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1 /* Title: Pure/General/length.scala |
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2 Author: Makarius |
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3 |
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4 Text length wrt. encoding. |
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5 */ |
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6 |
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7 package isabelle |
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8 |
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9 |
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10 trait Length |
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11 { |
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12 def apply(text: String): Int |
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13 def offset(text: String, i: Int): Option[Text.Offset] |
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14 } |
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15 |
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16 object Length extends Length |
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17 { |
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18 def apply(text: String): Int = text.length |
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19 def offset(text: String, i: Int): Option[Text.Offset] = |
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20 if (0 <= i && i <= text.length) Some(i) else None |
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21 |
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22 def encoding(name: String): Length = |
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23 name match { |
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24 case "UTF-8" => UTF8.Length |
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25 case "UTF-16" => Length |
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26 case "codepoints" => Codepoint.Length |
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27 case "symbols" => Symbol.Length |
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28 case _ => |
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29 error("Bad text encoding: " + name + " (expected UTF-8, UTF-16, codepoints, symbols)") |
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30 } |
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31 } |