view tests/test-template-basic.t @ 40326:fed697fa1734

sqlitestore: file storage backend using SQLite

This commit provides an extension which uses SQLite to store file
data (as opposed to revlogs).

As the inline documentation describes, there are still several
aspects to the extension that are incomplete. But it's a start.
The extension does support basic clone, checkout, and commit
workflows, which makes it suitable for simple use cases.

One notable missing feature is support for "bundlerepos." This is
probably responsible for the most test failures when the extension
is activated as part of the test suite.

All revision data is stored in SQLite. Data is stored as zstd
compressed chunks (default if zstd is available), zlib compressed
chunks (default if zstd is not available), or raw chunks (if
configured or if a compressed delta is not smaller than the raw
delta). This makes things very similar to revlogs.

Unlike revlogs, the extension doesn't yet enforce a limit on delta
chain length. This is an obvious limitation and should be addressed.
This is somewhat mitigated by the use of zstd, which is much faster
than zlib to decompress.

There is a dedicated table for storing deltas. Deltas are stored
by the SHA-1 hash of their uncompressed content. The "fileindex" table
has columns that reference the delta for each revision and the base
delta that delta should be applied against. A recursive SQL query
is used to resolve the delta chain along with the delta data.

By storing deltas by hash, we are able to de-duplicate delta storage!
With revlogs, the same deltas in different revlogs would result in
duplicate storage of that delta. In this scheme, inserting the
duplicate delta is a no-op and delta chains simply reference the
existing delta.

When initially implementing this extension, I did not have
content-indexed deltas and deltas could be duplicated across files
(just like revlogs). When I implemented content-indexed deltas, the
size of the SQLite database for a full clone of mozilla-unified
dropped:

before: 2,554,261,504 bytes
after:  2,488,754,176 bytes

Surprisingly, this is still larger than the bytes size of revlog
files:

revlog files: 2,104,861,230 bytes
du -b:        2,254,381,614

I would have expected storage to be smaller since we're not limiting
delta chain length and since we're using zstd instead of zlib. I
suspect the SQLite indexes and per-column overhead account for the
bulk of the differences. (Keep in mind that revlog uses a 64-byte
packed struct for revision index data and deltas are stored without
padding. Aside from the 12 unused bytes in the 32 byte node field,
revlogs are pretty efficient.) Another source of overhead is file
name storage. With revlogs, file names are stored in the filesystem.
But with SQLite, we need to store file names in the database. This is
roughly equivalent to the size of the fncache file, which for the
mozilla-unified repository is ~34MB.

Since the SQLite database isn't append-only and since delta chains
can reference any delta, this opens some interesting possibilities.
For example, we could store deltas in reverse, such that fulltexts
are stored for newer revisions and deltas are applied to reconstruct
older revisions. This is likely a more optimal storage strategy for
version control, as new data tends to be more frequently accessed
than old data. We would obviously need wire protocol support for
transferring revision data from newest to oldest. And we would
probably need some kind of mechanism for "re-encoding" stores. But
it should be doable.

This extension is very much experimental quality. There are a handful
of features that don't work. It probably isn't suitable for day-to-day
use. But it could be used in limited cases (e.g. read-only checkouts
like in CI). And it is also a good proving ground for alternate
storage backends. As we continue to define interfaces for all things
storage, it will be useful to have a viable alternate storage backend
to see how things shake out in practice.

test-storage.py passes on Python 2 and introduces no new test failures on
Python 3. Having the storage-level unit tests has proved to be insanely
useful when developing this extension. Those tests caught numerous bugs
during development and I'm convinced this style of testing is the way
forward for ensuring alternate storage backends work as intended. Of
course, test coverage isn't close to what it needs to be. But it is
a start. And what coverage we have gives me confidence that basic store
functionality is implemented properly.

Differential Revision: https://phab.mercurial-scm.org/D4928

Test template syntax and basic functionality
============================================

  $ hg init a
  $ cd a
  $ echo a > a
  $ hg add a
  $ echo line 1 > b
  $ echo line 2 >> b
  $ hg commit -l b -d '1000000 0' -u 'User Name <user@hostname>'

  $ hg add b
  $ echo other 1 > c
  $ echo other 2 >> c
  $ echo >> c
  $ echo other 3 >> c
  $ hg commit -l c -d '1100000 0' -u 'A. N. Other <other@place>'

  $ hg add c
  $ hg commit -m 'no person' -d '1200000 0' -u 'other@place'
  $ echo c >> c
  $ hg commit -m 'no user, no domain' -d '1300000 0' -u 'person'

  $ echo foo > .hg/branch
  $ hg commit -m 'new branch' -d '1400000 0' -u 'person'

  $ hg co -q 3
  $ echo other 4 >> d
  $ hg add d
  $ hg commit -m 'new head' -d '1500000 0' -u 'person'

