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annotate examples/OCaml-Kaleidoscope/Chapter4/lexer.ml @ 0:95c75e76d11b

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LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
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1 (*===----------------------------------------------------------------------===
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2 * Lexer
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3 *===----------------------------------------------------------------------===*)
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4
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5 let rec lex = parser
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6 (* Skip any whitespace. *)
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7 | [< ' (' ' | '\n' | '\r' | '\t'); stream >] -> lex stream
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8
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9 (* identifier: [a-zA-Z][a-zA-Z0-9] *)
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10 | [< ' ('A' .. 'Z' | 'a' .. 'z' as c); stream >] ->
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11 let buffer = Buffer.create 1 in
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12 Buffer.add_char buffer c;
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13 lex_ident buffer stream
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14
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15 (* number: [0-9.]+ *)
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16 | [< ' ('0' .. '9' as c); stream >] ->
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17 let buffer = Buffer.create 1 in
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18 Buffer.add_char buffer c;
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19 lex_number buffer stream
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20
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21 (* Comment until end of line. *)
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22 | [< ' ('#'); stream >] ->
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23 lex_comment stream
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24
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25 (* Otherwise, just return the character as its ascii value. *)
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26 | [< 'c; stream >] ->
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27 [< 'Token.Kwd c; lex stream >]
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28
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29 (* end of stream. *)
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30 | [< >] -> [< >]
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31
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32 and lex_number buffer = parser
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33 | [< ' ('0' .. '9' | '.' as c); stream >] ->
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34 Buffer.add_char buffer c;
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35 lex_number buffer stream
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36 | [< stream=lex >] ->
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37 [< 'Token.Number (float_of_string (Buffer.contents buffer)); stream >]
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38
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39 and lex_ident buffer = parser
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40 | [< ' ('A' .. 'Z' | 'a' .. 'z' | '0' .. '9' as c); stream >] ->
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41 Buffer.add_char buffer c;
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42 lex_ident buffer stream
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43 | [< stream=lex >] ->
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44 match Buffer.contents buffer with
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45 | "def" -> [< 'Token.Def; stream >]
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46 | "extern" -> [< 'Token.Extern; stream >]
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47 | id -> [< 'Token.Ident id; stream >]
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48
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49 and lex_comment = parser
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50 | [< ' ('\n'); stream=lex >] -> stream
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51 | [< 'c; e=lex_comment >] -> e
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52 | [< >] -> [< >]