feat(config): support placing configuration inside Cargo.toml (#46)

README.md

@@ -70,6 +70,8 @@
     - [date_order](#date_order)
     - [sort_commits](#sort_commits)
     - [link_parsers](#link_parsers)
+- [Project Integration](#project-integration)
+  - [Rust](#rust)
 - [Templating](#templating)
   - [Context](#context)
     - [Conventional Commits](#conventional-commits)
@@ -563,6 +565,34 @@ Examples:
 - `{ pattern = "RFC(\\d+)", text = "ietf-rfc$1", href = "https://datatracker.ietf.org/doc/html/rfc$1"}`,
   - Extract mentions of IETF RFCs and generate URLs linking to them. It also rewrites the text as "ietf-rfc...".
 
+## Project Integration
+
+### Rust
+
+For Rust projects, **git-cliff** can be configured in `Cargo.toml` via [metadata table](https://doc.rust-lang.org/cargo/reference/manifest.html#the-metadata-table). To do this, simply replace the available configuration sections with `[package.metadata.git-cliff.<section>]` and place them inside `Cargo.toml`. For example:
+
+```toml
+[package]
+name = "..."
+
+[dependencies]
+# ...
+
+[package.metadata.git-cliff.changelog]
+header = "All notable changes to this project will be documented in this file."
+body = "..."
+footer = "<!-- generated by git-cliff -->"
+# see [changelog] section for more keys
+
+[package.metadata.git-cliff.git]
+conventional_commits = true
+commit_parsers = []
+filter_commits = false
+# see [git] section for more keys
+```
+
+For Cargo workspaces, [`workspace.metadata`](https://doc.rust-lang.org/cargo/reference/workspaces.html#the-workspacemetadata-table) table can be used. (e.g. `[workspace.metadata.git-cliff.<section>]`)
+
 ## Templating
 
 A template is a text where variables and expressions get replaced with values when it is rendered.

git-cliff-core/src/config.rs

@@ -1,7 +1,16 @@
 use crate::error::Result;
-use regex::Regex;
+use regex::{
+	Regex,
+	RegexBuilder,
+};
+use std::ffi::OsStr;
+use std::fs;
 use std::path::Path;
 
+/// Regex for matching the metadata in Cargo.toml
+const CARGO_METADATA_REGEX: &str =
+	r"^\[(?:workspace|package)\.metadata\.git\-cliff\.";
+
 /// Configuration values.
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub struct Config {
@@ -85,8 +94,20 @@ pub struct LinkParser {
 impl Config {
 	/// Parses the config file and returns the values.
 	pub fn parse(path: &Path) -> Result<Config> {
-		Ok(config::Config::builder()
-			.add_source(config::File::from(path))
+		let config_builder = if path.file_name() == Some(OsStr::new("Cargo.toml")) {
+			let contents = fs::read_to_string(&path)?;
+			let metadata_regex = RegexBuilder::new(CARGO_METADATA_REGEX)
+				.multi_line(true)
+				.build()?;
+			let contents = metadata_regex.replace_all(&contents, "[");
+			config::Config::builder().add_source(config::File::from_str(
+				&contents,
+				config::FileFormat::Toml,
+			))
+		} else {
+			config::Config::builder().add_source(config::File::from(path))
+		};
+		Ok(config_builder
 			.add_source(config::Environment::with_prefix("CLIFF").separator("_"))
 			.build()?
 			.try_deserialize()?)

git-cliff-core/src/error.rs

@@ -47,6 +47,9 @@ pub enum Error {
 	/// Errors that may occur while de/serializing JSON format.
 	#[error("Cannot de/serialize JSON: `{0}`")]
 	JsonError(#[from] serde_json::Error),
+	/// Errors that may occur during parsing or compiling a regular expression.
+	#[error("Cannot parse/compile regex: `{0}`")]
+	RegexError(#[from] regex::Error),
 }
 
 /// Result type of the core library.