AST: Lazy evaluate boolean child nodes.

This adds circuit breaking to boolean evaluation.
An AND boolean resolves to false if the first operand is false, and an OR boolean resolves to true if the first operand is true.
With this, second operands and skipped if they can have no sway on the node's result.

integration_test/scenario_flow_test.go

@@ -529,11 +529,11 @@ func createDecisions(
 		assert.Nil(t, ruleExecution.Error, "Expected error to be nil, got \"%s\"", ruleExecution.Error)
 	}
 
-	// Create a decision [APPROVE] with a division by zero
+	// Create a decision [DECLINE] with a division by zero
 	transactionPayloadJson = []byte(`{
 		"object_id": "{transaction_id}",
 		"updated_at": "2020-01-01T00:00:00Z",
-		"account_id": "{account_id_approve}",
+		"account_id": "{account_id_decline}",
 		"amount": 0
 	}`)
 	approveDivisionByZeroDecision := createAndTestDecision(ctx, t, transactionPayloadJson, table,

models/ast/ast_function.go

@@ -82,6 +82,10 @@ type FuncAttributes struct {
 	// However, it is not consumed anywhere, and it is in NO WAY enforced by the compiler or even the runtime.
 	// The only source of truth for what named children an AST must/can have is in the ast nodes Evaluate function.
 	NamedArguments []string
+	// A function can define LazyChildEvaluation indicating that its children should be evaluated lazily,
+	// considering for every one of them if evaluation should continue or not. For the result value of one child, the
+	// function returns whether evaluation of subsequent children should continue (true) or not (false).
+	LazyChildEvaluation func(NodeEvaluation) bool
 }
 
 // If number of arguments -1 the function can take any number of arguments
@@ -141,10 +145,14 @@ var FuncAttributesMap = map[Function]FuncAttributes{
 	FUNC_AND: {
 		DebugName: "FUNC_AND",
 		AstName:   "And",
+		// Boolean AND returns false if any child node evaluates to false
+		LazyChildEvaluation: shortCircuitIfFalse,
 	},
 	FUNC_OR: {
 		DebugName: "FUNC_OR",
 		AstName:   "Or",
+		// Boolean OR returns true if any child nodes evluates to true
+		LazyChildEvaluation: shortCircuitIfTrue,
 	},
 	FUNC_TIME_ADD: {
 		DebugName:      "FUNC_TIME_ADD",
@@ -286,3 +294,19 @@ func NewNodeDatabaseAccess(tableName string, fieldName string, path []string) No
 		AddNamedChild(AttributeFuncDbAccess.ArgumentFieldName, NewNodeConstant(fieldName)).
 		AddNamedChild(AttributeFuncDbAccess.ArgumentPathName, NewNodeConstant(path))
 }
+
+func shortCircuitIfTrue(res NodeEvaluation) bool {
+	if b, ok := res.ReturnValue.(bool); ok {
+		// If node returned true, we stop (return !true = false), otherwise, continue with true
+		return !b
+	}
+	return true
+}
+
+func shortCircuitIfFalse(res NodeEvaluation) bool {
+	if b, ok := res.ReturnValue.(bool); ok {
+		// If node returned false, we stop (return false), otherwise, continue with true
+		return b
+	}
+	return true
+}

pure_utils/map.go

@@ -50,3 +50,37 @@ func MapValuesErr[Key comparable, T any, U any](src map[Key]T, f func(T) (U, err
 	}
 	return result, nil
 }
+
+// MapWhile maps over items in a slice and produces a slice of items of another type.
+// Contrary to regular Map(), the callbacks returns a second boolean value to indicate if the operation
+// should continue. It stops whenever the callback returns false.
+func MapWhile[T, U any](src []T, f func(T) (U, bool)) []U {
+	us := make([]U, 0, len(src))
+	for i := range src {
+		item, next := f(src[i])
+
+		us = append(us, item)
+
+		if !next {
+			break
+		}
+	}
+	return us
+}
+
+// MapValuesWhile maps over a map's values in a slice and produces a slice of items of another type.
+// Contrary to regular MapValues(), the callbacks returns a second boolean value to indicate if the operation
+// should continue. It stops whenever the callback returns false.
+func MapValuesWhile[Key comparable, T any, U any](src map[Key]T, f func(T) (U, bool)) map[Key]U {
+	result := make(map[Key]U, len(src))
+	for key, value := range src {
+		item, next := f(value)
+
+		result[key] = item
+
+		if !next {
+			break
+		}
+	}
+	return result
+}

