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