fn run_mutation(cursor: &mut Cursor, database: &mut Database) {
    let mut transaction = database.begin();
    let mut temporaries = Temporaries::new();
    let mut mutation = parse::parse_mutation(cursor, &mut temporaries).expect("Failed to parse query.");

    let temporaries = {
        let view = database.view(temporaries);

        // Resolve named attributes to id-based attributes, and plan the read-only
        // part of the query.
        mutation.fix_attributes(&view);

        let query = mutation.read_only_part();
        let types = query.infer_types(&view).expect("Type error.");

        let plan = Planner::plan(&query);

        let mut rows_to_return = Vec::new();

        // For each assignment of values to the bound variables, run the assertions.
        for result in Evaluator::new(&plan, &view) {
            // To generate the asserted datoms, we need a value for every variable.
            // For the bound variables, we get them from the query results. For the
            // free variables, we need to generate new entities. The read-only part
            // of the query selects all bound variables in their order of
            // occurrence, so we can map the result onto the bound values directly.
            let mut bound_values = Vec::with_capacity(mutation.variable_names.len());
            bound_values.extend_from_slice(&result[..]);

            for _ in mutation.free_variables.iter() {
                // Generate a fresh entity id for every new entity.
                let entity_id = transaction.create_entity();
                bound_values.push(Value::from_eid(entity_id));
            }

            for assertion in &mutation.assertions[..] {
                let entity = bound_values[assertion.entity.0 as usize].as_eid(view.heap());
                let attribute = match assertion.attribute {
                    QueryAttribute::Fixed(aid) => aid,
                    QueryAttribute::Named(..) => {
                        panic!("Should have resolved attribute name to id already.");
                    }
                };
                let value = match assertion.value {
                    QueryValue::Const(v) => v,
                    QueryValue::Var(var) => bound_values[var.0 as usize],
                };
                transaction.assert(entity, attribute, value);
            }

            // Collect the values to return from the query; those listed in the
            // select clause.
            let mut row = Vec::with_capacity(mutation.select.len());
            for &v in mutation.select.iter() {
                row.push(bound_values[v.0 as usize]);
            }
            rows_to_return.push(row.into_boxed_slice());
        }

        // Before we can print the results, we need to know the types of the
        // selected variables. For bound variables, we can get them from type
        // inference of the query. For free variables, the type is always ref,
        // because we create entities.
        let mut select_types = Vec::with_capacity(mutation.select.len());
        for &v in mutation.select.iter() {
            let is_bound = (v.0 as usize) < mutation.bound_variables.len();
            match is_bound {
                true => select_types.push(types[v.0 as usize]),
                false => select_types.push(Type::Ref),
            }
        }

        let stdout = io::stdout();
        types::draw_table(
            &mut stdout.lock(),
            view.heap(),
            mutation.select.iter().map(|&v| &mutation.variable_names[v.0 as usize][..]),
            rows_to_return.iter().map(|ref row| &row[..]),
            &select_types[..],
        ).unwrap();

