fix: preserve TOML decorations/comments across set mutations

.github/workflows/ci.yml

@@ -10,6 +10,22 @@ on:
       - main
 
 jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4
+
+      - name: Setup Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: llvm-tools-preview
+
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+
+      - name: Coverage check
+        run: cargo llvm-cov --lib --fail-under-lines 20
+
   lint:
     runs-on: ubuntu-latest
     steps:
@@ -79,4 +95,3 @@ jobs:
 
       - name: Test
         run: pnpm test
-

Cargo.toml

@@ -15,16 +15,16 @@ publish = false
 crate-type = ["cdylib"]
 
 [dependencies]
-toml_edit = { version = "0.23.7" }
-wasm-bindgen = { version = "0.2.105" }
+toml_edit = { version = "0.23.9" }
+wasm-bindgen = { version = "0.2.108" }
 console_error_panic_hook = "0.1.7"
-web-sys = { version = "0.3.82", features = ["console"] }
+web-sys = { version = "0.3.85", features = ["console"] }
 once_cell = "1.21.3"
-thiserror = "2.0.17"
+thiserror = "2.0.18"
 
 [dev-dependencies]
 indoc = "2.0.7"
-wasm-bindgen-test = "0.3.55"
+wasm-bindgen-test = "0.3.58"
 
 [profile.release]
 lto = true

eslint.config.js

@@ -8,5 +8,5 @@ export default defineConfig({
     toml: true,
     typescript: true,
 }, {
-    ignores: ["bench/fixture/5mb-mixed.toml"],
+    ignores: ["bench/fixture/5mb-mixed.toml", ".alma-snapshots"],
 })

package.json

@@ -15,6 +15,8 @@
         "release": "pnpm bump && pnpm build && pnpm -r publish",
         "test": "vitest",
         "test:wasm": "wasm-pack test --chrome",
+        "test:rust": "cargo test --lib",
+        "coverage:rust": "cargo llvm-cov --lib --fail-under-lines 20",
         "bench": "vitest bench",
         "typecheck": "tsc --noEmit"
     },

src/core/error.rs

@@ -1,20 +1,29 @@
+//! Error types and helpers shared by parse/stringify/edit flows.
+
 use thiserror::Error;
 use wasm_bindgen::JsValue;
 
+/// Domain errors returned by core editing routines.
 #[derive(Error, Debug)]
 pub enum TomlEditJsError<'a> {
+    /// Failed to parse input TOML text.
     #[error("Parse Error: {0}")]
     ParseError(#[from] toml_edit::TomlError),
+    /// Invalid key token in a path expression.
     #[error("Key Error: invalid key '{0}'")]
     KeyError(&'a str),
+    /// Array index is outside the current bounds.
     #[error("Key Error: index out of boundary '{0}' for '{1}'")]
     IndexOutOfBounds(usize, String),
+    /// Empty path key sequence was provided.
     #[error("Key Error: path key is empty")]
     EmptyKey,
+    /// Type mismatch for operation or option value.
     #[error("Type error: {0}")]
     TypeError(String),
 }
 
+/// Converts domain errors to JS-friendly string exceptions.
 impl From<TomlEditJsError<'_>> for JsValue {
     fn from(value: TomlEditJsError) -> Self {
         JsValue::from(value.to_string())

src/core/mod.rs

@@ -1,3 +1,6 @@
+//! High-level wasm-exposed APIs.
+//!
+//! This module bridges JavaScript values and `toml_edit` document structures.
 pub(crate) mod error;
 
 use toml_edit::{Document, DocumentMut, Item, Value};
@@ -15,11 +18,13 @@ use crate::{
 };
 
 #[wasm_bindgen(start)]
+/// Installs panic hooks for better browser console error output.
 pub fn init_panic_hook() {
     console_error_panic_hook::set_once();
 }
 
 #[wasm_bindgen]
+/// Parses a TOML string into a JavaScript value tree.
 pub fn parse(input: &str) -> Result<JsValue, JsValue> {
     match Document::parse(input) {
         Ok(doc) => Ok(from_item(doc.as_item())),
@@ -28,6 +33,9 @@ pub fn parse(input: &str) -> Result<JsValue, JsValue> {
 }
 
 #[wasm_bindgen]
+/// Serializes a JavaScript value into TOML text.
+///
+/// The conversion strategy depends on value shape and stringify options.
 pub fn stringify(input: JsValue, opts: Option<IStringifyOptions>) -> Result<String, JsValue> {
     let opts = StringifyOptions::new(opts)?;
 
@@ -47,6 +55,9 @@ pub fn stringify(input: JsValue, opts: Option<IStringifyOptions>) -> Result<Stri
 }
 
 #[wasm_bindgen]
+/// Edits a TOML document by path and returns the updated text.
+///
+/// Path segments support dotted keys and array index notation like `foo.bar.[0]`.
 pub fn edit(
     input: &str,
     path: &str,
@@ -58,13 +69,7 @@ pub fn edit(
 
     let edit_opts = EditOptions::new(opts)?;
     let (path_keys, value_key) = parse_edit_path(path);
-    set_value(
-        doc.as_item_mut(),
-        path_keys.iter().map(|x| &**x).collect(),
-        value_key,
-        value,
-        &edit_opts,
-    )?;
+    set_value(doc.as_item_mut(), &path_keys, value_key, value, &edit_opts)?;
 
     let mut result_str = doc.to_string();
     if !edit_opts.final_newline {

src/lib.rs

@@ -1,6 +1,14 @@
+//! Public crate surface for TOML parse/stringify/edit operations.
+//!
+//! The crate is organized by concern:
+//! - `core`: wasm bindings and high-level APIs
+//! - `ops`: low-level document mutation routines
+//! - `options`: JS option parsing and validation
+//! - `util`: conversion and formatting helpers
 pub mod core;
 pub mod ops;
 pub mod options;
 pub mod util;
 
+/// Re-export high-level APIs for JavaScript consumers.
 pub use core::{edit, parse, stringify};

src/ops/mod.rs

@@ -1 +1,2 @@
+//! Low-level mutation operations over `toml_edit::Item`.
 pub(crate) mod set;