Wax is a Rust library that provides opinionated and portable globs that can be matched against file paths and directory trees. Globs use a familiar syntax and support expressive features with semantics that emphasize component boundaries.
Match a specific path against a glob:
```rust use wax::Glob;
let glob = Glob::new("*.png").unwrap(); if glob.is_match("logo.png") { // ... } ```
Match a specific path against a glob and extract captures:
```rust use wax::{EncodedPath, Glob};
let glob = Glob::new("*/{.{go,rs}}").unwrap();
let path = EncodedPath::from("src/main.go"); let captures = glob.captures(&path).unwrap();
// Prints main.go.
println!("{}", captures.get(2).unwrap());
```
Match files in a directory tree against a glob:
```rust use wax::Glob;
let glob = Glob::new("*/.{md,txt}").unwrap(); for entry in glob.walk("doc", usize::MAX) { // ... } ```
See more details below.
Globs are encoded as UTF-8 strings called glob expressions that resemble Unix
paths consisting of nominal components delimited by separators. Wax exposes most
of its APIs via the [Glob] type, which is constructed from a glob expression
via inherent functions or standard conversion traits. All data is borrowed where
possible but can be copied into owned instances using an into_owned method
with most types.
```rust use wax::Glob;
let glob = Glob::new("site/img/logo.svg").unwrap(); assert!(!glob.has_root()); ```
Regardless of platform or operating system, globs always use the same format. In
particular, Forward slash / is always the path separator and back slashes
\ are forbidden (back slash is used for escape sequences, but the literal
sequence \\ is not supported). This means that it is impossible to represent
\ in nominal path components, but this character is generally forbidden as
such and its disuse avoids confusion.
Globs enforce various rules regarding meta-characters, patterns, and component boundaries (separators and tree wildcards) that reject nonsense expressions.
Globs resemble Unix paths, but additionally support patterns that can be matched
against paths and directory trees. Patterns use a syntax that resembles globbing
in Unix shells and tools like git, though there are some important
differences.
```rust use wax::Glob;
let glob = Glob::new("*/.{go,rs}").unwrap(); assert!(glob.is_match("src/lib.rs")); ```
Globs use a consistent and opinionated format and patterns are not
configurable; the semantics of a particular glob are always the same. For
example, * never matches across component boundaries.
Wildcards match some amount of arbitrary text in paths and are the most fundamental pattern provided by globs (and likely the most familiar).
The zero-or-more wildcards * and $ match zero or more of any character
except path separators. Zero-or-more wildcards cannot be adjacent to other
zero-or-more wildcards. The * wildcard is eager and will match the longest
possible text while the $ wildcard is lazy and will match the shortest
possible text. When followed by a literal, * stops at the last occurrence of
that literal while $ stops at the first occurence.
The exactly-one wildcard ? matches any single character except path
separators. Exactly-one wildcards do not group automatically, so a pattern of
contiguous wildcards such as ??? form distinct captures for each ? wildcard.
An alternative can be used to group exactly-one wildcards into
a single capture, such as {???}.
The tree wildcard ** matches zero or more sub-directories. This is the only
wildcard that may match across arbitrary component boundaries; all other
wildcards do not match across component (directory) boundaries. When a tree
wildcard participates in a match and does not terminate the pattern, its capture
includes a trailing forward slash /. If a tree wildcard does not participate
in a match, then its capture is an empty string. Tree wildcards must be
delimited by forward slashes or terminations (such as the beginning and/or end
of a glob or sub-glob). Tree wildcards and path separators are distinct and any
adjacent forward slashes that form a tree wildcard are parsed together. If a
glob expression consists solely of a tree wildcard, then it matches any and all
files in the working directory tree.
Character classes match any single character from a group of literals and ranges
except path separators. Classes are delimited by square brackets [...].
Individual character literals are specified as is, such as [ab] to match
either a or b. Character ranges are formed from two characters separated by
a hyphen, such as [x-z] to match x, y, or z. Note that character classes
match exact characters and are always case-sensitive, so the expressions [ab]
and {a,b} are not necessarily the same.
Any number of character literals and ranges can be used within a single
character class. For example, [qa-cX-Z] matches any of q, a, b, c,
X, Y, or Z.