usecases/ast_eval/evaluate_ast.go

@@ -19,19 +19,29 @@ func EvaluateAst(ctx context.Context, environment AstEvaluationEnvironment, node
 
 	childEvaluationFail := false
 
-	evalChild := func(child ast.Node) ast.NodeEvaluation {
+	// Only interested in lazy callback which will have default value if an error is returned
+	attrs, _ := node.Function.Attributes()
+
+	evalChild := func(child ast.Node) (childEval ast.NodeEvaluation, evalNext bool) {
 		childEval, ok := EvaluateAst(ctx, environment, child)
+
 		if !ok {
 			childEvaluationFail = true
 		}
-		return childEval
+
+		// Should we continue evaluating subsequent children nodes?
+		// We always do if circuit breaking is disabled in the environment or if the parent node does not support lazy evaluation.
+		// Otherwise, we run the lazy evaluator to determine if we should continue or stop.
+		evalNext = environment.disableCircuitBreaking || attrs.LazyChildEvaluation == nil || attrs.LazyChildEvaluation(childEval)
+
+		return
 	}
 
 	// eval each child
 	evaluation := ast.NodeEvaluation{
 		Function:      node.Function,
-		Children:      pure_utils.Map(node.Children, evalChild),
-		NamedChildren: pure_utils.MapValues(node.NamedChildren, evalChild),
+		Children:      pure_utils.MapWhile(node.Children, evalChild),
+		NamedChildren: pure_utils.MapValuesWhile(node.NamedChildren, evalChild),
 	}
 
 	if childEvaluationFail {

usecases/ast_eval/evaluate_ast_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/checkmarble/marble-backend/models/ast"
+	"github.com/checkmarble/marble-backend/utils"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -91,3 +92,89 @@ func NewAstOrFalse() ast.Node {
 		AddChild(ast.Node{Constant: false}).
 		AddChild(ast.Node{Constant: false})
 }
+
+func TestLazyAnd(t *testing.T) {
+	environment := NewAstEvaluationEnvironment()
+
+	for _, value := range []bool{true, false} {
+		root := ast.Node{Function: ast.FUNC_AND}.
+			AddChild(ast.Node{Function: ast.FUNC_EQUAL}.
+				AddChild(ast.Node{Constant: value}).
+				AddChild(ast.Node{Constant: true})).
+			AddChild(ast.Node{Function: ast.FUNC_UNKNOWN})
+
+		evaluation, ok := EvaluateAst(context.TODO(), environment, root)
+
+		switch value {
+		case false:
+			assert.True(t, ok, "unknown node should not be evaluated because of AND lazy evaluation")
+			assert.Len(t, evaluation.Children, 1, "lazy evaluated AND should only have one child")
+		case true:
+			assert.False(t, ok, "unknown node should be evaluated because of AND lazy evaluation")
+			assert.Len(t, evaluation.Children, 2, "lazy evaluated AND should have two children")
+		}
+	}
+}
+
+func TestLazyOr(t *testing.T) {
+	environment := NewAstEvaluationEnvironment()
+
+	for _, value := range []bool{true, false} {
+		root := ast.Node{Function: ast.FUNC_OR}.
+			AddChild(ast.Node{Function: ast.FUNC_EQUAL}.
+				AddChild(ast.Node{Constant: value}).
+				AddChild(ast.Node{Constant: true})).
+			AddChild(ast.Node{Function: ast.FUNC_UNKNOWN})
+
+		evaluation, ok := EvaluateAst(context.TODO(), environment, root)
+
+		switch value {
+		case true:
+			assert.True(t, ok, "unknown node should not be evaluated because of OR lazy evaluation")
+			assert.Len(t, evaluation.Children, 1, "lazy evaluates OR should only have one child")
+		case false:
+			assert.False(t, ok, "unknown node should be evaluated because of OR lazy evaluation")
+			assert.Len(t, evaluation.Children, 2, "lazy evaluated AND should have two children")
+		}
+	}
+}
+
+func TestLazyBooleanNulls(t *testing.T) {
+	tts := []struct {
+		fn            ast.Function
+		lhs, rhs, res *bool
+	}{
+		{ast.FUNC_OR, nil, utils.Ptr(true), utils.Ptr(true)},
+		{ast.FUNC_OR, utils.Ptr(true), nil, utils.Ptr(true)},
+		{ast.FUNC_OR, nil, utils.Ptr(false), nil},
+		{ast.FUNC_OR, utils.Ptr(false), nil, nil},
+		{ast.FUNC_AND, nil, utils.Ptr(true), nil},
+		{ast.FUNC_AND, utils.Ptr(true), nil, nil},
+		{ast.FUNC_AND, nil, utils.Ptr(false), utils.Ptr(false)},
+		{ast.FUNC_AND, utils.Ptr(false), nil, utils.Ptr(false)},
+	}
+
+	environment := NewAstEvaluationEnvironment()
+
+	for _, tt := range tts {
+		root := ast.Node{Function: tt.fn}
+
+		for _, op := range []*bool{tt.lhs, tt.rhs} {
+			switch op {
+			case nil:
+				root = root.AddChild(ast.Node{Constant: nil})
+			default:
+				root = root.AddChild(ast.Node{Constant: *op})
+			}
+		}
+
+		evaluation, _ := EvaluateAst(context.TODO(), environment, root)
+
+		switch {
+		case tt.res == nil:
+			assert.Equal(t, nil, evaluation.ReturnValue)
+		default:
+			assert.Equal(t, *tt.res, evaluation.ReturnValue)
+		}
+	}
+}

