Cherry-pick 72d91bd with conflicts

go/vt/schemadiff/key.go

@@ -0,0 +1,172 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package schemadiff
+
+import (
+	"vitess.io/vitess/go/vt/sqlparser"
+)
+
+// IndexDefinitionEntity represents an index definition in a CREATE TABLE statement,
+// and includes the list of columns that are part of the index.
+type IndexDefinitionEntity struct {
+	IndexDefinition *sqlparser.IndexDefinition
+	ColumnList      *ColumnDefinitionEntityList
+	Env             *Environment
+}
+
+func NewIndexDefinitionEntity(env *Environment, indexDefinition *sqlparser.IndexDefinition, columnDefinitionEntitiesList *ColumnDefinitionEntityList) *IndexDefinitionEntity {
+	return &IndexDefinitionEntity{
+		IndexDefinition: indexDefinition,
+		ColumnList:      columnDefinitionEntitiesList,
+		Env:             env,
+	}
+}
+
+func (i *IndexDefinitionEntity) Name() string {
+	return i.IndexDefinition.Info.Name.String()
+}
+
+func (i *IndexDefinitionEntity) NameLowered() string {
+	return i.IndexDefinition.Info.Name.Lowered()
+}
+
+// Clone returns a copy of this list, with copies of all the entities.
+func (i *IndexDefinitionEntity) Clone() *IndexDefinitionEntity {
+	clone := &IndexDefinitionEntity{
+		IndexDefinition: sqlparser.Clone(i.IndexDefinition),
+		ColumnList:      i.ColumnList.Clone(),
+		Env:             i.Env,
+	}
+	return clone
+}
+
+func (i *IndexDefinitionEntity) Len() int {
+	return len(i.IndexDefinition.Columns)
+}
+
+// IsPrimary returns true if the index is a primary key.
+func (i *IndexDefinitionEntity) IsPrimary() bool {
+	return i.IndexDefinition.Info.Type == sqlparser.IndexTypePrimary
+}
+
+// IsUnique returns true if the index is a unique key.
+func (i *IndexDefinitionEntity) IsUnique() bool {
+	return i.IndexDefinition.Info.IsUnique()
+}
+
+// HasExpression returns true if the index uses an expression, e.g. `KEY idx1 ((id + 1))`.
+func (i *IndexDefinitionEntity) HasExpression() bool {
+	for _, col := range i.IndexDefinition.Columns {
+		if col.Expression != nil {
+			return true
+		}
+	}
+	return false
+}
+
+// HasNullable returns true if any of the columns in the index are nullable.
+func (i *IndexDefinitionEntity) HasNullable() bool {
+	for _, col := range i.ColumnList.Entities {
+		if col.IsNullable() {
+			return true
+		}
+	}
+	return false
+}
+
+// HasFloat returns true if any of the columns in the index are floating point types.
+func (i *IndexDefinitionEntity) HasFloat() bool {
+	for _, col := range i.ColumnList.Entities {
+		if col.IsFloatingPointType() {
+			return true
+		}
+	}
+	return false
+}
+
+// HasColumnPrefix returns true if any of the columns in the index have a length prefix.
+func (i *IndexDefinitionEntity) HasColumnPrefix() bool {
+	for _, col := range i.IndexDefinition.Columns {
+		if col.Length != nil {
+			return true
+		}
+	}
+	return false
+}
+
+// ColumnNames returns the names of the columns in the index.
+func (i *IndexDefinitionEntity) ColumnNames() []string {
+	names := make([]string, 0, len(i.IndexDefinition.Columns))
+	for _, col := range i.IndexDefinition.Columns {
+		names = append(names, col.Column.String())
+	}
+	return names
+}
+
+// ContainsColumns returns true if the index contains all the columns in the given list.
+func (i *IndexDefinitionEntity) ContainsColumns(columns *ColumnDefinitionEntityList) bool {
+	return i.ColumnList.Contains(columns)
+}
+
+// CoveredByColumns returns true if the index is covered by the given list of columns.
+func (i *IndexDefinitionEntity) CoveredByColumns(columns *ColumnDefinitionEntityList) bool {
+	return columns.Contains(i.ColumnList)
+}
+
+// IndexDefinitionEntityList is a formalized list of IndexDefinitionEntity objects with a few
+// utility methods.
+type IndexDefinitionEntityList struct {
+	Entities []*IndexDefinitionEntity
+}
+
+func NewIndexDefinitionEntityList(entities []*IndexDefinitionEntity) *IndexDefinitionEntityList {
+	return &IndexDefinitionEntityList{
+		Entities: entities,
+	}
+}
+
+func (l *IndexDefinitionEntityList) Len() int {
+	return len(l.Entities)
+}
+
+// Names returns the names of the indexes in the list.
+func (l *IndexDefinitionEntityList) Names() []string {
+	names := make([]string, len(l.Entities))
+	for i, entity := range l.Entities {
+		names[i] = entity.Name()
+	}
+	return names
+}
+
+// SubsetCoveredByColumns returns a new list of indexes that are covered by the given list of columns.
+func (l *IndexDefinitionEntityList) SubsetCoveredByColumns(columns *ColumnDefinitionEntityList) *IndexDefinitionEntityList {
+	var subset []*IndexDefinitionEntity
+	for _, entity := range l.Entities {
+		if entity.CoveredByColumns(columns) {
+			subset = append(subset, entity)
+		}
+	}
+	return NewIndexDefinitionEntityList(subset)
+}
+
+// First returns the first index in the list, or nil if the list is empty.
+func (l *IndexDefinitionEntityList) First() *IndexDefinitionEntity {
+	if len(l.Entities) == 0 {
+		return nil
+	}
+	return l.Entities[0]
+}