1 // |
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2 // Blackfriday Markdown Processor |
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3 // Available at http://github.com/russross/blackfriday |
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4 // |
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5 // Copyright © 2011 Russ Ross <russ@russross.com>. |
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6 // Distributed under the Simplified BSD License. |
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7 // See README.md for details. |
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8 // |
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9 |
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10 // |
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11 // |
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12 // SmartyPants rendering |
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13 // |
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14 // |
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15 |
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16 package blackfriday |
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17 |
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18 import ( |
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19 "bytes" |
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20 "io" |
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21 ) |
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22 |
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23 // SPRenderer is a struct containing state of a Smartypants renderer. |
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24 type SPRenderer struct { |
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25 inSingleQuote bool |
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26 inDoubleQuote bool |
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27 callbacks [256]smartCallback |
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28 } |
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29 |
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30 func wordBoundary(c byte) bool { |
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31 return c == 0 || isspace(c) || ispunct(c) |
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32 } |
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33 |
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34 func tolower(c byte) byte { |
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35 if c >= 'A' && c <= 'Z' { |
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36 return c - 'A' + 'a' |
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37 } |
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38 return c |
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39 } |
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40 |
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41 func isdigit(c byte) bool { |
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42 return c >= '0' && c <= '9' |
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43 } |
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44 |
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45 func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote byte, isOpen *bool, addNBSP bool) bool { |
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46 // edge of the buffer is likely to be a tag that we don't get to see, |
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47 // so we treat it like text sometimes |
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48 |
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49 // enumerate all sixteen possibilities for (previousChar, nextChar) |
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50 // each can be one of {0, space, punct, other} |
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51 switch { |
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52 case previousChar == 0 && nextChar == 0: |
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53 // context is not any help here, so toggle |
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54 *isOpen = !*isOpen |
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55 case isspace(previousChar) && nextChar == 0: |
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56 // [ "] might be [ "<code>foo...] |
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57 *isOpen = true |
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58 case ispunct(previousChar) && nextChar == 0: |
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59 // [!"] hmm... could be [Run!"] or [("<code>...] |
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60 *isOpen = false |
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61 case /* isnormal(previousChar) && */ nextChar == 0: |
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62 // [a"] is probably a close |
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63 *isOpen = false |
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64 case previousChar == 0 && isspace(nextChar): |
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65 // [" ] might be [...foo</code>" ] |
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66 *isOpen = false |
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67 case isspace(previousChar) && isspace(nextChar): |
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68 // [ " ] context is not any help here, so toggle |
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69 *isOpen = !*isOpen |
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70 case ispunct(previousChar) && isspace(nextChar): |
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71 // [!" ] is probably a close |
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72 *isOpen = false |
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73 case /* isnormal(previousChar) && */ isspace(nextChar): |
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74 // [a" ] this is one of the easy cases |
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75 *isOpen = false |
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76 case previousChar == 0 && ispunct(nextChar): |
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77 // ["!] hmm... could be ["$1.95] or [</code>"!...] |
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78 *isOpen = false |
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79 case isspace(previousChar) && ispunct(nextChar): |
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80 // [ "!] looks more like [ "$1.95] |
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81 *isOpen = true |
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82 case ispunct(previousChar) && ispunct(nextChar): |
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83 // [!"!] context is not any help here, so toggle |
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84 *isOpen = !*isOpen |
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85 case /* isnormal(previousChar) && */ ispunct(nextChar): |
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86 // [a"!] is probably a close |
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87 *isOpen = false |
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88 case previousChar == 0 /* && isnormal(nextChar) */ : |
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89 // ["a] is probably an open |
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90 *isOpen = true |
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91 case isspace(previousChar) /* && isnormal(nextChar) */ : |
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92 // [ "a] this is one of the easy cases |
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93 *isOpen = true |
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94 case ispunct(previousChar) /* && isnormal(nextChar) */ : |
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95 // [!"a] is probably an open |
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96 *isOpen = true |
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97 default: |
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98 // [a'b] maybe a contraction? |
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99 *isOpen = false |
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100 } |
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101 |
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102 // Note that with the limited lookahead, this non-breaking |
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103 // space will also be appended to single double quotes. |
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104 if addNBSP && !*isOpen { |
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105 out.WriteString(" ") |
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106 } |
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107 |
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108 out.WriteByte('&') |
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109 if *isOpen { |
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110 out.WriteByte('l') |
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111 } else { |
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112 out.WriteByte('r') |
