Code refactor and update readme

readme.md

@@ -12,13 +12,22 @@ dub --compiler=ldc
 
 # Usage
 
+### Use in command line
+
 ```
 Usage: calcool [OPTION] [ARGUMENT]
         -h : Print this help message
         -i : Set input file (each expression in a separate line)
         -c : Calculate the given expression
 ```
 
+### Use as a library
+
+```d
+auto p = new Prser();
+string result = p.evaluateFromString("sin(45*2) - 22 * -exp(3)");
+```
+
 # License
 
 GPL-3.0+

source/app.d

@@ -50,7 +50,10 @@ void run(ref Parser p) {
 			stderr.writeln(u.msg);
 		} catch (EolException e) {
 			continue;
+		} catch (EofException e) {
+			break;
 		} catch (Exception e) {
+			stderr.writefln("Error: %s", e.msg);
 			break;
 		}
 	}
@@ -63,15 +66,19 @@ int run(ref Parser p, string input) {
 		p.evaluateFromString(input).writeln();
 	} catch (ParseException p) {
 		stderr.writefln("Parser error: %s", p.msg);
+		return 1;
 	} catch (LexerException l) {
 		stderr.writefln("Lexer error: %s", l.msg);
+		return 2;
 	} catch (UnsupportedTokenException u) {
 		stderr.writeln(u.msg);
+		return 3;
 	} catch (EolException e) {
 		return 0;
+	} catch (EofException e) {
+		return 0;
 	} catch (Exception e) {
-		return 1;
+		return 4;
 	}
-	return 1;
-
+	return 0;
 }

source/calcool/exceptions.d

@@ -21,6 +21,12 @@ class EolException : Exception {
     }
 }
 
+class EofException : Exception {
+    this(string msg) {
+        super(msg);
+    }
+}
+
 class LexerException : Exception {
     this(string msg) {
         super(msg);

source/calcool/parser.d

@@ -53,7 +53,7 @@ public:
         if (input.length == 0) {
             input = lexer.nextLine();
             if (input.length == 0) {
-                throw new Exception("END OF INPUT");
+                throw new EofException("END OF INPUT");
             }
         }
         const f = input.front();