        view.into_temporaries()
    };
    database.commit(&temporaries, transaction).expect("Failed to commit transaction.");
}
/// Evaluate the mutation, return the datoms produced.
Evaluate the mutation, return the datoms produced.
Evaluate the mutation return the datoms produced .
fn run_mutation(cursor: &mut Cursor, database: &mut Database) {
    let mut transaction = database.begin();
    let mut temporaries = Temporaries::new();
    let mut mutation = parse::parse_mutation(cursor, &mut temporaries).expect("Failed to parse query.");
    let temporaries = {
        let view = database.view(temporaries);
        // Resolve named attributes to id-based attributes, and plan the read-only
        // part of the query.
        mutation.fix_attributes(&view);
        let query = mutation.read_only_part();
        let types = query.infer_types(&view).expect("Type error.");
        let plan = Planner::plan(&query);
        let mut rows_to_return = Vec::new();
        // For each assignment of values to the bound variables, run the assertions.
        for result in Evaluator::new(&plan, &view) {
            // To generate the asserted datoms, we need a value for every variable.
            // For the bound variables, we get them from the query results. For the
            // free variables, we need to generate new entities. The read-only part
            // of the query selects all bound variables in their order of
            // occurrence, so we can map the result onto the bound values directly.
            let mut bound_values = Vec::with_capacity(mutation.variable_names.len());
            bound_values.extend_from_slice(&result[..]);
            for _ in mutation.free_variables.iter() {
                // Generate a fresh entity id for every new entity.
                let entity_id = transaction.create_entity();
                bound_values.push(Value::from_eid(entity_id));
            }
            for assertion in &mutation.assertions[..] {
                let entity = bound_values[assertion.entity.0 as usize].as_eid(view.heap());
                let attribute = match assertion.attribute {
                    QueryAttribute::Fixed(aid) => aid,
                    QueryAttribute::Named(..) => {
                        panic!("Should have resolved attribute name to id already.");
                    }
                };
                let value = match assertion.value {
                    QueryValue::Const(v) => v,
                    QueryValue::Var(var) => bound_values[var.0 as usize],
                };
                transaction.assert(entity, attribute, value);
            }
            // Collect the values to return from the query; those listed in the
            // select clause.
            let mut row = Vec::with_capacity(mutation.select.len());
            for &v in mutation.select.iter() {
                row.push(bound_values[v.0 as usize]);
            }
            rows_to_return.push(row.into_boxed_slice());
        }
        // Before we can print the results, we need to know the types of the
        // selected variables. For bound variables, we can get them from type
        // inference of the query. For free variables, the type is always ref,
        // because we create entities.
        let mut select_types = Vec::with_capacity(mutation.select.len());
        for &v in mutation.select.iter() {
            let is_bound = (v.0 as usize) < mutation.bound_variables.len();
            match is_bound {
                true => select_types.push(types[v.0 as usize]),
                false => select_types.push(Type::Ref),
            }
        }
        let stdout = io::stdout();
        types::draw_table(
            &mut stdout.lock(),
            view.heap(),
            mutation.select.iter().map(|&v| &mutation.variable_names[v.0 as usize][..]),
            rows_to_return.iter().map(|ref row| &row[..]),
            &select_types[..],
        ).unwrap();
        view.into_temporaries()
    };
    database.commit(&temporaries, transaction).expect("Failed to commit transaction.");
}
fn run_mutation ( cursor : & mut Cursor , database : & mut Database ) { let mut transaction = database . begin ( ) ; let mut temporaries = Temporaries :: new ( ) ; let mut mutation = parse :: parse_mutation ( cursor , & mut temporaries ) . expect ( " " ) ; let temporaries = { let view = database . view ( temporaries ) ; // Resolve named attributes to id-based attributes, and plan the read-only // part of the query. mutation . fix_attributes ( & view ) ; let query = mutation . read_only_part ( ) ; let types = query . infer_types ( & view ) . expect ( " " ) ; let plan = Planner :: plan ( & query ) ; let mut rows_to_return = Vec :: new ( ) ; // For each assignment of values to the bound variables, run the assertions. for result in Evaluator :: new ( & plan , & view ) { // To generate the asserted datoms, we need a value for every variable. // For the bound variables, we get them from the query results. For the // free variables, we need to generate new entities. The read-only part // of the query selects all bound variables in their order of // occurrence, so we can map the result onto the bound values directly. let mut bound_values = Vec :: with_capacity ( mutation . variable_names . len ( ) ) ; bound_values . extend_from_slice ( & result [ .. ] ) ; for _ in mutation . free_variables . iter ( ) { // Generate a fresh entity id for every new entity. let entity_id = transaction . create_entity ( ) ; bound_values . push ( Value :: from_eid ( entity_id ) ) ; } for assertion in & mutation . assertions [ .. ] { let entity = bound_values [ assertion . entity . 0 as usize ] . as_eid ( view . heap ( ) ) ; let attribute = match assertion . attribute { QueryAttribute :: Fixed ( aid ) => aid , QueryAttribute :: Named ( .. ) => { panic ! ( " " ) ; } } ; let value = match assertion . value { QueryValue :: Const ( v ) => v , QueryValue :: Var ( var ) => bound_values [ var . 0 as usize ] , } ; transaction . assert ( entity , attribute , value ) ; } // Collect the values to return from the query; those listed in the // select clause. let mut row = Vec :: with_capacity ( mutation . select . len ( ) ) ; for & v in mutation . select . iter ( ) { row . push ( bound_values [ v . 0 as usize ] ) ; } rows_to_return . push ( row . into_boxed_slice ( ) ) ; } // Before we can print the results, we need to know the types of the // selected variables. For bound variables, we can get them from type // inference of the query. For free variables, the type is always ref, // because we create entities. let mut select_types = Vec :: with_capacity ( mutation . select . len ( ) ) ; for & v in mutation . select . iter ( ) { let is_bound = ( v . 0 as usize ) < mutation . bound_variables . len ( ) ; match is_bound { true => select_types . push ( types [ v . 0 as usize ] ) , false => select_types . push ( Type :: Ref ) , } } let stdout = io :: stdout ( ) ; types :: draw_table ( & mut stdout . lock ( ) , view . heap ( ) , mutation . select . iter ( ) . map ( | & v | & mutation . variable_names [ v . 0 as usize ] [ .. ] ) , rows_to_return . iter ( ) . map ( | ref row | & row [ .. ] ) , & select_types [ .. ] , ) . unwrap ( ) ; view . into_temporaries ( ) } ; database . commit ( & temporaries , transaction ) . expect ( " " ) ; }
Evaluate the mutation, return the datoms produced.
Evaluate the mutation return the datoms produced .
cursor
&mut Cursor
database
&mut Database
cursor
&mut Cursor
database
&mut Database