Wax is a Rust library that provides opinionated and portable globs that can be matched against file paths and directory trees.

Basic Usage

Match a specific path against a glob:

```rust use wax::Glob;

let glob = Glob::new("*.png"); if glob.is_match("logo.png") { // ... } ```

Match a specific path against a glob and extract captures:

```rust use wax::{BytePath, Glob};

let glob = Glob::new("*/{.{go,rs}}").unwrap();

let path = BytePath::from_path("src/main.go"); let captures = glob.captures(&path).unwrap();

// Prints main.go. println!("{}", captures.get(2).unwrap().as_str().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.

Construction

Globs are encoded as strings called glob expressions that resemble Unix paths consisting of nominal components delimited by separators. Wax exposes its APIs via the [Glob] type, which is constructed from a glob expression via inherent functions or the [FromStr] trait. All data is borrowed where possible but can be copied into owned instances using into_owned.

```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 consistency rules regarding metacharacters, patterns, and component boundaries (separators and tree wildcards; see below).

Patterns

Globs resemble Unix paths, but additionally support wildcard, character class, and alternative patterns that can be matched against paths and directory trees. Patterns use a syntax that resembles globbing in Unix shells and similar tools.

```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 directory boundaries (see below).

Wildcards

Wildcards match some amount of arbitrary text in paths and are the most fundamental pattern provided by globs.

The tree wildcard ** matches zero or more sub-directories. This is the only way to match across arbitrary directory boundaries; all other wildcards do not match across 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 a termination (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 consists solely of a tree wildcard, then it matches all files in the working directory tree.

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 {???} (see below).

Character Classes

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.

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.

Note that character classes can also be used to escape metacharacters like *, $, etc., 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 -.

Alternatives

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, such as in {a,{b,{c,d}}}.

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.

Sub-globs must consider both neighboring patterns and component boundaries. For example, wildcards must respect adjacency rules, so *{a,b*} is allowed but *{a,*b} is not. Furthermore, component boundaries may never be adjacent, so a/{b/,c/**/}d and a{/b,/c} are allowed but a/{b/,/**/c}/d and a/{/b,/c} are not.

Importantly, both path separators and tree wildcards are considered component boundaries and tree wildcards are parsed together with their surrounding forward slashes: **, /**, **/, and /**/ are all considered tree wildcards and produce no independent path separators. This is typically intuitive, but means that despite no adjacent forward slashes, a/{**/b,c} and {a/**,b}/c are not allowed just as a//** is not allowed.

Unsupported Path Features

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.

Partitioning and Semantic Literals

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. The path 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"); assert!(glob.hassemanticliterals()); ```

Schemes and Prefixes

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/-C option provided by Nym. In most contexts, globs are applied relative to some such working directory.