Add any and all expression support. (#49)

* Add any and all expression support.

The syntax is inspired by Sentinel [Any, All Expressions](https://docs.hashicorp.com/sentinel/language/boolexpr#any-all-expressions)
and the [For Statements](https://docs.hashicorp.com/sentinel/language/loops#for-statements).

README.md

@@ -99,6 +99,6 @@ The [Makefile](Makefile) contains 3 main targets to aid with testing:
      `1s` seemed like too little to get results consistent enough for comparison between two runs.
      For the highest degree of confidence that performance has remained steady increase this value
      even further. The time it takes to run the bench testing suite grows linearly with this value.
-   * `BENCHTESTS=BenchmarkEvalute` - This is used to run a particular benchmark including all of its
+   * `BENCHTESTS=BenchmarkEvaluate` - This is used to run a particular benchmark including all of its
      sub-benchmarks. This is just an example and "BenchmarkEvaluate" can be replaced with any
      benchmark functions name.

evaluate.go

@@ -223,7 +223,7 @@ func getMatchExprValue(expression *grammar.MatchExpression, rvalue reflect.Kind)
 // be handled by the MatchOperator's NotPresentDisposition method.
 //
 // Returns false if the Selector Path has a length of 1, or if the parent of
-// the Selector's Path is not a map, a pointerstructure.ErrrNotFound error is
+// the Selector's Path is not a map, a pointerstructure.ErrNotFound error is
 // returned.
 func evaluateNotPresent(ptr pointerstructure.Pointer, datum interface{}) bool {
 	if len(ptr.Parts) < 2 {
@@ -237,10 +237,54 @@ func evaluateNotPresent(ptr pointerstructure.Pointer, datum interface{}) bool {
 	return reflect.ValueOf(val).Kind() == reflect.Map
 }
 
-func evaluateMatchExpression(expression *grammar.MatchExpression, datum interface{}, opt ...Option) (bool, error) {
+// getValue resolves path to the value it references by first looking into the
+// the local variables, then into the global datum state if it does not.
+//
+// When the path points to a local variable we have multiple cases we have to
+// take care of, in some constructions like
+//
+//	all Slice as item { item != "forbidden" }
+//
+// `item` is actually an alias to "/Slice/0", "/Slice/1", etc. In that case we
+// compute the full path because we tracked what each of them points to.
+//
+// In some other cases like
+//
+//	all Map as key { key != "forbidden" }
+//
+// `key` has no equivalent JSON Pointer. In that case we kept track of the the
+// concrete value instead of the path and we return it directly.
+func getValue(datum interface{}, path []string, opt ...Option) (interface{}, bool, error) {
 	opts := getOpts(opt...)
+	if len(path) != 0 && len(opts.withLocalVariables) > 0 {
+		for i := len(opts.withLocalVariables) - 1; i >= 0; i-- {
+			name := path[0]
+			lv := opts.withLocalVariables[i]
+			if name == lv.name {
+				if len(lv.path) == 0 {
+					// This local variable is a key or an index and we know its
+					// value without having to call pointerstructure, we stop
+					// here.
+					if len(path) > 1 {
+						first := pointerstructure.Pointer{Parts: []string{name}}
+						full := pointerstructure.Pointer{Parts: path}
+						return nil, false, fmt.Errorf("%s references a %T so %s is invalid", first.String(), lv.value, full.String())
+					}
+					return lv.value, true, nil
+				} else {
+					// This local variable references another value, we prepend the
+					// path of the selector it replaces and continue searching
+					prefix := append([]string(nil), lv.path...)
+					path = append(prefix, path[1:]...)
+				}
+			}
+		}
+	}
+
+	// This is not a local variable, we use pointerstructure to look for it
+	// in the global datum
 	ptr := pointerstructure.Pointer{
-		Parts: expression.Selector.Path,
+		Parts: path,
 		Config: pointerstructure.Config{
 			TagName:                 opts.withTagName,
 			ValueTransformationHook: opts.withHookFn,
@@ -256,15 +300,31 @@ func evaluateMatchExpression(expression *grammar.MatchExpression, datum interfac
 				err = nil
 				val = *opts.withUnknown
 			case evaluateNotPresent(ptr, datum):
-				return expression.Operator.NotPresentDisposition(), nil
+				return nil, false, nil
 			}
 		}
 
 		if err != nil {
-			return false, fmt.Errorf("error finding value in datum: %w", err)
+			return false, false, fmt.Errorf("error finding value in datum: %w", err)
 		}
 	}
 