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113 } |
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114 out.WriteByte(quote) |
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115 out.WriteString("quo;") |
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116 |
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117 if addNBSP && *isOpen { |
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118 out.WriteString(" ") |
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119 } |
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120 |
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121 return true |
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122 } |
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123 |
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124 func (r *SPRenderer) smartSingleQuote(out *bytes.Buffer, previousChar byte, text []byte) int { |
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125 if len(text) >= 2 { |
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126 t1 := tolower(text[1]) |
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127 |
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128 if t1 == '\'' { |
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129 nextChar := byte(0) |
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130 if len(text) >= 3 { |
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131 nextChar = text[2] |
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132 } |
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133 if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) { |
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134 return 1 |
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135 } |
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136 } |
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137 |
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138 if (t1 == 's' || t1 == 't' || t1 == 'm' || t1 == 'd') && (len(text) < 3 || wordBoundary(text[2])) { |
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139 out.WriteString("’") |
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140 return 0 |
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141 } |
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142 |
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143 if len(text) >= 3 { |
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144 t2 := tolower(text[2]) |
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145 |
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146 if ((t1 == 'r' && t2 == 'e') || (t1 == 'l' && t2 == 'l') || (t1 == 'v' && t2 == 'e')) && |
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147 (len(text) < 4 || wordBoundary(text[3])) { |
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148 out.WriteString("’") |
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149 return 0 |
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150 } |
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151 } |
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152 } |
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153 |
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154 nextChar := byte(0) |
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155 if len(text) > 1 { |
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156 nextChar = text[1] |
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157 } |
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158 if smartQuoteHelper(out, previousChar, nextChar, 's', &r.inSingleQuote, false) { |
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159 return 0 |
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160 } |
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161 |
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162 out.WriteByte(text[0]) |
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163 return 0 |
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164 } |
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165 |
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166 func (r *SPRenderer) smartParens(out *bytes.Buffer, previousChar byte, text []byte) int { |
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167 if len(text) >= 3 { |
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168 t1 := tolower(text[1]) |
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169 t2 := tolower(text[2]) |
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170 |
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171 if t1 == 'c' && t2 == ')' { |
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172 out.WriteString("©") |
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173 return 2 |
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174 } |
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175 |
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176 if t1 == 'r' && t2 == ')' { |
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177 out.WriteString("®") |
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178 return 2 |
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179 } |
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180 |
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181 if len(text) >= 4 && t1 == 't' && t2 == 'm' && text[3] == ')' { |
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182 out.WriteString("™") |
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183 return 3 |
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184 } |
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185 } |
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186 |
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187 out.WriteByte(text[0]) |
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188 return 0 |
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189 } |
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190 |
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191 func (r *SPRenderer) smartDash(out *bytes.Buffer, previousChar byte, text []byte) int { |
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192 if len(text) >= 2 { |
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193 if text[1] == '-' { |
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194 out.WriteString("—") |
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195 return 1 |
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196 } |
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197 |
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198 if wordBoundary(previousChar) && wordBoundary(text[1]) { |
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199 out.WriteString("–") |
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200 return 0 |
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201 } |
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202 } |
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203 |
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204 out.WriteByte(text[0]) |
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205 return 0 |
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206 } |
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207 |
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208 func (r *SPRenderer) smartDashLatex(out *bytes.Buffer, previousChar byte, text []byte) int { |
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209 if len(text) >= 3 && text[1] == '-' && text[2] == '-' { |
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210 out.WriteString("—") |
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211 return 2 |
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212 } |
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213 if len(text) >= 2 && text[1] == '-' { |
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214 out.WriteString("–") |
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215 return 1 |
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216 } |
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217 |
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218 out.WriteByte(text[0]) |
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219 return 0 |
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220 } |
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221 |
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222 func (r *SPRenderer) smartAmpVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte, addNBSP bool) int { |
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223 if bytes.HasPrefix(text, []byte(""")) { |
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224 nextChar := byte(0) |
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225 if len(text) >= 7 { |
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226 nextChar = text[6] |
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227 } |
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228 if smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, addNBSP) { |
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229 return 5 |
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230 } |
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231 } |
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232 |
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233 if bytes.HasPrefix(text, []byte("�")) { |
