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1 // Copyright © 2017 Mikael Berthe <mikael@lilotux.net> |
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2 // |
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3 // Licensed under the MIT license. |
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4 // Please see the LICENSE file is this directory. |
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5 |
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6 package printer |
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7 |
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8 import ( |
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9 "encoding/json" |
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10 "fmt" |
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11 "io" |
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12 "os" |
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13 "reflect" |
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14 "text/template" |
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15 |
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16 "github.com/McKael/madon" |
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17 ) |
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18 |
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19 // TemplatePrinter represents a Template printer |
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20 type TemplatePrinter struct { |
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21 rawTemplate string |
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22 template *template.Template |
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23 } |
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24 |
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25 // NewPrinterTemplate returns a Template ResourcePrinter |
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26 // For TemplatePrinter, the option parameter contains the template string. |
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27 func NewPrinterTemplate(option string) (*TemplatePrinter, error) { |
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28 tmpl := option |
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29 t, err := template.New("output").Parse(tmpl) |
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30 if err != nil { |
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31 return nil, err |
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32 } |
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33 return &TemplatePrinter{ |
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34 rawTemplate: tmpl, |
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35 template: t, |
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36 }, nil |
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37 } |
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38 |
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39 // PrintObj sends the object as text to the writer |
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40 // If the writer w is nil, standard output will be used. |
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41 func (p *TemplatePrinter) PrintObj(obj interface{}, w io.Writer, tmpl string) error { |
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42 if w == nil { |
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43 w = os.Stdout |
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44 } |
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45 |
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46 if p.template == nil { |
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47 return fmt.Errorf("template not built") |
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48 } |
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49 |
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50 switch ot := obj.(type) { // I wish I knew a better way... |
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51 case []madon.Account, []madon.Application, []madon.Attachment, []madon.Card, |
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52 []madon.Client, []madon.Context, []madon.Instance, []madon.Mention, |
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53 []madon.Notification, []madon.Relationship, []madon.Report, |
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54 []madon.Results, []madon.Status, []madon.StreamEvent, []madon.Tag: |
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55 return p.templateForeach(ot, w) |
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56 } |
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57 |
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58 return p.templatePrintSingleObj(obj, w) |
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59 } |
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60 |
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61 func (p *TemplatePrinter) templatePrintSingleObj(obj interface{}, w io.Writer) error { |
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62 // This code comes from Kubernetes. |
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63 data, err := json.Marshal(obj) |
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64 if err != nil { |
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65 return err |
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66 } |
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67 out := map[string]interface{}{} |
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68 if err := json.Unmarshal(data, &out); err != nil { |
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69 return err |
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70 } |
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71 if err = p.safeExecute(w, out); err != nil { |
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72 return fmt.Errorf("error executing template %q: %v", p.rawTemplate, err) |
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73 } |
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74 return nil |
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75 } |
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76 |
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77 // safeExecute tries to execute the template, but catches panics and returns an error |
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78 // should the template engine panic. |
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79 // This code comes from Kubernetes. |
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80 func (p *TemplatePrinter) safeExecute(w io.Writer, obj interface{}) error { |
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81 var panicErr error |
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82 // Sorry for the double anonymous function. There's probably a clever way |
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83 // to do this that has the defer'd func setting the value to be returned, but |
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84 // that would be even less obvious. |
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85 retErr := func() error { |
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86 defer func() { |
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87 if x := recover(); x != nil { |
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88 panicErr = fmt.Errorf("caught panic: %+v", x) |
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89 } |
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90 }() |
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91 return p.template.Execute(w, obj) |
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92 }() |
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93 if panicErr != nil { |
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94 return panicErr |
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95 } |
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96 return retErr |
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97 } |
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98 |
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99 func (p *TemplatePrinter) templateForeach(ol interface{}, w io.Writer) error { |
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100 switch reflect.TypeOf(ol).Kind() { |
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101 case reflect.Slice: |
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102 s := reflect.ValueOf(ol) |
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103 |
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104 for i := 0; i < s.Len(); i++ { |
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105 o := s.Index(i).Interface() |
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106 if err := p.templatePrintSingleObj(o, w); err != nil { |
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107 return err |
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108 } |
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109 } |
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110 } |
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111 return nil |
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112 } |