added support for comments in .while files

Author: felixbd

README.org

@@ -35,6 +35,8 @@ $S = Prog$
 
 $P = \{$
 
+$Prog \to // comment \dots$
+
 $Prog \to Prog; Prog$
 
 $Prog \to Var := Expr$
@@ -83,11 +85,17 @@ cat ./examples/multiplication-func.while
 
 #+RESULTS:
 #+begin_example
+// init var state
 rv := 0;
 a := 420;
 b := 69;
 
+// loop will be exec b-times
 while b != 0 do
+
+    // calculate rv += a (b-times)
+    //  -> a * b = a + a + ... b-times
+
     temp := rv;
     loop a do temp := temp + 1 end;
     rv := temp;

examples/multiplication-func.while

@@ -1,8 +1,14 @@
+// init var state
 rv := 0;
 a := 420;
 b := 69;
 
+// loop will be exec b-times
 while b != 0 do
+
+    // calculate rv += a
+    //  -> a * b = a + a + ... (b-times)
+
     temp := rv;
     loop a do temp := temp + 1 end;
     rv := temp;

src/WhileParser.hs

@@ -20,8 +20,8 @@ module WhileParser
 
 import Control.Applicative
 import Control.Monad
-import Data.Char (isDigit, isAlpha)
-import Data.List (stripPrefix)
+import Data.Char (isDigit, isAlpha, isSpace)
+import Data.List (stripPrefix, isPrefixOf)
 
 data Token = VarToken { getVarName :: String }  -- e.g. x_1 (has to start with letter - can contain digit and '_')
            | ConstToken { getConstInt :: Int }   -- e.g. 5 (positive int with 0 only)
@@ -116,7 +116,9 @@ tokenParser t = Parser $ \case
 readFileContent :: FilePath -> IO [(LineNum, String)]
 readFileContent filePath = putStrLn ("\ESC[92m[READING .WHILE FILE]\ESC[0m " ++ show filePath)
                                 >> readFile filePath
-                                >>= \c -> return $ zip [1..] (lines c)
+                                >>= \c -> return $ filterComments $ zip [1..] (lines c)
+  where
+    filterComments = filter (not . isPrefixOf "//" . dropWhile isSpace . snd)
 
 -- begin parser expression ----------------------------------------------------