+	return val, true, nil
+}
+
+func evaluateMatchExpression(expression *grammar.MatchExpression, datum interface{}, opt ...Option) (bool, error) {
+	val, present, err := getValue(
+		datum,
+		expression.Selector.Path,
+		opt...,
+	)
+	if err != nil {
+		return false, err
+	}
+	if !present {
+		return expression.Operator.NotPresentDisposition(), nil
+	}
+
 	if jn, ok := val.(json.Number); ok {
 		if jni, err := jn.Int64(); err == nil {
 			val = jni
@@ -314,6 +374,85 @@ func evaluateMatchExpression(expression *grammar.MatchExpression, datum interfac
 	}
 }
 
+func evaluateCollectionExpression(expression *grammar.CollectionExpression, datum interface{}, opt ...Option) (bool, error) {
+	val, present, err := getValue(
+		datum,
+		expression.Selector.Path,
+		opt...,
+	)
+	if err != nil {
+		return false, err
+	}
+	if !present {
+		return expression.Op == grammar.CollectionOpAll, nil
+	}
+
+	v := reflect.ValueOf(val)
+
+	var keys []reflect.Value
+	if v.Kind() == reflect.Map {
+		if v.Type().Key() != reflect.TypeOf("") {
+			return false, fmt.Errorf("%s can only iterate over maps indexed with strings", expression.Op)
+		}
+		keys = v.MapKeys()
+	}
+
+	switch v.Kind() {
+	case reflect.Slice, reflect.Array, reflect.Map:
+		for i := 0; i < v.Len(); i++ {
+			innerOpt := append([]Option(nil), opt...)
+
+			if expression.NameBinding.Mode == grammar.CollectionBindIndexAndValue &&
+				expression.NameBinding.Index == expression.NameBinding.Value {
+				return false, fmt.Errorf("%q cannot be used as a placeholder for both the index and the value", expression.NameBinding.Index)
+			}
+
+			if v.Kind() == reflect.Map {
+				key := keys[i]
+				if expression.NameBinding.Default != "" {
+					innerOpt = append(innerOpt, WithLocalVariable(expression.NameBinding.Default, nil, key.Interface()))
+				}
+				if expression.NameBinding.Index != "" {
+					innerOpt = append(innerOpt, WithLocalVariable(expression.NameBinding.Index, nil, key.Interface()))
+				}
+				if expression.NameBinding.Value != "" {
+					path := make([]string, 0, len(expression.Selector.Path)+1)
+					path = append(path, expression.Selector.Path...)
+					path = append(path, key.Interface().(string))
+					innerOpt = append(innerOpt, WithLocalVariable(expression.NameBinding.Value, path, nil))
+				}
+			} else {
+				if expression.NameBinding.Index != "" {
+					innerOpt = append(innerOpt, WithLocalVariable(expression.NameBinding.Index, nil, i))
+				}
+
+				pathValue := make([]string, 0, len(expression.Selector.Path)+1)
+				pathValue = append(pathValue, expression.Selector.Path...)
+				pathValue = append(pathValue, fmt.Sprintf("%d", i))
+				if expression.NameBinding.Default != "" {
+					innerOpt = append(innerOpt, WithLocalVariable(expression.NameBinding.Default, pathValue, nil))
+				}
+				if expression.NameBinding.Value != "" {
+					innerOpt = append(innerOpt, WithLocalVariable(expression.NameBinding.Value, pathValue, nil))
+				}
+			}
+
+			result, err := evaluate(expression.Inner, datum, innerOpt...)
+			if err != nil {
+				return false, err
+			}
+			if (result && expression.Op == grammar.CollectionOpAny) || (!result && expression.Op == grammar.CollectionOpAll) {
+				return result, nil
+			}
+		}
+
+		return expression.Op == grammar.CollectionOpAll, nil
+
+	default:
+		return false, fmt.Errorf(`%s is not a list or a map`, expression.Selector.String())
+	}
+}
+
 func evaluate(ast grammar.Expression, datum interface{}, opt ...Option) (bool, error) {
 	switch node := ast.(type) {
 	case *grammar.UnaryExpression:
@@ -342,6 +481,8 @@ func evaluate(ast grammar.Expression, datum interface{}, opt ...Option) (bool, e
 		}
 	case *grammar.MatchExpression:
 		return evaluateMatchExpression(node, datum, opt...)
+	case *grammar.CollectionExpression:
+		return evaluateCollectionExpression(node, datum, opt...)
 	}
 	return false, fmt.Errorf("Invalid AST node")
 }