  $ hg merge -q foo
  $ hg commit -m 'merge' -d '1500001 0' -u 'person'

Test arithmetic operators have the right precedence:

  $ hg log -l 1 -T '{date(date, "%Y") + 5 * 10} {date(date, "%Y") - 2 * 3}\n'
  2020 1964
  $ hg log -l 1 -T '{date(date, "%Y") * 5 + 10} {date(date, "%Y") * 3 - 2}\n'
  9860 5908

Test division:

  $ hg debugtemplate -r0 -v '{5 / 2} {mod(5, 2)}\n'
  (template
    (/
      (integer '5')
      (integer '2'))
    (string ' ')
    (func
      (symbol 'mod')
      (list
        (integer '5')
        (integer '2')))
    (string '\n'))
  * keywords: 
  * functions: mod
  2 1
  $ hg debugtemplate -r0 -v '{5 / -2} {mod(5, -2)}\n'
  (template
    (/
      (integer '5')
      (negate
        (integer '2')))
    (string ' ')
    (func
      (symbol 'mod')
      (list
        (integer '5')
        (negate
          (integer '2'))))
    (string '\n'))
  * keywords: 
  * functions: mod
  -3 -1
  $ hg debugtemplate -r0 -v '{-5 / 2} {mod(-5, 2)}\n'
  (template
    (/
      (negate
        (integer '5'))
      (integer '2'))
    (string ' ')
    (func
      (symbol 'mod')
      (list
        (negate
          (integer '5'))
        (integer '2')))
    (string '\n'))
  * keywords: 
  * functions: mod
  -3 1
  $ hg debugtemplate -r0 -v '{-5 / -2} {mod(-5, -2)}\n'
  (template
    (/
      (negate
        (integer '5'))
      (negate
        (integer '2')))
    (string ' ')
    (func
      (symbol 'mod')
      (list
        (negate
          (integer '5'))
        (negate
          (integer '2'))))
    (string '\n'))
  * keywords: 
  * functions: mod
  2 -1

Filters bind closer than arithmetic:

  $ hg debugtemplate -r0 -v '{revset(".")|count - 1}\n'
  (template
    (-
      (|
        (func
          (symbol 'revset')
          (string '.'))
        (symbol 'count'))
      (integer '1'))
    (string '\n'))
  * keywords: 
  * functions: count, revset
  0

But negate binds closer still:

  $ hg debugtemplate -r0 -v '{1-3|stringify}\n'
  (template
    (-
      (integer '1')
      (|
        (integer '3')
        (symbol 'stringify')))
    (string '\n'))
  * keywords: 
  * functions: stringify
  hg: parse error: arithmetic only defined on integers
  [255]
  $ hg debugtemplate -r0 -v '{-3|stringify}\n'
  (template
    (|
      (negate
        (integer '3'))
      (symbol 'stringify'))
    (string '\n'))
  * keywords: 
  * functions: stringify
  -3

Filters bind as close as map operator:

  $ hg debugtemplate -r0 -v '{desc|splitlines % "{line}\n"}'
  (template
    (%
      (|
        (symbol 'desc')
        (symbol 'splitlines'))
      (template
        (symbol 'line')
        (string '\n'))))
  * keywords: desc, line
  * functions: splitlines
  line 1
  line 2

Keyword arguments:

  $ hg debugtemplate -r0 -v '{foo=bar|baz}'
  (template
    (keyvalue
      (symbol 'foo')
      (|
        (symbol 'bar')
        (symbol 'baz'))))
  * keywords: bar, foo
  * functions: baz
  hg: parse error: can't use a key-value pair in this context
  [255]

  $ hg debugtemplate '{pad("foo", width=10, left=true)}\n'
         foo

Call function which takes named arguments by filter syntax:

  $ hg debugtemplate '{" "|separate}'
  $ hg debugtemplate '{("not", "an", "argument", "list")|separate}'
  hg: parse error: unknown method 'list'
  [255]

Second branch starting at nullrev:

  $ hg update null
  0 files updated, 0 files merged, 4 files removed, 0 files unresolved
  $ echo second > second
  $ hg add second
  $ hg commit -m second -d '1000000 0' -u 'User Name <user@hostname>'
  created new head

  $ echo third > third
  $ hg add third
  $ hg mv second fourth
  $ hg commit -m third -d "2020-01-01 10:01"

  $ hg log --template '{join(file_copies, ",\n")}\n' -r .
  fourth (second)
  $ hg log -T '{file_copies % "{source} -> {name}\n"}' -r .
  second -> fourth
  $ hg log -T '{rev} {ifcontains("fourth", file_copies, "t", "f")}\n' -r .:7
  8 t
  7 f

Internal resources shouldn't be exposed (issue5699):

  $ hg log -r. -T '{cache}{ctx}{repo}{revcache}{templ}{ui}'

