shrinkpath

Smart cross-platform path shortening for Rust.

/Users/john/Library/Application Support/Code/User/settings.json  (62 chars)
                            ↓  shrink_to(path, 35)
             /Users/john/.../User/settings.json                   (35 chars)

Filename is never truncated. Username is preserved when possible. Everything else adapts to fit your target length.

Why shrinkpath?

• Target-length guarantee — shrink_to(path, 30) always returns ≤ 30 chars (unless the filename itself is longer — filenames are sacred)
• Identity-preserving — the username/profile segment is the last thing to go, not the first
• Cross-platform — handles /home/..., ~/..., C:\Users\..., \\server\share\..., .\... from any host OS
• Zero dependencies — the library has no dependencies; clap is only pulled in for the optional CLI
• No filesystem access — works on path strings alone, so it runs in WASM, embedded, or anywhere (opt-in fs feature for filesystem-aware disambiguation)

Quick Start

# Cargo.toml
[dependencies]
shrinkpath = "0.1"

use shrinkpath::{shrink_to, shrink_fish};

// Hybrid strategy: graduated shortening to fit a target length
let short = shrink_to("/home/john/projects/rust/myapp/src/lib.rs", 30);
assert!(short.len() <= 30);
assert!(short.ends_with("lib.rs"));

// Fish strategy: every directory segment becomes its first character
let fish = shrink_fish("/home/john/projects/rust/myapp/src/lib.rs");
assert_eq!(fish, "/h/j/p/r/m/s/lib.rs");

Strategies

shrinkpath ships four strategies. Pick the one that fits your use case, or use Hybrid (the default) and let the algorithm decide.

Fish

Abbreviates every directory segment to its first character. Dot-prefixed directories keep the dot: .config → .c.

/home/john/projects/rust/myapp/src/lib.rs  →  /h/j/p/r/m/s/lib.rs
C:\Users\Admin\AppData\Local\Temp\file.txt →  C:\U\A\A\L\T\file.txt
~/projects/rust/file.rs                    →  ~/p/r/file.rs

Fish produces the shortest possible result. Use it when every character counts (prompts, status bars) and the user can infer the full path from context.

Tuning knobs:

use shrinkpath::{shrink, ShrinkOptions, Strategy};

// Keep 2 chars per segment instead of 1 (like Starship's fish_style_pwd_dir_length)
let opts = ShrinkOptions::new(50).strategy(Strategy::Fish).dir_length(2);
let result = shrink("/home/john/projects/rust/myapp/src/lib.rs", &opts);
assert_eq!(result, "/ho/jo/pr/ru/my/sr/lib.rs");

// Keep the last N directory segments unabbreviated
let opts = ShrinkOptions::new(50).strategy(Strategy::Fish).full_length_dirs(1);
let result = shrink("/home/john/projects/rust/myapp/src/lib.rs", &opts);
assert_eq!(result, "/h/j/p/r/m/src/lib.rs");

Ellipsis

Replaces middle segments with ..., keeping the identity head (username) and the segments nearest the filename.

/home/john/projects/rust/myapp/src/lib.rs  →  /home/john/.../src/lib.rs
C:\Users\Admin\AppData\Local\Temp\file.txt →  C:\Users\Admin\...\file.txt

Ellipsis is the most readable strategy. Use it when you have moderate space and want humans to immediately understand the path.

Hybrid (default)

A graduated four-phase approach that produces the best result for any target length:

Phase 1 — fish expendable segments only:    /home/john/p/r/m/src/lib.rs
Phase 2 — fish context segments too:        /h/john/p/r/m/s/lib.rs
Phase 3 — collapse abbreviated runs to ...: /h/john/.../s/lib.rs
Phase 4 — fish identity (last resort):      /h/j/.../s/lib.rs

Each phase stops as soon as the result fits. If nothing fits, it falls back to /.../<filename>, then the filename alone.

Unique

Disambiguates segments against each other within the same path. Each segment is abbreviated to the shortest prefix that distinguishes it from every other segment.

