{- BNF Converter: C# GPLEX Generator Copyright (C) 2006 Author: Johan Broberg Modified from CFtoFlex 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA -} {- ************************************************************** BNF Converter Module Description : This module generates the GPLEX file. Author : Johan Broberg (johan@pontemonti.com) License : GPL (GNU General Public License) Created : 23 November, 2006 Modified : 17 December, 2006 by Johan Broberg ************************************************************** -} module CFtoGPLEX (cf2gplex) where import CF import RegToGPLEX import Utils((+++), (++++)) import NamedVariables import Data.List import CSharpUtils --The environment must be returned for the parser to use. cf2gplex :: Namespace -> CF -> (String, SymEnv) cf2gplex namespace cf = (unlines [ prelude namespace, cMacros, prettyprinter $ (lexSymbols env) ++ (gplex namespace cf env'), "%%" ], env') where env = makeSymEnv (symbols cf ++ reservedWords cf) (0 :: Int) env' = env ++ (makeSymEnv (fst (unzip (tokenPragmas cf))) (length env)) -- GPPG doesn't seem to like tokens beginning with an underscore, so they (the underscores, nothing else) have been removed. makeSymEnv [] _ = [] makeSymEnv (s:symbs) n = (s, "SYMB_" ++ (show n)) : (makeSymEnv symbs (n+1)) prelude :: Namespace -> String prelude namespace = unlines [ "/* This GPLex file was machine-generated by the BNF converter */", "", "%namespace " ++ namespace, "", "%{", " /// ", " /// Buffer for escaped characters in strings.", " /// ", " private System.Text.StringBuilder strBuffer = new System.Text.StringBuilder();", "", " /// ", " /// Change to enable output - useful for debugging purposes", " /// ", " public bool Trace = false;", "", " /// ", " /// Culture-independent IFormatProvider for numbers. ", " /// This is just a \"wrapper\" for System.Globalization.NumberFormatInfo.InvariantInfo.", " /// ", " /// ", " /// This should be used when parsing numbers. Otherwise the parser might fail: ", " /// culture en-US uses a dot as decimal separator, while for example sv-SE uses a comma. ", " /// BNFC uses dot as decimal separator for Double values, so if your culture is sv-SE ", " /// the parse will fail if this InvariantInfo isn't used.", " /// ", " private static System.Globalization.NumberFormatInfo InvariantFormatInfo = System.Globalization.NumberFormatInfo.InvariantInfo;", "", " /// ", " /// Convenience method to create scanner AND initialize it correctly.", " /// As long as you don't want to enable trace output, this is all you ", " /// need to call and give to the parser to be able to parse.", " /// ", " public static Scanner CreateScanner(Stream stream)", " {", " Scanner scanner = new Scanner(stream);", " scanner.Begin();", " return scanner;", " }", "", " /// ", " /// Sets the scanner to the correct initial state (YYINITIAL). ", " /// You should call this method prior to calling parser.Parse().", " /// ", " public void Begin()", " {", " BEGIN(YYINITIAL);", " }", "", " /// ", " /// Convenience method to \"reset\" the buffer for escaped characters in strings.", " /// ", " private void BufferReset()", " {", " this.strBuffer = new System.Text.StringBuilder();", " }", "", "%}", "" ] --For now all categories are included. --Optimally only the ones that are used should be generated. cMacros :: String cMacros = unlines [ "alpha [a-zA-Z]", "alphaCapital [A-Z]", "alphaSmall [a-z]", "digit [0-9]", "ident [a-zA-Z0-9'_]", -- start states, must be defined one at a time "%s YYINITIAL", "%s COMMENT", "%s CHAR", "%s CHARESC", "%s CHAREND", "%s STRING", "%s ESCAPED", "%%" ] lexSymbols :: SymEnv -> [(String, String)] lexSymbols ss = map transSym ss where transSym (s,r) = ("\"" ++ s' ++ "\"" , "if(Trace) System.Console.Error.WriteLine(yytext); return (int)Tokens." ++ r ++ ";") where s' = escapeChars s gplex :: Namespace -> CF -> SymEnv -> [(String, String)] gplex namespace cf env = concat [ lexComments (comments cf), userDefTokens, ifC "String" strStates, ifC "Char" charStates, ifC "Double" [("{digit}+\".