diff --git a/src/pkg/go/printer/example_test.go b/src/pkg/go/printer/example_test.go new file mode 100644 index 00000000000..e570040ba1f --- /dev/null +++ b/src/pkg/go/printer/example_test.go @@ -0,0 +1,67 @@ +// 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.Replace(s, "\n\t", "\n", -1)) + + // 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.Replace(s, "\n\t", "\n", -1)) + // + // fmt.Println(s) +}