Never crash on internal resource not available:

  $ hg --cwd .. debugtemplate '{"c0bebeef"|shortest}\n'
  abort: template resource not available: repo
  [255]

  $ hg config -T '{author}'

Quoting for ui.logtemplate

  $ hg tip --config "ui.logtemplate={rev}\n"
  8
  $ hg tip --config "ui.logtemplate='{rev}\n'"
  8
  $ hg tip --config 'ui.logtemplate="{rev}\n"'
  8
  $ hg tip --config 'ui.logtemplate=n{rev}\n'
  n8

Check that recursive reference does not fall into RuntimeError (issue4758):

 common mistake:

  $ cat << EOF > issue4758
  > changeset = '{changeset}\n'
  > EOF
  $ hg log --style ./issue4758
  abort: recursive reference 'changeset' in template
  [255]

 circular reference:

  $ cat << EOF > issue4758
  > changeset = '{foo}'
  > foo = '{changeset}'
  > EOF
  $ hg log --style ./issue4758
  abort: recursive reference 'foo' in template
  [255]

 buildmap() -> gettemplate(), where no thunk was made:

  $ cat << EOF > issue4758
  > changeset = '{files % changeset}\n'
  > EOF
  $ hg log --style ./issue4758
  abort: recursive reference 'changeset' in template
  [255]

 not a recursion if a keyword of the same name exists:

  $ cat << EOF > issue4758
  > changeset = '{tags % rev}'
  > rev = '{rev} {tag}\n'
  > EOF
  $ hg log --style ./issue4758 -r tip
  8 tip

Set up phase:

  $ hg phase -r 5 --public
  $ hg phase -r 7 --secret --force

Add a dummy commit to make up for the instability of the above:

  $ echo a > a
  $ hg add a
  $ hg ci -m future

Add a commit that does all possible modifications at once

  $ echo modify >> third
  $ touch b
  $ hg add b
  $ hg mv fourth fifth
  $ hg rm a
  $ hg ci -m "Modify, add, remove, rename"

Error on syntax:

  $ cat <<EOF > t
  > changeset = '{c}'
  > c = q
  > x = "f
  > EOF
  $ echo '[ui]' > .hg/hgrc
  $ echo 'style = t' >> .hg/hgrc
  $ hg log
  hg: parse error at t:3: unmatched quotes
  [255]

  $ hg log -T '{date'
  hg: parse error at 1: unterminated template expansion
  ({date
    ^ here)
  [255]
  $ hg log -T '{date(}'
  hg: parse error at 6: not a prefix: end
  ({date(}
         ^ here)
  [255]
  $ hg log -T '{date)}'
  hg: parse error at 5: invalid token
  ({date)}
        ^ here)
  [255]
  $ hg log -T '{date date}'
  hg: parse error at 6: invalid token
  ({date date}
         ^ here)
  [255]

  $ hg log -T '{}'
  hg: parse error at 1: not a prefix: end
  ({}
    ^ here)
  [255]
  $ hg debugtemplate -v '{()}'
  (template
    (group
      None))
  * keywords: 
  * functions: 
  hg: parse error: missing argument
  [255]

Behind the scenes, this would throw TypeError without intype=bytes

  $ hg log -l 3 --template '{date|obfuscate}\n'
  &#48;&#46;&#48;&#48;
  &#48;&#46;&#48;&#48;
  &#49;&#53;&#55;&#55;&#56;&#55;&#50;&#56;&#54;&#48;&#46;&#48;&#48;

Behind the scenes, this will throw a ValueError

  $ hg log -l 3 --template 'line: {desc|shortdate}\n'
  hg: parse error: invalid date: 'Modify, add, remove, rename'
  (template filter 'shortdate' is not compatible with keyword 'desc')
  [255]

Behind the scenes, this would throw AttributeError without intype=bytes

  $ hg log -l 3 --template 'line: {date|escape}\n'
  line: 0.00
  line: 0.00
  line: 1577872860.00

  $ hg log -l 3 --template 'line: {extras|localdate}\n'
  hg: parse error: localdate expects a date information
  [255]

Behind the scenes, this will throw ValueError

  $ hg tip --template '{author|email|date}\n'
  hg: parse error: date expects a date information
  [255]

  $ hg tip -T '{author|email|shortdate}\n'
  hg: parse error: invalid date: 'test'
  (template filter 'shortdate' is not compatible with keyword 'author')
  [255]

  $ hg tip -T '{get(extras, "branch")|shortdate}\n'
  hg: parse error: invalid date: 'default'
  (incompatible use of template filter 'shortdate')
  [255]

Error in nested template:

  $ hg log -T '{"date'
  hg: parse error at 2: unterminated string
  ({"date
     ^ here)
  [255]

  $ hg log -T '{"foo{date|?}"}'
  hg: parse error at 11: syntax error
  ({"foo{date|?}"}
              ^ here)
  [255]

Thrown an error if a template function doesn't exist

  $ hg tip --template '{foo()}\n'
  hg: parse error: unknown function 'foo'
  [255]

  $ cd ..

