tidb texttree 源码
tidb texttree 代码
文件路径：/util/texttree/texttree.go
// Copyright 2019 PingCAP, Inc.
//
// 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 texttree
const (
// TreeBody indicates the current operator sub-tree is not finished, still
// has child operators to be attached on.
TreeBody = '│'
// TreeMiddleNode indicates this operator is not the last child of the
// current sub-tree rooted by its parent.
TreeMiddleNode = '├'
// TreeLastNode indicates this operator is the last child of the current
// sub-tree rooted by its parent.
TreeLastNode = '└'
// TreeGap is used to represent the gap between the branches of the tree.
TreeGap = ' '
// TreeNodeIdentifier is used to replace the treeGap once we need to attach
// a node to a sub-tree.
TreeNodeIdentifier = '─'
)
// Indent4Child appends more blank to the `indent` string
func Indent4Child(indent string, isLastChild bool) string {
if !isLastChild {
return string(append([]rune(indent), TreeBody, TreeGap))
}
// If the current node is the last node of the current operator tree, we
// need to end this sub-tree by changing the closest treeBody to a treeGap.
indentBytes := []rune(indent)
for i := len(indentBytes) - 1; i >= 0; i-- {
if indentBytes[i] == TreeBody {
indentBytes[i] = TreeGap
break
}
}
return string(append(indentBytes, TreeBody, TreeGap))
}
// PrettyIdentifier returns a pretty identifier which contains indent and tree node hierarchy indicator
func PrettyIdentifier(id, indent string, isLastChild bool) string {
if len(indent) == 0 {
return id
}
indentBytes := []rune(indent)
for i := len(indentBytes) - 1; i >= 0; i-- {
if indentBytes[i] != TreeBody {
continue
}
// Here we attach a new node to the current sub-tree by changing
// the closest treeBody to a:
// 1. treeLastNode, if this operator is the last child.
// 2. treeMiddleNode, if this operator is not the last child..
if isLastChild {
indentBytes[i] = TreeLastNode
} else {
indentBytes[i] = TreeMiddleNode
}
break
}
// Replace the treeGap between the treeBody and the node to a
// treeNodeIdentifier.
indentBytes[len(indentBytes)-1] = TreeNodeIdentifier
return string(indentBytes) + id
}
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