Fixing readonly ops not to modify context when paths dont exist

pkg/yqlib/operator_add.go

@@ -39,7 +39,7 @@ func toNodes(candidate *CandidateNode) []*yaml.Node {
 func addOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("Add operator")
 
-	return crossFunction(d, context, expressionNode, add, false)
+	return crossFunction(d, context.ReadOnlyClone(), expressionNode, add, false)
 }
 
 func add(d *dataTreeNavigator, context Context, lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, error) {

pkg/yqlib/operator_add_test.go

@@ -14,6 +14,22 @@ var addOperatorScenarios = []expressionScenario{
 			"D0, P[1 a], (!!int)::3\n",
 		},
 	},
+	{
+		skipDoc:    true,
+		document:   `{}`,
+		expression: "(.a + .b) as $x",
+		expected: []string{
+			"D0, P[], (doc)::{}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `a: 0`,
+		expression: ".a += .b.c",
+		expected: []string{
+			"D0, P[], (doc)::a: 0\n",
+		},
+	},
 	{
 		description: "Concatenate and assign arrays",
 		document:    `{a: {val: thing, b: [cat,dog]}}`,

pkg/yqlib/operator_alternative.go

@@ -2,7 +2,7 @@ package yqlib
 
 func alternativeOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("-- alternative")
-	return crossFunction(d, context, expressionNode, alternativeFunc, true)
+	return crossFunction(d, context.ReadOnlyClone(), expressionNode, alternativeFunc, true)
 }
 
 func alternativeFunc(d *dataTreeNavigator, context Context, lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, error) {

pkg/yqlib/operator_alternative_test.go

@@ -5,6 +5,14 @@ import (
 )
 
 var alternativeOperatorScenarios = []expressionScenario{
+	{
+		skipDoc:    true,
+		expression: `(.b // "hello") as $x`,
+		document:   `a: bridge`,
+		expected: []string{
+			"D0, P[], (doc)::a: bridge\n",
+		},
+	},
 	{
 		description: "LHS is defined",
 		expression:  `.a // "hello"`,

pkg/yqlib/operator_equals.go

@@ -4,7 +4,7 @@ import "gopkg.in/yaml.v3"
 
 func equalsOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("-- equalsOperation")
-	return crossFunction(d, context, expressionNode, isEquals(false), true)
+	return crossFunction(d, context.ReadOnlyClone(), expressionNode, isEquals(false), true)
 }
 
 func isEquals(flip bool) func(d *dataTreeNavigator, context Context, lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, error) {
@@ -50,5 +50,5 @@ func isEquals(flip bool) func(d *dataTreeNavigator, context Context, lhs *Candid
 
 func notEqualsOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("-- notEqualsOperator")
-	return crossFunction(d, context, expressionNode, isEquals(true), true)
+	return crossFunction(d, context.ReadOnlyClone(), expressionNode, isEquals(true), true)
 }

pkg/yqlib/operator_equals_test.go

@@ -14,6 +14,38 @@ var equalsOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!bool)::false\n",
 		},
 	},
+	{
+		skipDoc:    true,
+		document:   "{}",
+		expression: "(.a == .b) as $x",
+		expected: []string{
+			"D0, P[], (doc)::{}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   "{}",
+		expression: ".a == .b",
+		expected: []string{
+			"D0, P[], (!!bool)::true\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   "{}",
+		expression: "(.a != .b) as $x",
+		expected: []string{
+			"D0, P[], (doc)::{}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   "{}",
+		expression: ".a != .b",
+		expected: []string{
+			"D0, P[], (!!bool)::false\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   "{a: {b: 10}}",

pkg/yqlib/operator_subtract.go

@@ -25,7 +25,7 @@ func subtractAssignOperator(d *dataTreeNavigator, context Context, expressionNod
 func subtractOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("Subtract operator")
 
-	return crossFunction(d, context, expressionNode, subtract, false)
+	return crossFunction(d, context.ReadOnlyClone(), expressionNode, subtract, false)
 }
 
 func subtract(d *dataTreeNavigator, context Context, lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, error) {

pkg/yqlib/operator_subtract_test.go

@@ -5,6 +5,14 @@ import (
 )
 
 var subtractOperatorScenarios = []expressionScenario{
+	{
+		skipDoc:    true,
+		document:   `{}`,
+		expression: "(.a - .b) as $x",
+		expected: []string{
+			"D0, P[], (doc)::{}\n",
+		},
+	},
 	{
 		description:    "Number subtraction - float",
 		subdescription: "If the lhs or rhs are floats then the expression will be calculated with floats.",

pkg/yqlib/operator_traverse_path.go

@@ -89,7 +89,7 @@ func traverseArrayOperator(d *dataTreeNavigator, context Context, expressionNode
 
 	// rhs is a collect expression that will yield indexes to retreive of the arrays
 
-	rhs, err := d.GetMatchingNodes(context, expressionNode.Rhs)
+	rhs, err := d.GetMatchingNodes(context.ReadOnlyClone(), expressionNode.Rhs)
 
 	if err != nil {
 		return Context{}, err

pkg/yqlib/operator_traverse_path_test.go

@@ -78,6 +78,14 @@ var traversePathOperatorScenarios = []expressionScenario{
 			"D0, P[flying fox], (!!str)::frog\n",
 		},
 	},
+	{
+		skipDoc:    true,
+		document:   `c: dog`,
+		expression: `.[.a.b] as $x`,
+		expected: []string{
+			"D0, P[], (doc)::c: dog\n",
+		},
+	},
 	{
 		description:    "Dynamic keys",
 		subdescription: `Expressions within [] can be used to dynamically lookup / calculate keys`,