1 files changed, 56 insertions, 0 deletions
diff --git a/Source/Forro/Lexer.fsl b/Source/Forro/Lexer.fsl
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+++ b/Source/Forro/Lexer.fsl
@@ -0,0 +1,56 @@
+{
+module Lexer
+open System
+open Parser
+open Microsoft.FSharp.Text.Lexing
+}
+
+// These are some regular expression definitions
+let digit = ['0'-'9']
+let nondigit = [ 'a'-'z' 'A'-'Z' '_' ]
+let idchar = (nondigit | digit)
+let whitespace = [' ' '\t' ]
+let newline = ('\n' | '\r' '\n')
+
+rule tokenize = parse
+| whitespace    { tokenize lexbuf }
+| newline       { tokenize lexbuf }
+// operators
+| "=="          { EQ }
+| "!="          { NEQ }
+| "+"           { PLUS }
+| "-"           { MINUS }
+| "*"           { STAR }
+| "<"           { LESS }
+| "<="          { ATMOST }
+| "and"         { AND }
+| "or"          { OR }
+| "not"         { NOT }
+| "old"         { OLD }
+| "."           { DOT }
+// misc
+| "("           { LPAREN }
+| ")"           { RPAREN }
+| ";"           { SEMI }
+| ":="          { ASSIGN }
+// keywords
+| "procedure"   { PROCEDURE }
+| "requires"    { REQUIRES }
+| "ensures"     { ENSURES }
+| "do"          { DO }
+| "end"         { END }
+| "new"         { NEW }
+| "if"          { IF }
+| "then"        { THEN }
+| "else"        { ELSE }
+| "while"       { WHILE }
+| "invariant"   { INVARIANT }
+| "call"        { CALL }
+| "assert"      { ASSERT }
+// literals
+| ['-']?digit+  { INT32 (Int32.Parse(LexBuffer<char>.LexemeString lexbuf)) }
+| "null"        { NULL }
+// identifiers
+| idchar+       { ID (LexBuffer<char>.LexemeString lexbuf) }
+// EOF
+| eof   { EOF }