Set up latesttag repository:

  $ hg init latesttag
  $ cd latesttag

  $ echo a > file
  $ hg ci -Am a -d '0 0'
  adding file

  $ echo b >> file
  $ hg ci -m b -d '1 0'

  $ echo c >> head1
  $ hg ci -Am h1c -d '2 0'
  adding head1

  $ hg update -q 1
  $ echo d >> head2
  $ hg ci -Am h2d -d '3 0'
  adding head2
  created new head

  $ echo e >> head2
  $ hg ci -m h2e -d '4 0'

  $ hg merge -q
  $ hg ci -m merge -d '5 -3600'

  $ hg tag -r 1 -m t1 -d '6 0' t1
  $ hg tag -r 2 -m t2 -d '7 0' t2
  $ hg tag -r 3 -m t3 -d '8 0' t3
  $ hg tag -r 4 -m t4 -d '4 0' t4 # older than t2, but should not matter
  $ hg tag -r 5 -m t5 -d '9 0' t5
  $ hg tag -r 3 -m at3 -d '10 0' at3

  $ cd ..

Test new-style inline templating:

  $ hg log -R latesttag -r tip --template 'modified files: {file_mods % " {file}\n"}\n'
  modified files:  .hgtags
  

  $ hg log -R latesttag -r tip -T '{rev % "a"}\n'
  hg: parse error: 11 is not iterable of mappings
  (keyword 'rev' does not support map operation)
  [255]
  $ hg log -R latesttag -r tip -T '{get(extras, "unknown") % "a"}\n'
  hg: parse error: None is not iterable of mappings
  [255]
  $ hg log -R latesttag -r tip -T '{extras % "{key}\n" % "{key}\n"}'
  hg: parse error: list of strings is not mappable
  [255]

Test new-style inline templating of non-list/dict type:

  $ hg log -R latesttag -r tip -T '{manifest}\n'
  11:2bc6e9006ce2
  $ hg log -R latesttag -r tip -T 'string length: {manifest|count}\n'
  string length: 15
  $ hg log -R latesttag -r tip -T '{manifest % "{rev}:{node}"}\n'
  11:2bc6e9006ce29882383a22d39fd1f4e66dd3e2fc

  $ hg log -R latesttag -r tip -T '{get(extras, "branch") % "{key}: {value}\n"}'
  branch: default
  $ hg log -R latesttag -r tip -T '{get(extras, "unknown") % "{key}\n"}'
  hg: parse error: None is not iterable of mappings
  [255]
  $ hg log -R latesttag -r tip -T '{min(extras) % "{key}: {value}\n"}'
  branch: default
  $ hg log -R latesttag -l1 -T '{min(revset("0:9")) % "{rev}:{node|short}\n"}'
  0:ce3cec86e6c2
  $ hg log -R latesttag -l1 -T '{max(revset("0:9")) % "{rev}:{node|short}\n"}'
  9:fbc7cd862e9c

Test dot operator precedence:

  $ hg debugtemplate -R latesttag -r0 -v '{manifest.node|short}\n'
  (template
    (|
      (.
        (symbol 'manifest')
        (symbol 'node'))
      (symbol 'short'))
    (string '\n'))
  * keywords: manifest, node, rev
  * functions: formatnode, short
  89f4071fec70

 (the following examples are invalid, but seem natural in parsing POV)

  $ hg debugtemplate -R latesttag -r0 -v '{foo|bar.baz}\n' 2> /dev/null
  (template
    (|
      (symbol 'foo')
      (.
        (symbol 'bar')
        (symbol 'baz')))
    (string '\n'))
  [255]
  $ hg debugtemplate -R latesttag -r0 -v '{foo.bar()}\n' 2> /dev/null
  (template
    (.
      (symbol 'foo')
      (func
        (symbol 'bar')
        None))
    (string '\n'))
  * keywords: foo
  * functions: bar
  [255]

Test evaluation of dot operator:

  $ hg log -R latesttag -l1 -T '{min(revset("0:9")).node}\n'
  ce3cec86e6c26bd9bdfc590a6b92abc9680f1796
  $ hg log -R latesttag -r0 -T '{extras.branch}\n'
  default
  $ hg log -R latesttag -r0 -T '{date.unixtime} {localdate(date, "+0200").tzoffset}\n'
  0 -7200

  $ hg log -R latesttag -l1 -T '{author.invalid}\n'
  hg: parse error: 'test' is not a dictionary
  (keyword 'author' does not support member operation)
  [255]
  $ hg log -R latesttag -l1 -T '{min("abc").invalid}\n'
  hg: parse error: 'a' is not a dictionary
  [255]