usecases/ast_eval/evaluate_environment.go

@@ -10,7 +10,8 @@ import (
 )
 
 type AstEvaluationEnvironment struct {
-	availableFunctions map[ast.Function]evaluate.Evaluator
+	availableFunctions     map[ast.Function]evaluate.Evaluator
+	disableCircuitBreaking bool
 }
 
 func (environment *AstEvaluationEnvironment) AddEvaluator(function ast.Function, evaluator evaluate.Evaluator) {
@@ -27,6 +28,12 @@ func (environment *AstEvaluationEnvironment) GetEvaluator(function ast.Function)
 	return nil, errors.New(fmt.Sprintf("function '%s' is not available", function.DebugString()))
 }
 
+func (environment AstEvaluationEnvironment) WithoutCircuitBreaking() AstEvaluationEnvironment {
+	environment.disableCircuitBreaking = true
+
+	return environment
+}
+
 func NewAstEvaluationEnvironment() AstEvaluationEnvironment {
 	environment := AstEvaluationEnvironment{
 		availableFunctions: make(map[ast.Function]evaluate.Evaluator),

usecases/scenarios/scenario_validation.go

@@ -227,6 +227,8 @@ func (validator *AstValidatorImpl) MakeDryRunEnvironment(ctx context.Context,
 		ClientObject:                  clientObject,
 		DataModel:                     dataModel,
 		DatabaseAccessReturnFakeValue: true,
-	})
+	}).
+		WithoutCircuitBreaking()
+
 	return env, nil
 }