Character classes may be negated by including an exclamation mark ! at the
beginning of the class pattern. For example, [!a] matches any character except
for a. These are the only patterns that support negation.
It is possible to escape meta-characters like *, $, etc., using character
classes though globs also support escaping via a backslash \. To match the
control characters [, ], and - within a character class, they must be
escaped via a backslash, such as [a\-] to match a or -.
Character classes have notable platform-specific behavior, because they match
arbitrary characters in native paths but never match path separators. This means
that if a character class only matches path separators on a given platform,
then the character class is considered empty and matches nothing. For example,
in the expression a[/]b the character class [/] matches nothing on Unix and
Windows. Such character classes are not rejected, because the role of arbitrary
characters depends on the platform. In practice, this is rarely a concern, but
such patterns should be avoided.
Character classes have limited utility on their own, but compose particularly well with repetitions.
Alternatives match an arbitrary sequence of comma separated sub-globs delimited
by curly braces {...,...}. For example, {a?c,x?z,foo} matches any of the
sub-globs a?c, x?z, or foo. Alternatives may be arbitrarily nested and
composed with repetitions.
Alternatives form a single capture group regardless of the contents of their
sub-globs. This capture is formed from the complete match of the sub-glob, so if
the sub-glob a?c matches abc in {a?c,x?z}, then the capture text will be
abc (not b as it would be outside of an alternative sequence).
Alternatives can be used to group capture text using a single sub-glob, such as
{*.{go,rs}} to capture an entire file name with a particular extension or
{???} to group a sequence of exactly-one wildcards.
Alternatives must consider adjacency rules and neighboring patterns. For
example, *{a,b*} is allowed but *{a,*b} is not. Additionally, they may not
contain a sub-glob consisting of a singular tree wildcard ** and cannot root a
glob expression as this could cause the expression to match or walk overlapping
trees.
Repetitions match a sub-glob a specified number of times and more closely
resemble general purpose regular expressions. Repetitions are delimited by angle
brackets with a separating colon <...:...> where a sub-glob precedes the colon
and a bounds specification follows it. For example, <a*/:0,> matches zero or
more components beginning with a. Along with tree wildcards, this is the
only other way to match across arbitrary component boundaries. Repetitions may
be arbitrarily nested and composed with alternatives.
Bound specifications are formed from inclusive lower and upper bounds separated
by a comma ,, such as :1,4 to match between one and four times. The upper
bound is optional and may be omitted. For example, :1, matches one or more
times (note the presence of a comma ,). A singular bound is constant, so :3
matches exactly three times. If no lower or upper bound is specified, then the
sub-glob matches one or more times, so <a:> and <a:1,> are equivalent.
Similarly, if the colon : is additionally omitted, then the sub-glob matches
zero or more times, so <a> and <a:0,> are equivalent.
Repetitions form a singular capture group regardless of the contents of their
sub-glob. The capture is formed from the complete match of the sub-glob. If the
repetition <abc/> matches abc/abc/, then the capture text will be
abc/abc/.
Repetitions compose particularly well with character
classes. Most often, a glob expression like {????} is
sufficient, but the more specific expression <[0-9]:4> further constrains the
matched characters to digits, for example. Furthermore, repetitions can form
tree expressions that further constrain directories, such as <[!.]*/>[!.]* to
match paths that contain no leading dots ..
Repetitions must consider adjacency rules and neighboring patterns. For example,
a/<b/**:1,> is allowed but <a/**:1,>/b is not. Additionally, they may not
contain a sub-glob consisting of a singular separator /, a singular
zero-or-more wildcard * or $, nor a singular tree wildcard **. Repetitions
with a lower bound of zero may not root a glob expression, as this could cause
the expression to match or walk overlapping trees.
Flags toggle the matching behavior of globs. Importantly, flags are a part of a
glob expression rather than an API. Behaviors are toggled immediately following
flags in the order in which they appear in glob expressions. Flags are delimited
by parenthesis with a leading question mark (?...) and may appear anywhere
within a glob expression so long as they do not split tree wildcards (for
example, a/*(?i)*). Each flag is represented by a single character and can be
negated by preceding the corresponding character with a dash -. Flags are
toggled in the order in which they appear within (?...).
