, getattr(self, k)) for k in self.defaults)
        opts = pycompat.strkwargs(opts)
        opts.update(kwargs)
        return diffopts(**opts)

defaultopts = diffopts()

def wsclean(opts, text, blank=True):
    if opts.ignorews:
        text = bdiff.fixws(text, 1)
    elif opts.ignorewsamount:
        text = bdiff.fixws(text, 0)
    if blank and opts.ignoreblanklines:
        text = re.sub('\n+', '\n', text).strip('\n')
    if opts.ignorewseol:
        text = re.sub(r'[ \t\r\f]+\n', r'\n', text)
    return text

def splitblock(base1, lines1, base2, lines2, opts):
    # The input lines matches except for interwoven blank lines. We
    # transform it into a sequence of matching blocks and blank blocks.
    lines1 = [(wsclean(opts, l) and 1 or 0) for l in lines1]
    lines2 = [(wsclean(opts, l) and 1 or 0) for l in lines2]
    s1, e1 = 0, len(lines1)
    s2, e2 = 0, len(lines2)
    while s1 < e1 or s2 < e2:
        i1, i2, btype = s1, s2, '='
        if (i1 >= e1 or lines1[i1] == 0
            or i2 >= e2 or lines2[i2] == 0):
            # Consume the block of blank lines
            btype = '~'
            while i1 < e1 and lines1[i1] == 0:
                i1 += 1
            while i2 < e2 and lines2[i2] == 0:
                i2 += 1
        else:
            # Consume the matching lines
            while i1 < e1 and lines1[i1] == 1 and lines2[i2] == 1:
                i1 += 1
                i2 += 1
        yield [base1 + s1, base1 + i1, base2 + s2, base2 + i2], btype
        s1 = i1
        s2 = i2

def hunkinrange(hunk, linerange):
    """Return True if `hunk` defined as (start, length) is in `linerange`
    defined as (lowerbound, upperbound).

    >>> hunkinrange((5, 10), (2, 7))
    True
    >>> hunkinrange((5, 10), (6, 12))
    True
    >>> hunkinrange((5, 10), (13, 17))
    True
    >>> hunkinrange((5, 10), (3, 17))
    True
    >>> hunkinrange((5, 10), (1, 3))
    False
    >>> hunkinrange((5, 10), (18, 20))
    False
    >>> hunkinrange((5, 10), (1, 5))
    False
    >>> hunkinrange((5, 10), (15, 27))
    False
    """
    start, length = hunk
    lowerbound, upperbound = linerange
    return lowerbound < start + length and start < upperbound

def blocksinrange(blocks, rangeb):
    """filter `blocks` like (a1, a2, b1, b2) from items outside line range
    `rangeb` from ``(b1, b2)`` point of view.

    Return `filteredblocks, rangea` where:

    * `filteredblocks` is list of ``block = (a1, a2, b1, b2), stype`` items of
      `blocks` that are inside `rangeb` from ``(b1, b2)`` point of view; a
      block ``(b1, b2)`` being inside `rangeb` if
      ``rangeb[0] < b2 and b1 < rangeb[1]``;
    * `rangea` is the line range w.r.t. to ``(a1, a2)`` parts of `blocks`.
    """
    lbb, ubb = rangeb
    lba, uba = None, None
    filteredblocks = []
    for block in blocks:
        (a1, a2, b1, b2), stype = block
        if lbb >= b1 and ubb <= b2 and stype == '=':
            # rangeb is within a single "=" hunk, restrict back linerange1
            # by offsetting rangeb
            lba = lbb - b1 + a1
            uba = ubb - b1 + a1
        else:
            if b1 <= lbb < b2:
                if stype == '=':
                    lba = a2 - (b2 - lbb)
                else:
                    lba = a1
            if b1 < ubb <= b2:
                if stype == '=':
                    uba = a1 + (ubb - b1)
                else:
                    uba = a2
        if hunkinrange((b1, (b2 - b1)), rangeb):
            filteredblocks.append(block)
    if lba is None or uba is None or uba < lba:
        raise error.Abort(_('line range exceeds file size'))
    return filteredblocks, (lba, uba)

def allblocks(text1, text2, opts=None, lines1=None, lines2=None):
    """Return (block, type) tuples, where block is an mdiff.blocks
    line entry. type is '=' for blocks matching exactly one another
    (bdiff blocks), '!' for non-matching blocks and '~' for blocks
    matching only after having filtered blank lines.
    line1 and line2 are text1 and text2 split with splitnewlines() if
    they are already available.
    """
    if opts is None:
        opts = defaultopts
    if opts.ignorews or opts.ignorewsamount or opts.ignorewseol:
        text1 = wsclean(opts, text1, False)
        text2 = wsclean(opts, text2, False)
    diff = bdiff.blocks(text1, text2)
    for i, s1 in enumerate(diff):
        # The first match is special.
        # we've either found a match starting at line 0 or a match later
        # in the file.  If it starts later, old and new below will both be
        # empty and we'll continue to the next match.
        if i > 0:
            s = diff[i - 1]
        else:
            s = [0, 0, 0, 0]
        s = [s[1], s1[0], s[3], s1[2]]