usecases/scenarios/scenario_validation_test.go

@@ -91,7 +91,7 @@ func TestValidateScenarioIterationImpl_Validate(t *testing.T) {
 	validator := AstValidatorImpl{
 		DataModelRepository: mdmr,
 		AstEvaluationEnvironmentFactory: func(params ast_eval.EvaluationEnvironmentFactoryParams) ast_eval.AstEvaluationEnvironment {
-			return ast_eval.NewAstEvaluationEnvironment()
+			return ast_eval.NewAstEvaluationEnvironment().WithoutCircuitBreaking()
 		},
 		ExecutorFactory: executorFactory,
 	}
@@ -183,7 +183,107 @@ func TestValidateScenarioIterationImpl_Validate_notBool(t *testing.T) {
 	validator := AstValidatorImpl{
 		DataModelRepository: mdmr,
 		AstEvaluationEnvironmentFactory: func(params ast_eval.EvaluationEnvironmentFactoryParams) ast_eval.AstEvaluationEnvironment {
-			return ast_eval.NewAstEvaluationEnvironment()
+			return ast_eval.NewAstEvaluationEnvironment().WithoutCircuitBreaking()
+		},
+		ExecutorFactory: executorFactory,
+	}
+
+	siValidator := ValidateScenarioIterationImpl{
+		AstValidator: &validator,
+	}
+
+	result := siValidator.Validate(ctx, models.ScenarioAndIteration{
+		Scenario:  scenario,
+		Iteration: scenarioIteration,
+	})
+	assert.NotEmpty(t, ScenarioValidationToError(result))
+}
+
+func TestValidationShouldBypassCircuitBreaking(t *testing.T) {
+	ctx := utils.StoreLoggerInContext(context.Background(), utils.NewLogger("text"))
+	scenario := models.Scenario{
+		Id:                uuid.New().String(),
+		OrganizationId:    uuid.New().String(),
+		Name:              "scenario_name",
+		Description:       "description",
+		TriggerObjectType: "object_type",
+		CreatedAt:         time.Now(),
+		LiveVersionID:     utils.Ptr(uuid.New().String()),
+	}
+
+	scenarioIterationID := uuid.New().String()
+	scenarioIteration := models.ScenarioIteration{
+		Id:             scenarioIterationID,
+		OrganizationId: scenario.OrganizationId,
+		ScenarioId:     scenario.Id,
+		Version:        utils.Ptr(1),
+		CreatedAt:      time.Now(),
+		UpdatedAt:      time.Now(),
+		TriggerConditionAstExpression: utils.Ptr(ast.Node{
+			Constant: true,
+		}),
+		Rules: []models.Rule{
+			{
+				Id:                  "rule",
+				ScenarioIterationId: scenarioIterationID,
+				OrganizationId:      scenario.OrganizationId,
+				DisplayOrder:        0,
+				Name:                "rule",
+				Description:         "description",
+				FormulaAstExpression: utils.Ptr(ast.Node{
+					Function: ast.FUNC_AND,
+					Constant: nil,
+					Children: []ast.Node{
+						{
+							Function: ast.FUNC_EQUAL,
+							Children: []ast.Node{
+								{Constant: 100},
+								{Constant: 101},
+							},
+						},
+						{
+							Function: ast.FUNC_EQUAL,
+							Children: []ast.Node{
+								{Constant: 100},
+								{Constant: "oplop"},
+							},
+						},
+					},
+				}),
+				ScoreModifier: 10,
+				CreatedAt:     time.Now(),
+			},
+		},
+		ScoreReviewThreshold:         utils.Ptr(100),
+		ScoreBlockAndReviewThreshold: utils.Ptr(1000),
+		ScoreDeclineThreshold:        utils.Ptr(1000),
+		Schedule:                     "schedule",
+	}
+
+	exec := new(mocks.Executor)
+	executorFactory := new(mocks.ExecutorFactory)
+	executorFactory.On("NewExecutor").Once().Return(exec)
+	mdmr := new(mocks.DataModelRepository)
+	mdmr.On("GetDataModel", ctx, exec, scenario.OrganizationId, false).
+		Return(models.DataModel{
+			Version: "version",
+			Tables: map[string]models.Table{
+				"object_type": {
+					Name: "object_type",
+					Fields: map[string]models.Field{
+						"id": {
+							DataType: models.Int,
+						},
+					},
+					LinksToSingle: nil,
+				},
+			},
+		}, nil)
+
+	validator := AstValidatorImpl{
+		DataModelRepository: mdmr,
+		AstEvaluationEnvironmentFactory: func(params ast_eval.EvaluationEnvironmentFactoryParams) ast_eval.AstEvaluationEnvironment {
+			return ast_eval.NewAstEvaluationEnvironment().WithoutCircuitBreaking()
 		},
 		ExecutorFactory: executorFactory,
 	}