diff --git a/recursiveDescentParsers/cplusplus/interpreter/.gitignore b/recursiveDescentParsers/cplusplus/interpreter/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..dd56fba1f7d6b29681d74e8c2ac55afc270dc52b
--- /dev/null
+++ b/recursiveDescentParsers/cplusplus/interpreter/.gitignore
@@ -0,0 +1,3 @@
+interpreter
+tmp.txt
+
diff --git a/recursiveDescentParsers/cplusplus/interpreter/Makefile b/recursiveDescentParsers/cplusplus/interpreter/Makefile
index fd54984efa8f29c2ddfa4be5b66f752ceeb96c72..f41bbbcabdec7d4c41c9818ea1c74078aecb8ac2 100644
--- a/recursiveDescentParsers/cplusplus/interpreter/Makefile
+++ b/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
diff --git a/recursiveDescentParsers/cplusplus/interpreter/interpreter b/recursiveDescentParsers/cplusplus/interpreter/interpreter
deleted file mode 100755
index 066ac63171237fe93a4d8312b1af2aa713881b14..0000000000000000000000000000000000000000
Binary files a/recursiveDescentParsers/cplusplus/interpreter/interpreter and /dev/null differ
diff --git a/recursiveDescentParsers/cplusplus/interpreter/interpreter.cpp b/recursiveDescentParsers/cplusplus/interpreter/interpreter.cpp
index 5996dd5844aad6e7105d34e19e394bfc535034c0..c481e21910b2a1b85ad5d2b14a10fe9f729df087 100644
--- a/recursiveDescentParsers/cplusplus/interpreter/interpreter.cpp
+++ b/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!!!
}
diff --git a/recursiveDescentParsers/cplusplus/interpreter/testInput.txt b/recursiveDescentParsers/cplusplus/interpreter/testInput.txt
new file mode 100644
index 0000000000000000000000000000000000000000..7c49594be4b299e555ffbe7865109c33dcbf9497
--- /dev/null
+++ b/recursiveDescentParsers/cplusplus/interpreter/testInput.txt
@@ -0,0 +1,11 @@
+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
diff --git a/recursiveDescentParsers/cplusplus/interpreter/testOutput.txt b/recursiveDescentParsers/cplusplus/interpreter/testOutput.txt
new file mode 100644
index 0000000000000000000000000000000000000000..91ba1de4c0c4203951ea6357145c1320be54bad6
--- /dev/null
+++ b/recursiveDescentParsers/cplusplus/interpreter/testOutput.txt
@@ -0,0 +1,23 @@
+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!