/home/documents/downloads/file.txt  →  /h/doc/dow/file.txt
/Users/Admin/AppData/Application/f  →  /U/Ad/AppD/Appl/f

When all first characters are unique, Unique behaves like Fish. When segments share prefixes, it uses the minimum characters needed. Identical segments are kept in full (they can't be disambiguated).

use shrinkpath::shrink_unique;

let result = shrink_unique("/home/documents/downloads/file.txt");
assert_eq!(result, "/h/doc/dow/file.txt");

Features

Mapped Locations

Substitute known path prefixes before shortening. Useful for replacing home directories, project roots, or well-known paths with short aliases.

use shrinkpath::{shrink, ShrinkOptions};

let opts = ShrinkOptions::new(50)
    .map_location("/home/john", "~")
    .map_location("/home/john/projects", "PROJ:");

// Longest match wins
let result = shrink("/home/john/projects/rust/lib.rs", &opts);
assert!(result.starts_with("PROJ:"));

Anchor Segments

Mark directory names that should never be abbreviated, regardless of strategy.

use shrinkpath::{shrink, ShrinkOptions, Strategy};

let opts = ShrinkOptions::new(50)
    .strategy(Strategy::Fish)
    .anchor("src")
    .anchor("myapp");

let result = shrink("/home/john/projects/rust/myapp/src/lib.rs", &opts);
// "myapp" and "src" kept full, everything else abbreviated
assert!(result.contains("myapp"));
assert!(result.contains("/src/"));

Segment Metadata

shrink_detailed() returns per-segment metadata for building colored prompts, clickable breadcrumbs, or tooltip UIs.

use shrinkpath::{shrink_detailed, ShrinkOptions, Strategy};

let opts = ShrinkOptions::new(usize::MAX).strategy(Strategy::Fish);
let result = shrink_detailed("/home/john/projects/lib.rs", &opts);

for seg in &result.segments {
    if seg.was_abbreviated {
        // render abbreviated segments in dim color
        print!("{}", seg.shortened);
    } else if seg.is_filename {
        // render filename in bold
        print!("{}", seg.shortened);
    } else {
        print!("{}", seg.shortened);
    }
}
// seg.original always contains the full text for tooltips

Filesystem-Aware Features (opt-in)

Enable the fs feature for features that require filesystem access:

[dependencies]
shrinkpath = { version = "0.1", features = ["fs"] }

Git repo root detection — find the repository name for a file path:

use shrinkpath::fs_aware::find_git_root;

if let Some(repo) = find_git_root("/home/john/projects/myapp/src/lib.rs") {
    println!("repo: {}", repo); // "myapp"
}

Filesystem-aware disambiguation — find the shortest unique prefix by checking against actual sibling directories (like Powerlevel10k):

use shrinkpath::fs_aware::disambiguate_segment;
use std::path::Path;

// If /home contains "documents", "downloads", "desktop":
let short = disambiguate_segment(Path::new("/home"), "documents");
// Returns "doc" (shortest prefix unique among siblings)

How It Works

Path Parsing

Every input path is parsed into three parts:

  prefix       segments (directories)         filename
    │          │                                │
    ▼          ▼                                ▼
    /    home / john / projects / rust / src /  lib.rs
   ~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~────────────  ~~~~~~

Prefix is the root: /, ~, C:\, \\server\share, ., or empty. Filename is the last component. Segments are everything in between.

The path style (Unix or Windows) is auto-detected from the input string — drive letters, UNC prefixes, and backslash heuristics are all recognized. You can also force a style with ShrinkOptions::path_style().

Segment Priority

Each segment is classified by how important it is to keep:

Priority	What	Example	Dropped
Sacred	Filename	lib.rs	Never
Identity	Username / profile	john, Admin	Last
Context	Home root, well-known dirs	home, Users	Middle
Expendable	Everything else	projects, src	First

Identity is detected by recognizing the segment after a home root (home on Unix, Users on Windows). The tilde prefix (~) encodes identity implicitly.

Fish Algorithm

for each directory segment (from left, skipping last full_length_dirs):
    if segment is anchored:
        keep full text
    else if segment starts with '.':
        keep '.' + first dir_length chars after dot    (.config → .c)
    else:
        keep first dir_length chars                    (projects → p)
filename is never touched

Ellipsis Algorithm

1. Compute identity head = all segments up to and including the username
2. Base cost = prefix + separator + filename
3. Add head cost + ellipsis marker cost
4. With remaining budget, greedily add tail segments from right to left
5. If head doesn't fit, fall back to prefix + ... + filename

The greedy right-to-left fill keeps the segments closest to the filename, which provide the most context about what the file actually is.

