Mercurial > urweb
view src/utf8.sml @ 2274:0730e217fc9c
First draft of more specific formulas for queries.
author | Ziv Scully <ziv@mit.edu> |
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date | Thu, 05 Nov 2015 01:48:42 -0500 |
parents | 1c9f8f06c1d6 |
children |
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(* Copyright (c) 2011, Adam Chlipala * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * - Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * - The names of contributors may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. *) (* UTF-8 conversion *) structure Utf8 :> UTF8 = struct fun byte n = str (chr (Word.toInt n)) fun encode n = if n <= 0 then raise Fail "Invalid character to UTF-8-encode" else if n <= 0x7F then str (chr n) else if n <= 0x7FF then let val w = Word.fromInt n val b1 = Word.orb (Word.fromInt (128 + 64), Word.>> (w, Word.fromInt 6)) val b2 = Word.orb (Word.fromInt 128, Word.andb (w, Word.fromInt 63)) in byte b1 ^ byte b2 end else if n <= 0xFFFF then let val w = Word.fromInt n val b1 = Word.orb (Word.fromInt (128 + 64 + 32), Word.>> (w, Word.fromInt 12)) val b2 = Word.orb (Word.fromInt 128, Word.andb (Word.>> (w, Word.fromInt 6), Word.fromInt 63)) val b3 = Word.orb (Word.fromInt 128, Word.andb (w, Word.fromInt 63)) in byte b1 ^ byte b2 ^ byte b3 end else raise Fail "Exceeded supported range for UTF-8 characters" end