Finished Intepreter for now

recursiveDescentParsers/cplusplus/interpreter/.gitignore

+interpreter
+tmp.txt
+

recursiveDescentParsers/cplusplus/interpreter/Makefile

@@ -6,7 +6,7 @@
 
 
 PROGS := interpreter
-
+TESTFILES := testInput.txt testOutput.txt
 # Uncomment only one of the next two lines (choose your c++ compiler)
 # CC=g++
 CC := clang++
@@ -22,7 +22,7 @@ CFLAGS :=
 
 # Tell make that the following "targets" are "phony"
 # Cf. https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html#Phony-Targets
-.PHONY : all clean
+.PHONY : all clean test
 
 ##  Now, the targets -- the things that will get made!
 
@@ -32,5 +32,12 @@ $(PROGS): %: %.cpp
 	$(CC) -g $< $(CFLAGS) -o $@
 
 clean: 
-	$(RM) -fv *~ *.o $(PROGS)
+	$(RM) -v *~ *.o $(PROGS) tmp.txt
+
+test: $(PROGS) $(TESTFILES)
+	# "Running interpreter in test mode\n"
+	-./interpreter testInput.txt 2>&1 >tmp.txt
+	# "Checking output -- no news is good news!\n"
+	diff testOutput.txt tmp.txt
+	-rm tmp.txt
 

recursiveDescentParsers/cplusplus/interpreter/interpreter.cpp

@@ -48,6 +48,17 @@ static int	currentTokenLength = 0;
 static Token next_token; // again with the global variables... 
 static numberType currentNumber; // = zero....
 
+static void printErrorMsg( const std::string Error )
+{
+	std::cout << "ERROR on line " << currentLineNumber
+	          << ", column " << currentColumnNumber << " : " 
+	          << Error << std::endl;
+	std::cout << currentLine;
+	for ( int col = 0; col < currentColumnNumber-1; col++ )
+		std::cout << '-';
+	std::cout << '^' << std::endl;
+} // end printErrorMsg
+
 // The Lexer
 // ==========
 static bool skippedWhiteSpace( ) { // return true if not at EOF, i.e. if skipped
@@ -123,7 +134,81 @@ static Token gettok( ) {
 // Note that the recursive descent function for (e.g.) E´ 
 // is nameded "E2ndHalf"-
 
+// Forward Declarations
+static numberType E();
+static numberType E2ndHalf();
+static numberType T();
+static numberType T2ndHalf();
+static numberType F();
+
+// 	E	→ T E´
+numberType E() { return T() + E2ndHalf(); }
+
+// 	T	→ F T´
+numberType T() { return F() * T2ndHalf(); }
+
+// 	E´	→ + T E´  | - T E´ | ε
+numberType E2ndHalf() {
+    switch ( next_token ) {
+		case tok_plus : 
+			next_token = gettok(); // eat +
+            return T() + E2ndHalf();
+
+		case tok_minus : 
+			next_token = gettok(); // eat -
+			return (-1.0 * T()) + E2ndHalf();
 
+		default : 
+			return 0.0;
+    }; 
+} // end E2ndHalf
+
+// 	T´	→ * F T´  |  / F T´  |  ε
+numberType  T2ndHalf() { 
+	numberType tmp, rhs, acc;
+    switch ( next_token ) {
+		case tok_times : 
+			next_token = gettok(); // eat *
+			return F() * T2ndHalf();
+    case tok_div : 
+		next_token = gettok(); // eat /
+		tmp = F();
+		if ( 0.0 != tmp ) 
+			return (1.0/tmp) * T2ndHalf();
+		// else if T() returned zero
+		printErrorMsg( "Division by zero!" );
+		// fall through to default return one
+        
+    default : 
+		return 1.0;
+    }; 
+} // end T2ndHalf
+
+// 	F	→ ( E ) | num
+numberType  F() {
+	numberType result = 0; 
+    switch ( next_token ) {
+		case tok_lparen : 
+			next_token = gettok(); // eat lparen
+            result = E();
+            if ( tok_rparen == next_token ) {
+				next_token = gettok(); // eat rparen
+                return result;
+			}; 
+			// else if rparen not found
+            printErrorMsg( "Expected Right Parenthesis" );
+            return 0.0;
+
+		case tok_number : 
+			result = currentNumber; // side-effect of last gettok() 
+            next_token = gettok(); // eat id
+            return result;
+
+		default : 
+			printErrorMsg( "Expected Left Parenthesis or number" );
+            return 0.0;
+    }; 
+}
 
 
 // main (!)
@@ -148,12 +233,12 @@ int main( int argc, char **argv ) {
 	
 	// get tokens and dump them... 
 	while ( tok_eof != next_token ) {
-		std::cout << "TOKEN = " << (char)next_token 
-				  << " current num = " << currentNumber
-				  << std::endl;
-		next_token = gettok();
+		std::cout << currentLineNumber << ":" 
+		          << currentLine << std::endl;
+		numberType value = E( );
+		std::cout << "INTERPRETER: " << value << std::endl;
 	};
-	std::cout << "EOF" << std::endl;
+	std::cout << "End Of File!" << std::endl;
 	
 	return 0; // Alles klar!!!
 }

recursiveDescentParsers/cplusplus/interpreter/testInput.txt

+42
+40 + 2
+(44.44 - 2.44)
+(21 * 2.0)
+(84.0 / (3-1))
+88 / 2 - 2
+88 / (8 / 4) - 2
+44.0 - 2
+(4 * 11.0) - 2
+(8 * 11.0) / 2 - 2
+(8 * 11.0) / (8 / 4) - 2

recursiveDescentParsers/cplusplus/interpreter/testOutput.txt

+0:42
+INTERPRETER: 42
+1:40 + 2
+INTERPRETER: 42
+2:(44.44 - 2.44)
+INTERPRETER: 42
+3:(21 * 2.0)
+INTERPRETER: 42
+4:(84.0 / (3-1))
+INTERPRETER: 42
+5:88 / 2 - 2
+INTERPRETER: 42
+6:88 / (8 / 4) - 2
+INTERPRETER: 42
+7:44.0 - 2
+INTERPRETER: 42
+8:(4 * 11.0) - 2
+INTERPRETER: 42
+9:(8 * 11.0) / 2 - 2
+INTERPRETER: 42
+10:(8 * 11.0) / (8 / 4) - 2
+INTERPRETER: 42
+End Of File!