需求
将 var a,b,c= 3,4,5 改为 a,b,c :=3,4,5
将var m = 99 改为 m := 99
这种结构如果采用普通的正则替换是很难的，但是采用tree-sitter去做确实很容易实现的
请看下面的实例

package main

import (
    "fmt"

    tree_sitter "github.com/tree-sitter/go-tree-sitter"
    tree_sitter_go "github.com/tree-sitter/tree-sitter-go/bindings/go"
)

var (
    abc int
)

func main() {
    code := []byte(`
package main
import (
    "abcd"
    "fmt"
)

func main() {
    fmt.Println("Hello, world!123")
    var a,b,c =3,4,5;var test=88
    var kk =9
    var mm,ff,ll=88,99,100
}
`)

    parser := tree_sitter.NewParser()
    defer parser.Close()
    parser.SetLanguage(tree_sitter.NewLanguage(tree_sitter_go.Language()))

    tree := parser.Parse(code, nil)
    defer tree.Close()

    var walk func(node *tree_sitter.Node)
    walk = func(node *tree_sitter.Node) {
        if node.GrammarName() == "var_declaration" {
            var oldVarDeclarationRange = node.Range()
            varNode := node.Child(0)
            varNodeByteStart, varNodeByteEnd := varNode.ByteRange()
            for i := varNodeByteStart; i < varNodeByteEnd; i++ {
                code[i] = 0
            }
            childTwo := node.Child(1)
            if childTwo.Kind() == "var_spec" {
                varSpecNode := childTwo
                var i uint
                for i = 0; i < varSpecNode.ChildCount(); i++ {
                    if varSpecNode.Child(i).Kind() == "=" {
                        equalNode := varSpecNode.Child(i)
                        equalNodeByteStart, equalNodeByteEnd := equalNode.ByteRange()
                        code = append(code[:equalNodeByteStart], append([]byte(":="), code[equalNodeByteEnd:]...)...)
                        break
                    }
                }
                tree.Edit(&tree_sitter.InputEdit{
                    StartByte:  oldVarDeclarationRange.StartByte,
                    OldEndByte: oldVarDeclarationRange.EndByte,
                    NewEndByte: oldVarDeclarationRange.EndByte + 1,
                    StartPosition: tree_sitter.Point{
                        Row:    oldVarDeclarationRange.StartPoint.Row,
                        Column: oldVarDeclarationRange.StartPoint.Column,
                    },
                    OldEndPosition: tree_sitter.Point{
                        Row:    oldVarDeclarationRange.EndPoint.Row,
                        Column: oldVarDeclarationRange.EndPoint.Column,
                    },
                    NewEndPosition: tree_sitter.Point{
                        Row:    oldVarDeclarationRange.EndPoint.Row,
                        Column: oldVarDeclarationRange.EndPoint.Column + 1,
                    },
                })
            } else {

            }
        } else {
            childNum := node.ChildCount()
            if childNum == 0 {
            } else {
                var i uint
                for i = 0; i < (childNum); i++ {
                    walk(node.Child(i))
                }
            }
        }

    }
    walk(tree.RootNode())
    fmt.Println(string(code))

}

结果

package main
import (
        "abcd"
        "fmt"
)

func main() {
    fmt.Println("Hello, world!123")
         a,b,c :=3,4,5; test:=88
         kk :=9
         mm,ff,ll:=88,99,100
}