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// Copyright 2009 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.

// This file implements a simple printer performance benchmark:

// gotest -bench=BenchmarkPrint

package printer

import (

        "bytes"

        "go/ast"

        "go/parser"

        "io"

        "io/ioutil"

        "log"

        "testing"

)

var testfile *ast.File

func testprint(out io.Writer, file *ast.File) {

        if err := (&Config{TabIndent | UseSpaces, 8}).Fprint(out, fset, file); err != nil {

                log.Fatalf("print error: %s", err)

        }

}

// cannot initialize in init because (printer) Fprint launches goroutines.

func initialize() {

        const filename = "testdata/parser.go"

        src, err := ioutil.ReadFile(filename)

        if err != nil {

                log.Fatalf("%s", err)

        }

        file, err := parser.ParseFile(fset, filename, src, parser.ParseComments)

        if err != nil {

                log.Fatalf("%s", err)

        }

        var buf bytes.Buffer

        testprint(&buf, file)

        if !bytes.Equal(buf.Bytes(), src) {

                log.Fatalf("print error: %s not idempotent", filename)

        }

        testfile = file

}

func BenchmarkPrint(b *testing.B) {

        if testfile == nil {

                initialize()

        }

        for i := 0; i < b.N; i++ {

                testprint(ioutil.Discard, testfile)

        }

}