chematic-smiles

OpenSMILES parser and writer for Rust. Parses arbitrary SMILES strings into a molecular graph and generates canonical SMILES. Pure Rust, no FFI, WASM-compatible.

Features

• SMILES parsing: read OpenSMILES syntax (aromatic, charges, bonds, isotopes, stereo)
• Canonical SMILES: deterministic round-trip generation with sorted atom ordering
• Stereo chemistry: Up/Down bonds for 3D chirality, E/Z double bonds
• Aromaticity perception: automatic aromatic ring detection (Hückel 4n+2)
• Hydrogen handling: implicit/explicit hydrogens, valence checks
• WASM-compatible: zero C/C++ dependencies

Quick Start

use chematic_smiles::parse;

// Parse SMILES
let mol = parse("c1ccccc1O").expect("phenol");
println!("Atoms: {}", mol.atom_count());
println!("Bonds: {}", mol.bond_count());

// Iterate atoms
for i in 0..mol.atom_count() {
    let atom_idx = chematic_core::AtomIdx(i as u32);
    let atom = mol.atom(atom_idx);
    println!("Atom {}: {}", i, atom.element.symbol());
}

// Iterate bonds
for (_bond_idx, bond) in mol.bonds() {
    println!("Bond: {} - {} (order: {:?})", 
        bond.atom1.0, bond.atom2.0, bond.order);
}

API Overview

• parse(smiles: &str) -> Result<Molecule, ParseError> — parse SMILES string
• canonical_smiles(mol: &Molecule) -> String — generate canonical SMILES
• Molecule — molecular graph with atoms, bonds, and bond orders
• Atom, Bond — low-level types for graph data

Dependencies

• chematic-core — graph and chemistry types

References

• OpenSMILES spec: https://opensmiles.org/
• SMILES tutorial: https://www.daylight.com/dayhtml/doc/theory/theory.smiles.html

See Also

• chematic — main umbrella crate
• chematic-inchi — InChI generation
• chematic-smarts — SMARTS matching and reactions