tagver 0.1.2

Core library for minimalistic versioning using Git tags
Documentation 
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# TagVer

[![CI](https://github.com/scratchingmonkey/tagver/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/scratchingmonkey/tagver/actions/workflows/ci.yml?query=branch%3Amain) [![Crates.io Version](https://img.shields.io/crates/v/tagver)](https://crates.io/crates/tagver-cli) [![docs.rs](https://img.shields.io/docsrs/tagver?logo=docsdotrs&link=https%3A%2F%2Fdocs.rs%2Ftagver%2Flatest%2Ftagver%2F)](https://crates.io/crates/tagver-cli)
 ![Binary Size](https://img.shields.io/crates/size/tagver-cli?logo=rust) ![MSRV](https://img.shields.io/crates/msrv/tagver?logo=rust)


A fast, dependency-free, CLI tool and Rust library for calculating version numbers from Git repository tags.

This project is heavily influenced by the excellent [MinVer CLI](https://github.com/adamralph/minver) CLI .NET tool, written in Rust and incorporating the [`gitoxide`](https://github.com/GitoxideLabs/gitoxide) crate.

## Features

- **Tag-driven versioning**: Uses Git tags as the single source of truth for versions
- **Height calculation**: Automatically calculates distance from tagged commits to generate alpha versions
- **Cross-platform**: Single binary that runs anywhere Rust compiles
- **Zero dependencies**: Statically linked binary with no runtime dependencies
- **Environment variable support**: Fully configurable using environment variables
- **JSON formatted version output**: Outputs version information to JSON for easy scripting
- **First-parent traversal**: Correctly handles merge commits seamlessly
- **Semantic versioning**: Strict adherence to SemVer 2.0.0 specification
- **A GitHub Action**: Provides version information as outputs automatically

## Installation

```bash
cargo install tagver-cli
```

```bash
brew tap wyrd-company/tools
brew install tagver
```

## Usage

### Basic usage

```bash
# Calculate version for current repository
tagver

# Print all command-line options
tagver --help

# Output JSON
tagver --format JSON
```

### Environment variables

Most options can also be set via environment variables:

- `TAGVER_TAGPREFIX`
- `TAGVER_AUTOINCREMENT`
- `TAGVER_DEFAULTPRERELEASEIDENTIFIERS`
- `TAGVER_MINIMUMMAJORMINOR`
- `TAGVER_IGNOREHEIGHT`
- `TAGVER_BUILDMETADATA`
- `TAGVER_VERBOSITY`

## How it works

TagVer follows the following algorithm:

1. **Tag discovery**: Find all Git tags that match the configured prefix
2. **Version parsing**: Parse tags as semantic versions (SemVer 2.0.0)
3. **Commit traversal**: Walk the commit graph from HEAD to find the nearest tagged ancestor
4. **Height calculation**: Count commits between current position and the base tag
5. **Version synthesis**: 
   - If at exact tag: use version as-is
   - If not at tag: apply auto-increment, add pre-release identifiers, append height
   - Apply minimum major.minor constraint if configured
   - Append build metadata if provided

### Version calculation examples

| Git state | Result |
|-----------|--------|
| On tag `1.0.0` | `1.0.0` |
| 5 commits after `1.0.0` | `1.0.1-alpha.0.5` |
| On tag `1.0.0-beta.1` | `1.0.0-beta.1` |
| 3 commits after `1.0.0-beta.1` | `1.0.0-beta.1.3` |
| No tags | `0.0.0-alpha.0` |
| 2 commits from root | `0.0.0-alpha.0.2` |

## GitHub Action

This repository also ships a lightweight GitHub Action that downloads the pre-built `tagver` binary from releases and exposes the calculated version and components as outputs.

Usage:

```yaml
steps:
   - uses: actions/checkout@v4
      with:
         fetch-depth: 0

   - name: Calculate version
      id: tagver
      uses: scratchingmonkey/tagver@v0
      with: # All optional
         tag-prefix: 'v'
         auto-increment: patch
         default-pre-release-identifiers: "alpha.0"
         minimum-major-minor: "1.0"
         build-metadata: beta
         ignore-height: true
         working-directory: '.'
         tagver-version: "0.1.0"

   - name: Use version
      run: |
         echo "Full: ${{ steps.tagver.outputs.version }}"
         echo "Major: ${{ steps.tagver.outputs.major }}"
         echo "Minor: ${{ steps.tagver.outputs.minor }}"
         echo "Patch: ${{ steps.tagver.outputs.patch }}"
         echo "Pre-release: ${{ steps.tagver.outputs.pre-release }}"
         echo "Build-metadata: ${{ steps.tagver.outputs.build-metadata }}"
```

## Acknowledgments

- [Adam Ralph](https://github.com/adamralph) for creating the original MinVer
- [Gitoxide](https://github.com/GitoxideLabs/gitoxide) for the excellent pure-Rust Git implementation
- The Rust community for the amazing ecosystem of libraries