Note:

This page is primarily intended for developers of Mercurial.

Better Matcher API and File Patterns Plan

Status: Project

Main proponents: KatsunoriFujiwara, RodrigoDamazio

$/!\$ This is a speculative project and does not represent any firm decisions on future behavior.

Add a short summary of the idea here.

Contents

Goal
Detailed description
Roadmap
See Also

1. Goal

Short term: add non-recursive globs ?
Long term: extensible matcher API ?

2. Detailed description

2.1. Sprint Notes

Non-recursive globs (Rodrigo, spectral, Durham, :
    Issue is that * is sometimes recursive
    matcher API is a mess
    Should we re-write match.py or just add fileglob?
    Suggestion: add fileglob via a new, cleaner API, then migrate others over time
    Possible FB use case: pick parts of a tree to include and exclude (would add ordering dependency instead of excludes always trumping includes?)
    matcher API should be extensible
    matcher composition: anyof, allof, negate, per-file-type, etc.
    Inconsistencies in pattern behavior between hgignore, --include/--exclude, etc.
    FB: conversion between matchers and watchman expressions
    Proposal: wiki page, first group to have a use case proposes the initial API

2.2. Current Status

2.2.1. Summary of mode, relative-to, and recursion of each types

mode	root-ed	cwd-ed	any-of-path	control recursion by pattern	context depend recursion
wildcard	-	`glob:`	`relglob:`	by **	o
regexp	`re:`	-	`relre:`	by $	x (*A)
raw string	`path:`	`relpath:`	-	(always)	x

(*A) "regexp" mode ignore pattern matches recursively (e.g. "re:^foo$" ignores file foo/bar). Detail is explained later.

2.2.2. The list of contexts, in which pattern is specified

pattern for	default type	recursion of wildcard	related API
fileset	`glob:`	x	ctx.match()
files() template function	`glob:`	x	ctx.match()
diff() template function	`glob:`	o (*1)	ctx.match()
file() revset predicate	`glob:`	x	match.match()
follow() revset predicate	`path:` (*3)	x	match.match()
--include/--exclude	`glob:`	o (*1)	match.match()
hgignore	`relre:`	o (*1)	match.match()
`archive` web command	`path:`	- (*2)	scmutil.match()
`hg locate`	`relglob:`	x	scmutil.match()
`hg log`	`relpath:`	x	scmutil.matchandpats()
others (e.g. `hg files`)	`relpath:`	x	scmutil.match()

(*1) treated as include/exclude of match.match() (otherwise, treated as pats of match.match())
(*2) no wildcard pattern matching occurs for archive web command, becuase path: is forcibly added to specified pattern in this case
(*3) can't be relpath: because of backward compatibility (5618858dce26)

For "recursion of wildcard":

if "recursive of wildcard", pattern glob:foo/bar matches against file foo/bar/baz, for example
Inner context is used to decide "recursion of wildcard", if multiple contexts are combined

For example, file foo/bar/baz is:

not matched at: hg files glob:foo/bar
not matched at: hg files -I "set:'glob:foo/bar'"
but matched at: hg files -I glob:foo/bar

The last case seems to cause the issue mentioned by Rodrigo in "match: adding non-recursive directory matching". And the second case can be used as instant work around for that issue.

Table below re-summarizes about recursion (= matching against intermediate directory) of each modes.

mode	-I/-X	in "set:"	-I/-X with "set:"
wildcard	always	endswith("**")	endswith("**")
regexp	not endswith("$")	not endswith("$")	not endswith("$")
raw string	always	always	always

"Recursion of wildcard" of the pattern from a file follows one of what tries to read that file in. For example:

wildcard pattern read in by "-I listfile:FILE" matches recursively, but
one read in by "hg status listfile:FILE" doesn't

2.2.3. Reading patterns from file

read in by	type substitution	default type for hgignore	default type for otherwise
include:FILE	o	`relre:`	`relre:`
listfile:FILE	x	(*X)	(*Y)

(*X) this is prohibited by match.readpatternfile()
(*Y) decision about "default type" depends on the context, in which listfile:FILE is used (e.g. relglob: for "hg locate", but relpath: for "hg files").

If "type substitution", substitutions below occur always at reading patterns from file. This is mentioned in "hg help patterns" and "hg help hgignore", but type relglob: and relre: themselves aren't explained.

glob: => relglob:
re: => relre:

Reading from .hgignore and "[ui] ignore" is treated as a variant of include: internally (e.g. include:$REPOROOT/.hgignore)

2.2.4. Recursion of ignore patterns

As a ignore pattern, "wildcard" and "raw string" modes are obviously recursive, because:

treating as same as "--include PATTERN" makes "wildcard" mode recursive
"raw string" mode is always recursive, regardless of context

On the other hand, "regexp" mode itself is non-recursive. For example, with "re:^foo$" in .hgignore, "hg debugignore" shows the regexp, which doesn't match against file foo/bar.

But actually, "re:^foo$" in .hgignore ignores file foo/bar, because dirstate (and "hg debugignore") examines whether specified file does:

match against specified ignore patterns, or
exist under the directory, which matches against specified ignore patterns

and that file is ignored, if one of conditions above is true.

Therefore, "regexp" ignore pattern is recursive, even if it uses "$".

In conclusion, all ignore patterns are treated as recursive, regardless of pattern types.

This special recursion of "regexp" mode is specific for ignore patterns. In other cases, "regexp" mode pattern isn't recursive, if it uses "$".

