Validators for common literals and use cases.

Introduce validators for duration, timestamp, and regex string literals
as well as support for homogeneous aggregate literals with a carveout
for string format calls.

cel/BUILD.bazel

@@ -15,6 +15,7 @@ go_library(
         "macro.go",
         "options.go",
         "program.go",
+        "validator.go",
     ],
     importpath = "github.com/google/cel-go/cel",
     visibility = ["//visibility:public"],

cel/cel_test.go

@@ -275,105 +275,6 @@ func TestCustomEnv(t *testing.T) {
 	})
 }
 
-func TestHomogeneousAggregateLiterals(t *testing.T) {
-	e, err := NewCustomEnv(
-		Variable("name", StringType),
-		Function(operators.In,
-			Overload(overloads.InList, []*Type{StringType, ListType(StringType)}, BoolType,
-				BinaryBinding(func(lhs, rhs ref.Val) ref.Val {
-					return rhs.(traits.Container).Contains(lhs)
-				}),
-			),
-			Overload(overloads.InMap, []*Type{StringType, MapType(StringType, BoolType)}, BoolType,
-				BinaryBinding(func(lhs, rhs ref.Val) ref.Val {
-					return rhs.(traits.Container).Contains(lhs)
-				}),
-			),
-		),
-		HomogeneousAggregateLiterals(),
-	)
-	if err != nil {
-		t.Fatalf("NewCustomEnv() failed: %v", err)
-	}
-
-	tests := []struct {
-		name string
-		expr string
-		iss  string
-		vars map[string]any
-		out  ref.Val
-	}{
-		{
-			name: "err_list",
-			expr: `name in ['hello', 0]`,
-			iss: `
-			ERROR: <input>:1:19: expected type 'string' but found 'int'
-             | name in ['hello', 0]
-             | ..................^`,
-		},
-		{
-			name: "err_map_key",
-			expr: `name in {'hello':'world', 1:'!'}`,
-			iss: `
-			ERROR: <input>:1:6: found no matching overload for '@in' applied to '(string, map(!error!, string))'
-			 | name in {'hello':'world', 1:'!'}
-			 | .....^
-			ERROR: <input>:1:27: expected type 'string' but found 'int'
-             | name in {'hello':'world', 1:'!'}
-             | ..........................^`,
-		},
-		{
-			name: "err_map_value",
-			expr: `name in {'hello':'world', 'goodbye':true}`,
-			iss: `
-			ERROR: <input>:1:37: expected type 'string' but found 'bool'
-             | name in {'hello':'world', 'goodbye':true}
-             | ....................................^`,
-		},
-		{
-			name: "ok_list",
-			expr: `name in ['hello', 'world']`,
-			vars: map[string]any{"name": "world"},
-			out:  types.True,
-		},
-		{
-			name: "ok_map",
-			expr: `name in {'hello': false, 'world': true}`,
-			vars: map[string]any{"name": "world"},
-			out:  types.True,
-		},
-	}
-	for _, tst := range tests {
-		tc := tst
-		t.Run(tc.name, func(t *testing.T) {
-			ast, iss := e.Compile(tc.expr)
-			if tc.iss != "" {
-				if iss.Err() == nil {
-					t.Fatalf("e.Compile(%v) returned ast, expected error: %v", tc.expr, tc.iss)
-				}
-				if !test.Compare(iss.Err().Error(), tc.iss) {
-					t.Fatalf("e.Compile(%v) returned %v, expected error: %v", tc.expr, iss.Err(), tc.iss)
-				}
-				return
-			}
-			if iss.Err() != nil {
-				t.Fatalf("e.Compile(%v) failed: %v", tc.expr, iss.Err())
-			}
-			prg, err := e.Program(ast)
-			if err != nil {
-				t.Fatalf("e.Program() failed: %v", err)
-			}
-			out, _, err := prg.Eval(tc.vars)
-			if err != nil {
-				t.Fatalf("prg.Eval(%v) errored: %v", tc.vars, err)
-			}
-			if out != tc.out {
-				t.Errorf("program eval got %v, wanted %v", out, tc.out)
-			}
-		})
-	}
-}
-
 func TestCrossTypeNumericComparisons(t *testing.T) {
 	tests := []struct {
 		name string

cel/env.go

@@ -118,6 +118,7 @@ type Env struct {
 	features        map[int]bool
 	appliedFeatures map[int]bool
 	libraries       map[string]bool
+	validators      []ASTValidator
 
