Added get key examples

pkg/yqlib/doc/.gitignore

@@ -0,0 +1 @@
+*.zip

pkg/yqlib/doc/Path.md

@@ -1,4 +1,7 @@
 The path operator can be used to get the traversal paths of matching nodes in an expression. The path is returned as an array, which if traversed in order will lead to the matching node.
+
+You can get the key/index of matching nodes by using the `path` operator to return the path array then piping that through `.[-1]` to get the last element of that array, the key.
+
 ## Map path
 Given a sample.yml file of:
 ```yaml
@@ -15,6 +18,21 @@ will output
 - b
 ```
 
+## Get map key
+Given a sample.yml file of:
+```yaml
+a:
+  b: cat
+```
+then
+```bash
+yq eval '.a.b | path | .[-1]' sample.yml
+```
+will output
+```yaml
+b
+```
+
 ## Array path
 Given a sample.yml file of:
 ```yaml
@@ -32,6 +50,22 @@ will output
 - 1
 ```
 
+## Get array index
+Given a sample.yml file of:
+```yaml
+a:
+  - cat
+  - dog
+```
+then
+```bash
+yq eval '.a.[] | select(. == "dog") | path | .[-1]' sample.yml
+```
+will output
+```yaml
+1
+```
+
 ## Print path and value
 Given a sample.yml file of:
 ```yaml

pkg/yqlib/doc/headers/Path.md

@@ -1 +1,3 @@
 The path operator can be used to get the traversal paths of matching nodes in an expression. The path is returned as an array, which if traversed in order will lead to the matching node.
+
+You can get the key/index of matching nodes by using the `path` operator to return the path array then piping that through `.[-1]` to get the last element of that array, the key.

pkg/yqlib/operator_path_test.go

@@ -13,6 +13,14 @@ var pathOperatorScenarios = []expressionScenario{
 			"D0, P[a b], (!!seq)::- a\n- b\n",
 		},
 	},
+	{
+		description: "Get map key",
+		document:    `{a: {b: cat}}`,
+		expression:  `.a.b | path | .[-1]`,
+		expected: []string{
+			"D0, P[a b -1], (!!str)::b\n",
+		},
+	},
 	{
 		description: "Array path",
 		document:    `{a: [cat, dog]}`,
@@ -21,6 +29,14 @@ var pathOperatorScenarios = []expressionScenario{
 			"D0, P[a 1], (!!seq)::- a\n- 1\n",
 		},
 	},
+	{
+		description: "Get array index",
+		document:    `{a: [cat, dog]}`,
+		expression:  `.a.[] | select(. == "dog") | path | .[-1]`,
+		expected: []string{
+			"D0, P[a 1 -1], (!!int)::1\n",
+		},
+	},
 	{
 		description: "Print path and value",
 		document:    `{a: [cat, dog, frog]}`,