Fixed some bugs.
[llvm/zpu.git] / examples / OCaml-Kaleidoscope / Chapter7 / lexer.ml
blob922cabf0428141badf130e7e91bab9ff07783d3d
1 (*===----------------------------------------------------------------------===
2 * Lexer
3 *===----------------------------------------------------------------------===*)
5 let rec lex = parser
6 (* Skip any whitespace. *)
7 | [< ' (' ' | '\n' | '\r' | '\t'); stream >] -> lex stream
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
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
21 (* Comment until end of line. *)
22 | [< ' ('#'); stream >] ->
23 lex_comment stream
25 (* Otherwise, just return the character as its ascii value. *)
26 | [< 'c; stream >] ->
27 [< 'Token.Kwd c; lex stream >]
29 (* end of stream. *)
30 | [< >] -> [< >]
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 >]
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 | "if" -> [< 'Token.If; stream >]
48 | "then" -> [< 'Token.Then; stream >]
49 | "else" -> [< 'Token.Else; stream >]
50 | "for" -> [< 'Token.For; stream >]
51 | "in" -> [< 'Token.In; stream >]
52 | "binary" -> [< 'Token.Binary; stream >]
53 | "unary" -> [< 'Token.Unary; stream >]
54 | "var" -> [< 'Token.Var; stream >]
55 | id -> [< 'Token.Ident id; stream >]
57 and lex_comment = parser
58 | [< ' ('\n'); stream=lex >] -> stream
59 | [< 'c; e=lex_comment >] -> e
60 | [< >] -> [< >]