\"{digit}+(\"e\"(\\-)?{digit}+)?" , "if(Trace) System.Console.Error.WriteLine(yytext); yylval.double_ = Double.Parse(yytext, InvariantFormatInfo); return (int)Tokens.DOUBLE_;")], ifC "Integer" [("{digit}+" , "if(Trace) System.Console.Error.WriteLine(yytext); yylval.int_ = Int32.Parse(yytext, InvariantFormatInfo); return (int)Tokens.INTEGER_;")], ifC "Ident" [("{alpha}{ident}*" , "if(Trace) System.Console.Error.WriteLine(yytext); yylval.string_ = yytext; return (int)Tokens.IDENT_;")], [("[ \\t\\r\\n\\f]" , "/* ignore white space. */;")], [("." , "return (int)Tokens.error;")] ] where ifC cat s = if isUsedCat cf cat then s else [] userDefTokens = map tokenline (tokenPragmas cf) where tokenline (name, exp) = ("" ++ printRegGPLEX exp , action name) action n = "if(Trace) System.Console.Error.WriteLine(yytext); yylval." ++ varName (normCat n) ++ " = new " ++ identifier namespace n ++ "(yytext); return (int)Tokens." ++ sName n ++ ";" sName n = case lookup n env of Just x -> x Nothing -> n -- These handle escaped characters in Strings. strStates = [ ("\"\\\"\"" , "BEGIN(STRING);"), ("\\\\" , "BEGIN(ESCAPED);"), ("\\\"" , "yylval.string_ = this.strBuffer.ToString(); BufferReset(); BEGIN(YYINITIAL); return (int)Tokens.STRING_;"), ("." , "this.strBuffer.Append(yytext);"), ("n" , "this.strBuffer.Append(\"\\n\"); BEGIN(STRING);"), ("\\\"" , "this.strBuffer.Append(\"\\\"\"); BEGIN(STRING);"), ("\\\\" , "this.strBuffer.Append(\"\\\\\"); BEGIN(STRING);"), ("t" , "this.strBuffer.Append(\"\\t\"); BEGIN(STRING);"), ("." , "this.strBuffer.Append(yytext); BEGIN(STRING);") ] -- These handle escaped characters in Chars. charStates = [ ("\"'\"" , "BEGIN(CHAR);"), ("\\\\" , "BEGIN(CHARESC);"), ("[^']" , "BEGIN(CHAREND); yylval.char_ = yytext[0]; return (int)Tokens.CHAR_;"), ("n" , "BEGIN(CHAREND); yylval.char_ = '\\n'; return (int)Tokens.CHAR_;"), ("t" , "BEGIN(CHAREND); yylval.char_ = '\\t'; return (int)Tokens.CHAR_;"), ("." , "BEGIN(CHAREND); yylval.char_ = yytext[0]; return (int)Tokens.CHAR_;"), ("\"'\"" , "BEGIN(YYINITIAL);") ] lexComments :: ([(String, String)], [String]) -> [(String, String)] lexComments (m,s) = (map lexSingleComment s) ++ (concatMap lexMultiComment m) lexSingleComment :: String -> (String, String) lexSingleComment c = ("\"" ++ c ++ "\"[^\\n]*\\n" , "/* BNFC single-line comment */;") --There might be a possible bug here if a language includes 2 multi-line comments. --They could possibly start a comment with one character and end it with another. --However this seems rare. lexMultiComment :: (String, String) -> [(String, String)] lexMultiComment (b,e) = [ ("\"" ++ b ++ "\"" , "BEGIN(COMMENT);"), ("\"" ++ e ++ "\"" , "BEGIN(YYINITIAL);"), ("." , "/* BNFC multi-line comment */;"), ("[\\n]" , "/* BNFC multi-line comment */;") ] -- Used to print the lexer rules; makes sure that all rules are equally indented, to make the GPLEX file a little more readable. prettyprinter :: [(String, String)] -> String prettyprinter xs = unlines $ map prettyprinter' xs where padlength = 1 + (last $ sort $ map length $ map fst xs) prettyprinter' (x, y) = x ++ replicate (padlength - length x) ' ' ++ y