golang example_test 代码
文件路径：/src/go/printer/example_test.go
/ Copyright 2012 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 printer_test
import (
"bytes"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/token"
"strings"
"testing"
)
/ Dummy test function so that godoc does not use the entire file as example.
func Test(*testing.T) {}
func parseFunc(filename, functionname string) (fun *ast.FuncDecl, fset *token.FileSet) {
fset = token.NewFileSet()
if file, err := parser.ParseFile(fset, filename, nil, 0); err == nil {
for _, d := range file.Decls {
if f, ok := d.(*ast.FuncDecl); ok && f.Name.Name == functionname {
fun = f
return
}
}
}
panic("function not found")
}
func ExampleFprint() {
/ Parse source file and extract the AST without comments for
/ this function, with position information referring to the
/ file set fset.
funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
/ Print the function body into buffer buf.
/ The file set is provided to the printer so that it knows
/ about the original source formatting and can add additional
/ line breaks where they were present in the source.
var buf bytes.Buffer
printer.Fprint(&buf, fset, funcAST.Body)
/ Remove braces {} enclosing the function body, unindent,
/ and trim leading and trailing white space.
s := buf.String()
s = s[1 : len(s)-1]
s = strings.TrimSpace(strings.ReplaceAll(s, "\n\t", "\n"))
/ Print the cleaned-up body text to stdout.
fmt.Println(s)
/ output:
/ funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
/
/ var buf bytes.Buffer
/ printer.Fprint(&buf, fset, funcAST.Body)
/
/ s := buf.String()
/ s = s[1 : len(s)-1]
/ s = strings.TrimSpace(strings.ReplaceAll(s, "\n\t", "\n"))
/
/ fmt.Println(s)
}