Test integer literal:

  $ hg debugtemplate -v '{(0)}\n'
  (template
    (group
      (integer '0'))
    (string '\n'))
  * keywords: 
  * functions: 
  0
  $ hg debugtemplate -v '{(123)}\n'
  (template
    (group
      (integer '123'))
    (string '\n'))
  * keywords: 
  * functions: 
  123
  $ hg debugtemplate -v '{(-4)}\n'
  (template
    (group
      (negate
        (integer '4')))
    (string '\n'))
  * keywords: 
  * functions: 
  -4
  $ hg debugtemplate '{(-)}\n'
  hg: parse error at 3: not a prefix: )
  ({(-)}\n
      ^ here)
  [255]
  $ hg debugtemplate '{(-a)}\n'
  hg: parse error: negation needs an integer argument
  [255]

top-level integer literal is interpreted as symbol (i.e. variable name):

  $ hg debugtemplate -D 1=one -v '{1}\n'
  (template
    (integer '1')
    (string '\n'))
  * keywords: 
  * functions: 
  one
  $ hg debugtemplate -D 1=one -v '{if("t", "{1}")}\n'
  (template
    (func
      (symbol 'if')
      (list
        (string 't')
        (template
          (integer '1'))))
    (string '\n'))
  * keywords: 
  * functions: if
  one
  $ hg debugtemplate -D 1=one -v '{1|stringify}\n'
  (template
    (|
      (integer '1')
      (symbol 'stringify'))
    (string '\n'))
  * keywords: 
  * functions: stringify
  one

unless explicit symbol is expected:

  $ hg log -Ra -r0 -T '{desc|1}\n'
  hg: parse error: expected a symbol, got 'integer'
  [255]
  $ hg log -Ra -r0 -T '{1()}\n'
  hg: parse error: expected a symbol, got 'integer'
  [255]

Test string literal:

  $ hg debugtemplate -Ra -r0 -v '{"string with no template fragment"}\n'
  (template
    (string 'string with no template fragment')
    (string '\n'))
  * keywords: 
  * functions: 
  string with no template fragment
  $ hg debugtemplate -Ra -r0 -v '{"template: {rev}"}\n'
  (template
    (template
      (string 'template: ')
      (symbol 'rev'))
    (string '\n'))
  * keywords: rev
  * functions: 
  template: 0
  $ hg debugtemplate -Ra -r0 -v '{r"rawstring: {rev}"}\n'
  (template
    (string 'rawstring: {rev}')
    (string '\n'))
  * keywords: 
  * functions: 
  rawstring: {rev}
  $ hg debugtemplate -Ra -r0 -v '{files % r"rawstring: {file}"}\n'
  (template
    (%
      (symbol 'files')
      (string 'rawstring: {file}'))
    (string '\n'))
  * keywords: files
  * functions: 
  rawstring: {file}

Test string escaping:

  $ hg log -R latesttag -r 0 --template '>\n<>\\n<{if(rev, "[>\n<>\\n<]")}>\n<>\\n<\n'
  >
  <>\n<[>
  <>\n<]>
  <>\n<

  $ hg log -R latesttag -r 0 \
  > --config ui.logtemplate='>\n<>\\n<{if(rev, "[>\n<>\\n<]")}>\n<>\\n<\n'
  >
  <>\n<[>
  <>\n<]>
  <>\n<

  $ hg log -R latesttag -r 0 -T esc \
  > --config templates.esc='>\n<>\\n<{if(rev, "[>\n<>\\n<]")}>\n<>\\n<\n'
  >
  <>\n<[>
  <>\n<]>
  <>\n<

  $ cat <<'EOF' > esctmpl
  > changeset = '>\n<>\\n<{if(rev, "[>\n<>\\n<]")}>\n<>\\n<\n'
  > EOF
  $ hg log -R latesttag -r 0 --style ./esctmpl
  >
  <>\n<[>
  <>\n<]>
  <>\n<

Test string escaping of quotes:

  $ hg log -Ra -r0 -T '{"\""}\n'
  "
  $ hg log -Ra -r0 -T '{"\\\""}\n'
  \"
  $ hg log -Ra -r0 -T '{r"\""}\n'
  \"
  $ hg log -Ra -r0 -T '{r"\\\""}\n'
  \\\"


  $ hg log -Ra -r0 -T '{"\""}\n'
  "
  $ hg log -Ra -r0 -T '{"\\\""}\n'
  \"
  $ hg log -Ra -r0 -T '{r"\""}\n'
  \"
  $ hg log -Ra -r0 -T '{r"\\\""}\n'
  \\\"

Test exception in quoted template. single backslash before quotation mark is
stripped before parsing:

