// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file implements a simple printer performance benchmark:
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// go test -bench=BenchmarkPrint
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package printer
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import (
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"bytes"
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"go/ast"
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"go/parser"
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"io"
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"io/ioutil"
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"log"
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"testing"
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)
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var testfile *ast.File
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func testprint(out io.Writer, file *ast.File) {
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if err := (&Config{TabIndent | UseSpaces, 8, 0}).Fprint(out, fset, file); err != nil {
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log.Fatalf("print error: %s", err)
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}
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}
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// cannot initialize in init because (printer) Fprint launches goroutines.
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func initialize() {
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const filename = "testdata/parser.go"
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src, err := ioutil.ReadFile(filename)
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if err != nil {
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log.Fatalf("%s", err)
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}
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file, err := parser.ParseFile(fset, filename, src, parser.ParseComments)
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if err != nil {
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log.Fatalf("%s", err)
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}
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var buf bytes.Buffer
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testprint(&buf, file)
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if !bytes.Equal(buf.Bytes(), src) {
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log.Fatalf("print error: %s not idempotent", filename)
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}
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testfile = file
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}
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func BenchmarkPrint(b *testing.B) {
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if testfile == nil {
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initialize()
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}
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for i := 0; i < b.N; i++ {
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testprint(ioutil.Discard, testfile)
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}
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}
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