initial work on key entities

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>

go/vt/schemadiff/key.go

@@ -0,0 +1,61 @@
+/*
+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"
+)
+
+type IndexDefinitionEntity struct {
+	IndexDefinition *sqlparser.IndexDefinition
+	Env             *Environment
+}
+
+func NewIndexDefinitionEntity(env *Environment, i *sqlparser.IndexDefinition) *IndexDefinitionEntity {
+	return &IndexDefinitionEntity{
+		IndexDefinition: i,
+		Env:             env,
+	}
+}
+
+func (i *IndexDefinitionEntity) Name() string {
+	return i.IndexDefinition.Info.Name.String()
+}
+
+func (i *IndexDefinitionEntity) NameLowered() string {
+	return i.IndexDefinition.Info.Name.Lowered()
+}
+
+func (i *IndexDefinitionEntity) Clone() *IndexDefinitionEntity {
+	clone := &IndexDefinitionEntity{
+		IndexDefinition: sqlparser.Clone(i.IndexDefinition),
+		Env:             i.Env,
+	}
+	return clone
+}
+
+func (i *IndexDefinitionEntity) Len() int {
+	return len(i.IndexDefinition.Columns)
+}
+
+func (i *IndexDefinitionEntity) IsPrimary() bool {
+	return i.IndexDefinition.Info.Type == sqlparser.IndexTypePrimary
+}
+
+func (i *IndexDefinitionEntity) IsUnique() bool {
+	return i.IndexDefinition.Info.IsUnique()
+}