[revise] Remove Entity and EntitySource

Removes Entity and EntitySource. The solver takes in
the Variable Source directly. The constraints, filters, sort
or any transformation should be performed on variables before
providing it to solver.

Signed-off-by: Varsha Prasad Narsing <varshaprasad96@gmail.com>

cmd/dimacs/cmd.go

@@ -53,7 +53,7 @@ func solve(path string) error {
 	}
 
 	// build solver
-	so, err := solver.NewDeppySolver(NewDimacsEntitySource(dimacs), NewDimacsVariableSource(dimacs))
+	so, err := solver.NewDeppySolver(NewDimacsVariableSource(dimacs))
 	if err != nil {
 		return err
 	}

cmd/dimacs/dimacs_constraints.go

@@ -21,16 +21,13 @@ func NewDimacsVariableSource(dimacs *Dimacs) *ConstraintGenerator {
 	}
 }
 
-func (d *ConstraintGenerator) GetVariables(ctx context.Context, entitySource input.EntitySource) ([]deppy.Variable, error) {
+func (d *ConstraintGenerator) GetVariables(ctx context.Context) ([]deppy.Variable, error) {
 	varMap := make(map[deppy.Identifier]*input.SimpleVariable, len(d.dimacs.variables))
 	variables := make([]deppy.Variable, 0, len(d.dimacs.variables))
-	if err := entitySource.Iterate(ctx, func(entity *input.Entity) error {
-		variable := input.NewSimpleVariable(entity.Identifier())
+
+	for _, id := range d.dimacs.variables {
+		variable := input.NewSimpleVariable(deppy.IdentifierFromString(id))
 		variables = append(variables, variable)
-		varMap[entity.Identifier()] = variable
-		return nil
-	}); err != nil {
-		return nil, err
 	}
 
 	// create constraints out of the clauses

cmd/sudoku/cmd.go

@@ -23,8 +23,8 @@ func NewSudokuCommand() *cobra.Command {
 
 func solve() error {
 	// build solver
-	sudoku := NewSudoku()
-	so, err := solver.NewDeppySolver(sudoku, sudoku)
+	sudoku := &Sudoku{}
+	so, err := solver.NewDeppySolver(sudoku)
 	if err != nil {
 		return err
 	}

cmd/sudoku/sudoku.go

@@ -4,19 +4,18 @@ import (
 	"context"
 	"fmt"
 	"math/rand"
-	"strconv"
 	"time"
 
 	"github.com/operator-framework/deppy/pkg/deppy"
 	"github.com/operator-framework/deppy/pkg/deppy/constraint"
 	"github.com/operator-framework/deppy/pkg/deppy/input"
 )
 
-var _ input.EntitySource = &Sudoku{}
 var _ input.VariableSource = &Sudoku{}
 
+// TODO: this could be an empty struct
 type Sudoku struct {
-	*input.CacheEntitySource
+	variables []deppy.Variable
 }
 
 func GetID(row int, col int, num int) deppy.Identifier {
@@ -26,26 +25,7 @@ func GetID(row int, col int, num int) deppy.Identifier {
 	return deppy.Identifier(fmt.Sprintf("%03d", n))
 }
 
-func NewSudoku() *Sudoku {
-	var entities = make(map[deppy.Identifier]input.Entity, 9*9*9)
-	for row := 0; row < 9; row++ {
-		for col := 0; col < 9; col++ {
-			for num := 0; num < 9; num++ {
-				id := GetID(row, col, num)
-				entities[id] = *input.NewEntity(id, map[string]string{
-					"row": strconv.Itoa(row),
-					"col": strconv.Itoa(col),
-					"num": strconv.Itoa(num),
-				})
-			}
-		}
-	}
-	return &Sudoku{
-		CacheEntitySource: input.NewCacheQuerier(entities),
-	}
-}
-
-func (s Sudoku) GetVariables(ctx context.Context, _ input.EntitySource) ([]deppy.Variable, error) {
+func (s Sudoku) GetVariables(ctx context.Context) ([]deppy.Variable, error) {
 	// adapted from: https://github.com/go-air/gini/blob/871d828a26852598db2b88f436549634ba9533ff/sudoku_test.go#L10
 	variables := make(map[deppy.Identifier]*input.SimpleVariable, 0)
 	inorder := make([]deppy.Variable, 0)