  $ cat <<'EOF' > escquotetmpl
  > changeset = "\" \\" \\\" \\\\" {files % \"{file}\"}\n"
  > EOF
  $ cd latesttag
  $ hg log -r 2 --style ../escquotetmpl
  " \" \" \\" head1

  $ hg log -r 2 -T esc --config templates.esc='"{\"valid\"}\n"'
  valid
  $ hg log -r 2 -T esc --config templates.esc="'"'{\'"'"'valid\'"'"'}\n'"'"
  valid

Test compatibility with 2.9.2-3.4 of escaped quoted strings in nested
_evalifliteral() templates (issue4733):

  $ hg log -r 2 -T '{if(rev, "\"{rev}")}\n'
  "2
  $ hg log -r 2 -T '{if(rev, "{if(rev, \"\\\"{rev}\")}")}\n'
  "2
  $ hg log -r 2 -T '{if(rev, "{if(rev, \"{if(rev, \\\"\\\\\\\"{rev}\\\")}\")}")}\n'
  "2

  $ hg log -r 2 -T '{if(rev, "\\\"")}\n'
  \"
  $ hg log -r 2 -T '{if(rev, "{if(rev, \"\\\\\\\"\")}")}\n'
  \"
  $ hg log -r 2 -T '{if(rev, "{if(rev, \"{if(rev, \\\"\\\\\\\\\\\\\\\"\\\")}\")}")}\n'
  \"

  $ hg log -r 2 -T '{if(rev, r"\\\"")}\n'
  \\\"
  $ hg log -r 2 -T '{if(rev, "{if(rev, r\"\\\\\\\"\")}")}\n'
  \\\"
  $ hg log -r 2 -T '{if(rev, "{if(rev, \"{if(rev, r\\\"\\\\\\\\\\\\\\\"\\\")}\")}")}\n'
  \\\"

escaped single quotes and errors:

  $ hg log -r 2 -T "{if(rev, '{if(rev, \'foo\')}')}"'\n'
  foo
  $ hg log -r 2 -T "{if(rev, '{if(rev, r\'foo\')}')}"'\n'
  foo
  $ hg log -r 2 -T '{if(rev, "{if(rev, \")}")}\n'
  hg: parse error at 21: unterminated string
  ({if(rev, "{if(rev, \")}")}\n
                        ^ here)
  [255]
  $ hg log -r 2 -T '{if(rev, \"\\"")}\n'
  hg: parse error: trailing \ in string
  [255]
  $ hg log -r 2 -T '{if(rev, r\"\\"")}\n'
  hg: parse error: trailing \ in string
  [255]

  $ cd ..

Test leading backslashes:

  $ cd latesttag
  $ hg log -r 2 -T '\{rev} {files % "\{file}"}\n'
  {rev} {file}
  $ hg log -r 2 -T '\\{rev} {files % "\\{file}"}\n'
  \2 \head1
  $ hg log -r 2 -T '\\\{rev} {files % "\\\{file}"}\n'
  \{rev} \{file}
  $ cd ..

Test leading backslashes in "if" expression (issue4714):

  $ cd latesttag
  $ hg log -r 2 -T '{if("1", "\{rev}")} {if("1", r"\{rev}")}\n'
  {rev} \{rev}
  $ hg log -r 2 -T '{if("1", "\\{rev}")} {if("1", r"\\{rev}")}\n'
  \2 \\{rev}
  $ hg log -r 2 -T '{if("1", "\\\{rev}")} {if("1", r"\\\{rev}")}\n'
  \{rev} \\\{rev}
  $ cd ..

"string-escape"-ed "\x5c\x786e" becomes r"\x6e" (once) or r"n" (twice)

  $ hg log -R a -r 0 --template '{if("1", "\x5c\x786e", "NG")}\n'
  \x6e
  $ hg log -R a -r 0 --template '{if("1", r"\x5c\x786e", "NG")}\n'
  \x5c\x786e
  $ hg log -R a -r 0 --template '{if("", "NG", "\x5c\x786e")}\n'
  \x6e
  $ hg log -R a -r 0 --template '{if("", "NG", r"\x5c\x786e")}\n'
  \x5c\x786e

  $ hg log -R a -r 2 --template '{ifeq("no perso\x6e", desc, "\x5c\x786e", "NG")}\n'
  \x6e
  $ hg log -R a -r 2 --template '{ifeq(r"no perso\x6e", desc, "NG", r"\x5c\x786e")}\n'
  \x5c\x786e
  $ hg log -R a -r 2 --template '{ifeq(desc, "no perso\x6e", "\x5c\x786e", "NG")}\n'
  \x6e
  $ hg log -R a -r 2 --template '{ifeq(desc, r"no perso\x6e", "NG", r"\x5c\x786e")}\n'
  \x5c\x786e