evaluate_test.go

@@ -329,6 +329,26 @@ var evaluateTests map[string]expressionTest = map[string]expressionTest{
 			{expression: "Nested.Notfound is not empty", result: false, err: `error finding value in datum: /Nested/Notfound at part 1: couldn't find key: struct field with name "Notfound"`},
 			{expression: `Nested.Notfound matches ".*"`, result: false, err: `error finding value in datum: /Nested/Notfound at part 1: couldn't find key: struct field with name "Notfound"`},
 			{expression: `Nested.Notfound not matches ".*"`, result: false, err: `error finding value in datum: /Nested/Notfound at part 1: couldn't find key: struct field with name "Notfound"`},
+			// all
+			{expression: `all Nested.SliceOfInts as i { i != 42 }`, result: true},
+			{expression: `all Nested.SliceOfInts as i { i == 1 }`, result: false},
+			{expression: `all Nested.Map as v { v == "bar" }`, result: false},
+			{expression: `all Nested.Map as v { v != "hello" }`, result: true},
+			{expression: `all Nested.Map as k, k { TopInt == 5 }`, err: `"k" cannot be used as a placeholder for both the index and the value`},
+			{expression: `all Nested.Map as k, _ { k != "foo" }`, result: false},
+			{expression: `all Nested.Map as k, _ { k != "hello" }`, result: true},
+			{expression: `all Nested.Map as k, v { k != "foo" or v != "baz" }`, result: true},
+			{expression: `all TopInt as k, v { k != "foo" or v != "baz" }`, err: "TopInt is not a list or a map"},
+			// any
+			{expression: `any Nested.SliceOfInts as i { i == 1 }`, result: true},
+			{expression: `any Nested.SliceOfInts as i { i == 42 }`, result: false},
+			{expression: `any Nested.SliceOfStructs as i { "/i/X" == 1 }`, result: true},
+			{expression: `any Nested.Map as k { k != "bar" }`, result: true},
+			{expression: `any Nested.Map as k { k == "bar" }`, result: true},
+			{expression: `any Nested.Map as k { k == "hello" }`, result: false},
+			{expression: `any Nested.Map as k, v { k == "foo" and v == "bar" }`, result: true},
+			{expression: `any Nested.Map as k { k.Color == "red" }`, err: "/k references a string so /k/Color is invalid"},
+			{expression: `any Nested.SliceOfInts as i, _ { i.Color == "red" }`, err: "/i references a int so /i/Color is invalid"},
 		},
 	},
 }

