ast_inspect_comments2.go

package main

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
)

func main() {
	//Create a new token set for the file
	fset := token.NewFileSet()
	//Parse the file and create an AST
	file, err := parser.ParseFile(fset, "../nats_publisher/main.go", nil, parser.ParseComments)
	if err != nil {
		panic(err)
	}
	ast.Inspect(file, func(n ast.Node) bool {
		//Get the statement from the standalone expression (x) and attempt to cast to a function call
		funcCall, ok := n.(*ast.CallExpr)
		if ok {
			//Check if it is a selector expression
			mthd, ok := funcCall.Fun.(*ast.SelectorExpr)
			if ok {
				//Retrieve the identifier (the left side of the . in a selector expression)
				_, ok = mthd.X.(*ast.Ident)
				if ok {
					//If method matches and the identifier is "ec" (encoded nats connection), extract values
					if mthd.Sel.Name == "Publish" && mthd.X.(*ast.Ident).Name == "ec" {
						fmt.Printf("Topic: %s \n", funcCall.Args[0].(*ast.BasicLit).Value)
						line := fset.Position(mthd.Pos()).Line
						//Iterate over the comments in the file
						for _, cGroup := range file.Comments {
							//If the comment group matches the previous line, print the comment group as text
							if fset.Position(cGroup.End()).Line == line-1 {
								fmt.Println(cGroup.Text())
							}
						}
					}
				}
			}
		}
		return true
	})
}