Added DELPATHS operator

Author: mikefarah

pkg/yqlib/doc/operators/headers/path.md

@@ -1,5 +1,8 @@
 # Path
 
-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.
+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.
+
+Use `setpath` to set a value to the path array returned by `path`, and similarly `delpaths` for an array of path arrays.
+

pkg/yqlib/doc/operators/path.md

@@ -1,9 +1,12 @@
 # Path
 
-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.
+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.
 
+Use `setpath` to set a value to the path array returned by `path`, and similarly `delpaths` for an array of path arrays.
+
+
 {% hint style="warning" %}
 Note that versions prior to 4.18 require the 'eval/e' command to be specified. 
 
@@ -154,3 +157,58 @@ a:
   - things
 ```
 
+## Delete path
+Notice delpaths takes an _array_ of paths.
+
+Given a sample.yml file of:
+```yaml
+a:
+  b: cat
+  c: dog
+  d: frog
+```
+then
+```bash
+yq 'delpaths([["a", "c"], ["a", "d"]])' sample.yml
+```
+will output
+```yaml
+a:
+  b: cat
+```
+
+## Delete array path
+Given a sample.yml file of:
+```yaml
+a:
+  - cat
+  - frog
+```
+then
+```bash
+yq 'delpaths([["a", 0]])' sample.yml
+```
+will output
+```yaml
+a:
+  - frog
+```
+
+## Delete - wrong parameter
+delpaths does not work with a single path array
+
+Given a sample.yml file of:
+```yaml
+a:
+  - cat
+  - frog
+```
+then
+```bash
+yq 'delpaths(["a", 0])' sample.yml
+```
+will output
+```bash
+Error: DELPATHS: expected entry [0] to be a sequence, but its a !!str. Note that delpaths takes an array of path arrays, e.g. [["a", "b"]]
+```
+

pkg/yqlib/lexer_participle.go

@@ -129,6 +129,7 @@ var participleYqRules = []*participleYqRule{
 	simpleOp("file_?index|fileIndex|fi", getFileIndexOpType),
 	simpleOp("path", getPathOpType),
 	simpleOp("set_?path", setPathOpType),
+	simpleOp("del_?paths", delPathsOpType),
 
 	simpleOp("to_?entries|toEntries", toEntriesOpType),
 	simpleOp("from_?entries|fromEntries", fromEntriesOpType),

pkg/yqlib/lib.go

@@ -133,6 +133,7 @@ var getFileIndexOpType = &operationType{Type: "GET_FILE_INDEX", NumArgs: 0, Prec
 
 var getPathOpType = &operationType{Type: "GET_PATH", NumArgs: 0, Precedence: 50, Handler: getPathOperator}
 var setPathOpType = &operationType{Type: "SET_PATH", NumArgs: 1, Precedence: 50, Handler: setPathOperator}
+var delPathsOpType = &operationType{Type: "DEL_PATHS", NumArgs: 1, Precedence: 50, Handler: delPathsOperator}
 
 var explodeOpType = &operationType{Type: "EXPLODE", NumArgs: 1, Precedence: 50, Handler: explodeOperator}
 var sortByOpType = &operationType{Type: "SORT_BY", NumArgs: 1, Precedence: 50, Handler: sortByOperator}

pkg/yqlib/operator_path.go

@@ -16,34 +16,24 @@ func createPathNodeFor(pathElement interface{}) *yaml.Node {
 	}
 }
 
-func getPathArrayFromExp(d *dataTreeNavigator, context Context, pathExp *ExpressionNode) ([]interface{}, error) {
-	lhsPathContext, err := d.GetMatchingNodes(context.ReadOnlyClone(), pathExp)
-
-	if err != nil {
-		return nil, err
-	}
-
-	if lhsPathContext.MatchingNodes.Len() != 1 {
-		return nil, fmt.Errorf("expected single path but found %v results instead", lhsPathContext.MatchingNodes.Len())
-	}
-	lhsValue := lhsPathContext.MatchingNodes.Front().Value.(*CandidateNode)
-	if lhsValue.Node.Kind != yaml.SequenceNode {
-		return nil, fmt.Errorf("expected path array, but got %v instead", lhsValue.Node.Tag)
+func getPathArrayFromNode(funcName string, node *yaml.Node) ([]interface{}, error) {
+	if node.Kind != yaml.SequenceNode {
+		return nil, fmt.Errorf("%v: expected path array, but got %v instead", funcName, node.Tag)
 	}
 
-	path := make([]interface{}, len(lhsValue.Node.Content))
+	path := make([]interface{}, len(node.Content))
 
-	for i, childNode := range lhsValue.Node.Content {
+	for i, childNode := range node.Content {
 		if childNode.Tag == "!!str" {
 			path[i] = childNode.Value
 		} else if childNode.Tag == "!!int" {
 			number, err := parseInt(childNode.Value)
 			if err != nil {
-				return nil, fmt.Errorf("could not parse %v as an int: %w", childNode.Value, err)
+				return nil, fmt.Errorf("%v: could not parse %v as an int: %w", funcName, childNode.Value, err)
 			}
 			path[i] = number
 		} else {
-			return nil, fmt.Errorf("expected either a !!str or !!int in the path, found %v instead", childNode.Tag)
+			return nil, fmt.Errorf("%v: expected either a !!str or !!int in the path, found %v instead", funcName, childNode.Tag)
 		}
 
 	}
