update

Exercise 3/Lexer.c

@@ -9,27 +9,39 @@ int start(char* src) {
     return _STOP_;                          // stopping the state machine in any other case
 }
 
-int getNextCharacter(char* pos) {
-    if (isLetter(*pos)) {
-        return _READ_IDENTIFIER_;           // continues to read the identifier
-    }
+int getNextCharacter(char** ptr_current) {
+    char* pos = *ptr_current;
+    while(isWhiteSpace(*pos)) pos++;
+    if (isLetter(*pos)) return _READ_IDENTIFIER_;
+    if (isNum(*pos)) return _READ_NUM_LIT_;
+    if (isOperator(*pos)) return _READ_OPERATOR_;
     return _STOP_;                          // stopping the state machine in any other case
 }
 
-int readIdentifier(char* src) {
-    return _STOP_;                      // placeholder
+int readIdentifier(char** ptr_current) {
+    char* pos = *ptr_current;
+    printf("%c - Identifier\n", *pos);
+    pos++;
+    *ptr_current = pos;
+    return _GET_NEXT_CHARACTER_;
 }
 
-int readNumLit(char* src) {
-    return _STOP_;                      // placeholder
+int readNumLit(char** ptr_current) {
+    char* pos = *ptr_current;
+    printf("%c - Number\n", *pos);
+    return _GET_NEXT_CHARACTER_;
 }
 
-int readOperator(char* src) {
-    return _STOP_;                      // placeholder
+int readOperator(char** ptr_current) {
+    char* pos = *ptr_current;
+    printf("%c - Operator\n", *pos);
+    return _GET_NEXT_CHARACTER_;
 }
 
-int readPunctuation(char* src) {
-    return _STOP_;                      // placeholder
+int readPunctuation(char** ptr_current) {
+    char* pos = *ptr_current;
+    printf("%c - Punctuation\n", *pos);
+    return _GET_NEXT_CHARACTER_;
 }
 
 int isLetter(char in) {
@@ -45,3 +57,32 @@ int isLetter(char in) {
     }
     return 0;               // returning 0 if it's no letter
 }
+
+int isWhiteSpace(char in) {
+    if (in == ' ' || in == '\n') return 1;
+    return 0;
+}
+
+int isNum(char in) {
+    if (in >= '0' && in <= 0) return 1;
+    return 0;
+}
+
+int isOperator(char in) {
+    switch(in) {
+        case '=':
+            break;
+        case '*':
+            break;
+        case '+':
+            break;
+        default:
+            return 0;
+    }
+    return 1;
+}
+
+int isPunctuation(char in) {
+    if (in == ';') return 1;
+    return 0;
+}

Exercise 3/Lexer.h

@@ -18,10 +18,14 @@
 
 /* functions */
 int start(char*);
-int getNextCharacter(char*);
-int readIdentifier(char*);
-int readNumLit(char*);
-int readOperator(char*);
-int readPunctuation(char*);
+int getNextCharacter(char**);
+int readIdentifier(char**);
+int readNumLit(char**);
+int readOperator(char**);
+int readPunctuation(char**);
 int main();
 int isLetter(char);
+int isWhiteSpace(char);
+int isNum(char);
+int isOperator(char);
+int isPunctuation(char);

Exercise 3/TestLexer.c

@@ -6,9 +6,11 @@ int main() {
     // variables
     char* sourcecode = "index = 2 * count + 42;";               // input string
     int lexer_state = _START_;                                  // int var for the state machine
+    char* current_pos = sourcecode;
+    char** ptr_current = &current_pos;
 
     // checking var values
-    printf(sourcecode);                                         // printing the input string to check it
+    printf("%c\n", sourcecode);                                         // printing the input string to check it
 
     // main loop
     do {
@@ -17,19 +19,19 @@ int main() {
                 lexer_state = start(sourcecode);
                 break;
             case _GET_NEXT_CHARACTER_:
-                lexer_state = getNextCharacter(sourcecode);
+                lexer_state = getNextCharacter(ptr_current);
                 break;
             case _READ_IDENTIFIER_:
-                lexer_state = readIdentifier(sourcecode);
+                lexer_state = readIdentifier(ptr_current);
                 break;
             case _READ_NUM_LIT_:
-                lexer_state = readNumLit(sourcecode);
+                lexer_state = readNumLit(ptr_current);
                 break;
             case _READ_OPERATOR_:
-                lexer_state = readOperator(sourcecode);
+                lexer_state = readOperator(ptr_current);
                 break;
             case _READ_PUNCTUATION_:
-                lexer_state = readPunctuation(sourcecode);
+                lexer_state = readPunctuation(ptr_current);
                 break;
             default: lexer_state = _ERROR_;
         }