Hybrid Algorithm

Phase 1: Fish all Expendable segments (respect anchors)
         → check if result fits target length
Phase 2: Fish all Context segments
         → check fit
Phase 3: Collapse consecutive abbreviated segments into ...
         Try keeping 0-3 head + 0-3 tail segments, pick best fit
         → check fit
Phase 4: Fish all Identity segments (last resort)
         → try collapse again
Fallback: prefix + ... + filename
Last resort: filename only

The key insight is that each phase is strictly less destructive than the next. A 30-char budget on a moderately deep path might only need Phase 1. A 15-char budget on a deeply nested Windows path might need all four phases. The user sees the best possible result for their budget.

Unique Algorithm

1. Collect all segment texts
2. For each segment, find minimum prefix length L such that:
   - segment[..L] differs from every other segment's first L chars
   - For dot-prefixed: compare the part after the dot
3. Identical segments keep their full text (can't disambiguate)
4. Anchored segments are never abbreviated

CLI

cargo install shrinkpath

# Basic usage
shrinkpath "/home/john/projects/rust/myapp/src/lib.rs" -m 30

# Pipe paths from find, fd, rg, etc.
fd -t f | shrinkpath -m 40

# Fish strategy
shrinkpath -s fish "/home/john/projects/rust/myapp/src/lib.rs"

# Unique strategy
shrinkpath -s unique "/home/documents/downloads/file.txt"

# JSON output with metadata
shrinkpath --json "/home/john/projects/src/lib.rs" -m 25
# {"original":"/home/john/projects/src/lib.rs","shortened":"/home/john/.../lib.rs",...}

# Custom ellipsis marker
shrinkpath --ellipsis "~" -m 30 "C:\Users\Admin\AppData\Local\Temp\file.txt"

Flags:

Flag	Default	Description
-m, --max-len	40	Target maximum output length
-s, --strategy	hybrid	fish, ellipsis, hybrid, or unique
--style	auto	Force unix or windows separator style
--ellipsis	...	Custom ellipsis marker string
--json	off	Output JSON with original, shortened, lengths, style

API

// One-liner convenience functions
shrinkpath::shrink_to(path, 30)        // Hybrid strategy, target length
shrinkpath::shrink_fish(path)          // Fish abbreviation, no length target
shrinkpath::shrink_ellipsis(path, 30)  // Ellipsis strategy, target length
shrinkpath::shrink_unique(path)        // Unique disambiguation, no length target

// Full control
use shrinkpath::{shrink, ShrinkOptions, Strategy, PathStyle};

let opts = ShrinkOptions::new(30)
    .strategy(Strategy::Ellipsis)
    .path_style(PathStyle::Windows)
    .ellipsis("..")
    .dir_length(2)           // chars per abbreviated segment
    .full_length_dirs(1)     // keep last N dirs unabbreviated
    .anchor("src")           // never abbreviate "src"
    .map_location("~", "/home/john");

let result = shrink(path, &opts);

// With segment metadata
let detailed = shrinkpath::shrink_detailed(path, &opts);
for seg in &detailed.segments {
    println!("{} → {} (abbreviated: {})",
        seg.original, seg.shortened, seg.was_abbreviated);
}

Platform Support

Path format	Example	Detected as
Unix absolute	/home/john/file.rs	Unix
Tilde home	~/projects/file.rs	Unix
macOS /Users	/Users/john/Documents/file.txt	Unix
Windows drive	C:\Users\Admin\file.txt	Windows
Windows UNC	\\server\share\dept\file.xlsx	Windows
Dot-relative	.\src\main.rs	Windows
Forward-slash drive	C:/Users/Admin/file.txt	Windows
Relative (no prefix)	src/lib.rs	Unix
Backslash heuristic	Users\Admin\file.txt	Windows

Detection is automatic. Use ShrinkOptions::path_style() to override.

Cargo Features

Feature	Default	Description
cli	Yes	Builds the shrinkpath binary (pulls in clap)
fs	No	Enables filesystem-aware features (find_git_root, disambiguate_segment)

# Library only, zero dependencies
shrinkpath = { version = "0.1", default-features = false }

# With filesystem features
shrinkpath = { version = "0.1", features = ["fs"] }

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.