  $ hg log -R a -r 8 --template '{join(files, "\n")}\n'
  fourth
  second
  third
  $ hg log -R a -r 8 --template '{join(files, r"\n")}\n'
  fourth\nsecond\nthird

  $ hg log -R a -r 2 --template '{rstdoc("1st\n\n2nd", "htm\x6c")}'
  <p>
  1st
  </p>
  <p>
  2nd
  </p>
  $ hg log -R a -r 2 --template '{rstdoc(r"1st\n\n2nd", "html")}'
  <p>
  1st\n\n2nd
  </p>
  $ hg log -R a -r 2 --template '{rstdoc("1st\n\n2nd", r"htm\x6c")}'
  1st
  
  2nd

  $ hg log -R a -r 2 --template '{strip(desc, "\x6e")}\n'
  o perso
  $ hg log -R a -r 2 --template '{strip(desc, r"\x6e")}\n'
  no person
  $ hg log -R a -r 2 --template '{strip("no perso\x6e", "\x6e")}\n'
  o perso
  $ hg log -R a -r 2 --template '{strip(r"no perso\x6e", r"\x6e")}\n'
  no perso

  $ hg log -R a -r 2 --template '{sub("\\x6e", "\x2d", desc)}\n'
  -o perso-
  $ hg log -R a -r 2 --template '{sub(r"\\x6e", "-", desc)}\n'
  no person
  $ hg log -R a -r 2 --template '{sub("n", r"\\x2d", desc)}\n'
  \x2do perso\x2d
  $ hg log -R a -r 2 --template '{sub("n", "\x2d", "no perso\x6e")}\n'
  -o perso-
  $ hg log -R a -r 2 --template '{sub("n", r"\\x2d", r"no perso\x6e")}\n'
  \x2do perso\x6e

  $ hg log -R a -r 8 --template '{files % "{file}\n"}'
  fourth
  second
  third

Test string escaping in nested expression:

  $ hg log -R a -r 8 --template '{ifeq(r"\x6e", if("1", "\x5c\x786e"), join(files, "\x5c\x786e"))}\n'
  fourth\x6esecond\x6ethird
  $ hg log -R a -r 8 --template '{ifeq(if("1", r"\x6e"), "\x5c\x786e", join(files, "\x5c\x786e"))}\n'
  fourth\x6esecond\x6ethird

  $ hg log -R a -r 8 --template '{join(files, ifeq(branch, "default", "\x5c\x786e"))}\n'
  fourth\x6esecond\x6ethird
  $ hg log -R a -r 8 --template '{join(files, ifeq(branch, "default", r"\x5c\x786e"))}\n'
  fourth\x5c\x786esecond\x5c\x786ethird

  $ hg log -R a -r 3:4 --template '{rev}:{sub(if("1", "\x6e"), ifeq(branch, "foo", r"\x5c\x786e", "\x5c\x786e"), desc)}\n'
  3:\x6eo user, \x6eo domai\x6e
  4:\x5c\x786eew bra\x5c\x786ech

Test quotes in nested expression are evaluated just like a $(command)
substitution in POSIX shells:

  $ hg log -R a -r 8 -T '{"{"{rev}:{node|short}"}"}\n'
  8:95c24699272e
  $ hg log -R a -r 8 -T '{"{"\{{rev}} \"{node|short}\""}"}\n'
  {8} "95c24699272e"

Test recursive evaluation:

  $ hg init r
  $ cd r
  $ echo a > a
  $ hg ci -Am '{rev}'
  adding a
  $ hg log -r 0 --template '{if(rev, desc)}\n'
  {rev}
  $ hg log -r 0 --template '{if(rev, "{author} {rev}")}\n'
  test 0

  $ hg branch -q 'text.{rev}'
  $ echo aa >> aa
  $ hg ci -u '{node|short}' -m 'desc to be wrapped desc to be wrapped'

  $ hg log -l1 --template '{fill(desc, "20", author, branch)}'
  {node|short}desc to
  text.{rev}be wrapped
  text.{rev}desc to be
  text.{rev}wrapped (no-eol)
  $ hg log -l1 --template '{fill(desc, "20", "{node|short}:", "text.{rev}:")}'
  bcc7ff960b8e:desc to
  text.1:be wrapped
  text.1:desc to be
  text.1:wrapped (no-eol)
  $ hg log -l1 -T '{fill(desc, date, "", "")}\n'
  hg: parse error: fill expects an integer width
  [255]

  $ hg log -l 1 --template '{sub(r"[0-9]", "-", author)}'
  {node|short} (no-eol)
  $ hg log -l 1 --template '{sub(r"[0-9]", "-", "{node|short}")}'
  bcc-ff---b-e (no-eol)

  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > color=
  > [color]
  > mode=ansi
  > text.{rev} = red
  > text.1 = green
  > EOF
  $ hg log --color=always -l 1 --template '{label(branch, "text\n")}'
  \x1b[0;31mtext\x1b[0m (esc)
  $ hg log --color=always -l 1 --template '{label("text.{rev}", "text\n")}'
  \x1b[0;32mtext\x1b[0m (esc)

  $ cd ..