@@ -58,7 +48,18 @@ func setPathOperator(d *dataTreeNavigator, context Context, expressionNode *Expr
 		return Context{}, fmt.Errorf("SETPATH must be given a block (;), got %v instead", expressionNode.RHS.Operation.OperationType.Type)
 	}
 
-	lhsPath, err := getPathArrayFromExp(d, context, expressionNode.RHS.LHS)
+	lhsPathContext, err := d.GetMatchingNodes(context.ReadOnlyClone(), expressionNode.RHS.LHS)
+
+	if err != nil {
+		return Context{}, err
+	}
+
+	if lhsPathContext.MatchingNodes.Len() != 1 {
+		return Context{}, fmt.Errorf("SETPATH: expected single path but found %v results instead", lhsPathContext.MatchingNodes.Len())
+	}
+	lhsValue := lhsPathContext.MatchingNodes.Front().Value.(*CandidateNode)
+
+	lhsPath, err := getPathArrayFromNode("SETPATH", lhsValue.Node)
 
 	if err != nil {
 		return Context{}, err
@@ -68,8 +69,6 @@ func setPathOperator(d *dataTreeNavigator, context Context, expressionNode *Expr
 
 	assignmentOp := &Operation{OperationType: assignOpType}
 
-	//TODO if context is empty, create a new one
-
 	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
 		candidate := el.Value.(*CandidateNode)
 
@@ -79,7 +78,7 @@ func setPathOperator(d *dataTreeNavigator, context Context, expressionNode *Expr
 		}
 
 		if targetContextValue.MatchingNodes.Len() != 1 {
-			return Context{}, fmt.Errorf("Expected single value on RHS but found %v", targetContextValue.MatchingNodes.Len())
+			return Context{}, fmt.Errorf("SETPATH: expected single value on RHS but found %v", targetContextValue.MatchingNodes.Len())
 		}
 
 		rhsOp := &Operation{OperationType: valueOpType, CandidateNode: targetContextValue.MatchingNodes.Front().Value.(*CandidateNode)}
@@ -100,6 +99,56 @@ func setPathOperator(d *dataTreeNavigator, context Context, expressionNode *Expr
 	return context, nil
 }
 
+func delPathsOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	log.Debugf("delPaths")
+	// single RHS expression that returns an array of paths (array of arrays)
+
+	pathArraysContext, err := d.GetMatchingNodes(context.ReadOnlyClone(), expressionNode.RHS)
+	if err != nil {
+		return Context{}, err
+	}
+	if pathArraysContext.MatchingNodes.Len() != 1 {
+		return Context{}, fmt.Errorf("DELPATHS: expected single value but found %v", pathArraysContext.MatchingNodes.Len())
+	}
+	pathArraysNode := pathArraysContext.MatchingNodes.Front().Value.(*CandidateNode).Node
+
+	if pathArraysNode.Tag != "!!seq" {
+		return Context{}, fmt.Errorf("DELPATHS: expected a sequence of sequences, but found %v", pathArraysNode.Tag)
+	}
+
+	updatedContext := context
+
+	for i, child := range pathArraysNode.Content {
+
+		if child.Tag != "!!seq" {
+			return Context{}, fmt.Errorf("DELPATHS: expected entry [%v] to be a sequence, but its a %v. Note that delpaths takes an array of path arrays, e.g. [[\"a\", \"b\"]]", i, child.Tag)
+		}
+		childPath, err := getPathArrayFromNode("DELPATHS", child)
+
+		if err != nil {
+			return Context{}, err
+		}
+
+		childTraversalExp := createTraversalTree(childPath, traversePreferences{}, false)
+		deleteChildOp := &Operation{OperationType: deleteChildOpType}
+
+		deleteChildOpNode := &ExpressionNode{
+			Operation: deleteChildOp,
+			RHS:       childTraversalExp,
+		}
+
+		updatedContext, err = d.GetMatchingNodes(updatedContext, deleteChildOpNode)
+
+		if err != nil {
+			return Context{}, err
+		}
+
+	}
+
+	return updatedContext, nil
+
+}
+
 func getPathOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("GetPath")
 

pkg/yqlib/operator_path_test.go

@@ -93,6 +93,30 @@ var pathOperatorScenarios = []expressionScenario{
 			"D0, P[], ()::a:\n    - things\n",
 		},
 	},
+	{
+		description:    "Delete path",
+		subdescription: "Notice delpaths takes an _array_ of paths.",
+		document:       `{a: {b: cat, c: dog, d: frog}}`,
+		expression:     `delpaths([["a", "c"], ["a", "d"]])`,
+		expected: []string{
+			"D0, P[], (doc)::{a: {b: cat}}\n",
+		},
+	},
+	{
+		description: "Delete array path",
+		document:    `a: [cat, frog]`,
+		expression:  `delpaths([["a", 0]])`,
+		expected: []string{
+			"D0, P[], (doc)::a: [frog]\n",
+		},
+	},
+	{
+		description:    "Delete - wrong parameter",
+		subdescription: "delpaths does not work with a single path array",
+		document:       `a: [cat, frog]`,
+		expression:     `delpaths(["a", 0])`,
+		expectedError:  "DELPATHS: expected entry [0] to be a sequence, but its a !!str. Note that delpaths takes an array of path arrays, e.g. [[\"a\", \"b\"]]",
+	},
 }
 
 func TestPathOperatorsScenarios(t *testing.T) {