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1 package gcss
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2
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3 import (
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4 "bytes"
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5 "fmt"
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6 "io"
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7 "strings"
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8 )
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9
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10 // declaration represents a declaration of CSS.
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11 type declaration struct {
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12 elementBase
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13 property string
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14 value string
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15 }
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16
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17 // WriteTo writes the declaration to the writer.
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18 func (dec *declaration) WriteTo(w io.Writer) (int64, error) {
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19 return dec.writeTo(w, nil)
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20 }
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21
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22 // writeTo writes the declaration to the writer.
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23 func (dec *declaration) writeTo(w io.Writer, params map[string]string) (int64, error) {
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24 bf := new(bytes.Buffer)
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25
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26 bf.WriteString(dec.property)
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27 bf.WriteString(colon)
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28
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29 for i, v := range strings.Split(dec.value, space) {
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30 if i > 0 {
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31 bf.WriteString(space)
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32 }
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33
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34 for j, w := range strings.Split(v, comma) {
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35 if j > 0 {
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36 bf.WriteString(comma)
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37 }
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38
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39 if strings.HasPrefix(w, dollarMark) {
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40 // Writing to the bytes.Buffer never returns an error.
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41 dec.writeParamTo(bf, strings.TrimPrefix(w, dollarMark), params)
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42 } else {
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43 bf.WriteString(w)
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44 }
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45 }
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46 }
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47
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48 bf.WriteString(semicolon)
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49
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50 n, err := w.Write(bf.Bytes())
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51
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52 return int64(n), err
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53 }
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54
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55 // writeParam writes the param to the writer.
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56 func (dec *declaration) writeParamTo(w io.Writer, name string, params map[string]string) (int64, error) {
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57 if s, ok := params[name]; ok {
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58 if strings.HasPrefix(s, dollarMark) {
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59 if v, ok := dec.Context().vars[strings.TrimPrefix(s, dollarMark)]; ok {
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60 return v.WriteTo(w)
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61 }
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62 return 0, nil
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63 }
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64
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65 n, err := w.Write([]byte(s))
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66 return int64(n), err
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67 }
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68
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69 if v, ok := dec.Context().vars[name]; ok {
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70 return v.WriteTo(w)
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71 }
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72
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73 return 0, nil
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74 }
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75
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76 // declarationPV extracts a declaration property and value
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77 // from the line.
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78 func declarationPV(ln *line) (string, string, error) {
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79 pv := strings.SplitN(strings.TrimSpace(ln.s), space, 2)
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80
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81 if len(pv) < 2 {
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82 return "", "", fmt.Errorf("declaration's property and value should be divided by a space [line: %d]", ln.no)
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83 }
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84
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85 if !strings.HasSuffix(pv[0], colon) {
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86 return "", "", fmt.Errorf("property should end with a colon [line: %d]", ln.no)
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87 }
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88
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89 return strings.TrimSuffix(pv[0], colon), pv[1], nil
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90 }
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91
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92 // newDeclaration creates and returns a declaration.
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93 func newDeclaration(ln *line, parent element) (*declaration, error) {
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94 property, value, err := declarationPV(ln)
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95
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96 if err != nil {
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97 return nil, err
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98 }
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99
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100 if strings.HasSuffix(value, semicolon) {
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101 return nil, fmt.Errorf("declaration must not end with %q [line: %d]", semicolon, ln.no)
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102 }
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103
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104 return &declaration{
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105 elementBase: newElementBase(ln, parent),
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106 property: property,
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107 value: value,
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108 }, nil
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109 }
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