omit operator (#1989)

pkg/yqlib/doc/operators/omit.md

@@ -0,0 +1,41 @@
+
+## Omit keys from map
+Note that the order of the keys matches the omit order and non existent keys are skipped.
+
+Given a sample.yml file of:
+```yaml
+myMap:
+  cat: meow
+  dog: bark
+  thing: hamster
+  hamster: squeak
+```
+then
+```bash
+yq '.myMap |= omit(["hamster", "cat", "goat"])' sample.yml
+```
+will output
+```yaml
+myMap:
+  dog: bark
+  thing: hamster
+```
+
+## Omit indices from array
+Note that the order of the indices matches the omit order and non existent indices are skipped.
+
+Given a sample.yml file of:
+```yaml
+- cat
+- leopard
+- lion
+```
+then
+```bash
+yq 'omit([2, 0, 734, -5])' sample.yml
+```
+will output
+```yaml
+- leopard
+```
+

pkg/yqlib/lexer_participle.go

@@ -40,6 +40,7 @@ var participleYqRules = []*participleYqRule{
 	simpleOp("map", mapOpType),
 	simpleOp("filter", filterOpType),
 	simpleOp("pick", pickOpType),
+	simpleOp("omit", omitOpType),
 
 	{"FlattenWithDepth", `flatten\([0-9]+\)`, flattenWithDepth(), 0},
 	{"Flatten", `flatten`, opTokenWithPrefs(flattenOpType, nil, flattenPreferences{depth: -1}), 0},

pkg/yqlib/operation.go

@@ -90,6 +90,7 @@ var mapOpType = &operationType{Type: "MAP", NumArgs: 1, Precedence: 50, Handler:
 var filterOpType = &operationType{Type: "FILTER", NumArgs: 1, Precedence: 50, Handler: filterOperator}
 var errorOpType = &operationType{Type: "ERROR", NumArgs: 1, Precedence: 50, Handler: errorOperator}
 var pickOpType = &operationType{Type: "PICK", NumArgs: 1, Precedence: 50, Handler: pickOperator}
+var omitOpType = &operationType{Type: "OMIT", NumArgs: 1, Precedence: 50, Handler: omitOperator}
 var evalOpType = &operationType{Type: "EVAL", NumArgs: 1, Precedence: 50, Handler: evalOperator}
 var mapValuesOpType = &operationType{Type: "MAP_VALUES", NumArgs: 1, Precedence: 50, Handler: mapValuesOperator}
 

pkg/yqlib/operator_omit.go

@@ -0,0 +1,73 @@
+package yqlib
+
+import (
+	"container/list"
+	"strconv"
+)
+
+func omitMap(original *CandidateNode, indices *CandidateNode) *CandidateNode {
+	filteredContent := make([]*CandidateNode, 0, max(0, len(original.Content)-len(indices.Content)*2))
+
+	for index := 0; index < len(original.Content); index += 2 {
+		pos := findInArray(indices, original.Content[index])
+		if pos < 0 {
+			clonedKey := original.Content[index].Copy()
+			clonedValue := original.Content[index+1].Copy()
+			filteredContent = append(filteredContent, clonedKey, clonedValue)
+		}
+	}
+	result := original.CopyWithoutContent()
+	result.AddChildren(filteredContent)
+	return result
+}
+
+func omitSequence(original *CandidateNode, indices *CandidateNode) *CandidateNode {
+	filteredContent := make([]*CandidateNode, 0, max(0, len(original.Content)-len(indices.Content)))
+
+	for index := 0; index < len(original.Content); index++ {
+		pos := findInArray(indices, createScalarNode(index, strconv.Itoa(index)))
+		if pos < 0 {
+			filteredContent = append(filteredContent, original.Content[index].Copy())
+		}
+	}
+	result := original.CopyWithoutContent()
+	result.AddChildren(filteredContent)
+	return result
+}
+
+func omitOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	log.Debugf("Omit")
+
+	contextIndicesToOmit, err := d.GetMatchingNodes(context, expressionNode.RHS)
+
+	if err != nil {
+		return Context{}, err
+	}
+	indicesToOmit := &CandidateNode{}
+	if contextIndicesToOmit.MatchingNodes.Len() > 0 {
+		indicesToOmit = contextIndicesToOmit.MatchingNodes.Front().Value.(*CandidateNode)
+	}
+	if len(indicesToOmit.Content) == 0 {
+		log.Debugf("No omit indices specified")
+		return context, nil
+	}
+	var results = list.New()
+
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		node := el.Value.(*CandidateNode)
+
+		var replacement *CandidateNode
+
+		if node.Kind == MappingNode {
+			replacement = omitMap(node, indicesToOmit)
+		} else if node.Kind == SequenceNode {
+			replacement = omitSequence(node, indicesToOmit)
+		} else {
+			log.Debugf("Omit from type %v (%v) is noop", node.Tag, node.GetNicePath())
+			return context, nil
+		}
+		replacement.LeadingContent = node.LeadingContent
+		results.PushBack(replacement)
+	}
+	return context.ChildContext(results), nil
+}

pkg/yqlib/operator_omit_test.go

@@ -0,0 +1,60 @@
+package yqlib
+
+import (
+	"testing"
+)
+
+var omitOperatorScenarios = []expressionScenario{
+	{
+		description:    "Omit keys from map",
+		subdescription: "Note that the order of the keys matches the omit order and non existent keys are skipped.",
+		document:       "myMap: {cat: meow, dog: bark, thing: hamster, hamster: squeak}\n",
+		expression:     `.myMap |= omit(["hamster", "cat", "goat"])`,
+		expected: []string{
+			"D0, P[], (!!map)::myMap: {dog: bark, thing: hamster}\n",
+		},
+	},
+	{
+		description: "Omit keys from map",
+		skipDoc:     true,
+		document:    "!things myMap: {cat: meow, dog: bark, thing: hamster, hamster: squeak}\n",
+		expression:  `.myMap |= omit(["hamster", "cat", "goat"])`,
+		expected: []string{
+			"D0, P[], (!!map)::!things myMap: {dog: bark, thing: hamster}\n",
+		},
+	},
+	{
+		description: "Omit keys from map with comments",
+		skipDoc:     true,
+		document:    "# abc\nmyMap: {cat: meow, dog: bark, thing: hamster, hamster: squeak}\n# xyz\n",
+		expression:  `.myMap |= omit(["hamster", "cat", "goat"])`,
+		expected: []string{
+			"D0, P[], (!!map)::# abc\nmyMap: {dog: bark, thing: hamster}\n# xyz\n",
+		},
+	},
+	{
+		description:    "Omit indices from array",
+		subdescription: "Note that the order of the indices matches the omit order and non existent indices are skipped.",
+		document:       `[cat, leopard, lion]`,
+		expression:     `omit([2, 0, 734, -5])`,
+		expected: []string{
+			"D0, P[], (!!seq)::[leopard]\n",
+		},
+	},
+	{
+		description: "Omit indices from array with comments",
+		skipDoc:     true,
+		document:    "# abc\n[cat, leopard, lion]\n# xyz",
+		expression:  `omit([2, 0, 734, -5])`,
+		expected: []string{
+			"D0, P[], (!!seq)::# abc\n[leopard]\n# xyz\n",
+		},
+	},
+}
+
+func TestOmitOperatorScenarios(t *testing.T) {
+	for _, tt := range omitOperatorScenarios {
+		testScenario(t, &tt)
+	}
+	documentOperatorScenarios(t, "omit", omitOperatorScenarios)
+}