grammar/ast.go

@@ -192,3 +192,55 @@ func (expr *MatchExpression) ExpressionDump(w io.Writer, indent string, level in
 		fmt.Fprintf(w, "%[1]s%[3]s {\n%[2]sSelector: %[4]v\n%[1]s}\n", strings.Repeat(indent, level), strings.Repeat(indent, level+1), expr.Operator.String(), expr.Selector)
 	}
 }
+
+type CollectionBindMode string
+
+const (
+	CollectionBindDefault       CollectionBindMode = "Default"
+	CollectionBindIndex         CollectionBindMode = "Index"
+	CollectionBindValue         CollectionBindMode = "Value"
+	CollectionBindIndexAndValue CollectionBindMode = "Index & Value"
+)
+
+type CollectionNameBinding struct {
+	Mode    CollectionBindMode
+	Default string
+	Index   string
+	Value   string
+}
+
+func (b *CollectionNameBinding) String() string {
+	switch b.Mode {
+	case CollectionBindDefault:
+		return fmt.Sprintf("%v (%s)", b.Mode, b.Default)
+	case CollectionBindIndex:
+		return fmt.Sprintf("%v (%s)", b.Mode, b.Index)
+	case CollectionBindValue:
+		return fmt.Sprintf("%v (%s)", b.Mode, b.Value)
+	case CollectionBindIndexAndValue:
+		return fmt.Sprintf("%v (%s, %s)", b.Mode, b.Index, b.Value)
+	default:
+		return fmt.Sprintf("UNKNOWN (%s, %s, %s)", b.Default, b.Index, b.Value)
+	}
+}
+
+type CollectionOperator string
+
+const (
+	CollectionOpAll CollectionOperator = "ALL"
+	CollectionOpAny CollectionOperator = "ANY"
+)
+
+type CollectionExpression struct {
+	Op          CollectionOperator
+	Selector    Selector
+	Inner       Expression
+	NameBinding CollectionNameBinding
+}
+
+func (expr *CollectionExpression) ExpressionDump(w io.Writer, indent string, level int) {
+	localIndent := strings.Repeat(indent, level)
+	fmt.Fprintf(w, "%s%s %s on %v {\n", localIndent, expr.Op, expr.NameBinding.String(), expr.Selector)
+	expr.Inner.ExpressionDump(w, indent, level+1)
+	fmt.Fprintf(w, "%s}\n", localIndent)
+}

grammar/ast_test.go

@@ -78,6 +78,79 @@ func TestAST_Dump(t *testing.T) {
 			},
 			expected: "UNKNOWN {\n   Is Empty {\n      Selector: foo.bar\n   }\n   Is Empty {\n      Selector: foo.bar\n   }\n}\n",
 		},
+		"All single variation": {
+			expr: &CollectionExpression{
+				NameBinding: CollectionNameBinding{
+					Mode:    CollectionBindDefault,
+					Default: "k",
+				},
+				Op: CollectionOpAll,
+				Selector: Selector{
+					Type: SelectorTypeBexpr,
+					Path: []string{"obj"},
+				},
+				Inner: &MatchExpression{
+					Selector: Selector{
+						Type: SelectorTypeBexpr,
+						Path: []string{"v"},
+					},
+					Operator: 0,
+					Value: &MatchValue{
+						Raw: "hello",
+					},
+				},
+			},
+			expected: "ALL Default (k) on obj {\n   Equal {\n      Selector: v\n      Value: \"hello\"\n   }\n}\n",
+		},
+		"All": {
+			expr: &CollectionExpression{
+				NameBinding: CollectionNameBinding{
+					Mode:  CollectionBindIndexAndValue,
+					Index: "k",
+					Value: "v",
+				},
+				Op: CollectionOpAll,
+				Selector: Selector{
+					Type: SelectorTypeBexpr,
+					Path: []string{"obj"},
+				},
+				Inner: &MatchExpression{
+					Selector: Selector{
+						Type: SelectorTypeBexpr,
+						Path: []string{"v"},
+					},
+					Operator: 0,
+					Value: &MatchValue{
+						Raw: "hello",
+					},
+				},
+			},
+			expected: "ALL Index & Value (k, v) on obj {\n   Equal {\n      Selector: v\n      Value: \"hello\"\n   }\n}\n",
+		},
+		"Any": {
+			expr: &CollectionExpression{
+				NameBinding: CollectionNameBinding{
+					Mode:  CollectionBindIndex,
+					Index: "k",
+				},
+				Op: CollectionOpAny,
+				Selector: Selector{
+					Type: SelectorTypeBexpr,
+					Path: []string{"obj"},
+				},
+				Inner: &MatchExpression{
+					Selector: Selector{
+						Type: SelectorTypeBexpr,
+						Path: []string{"v"},
+					},
+					Operator: 0,
+					Value: &MatchValue{
+						Raw: "hello",
+					},
+				},
+			},
+			expected: "ANY Index (k) on obj {\n   Equal {\n      Selector: v\n      Value: \"hello\"\n   }\n}\n",
+		},
 	}
 
 	for name, tcase := range tests {