Initial commit: parser for tiny subset of SCADE language...

1 files changed, 105 insertions, 0 deletions

diff --git a/frontend/lexer.mll b/frontend/lexer.mll
new file mode 100644
index 0000000..9d6c208
--- /dev/null
+++ b/frontend/lexer.mll
@@ -0,0 +1,105 @@
+{
+    open Lexing
+    open Ast
+    open Parser
+
+    let kwd_table = Hashtbl.create 10
+    let () =
+        List.iter (fun (a, b) -> Hashtbl.add kwd_table a b)
+        [
+            "bool",     BOOL;
+            "int",      INT;
+            "real",     REAL;
+
+            "const",    CONST;
+            "node",     NODE;
+            "returns",  RETURNS;
+            "var",      VAR;
+            "let",      LET;
+            "tel",      TEL;
+
+            "if",       IF;
+            "then",     THEN;
+            "else",     ELSE;
+            "pre",      PRE;
+            "not",      NOT;
+            "and",      AND;
+            "or",       OR;
+            "mod",      MOD;
+
+            "true",     TRUE;
+            "false",    FALSE;
+
+            "assume",   ASSUME;
+            "guarantee",GUARANTEE;
+            "probe",    PROBE;
+        ]
+
+}
+
+
+(* special character classes *)
+let space = [' ' '\t' '\r']+
+let newline = "\n" | "\r" | "\r\n"
+
+(* utilities *)
+let digit = ['0'-'9']
+let digit_ = ['0'-'9' '_']
+
+(* integers *)
+let int_dec = digit digit_*
+let int_bin = ("0b" | "0B") ['0'-'1'] ['0'-'1' '_']*
+let int_oct = ("0o" | "0O") ['0'-'7'] ['0'-'7' '_']*
+let int_hex = ("0x" | "0X") ['0'-'9' 'a'-'f' 'A'-'F'] ['0'-'9' 'a'-'f' 'A'-'F' '_']*
+let const_int = int_bin | int_oct | int_dec | int_hex
+
+(* tokens *)
+rule token = parse
+
+(* identifier (TOK_id) or reserved keyword *)
+| ['a'-'z' 'A'-'Z' '_'] ['a'-'z' 'A'-'Z' '0'-'9' '_']* as id
+{ try Hashtbl.find kwd_table id with Not_found -> IDENT id }
+
+(* symbols *)
+| "("    { LPAREN }
+| ")"    { RPAREN }
+| "{"    { LCURLY }
+| "}"    { RCURLY }
+| "*"    { STAR }
+| "+"    { PLUS }
+| "-"    { MINUS }
+| "!"    { EXCLAIM }
+| "/"    { DIVIDE }
+| "%"    { PERCENT }
+| "<"    { LESS }
+| ">"    { GREATER }
+| "<="   { LESS_EQUAL }
+| ">="   { GREATER_EQUAL }
+| "=="   { EQUAL_EQUAL }
+| "<>"   { DIFF }
+| "&&"   { AND_AND }
+| "||"   { BAR_BAR }
+| ";"    { SEMICOLON }
+| ":"    { COLON }
+| ","    { COMMA }
+| "="    { EQUAL }
+| "->"   { ARROW }
+
+(* literals *)
+| const_int    as c { INTVAL c }
+
+(* spaces, comments *)
+| "(*" { comment lexbuf; token lexbuf }
+| "--" [^ '\n' '\r']* { token lexbuf }
+| newline { new_line lexbuf; token lexbuf }
+| space { token lexbuf }
+
+(* end of files *)
+| eof { EOF }
+
+
+(* nested comments (handled recursively)  *)
+and comment = parse
+| "*)" { () }
+| [^ '\n' '\r'] { comment lexbuf }
+| newline { new_line lexbuf; comment lexbuf }