Metadata parser.

[virt-top.git] / virt-df / virt_df_lvm2_lexer.mll

diff --git a/virt-df/virt_df_lvm2_lexer.mll b/virt-df/virt_df_lvm2_lexer.mll
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+(* 'df' command for virtual domains.
+   (C) Copyright 2007-2008 Richard W.M. Jones, Red Hat Inc.
+   http://libvirt.org/
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *)
+
+(* Scanner for LVM2 metadata.
+ * ocamllex tutorial:
+ * http://plus.kaist.ac.kr/~shoh/ocaml/ocamllex-ocamlyacc/ocamllex-tutorial/
+ *)
+
+{
+  open Printf
+  open Lexing
+
+  open Virt_df
+  open Virt_df_lvm2_parser
+
+  (* Temporary buffer used for parsing strings, etc. *)
+  let tmp = Buffer.create 80
+
+  exception Error of string
+}
+
+let digit = ['0'-'9']
+let alpha = ['a'-'z' 'A'-'Z']
+let alphau = ['a'-'z' 'A'-'Z' '_']
+let alnum = ['a'-'z' 'A'-'Z' '0'-'9']
+let alnumu = ['a'-'z' 'A'-'Z' '0'-'9' '_']
+let ident = alphau alnumu*
+
+let whitespace = [' ' '\t' '\r' '\n']+
+
+let escaped_char = '\\' _
+
+rule token = parse
+  (* ignore whitespace and comments *)
+  | whitespace
+  | '#' [^ '\n']*
+      { token lexbuf }
+
+  (* scan single character tokens *)
+  | '{'  { LBRACE }
+  | '}'  { RBRACE }
+  | '['  { LSQUARE }
+  | ']'  { RSQUARE }
+  | '='  { EQ }
+  | ','  { COMMA }
+
+  (* strings - see LVM2/lib/config/config.c *)
+  | '"'
+      {
+       Buffer.reset tmp;
+       STRING (dq_string lexbuf)
+      }
+  | '\''
+      {
+       Buffer.reset tmp;
+       STRING (dq_string lexbuf)
+      }
+
+  (* floats *)
+  | ('-'? digit+ '.' digit*) as f
+      {
+       let f = float_of_string f in
+       FLOAT f
+      }
+
+  (* integers *)
+  | ('-'? digit+) as i
+      {
+       let i = Int64.of_string i in
+       INT i
+      }
+
+  (* identifiers *)
+  | ident as id
+      { IDENT id }
+
+  (* end of file *)
+  | eof
+      { EOF }
+
+  | _ as c
+      { raise (Error (sprintf "%c: invalid character in input" c)) }
+
+and dq_string = parse
+  | '"'
+      { Buffer.contents tmp }
+  | escaped_char as str
+      { Buffer.add_char tmp str.[1]; dq_string lexbuf }
+  | eof
+      { raise (Error "unterminated string in metadata") }
+  | _ as c
+      { Buffer.add_char tmp c; dq_string lexbuf }
+
+and q_string = parse
+  | '\''
+      { Buffer.contents tmp }
+  | escaped_char as str
+      { Buffer.add_char tmp str.[1]; q_string lexbuf }
+  | eof
+      { raise (Error "unterminated string in metadata") }
+  | _ as c
+      { Buffer.add_char tmp c; q_string lexbuf }
+
+{
+  (* Demonstration of how to wrap the token function
+     with extra debugging statements:
+  let token lexbuf =
+    try
+      let r = token lexbuf in
+      if debug then
+       eprintf "Lexer: token returned is %s\n"
+         (match r with
+          | LBRACE -> "LBRACE"
+          | RBRACE -> "RBRACE"
+          | LSQUARE -> "LSQUARE"
+          | RSQUARE -> "RSQUARE"
+          | EQ -> "EQ"
+          | COMMA -> "COMMA"
+          | STRING s -> sprintf "STRING(%S)" s
+          | INT i -> sprintf "INT(%Ld)" i
+          | FLOAT f -> sprintf "FLOAT(%g)" f
+          | IDENT s -> sprintf "IDENT(%s)" s
+           | EOF -> "EOF");
+      r
+    with
+      exn ->
+       prerr_endline (Printexc.to_string exn);
+       raise exn
+  *)
+
+  (* Lex and parse input.
+   *
+   * Return the parsed metadata structure if everything went to plan.
+   * Raises [Error msg] if there was some parsing problem.
+   *)
+  let rec parse_lvm2_metadata_from_string str =
+    let lexbuf = Lexing.from_string str in
+    parse_lvm2_metadata lexbuf
+  and parse_lvm2_metadata_from_channel chan =
+    let lexbuf = Lexing.from_channel chan in
+    parse_lvm2_metadata lexbuf
+  and parse_lvm2_metadata lexbuf =
+    try
+      input token lexbuf
+    with
+    | Error _ as exn -> raise exn
+    | Parsing.Parse_error -> raise (Error "Parse error")
+    | exn -> raise (Error ("Exception: " ^ Printexc.to_string exn))
+}