Added kind operator

pkg/yqlib/doc/operators/kind.md

@@ -0,0 +1,77 @@
+
+## Get kind
+Given a sample.yml file of:
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+f: []
+g: {}
+h: null
+```
+then
+```bash
+yq '.. | kind' sample.yml
+```
+will output
+```yaml
+map
+scalar
+scalar
+scalar
+scalar
+seq
+map
+scalar
+```
+
+## Get kind, ignores custom tags
+Unlike tag, kind is not affected by custom tags.
+
+Given a sample.yml file of:
+```yaml
+a: !!thing cat
+b: !!foo {}
+c: !!bar []
+```
+then
+```bash
+yq '.. | kind' sample.yml
+```
+will output
+```yaml
+map
+scalar
+map
+seq
+```
+
+## Add comments only to scalars
+An example of how you can use kind
+
+Given a sample.yml file of:
+```yaml
+a:
+  b: 5
+  c: 3.2
+e: true
+f: []
+g: {}
+h: null
+```
+then
+```bash
+yq '(.. | select(kind == "scalar")) line_comment = "this is a scalar"' sample.yml
+```
+will output
+```yaml
+a:
+  b: 5 # this is a scalar
+  c: 3.2 # this is a scalar
+e: true # this is a scalar
+f: []
+g: {}
+h: null # this is a scalar
+```
+

pkg/yqlib/lexer_participle.go

@@ -152,6 +152,7 @@ var participleYqRules = []*participleYqRule{
 
 	assignableOp("style", getStyleOpType, assignStyleOpType),
 	assignableOp("tag|type", getTagOpType, assignTagOpType),
+	simpleOp("kind", getKindOpType),
 	assignableOp("anchor", getAnchorOpType, assignAnchorOpType),
 	assignableOp("alias", getAliasOpType, assignAliasOpType),
 

pkg/yqlib/lib.go

@@ -120,6 +120,7 @@ var splitDocumentOpType = &operationType{Type: "SPLIT_DOC", NumArgs: 0, Preceden
 var getVariableOpType = &operationType{Type: "GET_VARIABLE", NumArgs: 0, Precedence: 55, Handler: getVariableOperator}
 var getStyleOpType = &operationType{Type: "GET_STYLE", NumArgs: 0, Precedence: 50, Handler: getStyleOperator}
 var getTagOpType = &operationType{Type: "GET_TAG", NumArgs: 0, Precedence: 50, Handler: getTagOperator}
+var getKindOpType = &operationType{Type: "GET_KIND", NumArgs: 0, Precedence: 50, Handler: getKindOperator}
 
 var getKeyOpType = &operationType{Type: "GET_KEY", NumArgs: 0, Precedence: 50, Handler: getKeyOperator}
 var isKeyOpType = &operationType{Type: "IS_KEY", NumArgs: 0, Precedence: 50, Handler: isKeyOperator}

pkg/yqlib/operator_kind.go

@@ -0,0 +1,39 @@
+package yqlib
+
+import (
+	"container/list"
+
+	yaml "gopkg.in/yaml.v3"
+)
+
+func kindToText(kind yaml.Kind) string {
+	switch kind {
+	case yaml.MappingNode:
+		return "map"
+	case yaml.SequenceNode:
+		return "seq"
+	case yaml.DocumentNode:
+		return "doc"
+	case yaml.ScalarNode:
+		return "scalar"
+	case yaml.AliasNode:
+		return "alias"
+	default:
+		return "unknown"
+	}
+}
+
+func getKindOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	log.Debugf("GetKindOperator")
+
+	var results = list.New()
+
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		node := &yaml.Node{Kind: yaml.ScalarNode, Value: kindToText(candidate.Node.Kind), Tag: "!!str"}
+		result := candidate.CreateReplacement(node)
+		results.PushBack(result)
+	}
+
+	return context.ChildContext(results), nil
+}

pkg/yqlib/operator_kind_test.go

@@ -0,0 +1,49 @@
+package yqlib
+
+import (
+	"testing"
+)
+
+var kindOperatorScenarios = []expressionScenario{
+	{
+		description: "Get kind",
+		document:    `{a: cat, b: 5, c: 3.2, e: true, f: [], g: {}, h: null}`,
+		expression:  `.. | kind`,
+		expected: []string{
+			"D0, P[], (!!str)::map\n",
+			"D0, P[a], (!!str)::scalar\n",
+			"D0, P[b], (!!str)::scalar\n",
+			"D0, P[c], (!!str)::scalar\n",
+			"D0, P[e], (!!str)::scalar\n",
+			"D0, P[f], (!!str)::seq\n",
+			"D0, P[g], (!!str)::map\n",
+			"D0, P[h], (!!str)::scalar\n",
+		},
+	},
+	{
+		description:    "Get kind, ignores custom tags",
+		subdescription: "Unlike tag, kind is not affected by custom tags.",
+		document:       `{a: !!thing cat, b: !!foo {}, c: !!bar []}`,
+		expression:     `.. | kind`,
+		expected: []string{
+			"D0, P[], (!!str)::map\n",
+			"D0, P[a], (!!str)::scalar\n",
+			"D0, P[b], (!!str)::map\n",
+			"D0, P[c], (!!str)::seq\n",
+		},
+	},
+	{
+		description:    "Add comments only to scalars",
+		subdescription: "An example of how you can use kind",
+		document:       "a:\n  b: 5\n  c: 3.2\ne: true\nf: []\ng: {}\nh: null",
+		expression:     `(.. | select(kind == "scalar")) line_comment = "this is a scalar"`,
+		expected:       []string{"D0, P[], (!!map)::a:\n    b: 5 # this is a scalar\n    c: 3.2 # this is a scalar\ne: true # this is a scalar\nf: []\ng: {}\nh: null # this is a scalar\n"},
+	},
+}
+
+func TestKindOperatorScenarios(t *testing.T) {
+	for _, tt := range kindOperatorScenarios {
+		testScenario(t, &tt)
+	}
+	documentOperatorScenarios(t, "kind", kindOperatorScenarios)
+}