Struct Backend 

pub struct Backend<'a> { /* private fields */ }

Handle to the backend to add directives in aspif format.

Implementations

impl<'a> Backend<'a>

pub fn rule( &mut self, choice: bool, head: &[Atom], body: &[SolverLiteral], ) -> Result<(), ClingoError>

Add a rule to the program.

Arguments

• choice determines if the head is a choice or a disjunction
• head - the head atoms
• body - the body literals

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn weight_rule( &mut self, choice: bool, head: &[Atom], lower_bound: i32, body: &[WeightedLiteral], ) -> Result<(), ClingoError>

Add a weight rule to the program.

Attention: All weights and the lower bound must be positive.

Arguments

• choice - determines if the head is a choice or a disjunction
• head - the head atoms
• lower_bound - the lower bound of the weight rule
• body - the weighted body literals

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn minimize( &mut self, priority: i32, literals: &[WeightedLiteral], ) -> Result<(), ClingoError>

Add a minimize constraint (or weak constraint) to the program.

Arguments

• priority - the priority of the constraint
• literals - the weighted literals whose sum to minimize

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn project(&mut self, atoms: &[Atom]) -> Result<(), ClingoError>

Add a projection directive.

Arguments

• atoms - the atoms to project on

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn external( &mut self, atom: Atom, type_: ExternalType, ) -> Result<(), ClingoError>

Add an external statement.

Arguments

• atom - the external atom
• type - the type of the external statement

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn assume(&mut self, literals: &[SolverLiteral]) -> Result<(), ClingoError>

Add an assumption directive.

Arguments

• literals - the literals to assume (positive literals are true and negative literals false for the next solve call)

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn heuristic( &mut self, atom: Atom, htype: HeuristicType, bias: i32, priority: u32, condition: &[SolverLiteral], ) -> Result<(), ClingoError>

Add an heuristic directive.

Arguments

• atom - the target atom
• htype - the type of the heuristic modification
• bias - the heuristic bias
• priority - the heuristic priority
• condition - the condition under which to apply the heuristic modification

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn acyc_edge( &mut self, node_u: i32, node_v: i32, condition: &[SolverLiteral], ) -> Result<(), ClingoError>

Add an edge directive.

Arguments

• node_u - the start vertex of the edge
• node_v - the end vertex of the edge
• condition - the condition under which the edge is part of the graph

Errors

• ClingoError::InternalError with ErrorCode::BadAlloc

pub fn add_atom(&mut self, symbol: Option<Symbol>) -> Result<Atom, ClingoError>

Get a fresh atom to be used in aspif directives.

Arguments

• symbol - optional symbol to associate the atom with

Trait Implementations

impl<'a> Debug for Backend<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> Drop for Backend<'a>

fn drop(&mut self)

Finalize the backend after using it.