# chematic-rxn
Reaction SMILES and SMIRKS parser for Rust. Parses chemical transformations (reactants → products) and reaction patterns (transform rules). Pure Rust, RDKit-compatible, WASM-compatible.
## Features
- **Reaction SMILES parsing**: parse reaction equations (e.g., `CC(C)C>>CC(C)[O]`)
- **SMIRKS parsing**: transform patterns for reaction template matching
- **Atom mapping**: track which atoms in reactants map to which atoms in products
- **Reaction properties**: count reactants, products, and agents
- **RDKit compatibility**: parses RDKit reaction SMILES, produces identical results
- **WASM-compatible**: zero C/C++ dependencies
## Quick Start
```rust
use chematic_rxn::parse_reaction;
// Parse a reaction SMILES
let rxn = parse_reaction("CC(C)Br.[Na+].[OH-]>>CC(C)O.[Na+].[Br-]")
.expect("bimolecular substitution");
println!("Reactants: {}", rxn.reactant_count());
println!("Products: {}", rxn.product_count());
// Access reactants and products as Molecule objects
for mol in rxn.reactants() {
println!("Atoms: {}", mol.atom_count());
}
```
## API Overview
### Parsing
- `parse_reaction(rxn_smiles: &str) -> Result<Reaction, ParseError>` — parse reaction SMILES
- `parse_smirks(pattern: &str) -> Result<ReactionPattern, ParseError>` — parse SMIRKS pattern
### Reaction Structure
- `Reaction` — contains reactants, agents, products, and optional atom mappings
- `Molecule` — each reactant/product is a standard Molecule
- `ReactionPattern` — SMIRKS pattern for template matching
### Properties
```rust
let rxn = parse_reaction("C.C>>CC")?;
assert_eq!(rxn.reactant_count(), 2);
assert_eq!(rxn.product_count(), 1);
assert_eq!(rxn.agent_count(), 0);
// Get individual molecules
let mol1 = rxn.reactant(0).expect("first reactant");
let prod = rxn.product(0).expect("first product");
```
## Dependencies
- [`chematic-core`](../chematic-core/README.md) — molecular graph
- [`chematic-smiles`](../chematic-smiles/README.md) — SMILES parser
## References
- Reaction SMILES: https://www.daylight.com/dayhtml/doc/theory/theory.smiles.html#reactions
- SMIRKS: https://www.daylight.com/meetings/emug05/Friedman_SMIRKS.pdf
## See Also
- [`chematic`](../chematic) — main umbrella crate
- [`chematic-smiles`](../chematic-smiles) — SMILES parser
- [`chematic-smarts`](../chematic-smarts) — substructure matching and reactions
- [`chematic-depict`](../chematic-depict) — reaction scheme visualization