golang example_test 代码
文件路径：/src/go/token/example_test.go
/ Copyright 2018 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package token_test
import (
"fmt"
"go/ast"
"go/parser"
"go/token"
)
func Example_retrievePositionInfo() {
fset := token.NewFileSet()
const src = `package main
import "fmt"
import "go/token"
/line :1:5
type p = token.Pos
const bad = token.NoPos
/line fake.go:42:11
func ok(pos p) bool {
return pos != bad
}
/*line :7:9*/func main() {
fmt.Println(ok(bad) == bad.IsValid())
}
`
f, err := parser.ParseFile(fset, "main.go", src, 0)
if err != nil {
fmt.Println(err)
return
}
/ Print the location and kind of each declaration in f.
for _, decl := range f.Decls {
/ Get the filename, line, and column back via the file set.
/ We get both the relative and absolute position.
/ The relative position is relative to the last line directive.
/ The absolute position is the exact position in the source.
pos := decl.Pos()
relPosition := fset.Position(pos)
absPosition := fset.PositionFor(pos, false)
/ Either a FuncDecl or GenDecl, since we exit on error.
kind := "func"
if gen, ok := decl.(*ast.GenDecl); ok {
kind = gen.Tok.String()
}
/ If the relative and absolute positions differ, show both.
fmtPosition := relPosition.String()
if relPosition != absPosition {
fmtPosition += "[" + absPosition.String() + "]"
}
fmt.Printf("%s: %s\n", fmtPosition, kind)
}
/Output:
/
/ main.go:3:1: import
/ main.go:5:1: import
/ main.go:1:5[main.go:8:1]: type
/ main.go:3:1[main.go:10:1]: const
/ fake.go:42:11[main.go:13:1]: func
/ fake.go:7:9[main.go:17:14]: func
}