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234 return 3 |
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235 } |
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236 |
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237 out.WriteByte('&') |
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238 return 0 |
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239 } |
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240 |
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241 func (r *SPRenderer) smartAmp(angledQuotes, addNBSP bool) func(*bytes.Buffer, byte, []byte) int { |
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242 var quote byte = 'd' |
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243 if angledQuotes { |
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244 quote = 'a' |
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245 } |
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246 |
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247 return func(out *bytes.Buffer, previousChar byte, text []byte) int { |
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248 return r.smartAmpVariant(out, previousChar, text, quote, addNBSP) |
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249 } |
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250 } |
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251 |
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252 func (r *SPRenderer) smartPeriod(out *bytes.Buffer, previousChar byte, text []byte) int { |
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253 if len(text) >= 3 && text[1] == '.' && text[2] == '.' { |
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254 out.WriteString("…") |
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255 return 2 |
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256 } |
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257 |
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258 if len(text) >= 5 && text[1] == ' ' && text[2] == '.' && text[3] == ' ' && text[4] == '.' { |
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259 out.WriteString("…") |
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260 return 4 |
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261 } |
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262 |
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263 out.WriteByte(text[0]) |
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264 return 0 |
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265 } |
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266 |
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267 func (r *SPRenderer) smartBacktick(out *bytes.Buffer, previousChar byte, text []byte) int { |
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268 if len(text) >= 2 && text[1] == '`' { |
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269 nextChar := byte(0) |
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270 if len(text) >= 3 { |
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271 nextChar = text[2] |
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272 } |
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273 if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) { |
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274 return 1 |
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275 } |
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276 } |
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277 |
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278 out.WriteByte(text[0]) |
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279 return 0 |
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280 } |
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281 |
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282 func (r *SPRenderer) smartNumberGeneric(out *bytes.Buffer, previousChar byte, text []byte) int { |
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283 if wordBoundary(previousChar) && previousChar != '/' && len(text) >= 3 { |
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284 // is it of the form digits/digits(word boundary)?, i.e., \d+/\d+\b |
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285 // note: check for regular slash (/) or fraction slash (⁄, 0x2044, or 0xe2 81 84 in utf-8) |
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286 // and avoid changing dates like 1/23/2005 into fractions. |
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287 numEnd := 0 |
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288 for len(text) > numEnd && isdigit(text[numEnd]) { |
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289 numEnd++ |
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290 } |
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291 if numEnd == 0 { |
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292 out.WriteByte(text[0]) |
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293 return 0 |
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294 } |
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295 denStart := numEnd + 1 |
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296 if len(text) > numEnd+3 && text[numEnd] == 0xe2 && text[numEnd+1] == 0x81 && text[numEnd+2] == 0x84 { |
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297 denStart = numEnd + 3 |
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298 } else if len(text) < numEnd+2 || text[numEnd] != '/' { |
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299 out.WriteByte(text[0]) |
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300 return 0 |
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301 } |
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302 denEnd := denStart |
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303 for len(text) > denEnd && isdigit(text[denEnd]) { |
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304 denEnd++ |
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305 } |
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306 if denEnd == denStart { |
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307 out.WriteByte(text[0]) |
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308 return 0 |
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309 } |
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310 if len(text) == denEnd || wordBoundary(text[denEnd]) && text[denEnd] != '/' { |
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311 out.WriteString("<sup>") |
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312 out.Write(text[:numEnd]) |
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313 out.WriteString("</sup>⁄<sub>") |
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314 out.Write(text[denStart:denEnd]) |
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315 out.WriteString("</sub>") |
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316 return denEnd - 1 |
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317 } |
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318 } |
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319 |
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320 out.WriteByte(text[0]) |
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321 return 0 |
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322 } |
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323 |
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324 func (r *SPRenderer) smartNumber(out *bytes.Buffer, previousChar byte, text []byte) int { |
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325 if wordBoundary(previousChar) && previousChar != '/' && len(text) >= 3 { |
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326 if text[0] == '1' && text[1] == '/' && text[2] == '2' { |
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327 if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' { |
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328 out.WriteString("½") |
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329 return 2 |
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330 } |
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331 } |
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332 |
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333 if text[0] == '1' && text[1] == '/' && text[2] == '4' { |
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334 if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' || (len(text) >= 5 && tolower(text[3]) == 't' && tolower(text[4]) == 'h') { |
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335 out.WriteString("¼") |
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336 return 2 |
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337 } |
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338 } |
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339 |
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340 if text[0] == '3' && text[1] == '/' && text[2] == '4' { |
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341 if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' || (len(text) >= 6 && tolower(text[3]) == 't' && tolower(text[4]) == 'h' && tolower(text[5]) == 's') { |
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342 out.WriteString("¾") |
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343 return 2 |