2.3. Proposal by foozy

By introducing systematic new pattern types, both "start point" and "recursion" of matching can be fully controlled arbitrarily in any contexts (as PATTERN, -I/-X, and so on).

2.3.1. Control start point of matching arbitrarily

New types and their start point.

mode	root-ed	cwd-ed	any-of-path
wildcard	`rootglob:`	`cwdglob:`	`anyglob:`
regexp	`rootre:`	`cwdre:`	`anyre:`
raw string	`rootpath:`	`cwdpath:`	`anypath:`

New "wildcard" and "regexp" types other than anyglob: match recursively, fully according to specified pattern, as below. anyglob: pattern should be always recursive, because this type is "any-of-path" matching.

type	recursive
`rootglob:`	endswith("**")
`cwdglob:`	endswith("**")
`anyglob:`	always
`rootre:`	not endswith("$")
`cwdre:`	not endswith("$")
`anyre:`	not endswith("$")
`rootpath:`	always
`cwdpath:`	always
`anypath:`	always

2.3.2. Emulate legacy types as an alias of new types

Current match.py implementation adds prefix/suffix regexp below to the specified pattern internally, according to what it is used for. See implementation of _regex() and match._normalize(), and _buildmatch() invocations in match.__init__() in match.py, for detail.

type	used for	prefix	suffix	recursive
`glob:`	pattern	"`$CWD/`"	"`$`"	endswith("**")
	include/exclude	"`$CWD/`"	"`(?:/\|$)`"	always
`relglob:`	pattern	"`(?:\|.*/)`"	"`$`"	endswith("**")
	include/exclude	"`(?:\|.*/)`"	"`(?:/\|$)`"	always
`re:`	(always)	(none)	(none)	not endswith("$")
`relre:`	(always)	"`.`" (1)	(none)	not endswith("$")
`path:`	(always)	"`^`" (*2)	"`(?:/\|$)`"	always
`relpath:`	(always)	"`$CWD/`"	"`(?:/\|$)`"	always

(*1) add this prefix, only if pattern doesn't start with "^"
(*2) (just nit picking) this may be redundant, because patterns are examined by re.match(), which requires matching from the beginning of a target string.

So, at first, let assume that newly introduced types use additional prefix/suffix regexp below BY DEFAULT (now, controlling recursion in "wildcard" and "regexp" mode is user responsibility).

type	prefix	suffix	recursive
`rootglob:`	(none)	"`$`"	endswith("**")
`cwdglob:`	"`$CWD/`"	"`$`"	endswith("**")
`anyglob:`	"`(?:\|.*/)`"	"`(?:/\|$)`"	always
`rootre:`	(none)	(none)	not endswith("$")
`cwdre:`	"`$CWD/`"	(none)	not endswith("$")
`anyre:`	"`.*`"	(none)	not endswith("$")
`rootpath:`	(none)	"`(?:/\|$)`"	always
`cwdpath:`	"`$CWD/`"	"`(?:/\|$)`"	always
`anypath:`	"`(?:\|.*/)`"	"`(?:/\|$)`"	always

Then, legacy types can be emulated as an alias of newly introduced type as below:

type	used as	alias of	needed suffix
`glob:`	pattern	`cwdglob:`	"`$`" (= default of `cwdglob:`)
	include/exclude	`cwdglob:`	"`(?:/\|$)`"
`relglob:`	pattern	`anyglob:`	"`$`"
	include/exclude	`anyglob:`	"`(?:/\|$)`" (= default of `anyglob:`)
`re:`	(always)	`rootre:`	(none) (= default of `rootre:`)
`relre:`	(always)	`anyre:`	(none) (= default of `anyre:`)
`path:`	(always)	`rootpath:`	"`(?:/\|$)`" (= default of `rootpath:`)
`relpath:`	(always)	`cwdpath:`	"`(?:/\|$)`" (= default of `cwdpath:`)

At this point, using suffix below forcibly for legacy glob: and relglob: is as same as current match.py implementation.

"$" for pattern
"(?:/|$)" for include/exclude

Therefore,aliasing should be emulated easily.

2.3.3. Control recursion of matching arbitrarily

With current Mercurial (at least, 4.0 or earlier), recursion of each pattern types can be controlled by:

mode	recursive
wildcard	endswith("**")
regexp	not endswith("$")
raw string	always

User can't control recursion of matching with "raw string" pattern arbitrarily (it matches against both directory and file).

Therefore, how about introducing two more additional modes "raw file" and "raw dir" ? Additional suffix regexp can control these matching.

mode	recursive	suffix
raw file name	never	"`$`"
raw dir name	always, but matches against only directory	"`/`"

After adding these modes, there are 5 (modes) x 3 (start points) = 15 types

mode	root-ed	cwd-ed	any-of-path
wildcard	`rootglob:`	`cwdglob:`	`anyglob:`
regexp	`rootre:`	`cwdre:`	`anyre:`
raw string	`rootpath:`	`cwdpath:`	`anypath:`
raw file name	`rootfile:`	`cwdfile:`	`anyfile:`
raw dir name	`rootdir:`	`cwddir:`	`anydir:`

2.4. Proposal by Rodrigo

Add rootglob: to get over the issue of -I/-X patterns.

https://patchwork.mercurial-scm.org/patch/17311/

3. Roadmap

4. See Also

http://d.hatena.ne.jp/flying-foozy/20140107/1389087728

CategoryDeveloper CategoryNewFeatures

FileNamePatternsPlan