From ed4d888bfa27895cce5348bb93e90f7021af4bba Mon Sep 17 00:00:00 2001
From: Mike Farah <mikefarah@gmail.com>
Date: Mon, 11 Oct 2021 14:46:46 +1100
Subject: [PATCH] Speed up multiply

---
 pkg/yqlib/doc/Multiply (Merge).md   |  2 +-
 pkg/yqlib/expression_tokeniser.go   |  1 +
 pkg/yqlib/operator_multiply.go      | 18 +++++++++++++-----
 pkg/yqlib/operator_multiply_test.go | 17 ++++++++++++++++-
 4 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/pkg/yqlib/doc/Multiply (Merge).md b/pkg/yqlib/doc/Multiply (Merge).md
index 32d52e9c..e2d2c856 100644
--- a/pkg/yqlib/doc/Multiply (Merge).md	
+++ b/pkg/yqlib/doc/Multiply (Merge).md	
@@ -357,7 +357,7 @@ yq eval '.foobar * .foobarList' sample.yml
 will output
 ```yaml
 c: foobarList_c
-<<:
+!!merge <<:
   - *foo
   - *bar
 thing: foobar_thing
diff --git a/pkg/yqlib/expression_tokeniser.go b/pkg/yqlib/expression_tokeniser.go
index 1b23a08d..f19c5447 100644
--- a/pkg/yqlib/expression_tokeniser.go
+++ b/pkg/yqlib/expression_tokeniser.go
@@ -111,6 +111,7 @@ func multiplyWithPrefs() lex.Action {
 		if strings.Contains(options, "d") {
 			prefs.DeepMergeArrays = true
 		}
+		prefs.TraversePrefs.DontFollowAlias = true
 		op := &Operation{OperationType: multiplyOpType, Value: multiplyOpType.Type, StringValue: options, Preferences: prefs}
 		return &token{TokenType: operationToken, Operation: op}, nil
 	}
diff --git a/pkg/yqlib/operator_multiply.go b/pkg/yqlib/operator_multiply.go
index ecf12623..00265387 100644
--- a/pkg/yqlib/operator_multiply.go
+++ b/pkg/yqlib/operator_multiply.go
@@ -6,6 +6,7 @@ import (
 
 	"container/list"
 
+	"github.com/jinzhu/copier"
 	yaml "gopkg.in/yaml.v3"
 )
 
@@ -50,14 +51,21 @@ func multiply(preferences multiplyPreferences) func(d *dataTreeNavigator, contex
 
 		if lhs.Node.Kind == yaml.MappingNode && rhs.Node.Kind == yaml.MappingNode ||
 			(lhs.Node.Kind == yaml.SequenceNode && rhs.Node.Kind == yaml.SequenceNode) {
-
-			var newBlank = lhs.CreateChild(nil, newBlankNode)
-			log.Debugf("merge - merge lhs into blank")
-			var newThing, err = mergeObjects(d, context.WritableClone(), newBlank, lhs, multiplyPreferences{})
+			var newBlank = CandidateNode{}
+			err := copier.CopyWithOption(&newBlank, lhs, copier.Option{IgnoreEmpty: true, DeepCopy: true})
 			if err != nil {
 				return nil, err
 			}
-			return mergeObjects(d, context.WritableClone(), newThing, rhs, preferences)
+			newBlank.Node.HeadComment = newBlankNode.HeadComment
+			newBlank.Node.FootComment = newBlankNode.FootComment
+
+			// var newBlank = lhs.CreateChild(nil, newBlankNode)
+			// log.Debugf("merge - merge lhs into blank")
+			// var newThing, err = mergeObjects(d, context.WritableClone(), newBlank, lhs, multiplyPreferences{})
+			// if err != nil {
+			// 	return nil, err
+			// }
+			return mergeObjects(d, context.WritableClone(), &newBlank, rhs, preferences)
 		} else if lhs.Node.Tag == "!!int" && rhs.Node.Tag == "!!int" {
 			return multiplyIntegers(lhs, rhs)
 		} else if (lhs.Node.Tag == "!!int" || lhs.Node.Tag == "!!float") && (rhs.Node.Tag == "!!int" || rhs.Node.Tag == "!!float") {
diff --git a/pkg/yqlib/operator_multiply_test.go b/pkg/yqlib/operator_multiply_test.go
index c1c93adf..b8a294e2 100644
--- a/pkg/yqlib/operator_multiply_test.go
+++ b/pkg/yqlib/operator_multiply_test.go
@@ -60,6 +60,13 @@ var nodeWithFooter = `
 a: apple
 # footer`
 
+var document = `
+a: &cat {name: cat}
+b: {name: dog}
+c: 
+  <<: *cat
+`
+
 var multiplyOperatorScenarios = []expressionScenario{
 	{
 		skipDoc:    true,
@@ -405,7 +412,15 @@ var multiplyOperatorScenarios = []expressionScenario{
 		document:    mergeDocSample,
 		expression:  `.foobar * .foobarList`,
 		expected: []string{
-			"D0, P[foobar], (!!map)::c: foobarList_c\n<<: [*foo, *bar]\nthing: foobar_thing\nb: foobarList_b\n",
+			"D0, P[foobar], (!!map)::c: foobarList_c\n!!merge <<: [*foo, *bar]\nthing: foobar_thing\nb: foobarList_b\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   document,
+		expression: `.b * .c`,
+		expected: []string{
+			"D0, P[b], (!!map)::{name: dog, <<: *cat}\n",
 		},
 	},
 }