Test bad template with better error message

  $ hg log -Gv -R a --template '{desc|user()}'
  hg: parse error: expected a symbol, got 'func'
  [255]

Test broken string escapes:

  $ hg log -T "bogus\\" -R a
  hg: parse error: trailing \ in string
  [255]
  $ hg log -T "\\xy" -R a
  hg: parse error: invalid \x escape* (glob)
  [255]

Templater supports aliases of symbol and func() styles:

  $ hg clone -q a aliases
  $ cd aliases
  $ cat <<EOF >> .hg/hgrc
  > [templatealias]
  > r = rev
  > rn = "{r}:{node|short}"
  > status(c, files) = files % "{c} {file}\n"
  > utcdate(d) = localdate(d, "UTC")
  > EOF

  $ hg debugtemplate -vr0 '{rn} {utcdate(date)|isodate}\n'
  (template
    (symbol 'rn')
    (string ' ')
    (|
      (func
        (symbol 'utcdate')
        (symbol 'date'))
      (symbol 'isodate'))
    (string '\n'))
  * expanded:
  (template
    (template
      (symbol 'rev')
      (string ':')
      (|
        (symbol 'node')
        (symbol 'short')))
    (string ' ')
    (|
      (func
        (symbol 'localdate')
        (list
          (symbol 'date')
          (string 'UTC')))
      (symbol 'isodate'))
    (string '\n'))
  * keywords: date, node, rev
  * functions: isodate, localdate, short
  0:1e4e1b8f71e0 1970-01-12 13:46 +0000

  $ hg debugtemplate -vr0 '{status("A", file_adds)}'
  (template
    (func
      (symbol 'status')
      (list
        (string 'A')
        (symbol 'file_adds'))))
  * expanded:
  (template
    (%
      (symbol 'file_adds')
      (template
        (string 'A')
        (string ' ')
        (symbol 'file')
        (string '\n'))))
  * keywords: file, file_adds
  * functions: 
  A a

A unary function alias can be called as a filter:

  $ hg debugtemplate -vr0 '{date|utcdate|isodate}\n'
  (template
    (|
      (|
        (symbol 'date')
        (symbol 'utcdate'))
      (symbol 'isodate'))
    (string '\n'))
  * expanded:
  (template
    (|
      (func
        (symbol 'localdate')
        (list
          (symbol 'date')
          (string 'UTC')))
      (symbol 'isodate'))
    (string '\n'))
  * keywords: date
  * functions: isodate, localdate
  1970-01-12 13:46 +0000

Aliases should be applied only to command arguments and templates in hgrc.
Otherwise, our stock styles and web templates could be corrupted:

  $ hg log -r0 -T '{rn} {utcdate(date)|isodate}\n'
  0:1e4e1b8f71e0 1970-01-12 13:46 +0000

  $ hg log -r0 --config ui.logtemplate='"{rn} {utcdate(date)|isodate}\n"'
  0:1e4e1b8f71e0 1970-01-12 13:46 +0000

  $ cat <<EOF > tmpl
  > changeset = 'nothing expanded:{rn}\n'
  > EOF
  $ hg log -r0 --style ./tmpl
  nothing expanded:

Aliases in formatter:

  $ hg branches -T '{pad(branch, 7)} {rn}\n'
  default 6:d41e714fe50d
  foo     4:bbe44766e73d

Aliases should honor HGPLAIN:

  $ HGPLAIN= hg log -r0 -T 'nothing expanded:{rn}\n'
  nothing expanded:
  $ HGPLAINEXCEPT=templatealias hg log -r0 -T '{rn}\n'
  0:1e4e1b8f71e0

Unparsable alias:

  $ hg debugtemplate --config templatealias.bad='x(' -v '{bad}'
  (template
    (symbol 'bad'))
  abort: bad definition of template alias "bad": at 2: not a prefix: end
  [255]
  $ hg log --config templatealias.bad='x(' -T '{bad}'
  abort: bad definition of template alias "bad": at 2: not a prefix: end
  [255]

  $ cd ..

Test that template function in extension is registered as expected

  $ cd a

  $ cat <<EOF > $TESTTMP/customfunc.py
  > from mercurial import registrar
  > 
  > templatefunc = registrar.templatefunc()
  > 
  > @templatefunc(b'custom()')
  > def custom(context, mapping, args):
  >     return b'custom'
  > EOF
  $ cat <<EOF > .hg/hgrc
  > [extensions]
  > customfunc = $TESTTMP/customfunc.py
  > EOF

  $ hg log -r . -T "{custom()}\n" --config customfunc.enabled=true
  custom

  $ cd ..