Added more tests

pkg/yqlib/doc/keys.md

@@ -34,6 +34,49 @@ will output
 - 1
 ```
 
+## Retrieve array key
+Given a sample.yml file of:
+```yaml
+- 1
+- 2
+- 3
+```
+then
+```bash
+yq eval '.[1] | key' sample.yml
+```
+will output
+```yaml
+1
+```
+
+## Retrieve map key
+Given a sample.yml file of:
+```yaml
+a: thing
+```
+then
+```bash
+yq eval '.a | key' sample.yml
+```
+will output
+```yaml
+a
+```
+
+## No key
+Given a sample.yml file of:
+```yaml
+{}
+```
+then
+```bash
+yq eval 'key' sample.yml
+```
+will output
+```yaml
+```
+
 ## Update map key
 Given a sample.yml file of:
 ```yaml

pkg/yqlib/doc/parent.md

@@ -0,0 +1,46 @@
+
+## Simple example
+Given a sample.yml file of:
+```yaml
+a:
+  nested: cat
+```
+then
+```bash
+yq eval '.a.nested | parent' sample.yml
+```
+will output
+```yaml
+nested: cat
+```
+
+## Show parent
+Given a sample.yml file of:
+```yaml
+a:
+  fruit: apple
+b:
+  fruit: banana
+```
+then
+```bash
+yq eval '.. | select(. == "banana") | parent' sample.yml
+```
+will output
+```yaml
+fruit: banana
+```
+
+## No parent
+Given a sample.yml file of:
+```yaml
+{}
+```
+then
+```bash
+yq eval 'parent' sample.yml
+```
+will output
+```yaml
+```
+

pkg/yqlib/expression_tokeniser.go

@@ -369,6 +369,7 @@ func initLexer() (*lex.Lexer, error) {
 
 	lexer.Add([]byte(`split`), opToken(splitStringOpType))
 
+	lexer.Add([]byte(`parent`), opToken(getParentOpType))
 	lexer.Add([]byte(`key`), opToken(getKeyOpType))
 	lexer.Add([]byte(`keys`), opToken(keysOpType))
 

pkg/yqlib/lib.go

@@ -80,6 +80,7 @@ var getStyleOpType = &operationType{Type: "GET_STYLE", NumArgs: 0, Precedence: 5
 var getTagOpType = &operationType{Type: "GET_TAG", NumArgs: 0, Precedence: 50, Handler: getTagOperator}
 
 var getKeyOpType = &operationType{Type: "GET_KEY", NumArgs: 0, Precedence: 50, Handler: getKeyOperator}
+var getParentOpType = &operationType{Type: "GET_PARENT", NumArgs: 0, Precedence: 50, Handler: getParentOperator}
 
 var getCommentOpType = &operationType{Type: "GET_COMMENT", NumArgs: 0, Precedence: 50, Handler: getCommentsOperator}
 var getAnchorOpType = &operationType{Type: "GET_ANCHOR", NumArgs: 0, Precedence: 50, Handler: getAnchorOperator}

pkg/yqlib/operator_keys.go

@@ -15,7 +15,9 @@ func getKeyOperator(d *dataTreeNavigator, context Context, expressionNode *Expre
 	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
 		candidate := el.Value.(*CandidateNode)
 
-		results.PushBack(candidate.CreateReplacement(candidate.Key))
+		if candidate.Key != nil {
+			results.PushBack(candidate.CreateReplacement(candidate.Key))
+		}
 	}
 
 	return context.ChildContext(results), nil

pkg/yqlib/operator_keys_test.go

@@ -37,6 +37,28 @@ var keysOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!seq)::[]\n",
 		},
 	},
+	{
+		description: "Retrieve array key",
+		document:    "[1,2,3]",
+		expression:  `.[1] | key`,
+		expected: []string{
+			"D0, P[1], (!!int)::1\n",
+		},
+	},
+	{
+		description: "Retrieve map key",
+		document:    "a: thing",
+		expression:  `.a | key`,
+		expected: []string{
+			"D0, P[a], (!!str)::a\n",
+		},
+	},
+	{
+		description: "No key",
+		document:    "{}",
+		expression:  `key`,
+		expected:    []string{},
+	},
 	{
 		description: "Update map key",
 		document:    "a:\n  x: 3\n  y: 4",

pkg/yqlib/operator_parent.go

@@ -0,0 +1,19 @@
+package yqlib
+
+import "container/list"
+
+func getParentOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	log.Debugf("-- getParentOperator")
+
+	var results = list.New()
+
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		if candidate.Parent != nil {
+			results.PushBack(candidate.Parent)
+		}
+	}
+
+	return context.ChildContext(results), nil
+
+}

pkg/yqlib/operator_parent_test.go

@@ -0,0 +1,37 @@
+package yqlib
+
+import (
+	"testing"
+)
+
+var parentOperatorScenarios = []expressionScenario{
+	{
+		description: "Simple example",
+		document:    `a: {nested: cat}`,
+		expression:  `.a.nested | parent`,
+		expected: []string{
+			"D0, P[a], (!!map)::{nested: cat}\n",
+		},
+	},
+	{
+		description: "Show parent",
+		document:    `{a: {fruit: apple}, b: {fruit: banana}}`,
+		expression:  `.. | select(. == "banana") | parent`,
+		expected: []string{
+			"D0, P[b], (!!map)::{fruit: banana}\n",
+		},
+	},
+	{
+		description: "No parent",
+		document:    `{}`,
+		expression:  `parent`,
+		expected:    []string{},
+	},
+}
+
+func TestParentOperatorScenarios(t *testing.T) {
+	for _, tt := range parentOperatorScenarios {
+		testScenario(t, &tt)
+	}
+	documentScenarios(t, "parent", parentOperatorScenarios)
+}