Struct LogicDb 

pub struct LogicDb { /* private fields */ }

An indexed store of logic Clauses queried by goal.

Clauses are kept in assertion order and indexed by predicate symbol and by first ground argument to speed candidate lookup.

Implementations

impl LogicDb

pub fn new() -> Self

Creates an empty clause database.

Examples

use sim_kernel::{Expr, Symbol};
use sim_lib_logic::LogicDb;

let mut db = LogicDb::new();
db.assert_clause_expr(Expr::List(vec![
    Expr::Symbol(Symbol::new("fact")),
    Expr::List(vec![
        Expr::Symbol(Symbol::new("parent")),
        Expr::Symbol(Symbol::new("alice")),
        Expr::Symbol(Symbol::new("bob")),
    ]),
]))
.unwrap();
assert!(db.predicate_exists(&Symbol::new("parent")));
assert_eq!(db.clauses().len(), 1);

pub fn clauses(&self) -> &[Clause]

Returns all stored clauses in assertion order.

pub fn predicate_exists(&self, predicate: &Symbol) -> bool

Returns whether any clause defines the given predicate symbol.

pub fn assert_clause_expr(&mut self, expr: Expr) -> Result<ClauseId>

Parses a clause expression and asserts it, returning its new id.

pub fn assert_clause(&mut self, clause: Clause) -> Result<ClauseId>

Adds a parsed clause to the database and updates the indexes.

pub fn retract_clause_expr(&mut self, expr: &Expr) -> Result<bool>

Removes the first clause matching expr, rebuilding the indexes.

Returns whether a matching clause was found and removed.

pub fn facts(&self, predicate: &Symbol) -> Vec<Expr>

Returns the surface expressions of every fact for the given predicate.

pub fn clause_by_id(&self, id: ClauseId) -> Option<&Clause>

Looks up a clause by its identifier.

pub fn clauses_for_goal( &self, goal: &Expr, indexing: bool, ) -> Result<Vec<&Clause>>

Returns the candidate clauses that could resolve goal.

When indexing is true the first-argument index is consulted before falling back to the predicate index.

Trait Implementations

impl Clone for LogicDb

fn clone(&self) -> LogicDb

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LogicDb

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

Formats the value using the given formatter.

impl Default for LogicDb

fn default() -> LogicDb

Returns the “default value” for a type.