        # bdiff sometimes gives huge matches past eof, this check eats them,
        # and deals with the special first match case described above
        if s[0] != s[1] or s[2] != s[3]:
            type = '!'
            if opts.ignoreblanklines:
                if lines1 is None:
                    lines1 = splitnewlines(text1)
                if lines2 is None:
                    lines2 = splitnewlines(text2)
                old = wsclean(opts, "".join(lines1[s[0]:s[1]]))
                new = wsclean(opts, "".join(lines2[s[2]:s[3]]))
                if old == new:
                    type = '~'
            yield s, type
        yield s1, '='

def unidiff(a, ad, b, bd, fn1, fn2, opts=defaultopts):
    """Return a unified diff as a (headers, hunks) tuple.

    If the diff is not null, `headers` is a list with unified diff header
    lines "--- <original>" and "+++ <new>" and `hunks` is a generator yielding
    (hunkrange, hunklines) coming from _unidiff().
    Otherwise, `headers` and `hunks` are empty.
    """
    def datetag(date, fn=None):
        if not opts.git and not opts.nodates:
            return '\t%s' % date
        if fn and ' ' in fn:
            return '\t'
        return ''

    sentinel = [], ()
    if not a and not b:
        return sentinel

    if opts.noprefix:
        aprefix = bprefix = ''
    else:
        aprefix = 'a/'
        bprefix = 'b/'

    epoch = util.datestr((0, 0))

    fn1 = util.pconvert(fn1)
    fn2 = util.pconvert(fn2)

    def checknonewline(lines):
        for text in lines:
            if text[-1:] != '\n':
                text += "\n\ No newline at end of file\n"
            yield text

    if not opts.text and (util.binary(a) or util.binary(b)):
        if a and b and len(a) == len(b) and a == b:
            return sentinel
        headerlines = []
        hunks = (None, ['Binary file %s has changed\n' % fn1]),
    elif not a:
        b = splitnewlines(b)
        if a is None:
            l1 = '--- /dev/null%s' % datetag(epoch)
        else:
            l1 = "--- %s%s%s" % (aprefix, fn1, datetag(ad, fn1))
        l2 = "+++ %s%s" % (bprefix + fn2, datetag(bd, fn2))
        headerlines = [l1, l2]
        size = len(b)
        hunkrange = (0, 0, 1, size)
        hunklines = ["@@ -0,0 +1,%d @@\n" % size] + ["+" + e for e in b]
        hunks = (hunkrange, checknonewline(hunklines)),
    elif not b:
        a = splitnewlines(a)
        l1 = "--- %s%s%s" % (aprefix, fn1, datetag(ad, fn1))
        if b is None:
            l2 = '+++ /dev/null%s' % datetag(epoch)
        else:
            l2 = "+++ %s%s%s" % (bprefix, fn2, datetag(bd, fn2))
        headerlines = [l1, l2]
        size = len(a)
        hunkrange = (1, size, 0, 0)
        hunklines = ["@@ -1,%d +0,0 @@\n" % size] + ["-" + e for e in a]
        hunks = (hunkrange, checknonewline(hunklines)),
    else:
        diffhunks = _unidiff(a, b, opts=opts)
        try:
            hunkrange, hunklines = next(diffhunks)
        except StopIteration:
            return sentinel

        headerlines = [
            "--- %s%s%s" % (aprefix, fn1, datetag(ad, fn1)),
            "+++ %s%s%s" % (bprefix, fn2, datetag(bd, fn2)),
        ]
        def rewindhunks():
            yield hunkrange, checknonewline(hunklines)
            for hr, hl in diffhunks:
                yield hr, checknonewline(hl)

        hunks = rewindhunks()

    return headerlines, hunks

def _unidiff(t1, t2, opts=defaultopts):
    """Yield hunks of a headerless unified diff from t1 and t2 texts.

