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// 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)
}
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