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344 } |
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345 } |
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346 } |
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347 |
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348 out.WriteByte(text[0]) |
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349 return 0 |
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350 } |
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351 |
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352 func (r *SPRenderer) smartDoubleQuoteVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte) int { |
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353 nextChar := byte(0) |
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354 if len(text) > 1 { |
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355 nextChar = text[1] |
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356 } |
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357 if !smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, false) { |
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358 out.WriteString(""") |
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359 } |
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360 |
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361 return 0 |
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362 } |
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363 |
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364 func (r *SPRenderer) smartDoubleQuote(out *bytes.Buffer, previousChar byte, text []byte) int { |
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365 return r.smartDoubleQuoteVariant(out, previousChar, text, 'd') |
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366 } |
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367 |
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368 func (r *SPRenderer) smartAngledDoubleQuote(out *bytes.Buffer, previousChar byte, text []byte) int { |
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369 return r.smartDoubleQuoteVariant(out, previousChar, text, 'a') |
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370 } |
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371 |
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372 func (r *SPRenderer) smartLeftAngle(out *bytes.Buffer, previousChar byte, text []byte) int { |
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373 i := 0 |
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374 |
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375 for i < len(text) && text[i] != '>' { |
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376 i++ |
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377 } |
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378 |
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379 out.Write(text[:i+1]) |
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380 return i |
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381 } |
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382 |
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383 type smartCallback func(out *bytes.Buffer, previousChar byte, text []byte) int |
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384 |
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385 // NewSmartypantsRenderer constructs a Smartypants renderer object. |
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386 func NewSmartypantsRenderer(flags HTMLFlags) *SPRenderer { |
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387 var ( |
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388 r SPRenderer |
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389 |
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390 smartAmpAngled = r.smartAmp(true, false) |
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391 smartAmpAngledNBSP = r.smartAmp(true, true) |
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392 smartAmpRegular = r.smartAmp(false, false) |
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393 smartAmpRegularNBSP = r.smartAmp(false, true) |
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394 |
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395 addNBSP = flags&SmartypantsQuotesNBSP != 0 |
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396 ) |
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397 |
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398 if flags&SmartypantsAngledQuotes == 0 { |
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399 r.callbacks['"'] = r.smartDoubleQuote |
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400 if !addNBSP { |
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401 r.callbacks['&'] = smartAmpRegular |
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402 } else { |
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403 r.callbacks['&'] = smartAmpRegularNBSP |
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404 } |
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405 } else { |
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406 r.callbacks['"'] = r.smartAngledDoubleQuote |
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407 if !addNBSP { |
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408 r.callbacks['&'] = smartAmpAngled |
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409 } else { |
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410 r.callbacks['&'] = smartAmpAngledNBSP |
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411 } |
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412 } |
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413 r.callbacks['\''] = r.smartSingleQuote |
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414 r.callbacks['('] = r.smartParens |
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415 if flags&SmartypantsDashes != 0 { |
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416 if flags&SmartypantsLatexDashes == 0 { |
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417 r.callbacks['-'] = r.smartDash |
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418 } else { |
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419 r.callbacks['-'] = r.smartDashLatex |
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420 } |
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421 } |
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422 r.callbacks['.'] = r.smartPeriod |
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423 if flags&SmartypantsFractions == 0 { |
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424 r.callbacks['1'] = r.smartNumber |
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425 r.callbacks['3'] = r.smartNumber |
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426 } else { |
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427 for ch := '1'; ch <= '9'; ch++ { |
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428 r.callbacks[ch] = r.smartNumberGeneric |
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429 } |
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430 } |
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431 r.callbacks['<'] = r.smartLeftAngle |
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432 r.callbacks['`'] = r.smartBacktick |
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433 return &r |
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434 } |
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435 |
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436 // Process is the entry point of the Smartypants renderer. |
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437 func (r *SPRenderer) Process(w io.Writer, text []byte) { |
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438 mark := 0 |
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439 for i := 0; i < len(text); i++ { |
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440 if action := r.callbacks[text[i]]; action != nil { |
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441 if i > mark { |
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442 w.Write(text[mark:i]) |
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443 } |
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444 previousChar := byte(0) |
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445 if i > 0 { |
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446 previousChar = text[i-1] |
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447 } |
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448 var tmp bytes.Buffer |
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449 i += action(&tmp, previousChar, text[i:]) |
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450 w.Write(tmp.Bytes()) |
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451 mark = i + 1 |
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452 } |
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453 } |
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454 if mark < len(text) { |
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455 w.Write(text[mark:]) |
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456 } |
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457 } |
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