The only supported flag is the case-insensitivty flag i. By default, glob
expressions use the same case sensitivity as the target platforms's file system
APIs (case-sensitive on Unix and case-insensitive on Windows), but i can be
used to toggle this explicitly as needed. For example,
(?-i)photos/**/*.(?i){jpg,jpeg} matches file paths beneath a photos
directory with a case-sensitive base and a case-insensitive extension jpg
or jpeg.
Wax considers literals, their configured case sensitivity, and the case
sensitivity of the target platform's file system when partitioning glob
expressions with [Glob::partitioned].
Partitioning is unaffected in glob expressions with no flags.
The [GlobError] type represents error conditions that can occur when parsing a
glob expression, validating a glob expression, or walking a directory tree with
a glob. [GlobError] and its sub-errors implement the standard [Error] and
[Display] traits via thiserror, which express basic information
about failures.
Wax optionally integrates with the miette crate, which can be used
to capture and display diagnostics. This can be useful for reporting errors to
users that provide glob expressions.
``` Error: glob::rule
x malformed glob expression: adjacent zero-or-more wildcards * or $
,----
1 | doc/*/{.md,.tex,*.txt}
: |^^^^^^^^|^^^^^^^
: | | -- here
: |-- in this alternative
: -- here
----
```
Diagnostics are disabled by default and can be enabled with the diagnostics
feature. This can be done via Cargo in a crate's Cargo.toml file.
toml
[dependency.wax]
version = "^0.0.0"
features = ["diagnostics"]
Any components not recognized as separators nor patterns are interpreted as literals. In combination with strict rules, this means some platform-specific path features cannot be used directly in globs. This limitation is by design and additional code may be necessary to bridge this gap for some use cases.
Globs support no notion of a current or parent directory. The path components
. and .. are interpreted as literals and only match paths with the
corresponding components (even on Unix and Windows). For example, the glob
src/../*.rs matches the path src/../lib.rs but does not match the path
lib.rs.
Parent directory components have unclear meaning and far less utility when they
follow patterns in a glob. However, such components are intuitive and are often
important for escaping a working directory when they precede patterns (i.e., as
a prefix). For example, the glob ../src/**/*.rs has more obvious meaning than
the glob src/**/../*.rs. As seen above though, the first glob would only match
the literal path component .. and not paths that replace this with a parent
directory.
[Glob::partitioned] can be used to parse glob expressions that contain
semantic components that precede patterns and would be interpreted as literals
(namely ..). [Glob::partitioned] partitions a glob expression into an
invariant [PathBuf] prefix and a variant [Glob] postfix. Here, invariant
means that the partition contains no glob patterns and resolves the same literal
paths on the target platform's file system. The prefix can be used as needed in
combination with the glob.
```rust use std::path::Path; use wax::Glob;
let path = Path::new("."); // Working directory. let (prefix, glob) = Glob::partitioned("../site/img/*.{jpg,png}").unwrap(); for entry in glob.walk(path.join(prefix), usize::MAX) { // ... } ```
Additionally, [Glob::has_semantic_literals] can be used to detect literal
components in a glob that have special semantics on the target platform.
```rust use wax::Glob;
let glob = Glob::new("..//src//main.rs").unwrap(); assert!(glob.hassemanticliterals()); ```
While globs can be rooted, they cannot include schemes nor Windows path
prefixes. For example, the Windows UNC share path \\server\share\src cannot be
represented directly as a glob.
This can be limiting, but the design of Wax explicitly forbids this: Windows
prefixes and other volume components are not portable. Instead, when this is
needed, an additional native path or working directory can be used, such as the
--tree option provided by Nym. In most contexts, globs are applied
relative to some such working directory.
Globs operate exclusively on UTF-8 encoded text. However, this encoding is not
used for file names and paths on all platforms. Wax uses the [EncodedPath]
type to re-encode native paths via lossy conversions that use Unicode
replacement codepoints whenever a part of a path cannot be represented as valid
UTF-8. On some platforms these conversions are always no-ops. In practice, the
overwhelming majority of paths can be losslessly encoded in UTF-8.
At the time of writing, Wax is experimental and unstable. It is possible that
glob expression syntax and semantics may change between versions in the 0.y.z
series without warning.