 	// Internal parser representation
 	prsr     *parser.Parser
@@ -178,6 +179,7 @@ func NewCustomEnv(opts ...EnvOption) (*Env, error) {
 		features:        map[int]bool{},
 		appliedFeatures: map[int]bool{},
 		libraries:       map[string]bool{},
+		validators:      []ASTValidator{},
 		progOpts:        []ProgramOption{},
 	}).configure(opts)
 }
@@ -207,12 +209,22 @@ func (e *Env) Check(ast *Ast) (*Ast, *Issues) {
 	}
 	// Manually create the Ast to ensure that the Ast source information (which may be more
 	// detailed than the information provided by Check), is returned to the caller.
-	return &Ast{
+	ast = &Ast{
 		source:  ast.Source(),
 		expr:    res.Expr,
 		info:    res.SourceInfo,
 		refMap:  res.ReferenceMap,
-		typeMap: res.TypeMap}, nil
+		typeMap: res.TypeMap}
+
+	// Apply additional validators on the type-checked result.
+	iss := NewIssues(errs)
+	for _, v := range e.validators {
+		v.Validate(e, ast, iss)
+	}
+	if iss.Err() != nil {
+		return nil, iss
+	}
+	return ast, nil
 }
 
 // Compile combines the Parse and Check phases CEL program compilation to produce an Ast and
@@ -331,6 +343,8 @@ func (e *Env) Extend(opts ...EnvOption) (*Env, error) {
 	for k, v := range e.libraries {
 		libsCopy[k] = v
 	}
+	validatorsCopy := make([]ASTValidator, len(e.validators))
+	copy(validatorsCopy, e.validators)
 
 	ext := &Env{
 		Container:       e.Container,
@@ -342,6 +356,7 @@ func (e *Env) Extend(opts ...EnvOption) (*Env, error) {
 		features:        featuresCopy,
 		appliedFeatures: appliedFeaturesCopy,
 		libraries:       libsCopy,
+		validators:      validatorsCopy,
 		provider:        provider,
 		chkOpts:         chkOptsCopy,
 		prsrOpts:        prsrOptsCopy,
@@ -362,6 +377,16 @@ func (e *Env) HasLibrary(libName string) bool {
 	return exists && configured
 }
 
+// HasValidator returns whether a specific ASTValidator has been configured in the environment.
+func (e *Env) HasValidator(name string) bool {
+	for _, v := range e.validators {
+		if v.Name() == name {
+			return true
+		}
+	}
+	return false
+}
+
 // Parse parses the input expression value `txt` to a Ast and/or a set of Issues.
 //
 // This form of Parse creates a Source value for the input `txt` and forwards to the
@@ -534,8 +559,6 @@ func (e *Env) initChecker() (*checker.Env, error) {
 		chkOpts := []checker.Option{}
 		chkOpts = append(chkOpts, e.chkOpts...)
 		chkOpts = append(chkOpts,
-			checker.HomogeneousAggregateLiterals(
-				e.HasFeature(featureDisableDynamicAggregateLiterals)),
 			checker.CrossTypeNumericComparisons(
 				e.HasFeature(featureCrossTypeNumericComparisons)))
 

cel/options.go

@@ -41,13 +41,6 @@ import (
 const (
 	_ = iota
 
-	// Disallow heterogeneous aggregate (list, map) literals.
-	// Note, it is still possible to have heterogeneous aggregates when
-	// provided as variables to the expression, as well as via conversion
-	// of well-known dynamic types, or with unchecked expressions.
-	// Affects checking.  Provides a subset of standard behavior.
-	featureDisableDynamicAggregateLiterals
-
 	// Enable the tracking of function call expressions replaced by macros.
 	featureEnableMacroCallTracking
 
@@ -63,10 +56,6 @@ const (
 	// is not already in UTC.
 	featureDefaultUTCTimeZone
 
-	// Enable the use of optional types in the syntax, type-system, type-checking,
-	// and runtime.
-	featureOptionalTypes
-
 	// Enable the serialization of logical operator ASTs as variadic calls, thus
 	// compressing the logic graph to a single call when multiple like-operator
 	// expressions occur: e.g. a && b && c && d -> call(_&&_, [a, b, c, d])
@@ -157,7 +146,7 @@ func EagerlyValidateDeclarations(enabled bool) EnvOption {
 // expression, as well as via conversion of well-known dynamic types, or with unchecked
 // expressions.
 func HomogeneousAggregateLiterals() EnvOption {
-	return features(featureDisableDynamicAggregateLiterals, true)
+	return ASTValidators(ValidateHomogeneousAggregateLiterals())
 }
 
 // variadicLogicalOperatorASTs flatten like-operator chained logical expressions into a single