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