# Easy Macros
[](https://crates.io/crates/easy-macros)
[](https://docs.rs/easy-macros)
[](https://github.com/LimitLost/easy-macros/blob/master/LICENSE)
Automatic error context for any Rust project + powerful procedural macro utilities.
## Quick Start
```toml
# Only automatic error context
[dependencies]
easy-macros = { version = "...", features = ["general"] }
# All tools for proc-macro development
[dependencies]
easy-macros = { version = "...", features = ["full"] }
```
## Features
### 1. Automatic Error Context - **Works in Any Project**
**Feature flag**: `always-context` (included in `general` and `full`)
Add `.with_context()` to all `?` operators automatically:
```rust
use easy_macros::always_context;
use anyhow::Result;
#[always_context]
fn process_data(user_id: u64) -> Result<Data> {
let user = find_user(user_id)?; // Auto-context with user_id
let profile = load_profile(&user)?; // Auto-context
let data = fetch_data(profile.id)?; // Auto-context
Ok(data)
}
```
**Control attributes**: `#[no_context]`, `#[context(display)]`, `#[context(ignore)]`
### 2. Attribute Pattern Matching
**Feature flag**: `attributes` (included in `full`)
Extract values from attributes using `__unknown__` placeholder:
```rust
use easy_macros::{get_attributes, fields_get_attributes};
// Extract from type attributes
let routes: Vec<TokenStream> = get_attributes!(input, #[route(__unknown__)]);
// Extract from field attributes
let methods: Vec<(usize, Field, Vec<TokenStream>)> =
fields_get_attributes!(input, #[http(__unknown__, "/api")]);
// Partial identifier matching
let tests: Vec<TokenStream> = get_attributes!(input, #[test_case___unknown__]);
// Matches: #[test_case_one], #[test_case_two], etc.
```
Check attributes: `has_attributes!(input, #[derive(Debug)] #[serde(...)])`
Filter fields: `fields_with_attributes!(input, #[validate])`
### 3. Exhaustive AST Traversal
**Feature flag**: `all-syntax-cases` (included in `full`)
Generate recursive handlers for all syn types:
```rust
use easy_macros::all_syntax_cases;
all_syntax_cases! {
setup => {
generated_fn_prefix: "process",
additional_input_type: &mut Context,
}
default_cases => {
// Called for matching types across entire AST
fn handle_expr(expr: &mut syn::Expr, ctx: &mut Context);
#[after_system] // Run after children processed
fn finalize(item: &mut syn::Item, ctx: &mut Context);
// Handle multiple syn types together (e.g., attributes + generics)
fn check_attrs_and_generics(
attrs: &mut Vec<syn::Attribute>,
generics: &mut syn::Generics,
ctx: &mut Context
);
}
special_cases => {
// Override for specific variants
fn handle_call(call: &mut syn::ExprCall, ctx: &mut Context);
}
}
```
Smart unwrapping of `Box<T>`, `Vec<T>`, `Punctuated<T, _>`. Generates handlers for Item, Expr, Stmt, Pat, Type, and more.
### 4. Helper Utilities
**Feature flags**: Individual helpers or `full` for all
```rust
use easy_macros::*;
// Manual error context with file/line info
// Feature: `context` (included in `general` and `full`)
fs::read("file.txt").with_context(context!("Loading config"))?;
// Token stream builder
// Feature: `tokens-builder` (included in `full`)
let mut tokens = TokensBuilder::default();
tokens.add(quote! { println!("Hello"); });
tokens.braced(); // Wrap in { }
// Parse with compile_error! on failure
// Feature: `parse-macro-input` (included in `full`)
let parsed = parse_macro_input!(input as syn::DeriveInput);
// Generate indexed names: field0, field1, field2
// Feature: `indexed-name` (included in `full`)
let names = indexed_name(syn::parse_quote!(field), 3);
// Find crates (handles renames)
// Feature: `find-crate` (included in `full`)
let path = find_crate("serde", quote!(::Serialize))?;
let async_rt = find_crate_list(&[("tokio", quote!()), ("async-std", quote!())])?;
```
### 5. Result Type for Proc Macros
**Feature flag**: `anyhow-result` (included in `full`)
Use `anyhow::Result<TokenStream>` in proc macros:
```rust
use easy_macros::anyhow_result;
#[proc_macro_derive(MyTrait)]
#[anyhow_result]
fn derive_my_trait(input: TokenStream) -> anyhow::Result<TokenStream> {
let parsed: syn::DeriveInput = syn::parse(input)?;
anyhow::ensure!(!parsed.fields.is_empty(), "Struct must have fields");
Ok(quote! { /* generated */ }.into())
}
// Errors convert to compile_error! automatically
```
## Complete Example
```rust
use easy_macros::{
anyhow_result, always_context, fields_get_attributes, TokensBuilder, parse_macro_input
};
#[proc_macro_derive(Routes, attributes(route))]
#[anyhow_result]
#[always_context]
pub fn derive_routes(input: TokenStream) -> anyhow::Result<TokenStream> {
let input = parse_macro_input!(input as DeriveInput);
let routes: Vec<(usize, Field, Vec<TokenStream>)> =
fields_get_attributes!(input, #[route(__unknown__)]);
anyhow::ensure!(!routes.is_empty(), "No routes found");
let mut output = TokensBuilder::default();
for (_, field, methods) in routes {
let name = field.ident.as_ref().context("Field needs name")?;
for method in methods {
output.add(quote! {
pub fn #name() -> Route { Route::new(stringify!(#method)) }
});
}
}
Ok(quote! { impl Routes { #output } }.into())
}
```
## Feature Flags
### Feature Groups
- **`general`** - Automatic error context for any project
- Includes: `always-context`, `context`
- Use when you only need automatic error context, not proc-macro development tools
- **`full`** - Complete toolkit for proc-macro development
- Includes: `all-syntax-cases`, `always-context`, `attributes`, `anyhow-result`, and all helpers
- Use when building procedural macros or need the full feature set
- **`build`** - Build-time macro that auto-adds `#[always_context]` to all functions returning `anyhow::Result`
- Standalone feature, not included in `general` or `full`
- Add to `[build-dependencies]` and configure via `build.rs`
### Individual Features
**Core Proc-Macro Tools**:
- **`all-syntax-cases`** - Exhaustive AST traversal and handler generation
- **`always-context`** - `#[always_context]` attribute for automatic error context
- **`attributes`** - Attribute pattern matching macros (`has_attributes!`, `get_attributes!`, etc.)
- **`anyhow-result`** - `#[anyhow_result]` for using `anyhow::Result<TokenStream>` in proc-macros
**Helper Utilities** (granular control):
- **`context`** - `context!()` macro for manual error context with file/line info
- **`tokens-builder`** - `TokensBuilder` for incrementally building token streams
- **`indexed-name`** - `indexed_name()` for generating indexed identifiers
- **`find-crate`** - `find_crate()` and `find_crate_list()` for locating crates with rename support
- **`parse-macro-input`** - `parse_macro_input!()` with automatic `compile_error!` on parse failure
- **`expr-error-wrap`** - `expr_error_wrap()` utilities for wrapping expressions
- **`readable-token-stream`** - Token stream formatting utilities
- **`token-stream-consistent`** - Consistent token stream string conversion
### Integration Features
- **`easy-sql`** - Integration with Easy-SQL crate
- Adds Easy-SQL support to `#[always_context]` and attribute macros
- Optional: only needed if using Easy-SQL in your project
## License
Apache License, Version 2.0 - See [LICENSE](LICENSE)