Mastering Go - Second Edition

The go/parser package

A parser reads the output of a scanner (tokens) in order to generate a structure from those tokens. Parsers use a grammar that describes a programming language to make sure that the given tokens compose a valid program. That structure is represented as a tree, which is the AST.

The use of the go/parser package that processes the output of go/token is illustrated in goParser.go, which is going to be presented in four parts.

The first part of goParser.go is as follows:

package main 
 
import ( 
    "fmt" 
    "go/ast" 
    "go/parser" 
    "go/token" 
    "os" 
    "strings" 
) 
 
type visitor int 

The second part of goParser.go contains the following Go code:

func (v visitor) Visit(n ast.Node) ast.Visitor { if n == nil { return nil } fmt.Printf("%s%T\n", ...