    Each hunk consists of a (hunkrange, hunklines) tuple where `hunkrange` is a
    tuple (s1, l1, s2, l2) representing the range information of the hunk to
    form the '@@ -s1,l1 +s2,l2 @@' header and `hunklines` is a list of lines
    of the hunk combining said header followed by line additions and
    deletions.
    """
    l1 = splitnewlines(t1)
    l2 = splitnewlines(t2)
    def contextend(l, len):
        ret = l + opts.context
        if ret > len:
            ret = len
        return ret

    def contextstart(l):
        ret = l - opts.context
        if ret < 0:
            return 0
        return ret

    lastfunc = [0, '']
    def yieldhunk(hunk):
        (astart, a2, bstart, b2, delta) = hunk
        aend = contextend(a2, len(l1))
        alen = aend - astart
        blen = b2 - bstart + aend - a2

        func = ""
        if opts.showfunc:
            lastpos, func = lastfunc
            # walk backwards from the start of the context up to the start of
            # the previous hunk context until we find a line starting with an
            # alphanumeric char.
            for i in xrange(astart - 1, lastpos - 1, -1):
                if l1[i][0].isalnum():
                    func = ' ' + l1[i].rstrip()[:40]
                    lastfunc[1] = func
                    break
            # by recording this hunk's starting point as the next place to
            # start looking for function lines, we avoid reading any line in
            # the file more than once.
            lastfunc[0] = astart

        # zero-length hunk ranges report their start line as one less
        if alen:
            astart += 1
        if blen:
            bstart += 1

        hunkrange = astart, alen, bstart, blen
        hunklines = (
            ["@@ -%d,%d +%d,%d @@%s\n" % (hunkrange + (func,))]
            + delta
            + [' ' + l1[x] for x in xrange(a2, aend)]
        )
        yield hunkrange, hunklines

    # bdiff.blocks gives us the matching sequences in the files.  The loop
    # below finds the spaces between those matching sequences and translates
    # them into diff output.
    #
    hunk = None
    ignoredlines = 0
    for s, stype in allblocks(t1, t2, opts, l1, l2):
        a1, a2, b1, b2 = s
        if stype != '!':
            if stype == '~':
                # The diff context lines are based on t1 content. When
                # blank lines are ignored, the new lines offsets must
                # be adjusted as if equivalent blocks ('~') had the
                # same sizes on both sides.
                ignoredlines += (b2 - b1) - (a2 - a1)
            continue
        delta = []
        old = l1[a1:a2]
        new = l2[b1:b2]

        b1 -= ignoredlines
        b2 -= ignoredlines
        astart = contextstart(a1)
        bstart = contextstart(b1)
        prev = None
        if hunk:
            # join with the previous hunk if it falls inside the context
            if astart < hunk[1] + opts.context + 1:
                prev = hunk
                astart = hunk[1]
                bstart = hunk[3]
            else:
                for x in yieldhunk(hunk):
                    yield x
        if prev:
            # we've joined the previous hunk, record the new ending points.
            hunk[1] = a2
            hunk[3] = b2
            delta = hunk[4]
        else:
            # create a new hunk
            hunk = [astart, a2, bstart, b2, delta]

        delta[len(delta):] = [' ' + x for x in l1[astart:a1]]
        delta[len(delta):] = ['-' + x for x in old]
        delta[len(delta):] = ['+' + x for x in new]

    if hunk:
        for x in yieldhunk(hunk):
            yield x

def b85diff(to, tn):
    '''print base85-encoded binary diff'''
    def fmtline(line):
        l = len(line)
        if l <= 26:
            l = chr(ord('A') + l - 1)
        else:
            l = chr(l - 26 + ord('a') - 1)
        return '%c%s\n' % (l, util.b85encode(line, True))

    def chunk(text, csize=52):
        l = len(text)
        i = 0
        while i < l:
            yield text[i:i + csize]
            i += csize

    if to is None:
        to = ''
    if tn is None:
        tn = ''

    if to == tn:
        return ''

    # TODO: deltas
    ret = []
    ret.append('GIT binary patch\n')
    ret.append('literal %d\n' % len(tn))
    for l in chunk(zlib.compress(tn)):
        ret.append(fmtline(l))
    ret.append('\n')

    return ''.join(ret)

def patchtext(bin):
    pos = 0
    t = []
    while pos < len(bin):
        p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])
        pos += 12
        t.append(bin[pos:pos + l])
        pos += l
    return "".join(t)

def patch(a, bin):
    if len(a) == 0:
        # skip over trivial delta header
        return util.buffer(bin, 12)
    return mpatch.patches(a, [bin])

# similar to difflib.SequenceMatcher.get_matching_blocks
def get_matching_blocks(a, b):
    return [(d[0], d[2], d[1] - d[0]) for d in bdiff.blocks(a, b)]

def trivialdiffheader(length):
    return struct.pack(">lll", 0, 0, length) if length else ''

def replacediffheader(oldlen, newlen):
    return struct.pack(">lll", 0, oldlen, newlen)