Parser refactoring

src/compiler/compiler.go

@@ -7,7 +7,7 @@ import (
 	"strings"
 )
 
-var automata map[TokenType][]TokenType 
+type Question interface {}
 
 type SingleAnswerQuestion struct {
 	id string;
@@ -21,33 +21,41 @@ type Choice struct {
 	isCorrect bool;
 }
 
-type ChoiceQuestion struct {
+type MultipleChoiceQuestion struct {
 	id string;
 	question string;
 	choices []Choice;
 	section string;
 }
 
-type Question interface {}
+type QuestionElement struct {
+	isDash bool;
+	content string;
+} 
 
-func main() {
-	log.Println("Compilation started")
+var automata map[TokenType][]TokenType 
 
-	file, err := os.ReadFile("/home/jorenchik/Code/mdemory/src/compiler/input.mdem")
-	if (err != nil) { 
-		log.Fatalf("Cannot open the input file: %s", err.Error())
-		return
-	}
-	fileContents := string(file)
+type CompilerErr struct {
+	message string;	
+	row	     int32;
+	column   int32;
+}
 
-	tokens, err := tokenize([]rune(fileContents))
-	if (err != nil) {
-		fmt.Printf("%s\n", err.Error())	
-		return
-	}
+func (e CompilerErr) Error() string {
+	return fmt.Sprintf("%d:%d - %s", e.row, e.column, e.message)
+}
 
-	// defineParserAutomata 
-	automata = make(map[TokenType][]TokenType)
+func contains(s []TokenType, e TokenType) bool {
+    for _, a := range s {
+        if a == e {
+            return true
+        }
+    }
+    return false
+}
+
+func parserAutomata() map[TokenType][]TokenType {
+	automata := make(map[TokenType][]TokenType)
 	automata[TextFragment] = []TokenType{
 		QuestionEnd, ElementDashStart, ElementPlusStart, SectionIdentifierStart, SectionStart, EOF, SectionEnd,
 	}
@@ -82,8 +90,10 @@ func main() {
 		ElementDashStart, SectionIdentifierStart, EOF,
 	}
 	automata[EOF] = []TokenType{}
-	
-	// validateGrammar
+	return automata
+}
+
+func validateGrammar() error {
 	for i := 0; i < len(tokens) - 1; i++ {
 		token := tokens[i]
 		content := token.content
@@ -112,16 +122,21 @@ func main() {
 			fmt.Print("\n:")
 		}
 		if (!contains(automata[token.tokenType], nextToken.tokenType)) {
-			fmt.Printf(
-				"Token %s cannot precede %s\n",
-				ToString(&token.tokenType),
-				ToString(&nextToken.tokenType),
-			)
-			return
+			return CompilerErr{
+				message: fmt.Sprintf(
+					"Token %s cannot precede %s\n",
+					ToString(&token.tokenType),
+					ToString(&nextToken.tokenType),
+				),
+				row: token.row,
+				column: token.column,
+			}
 		}
 	} 
+	return nil
+}
 
-	// extract questions
+func ParseQuestions(tokens []Token) ([]Question, error) {
 	questions := []Question{}
 	section := ""
 	i := 0
@@ -152,7 +167,7 @@ func main() {
 				i += 2
 			}
 			if len(quesitonElements) > 1 {
-				question := ChoiceQuestion{
+				question := MultipleChoiceQuestion{
 					id: id,
 					question: question,
 				}
@@ -192,10 +207,42 @@ func main() {
 				"Not handled: %s",
 				ToString(&tokens[i].tokenType),
 			)
-			return
+			return nil, CompilerErr{
+				message: "",
+				row: tokens[i].row,
+				column: tokens[i].column,
+			}
 		}
 	}
+	return questions, nil
+}
 
+func main() {
+	log.Println("Compilation started")
+
+	file, err := os.ReadFile("/home/jorenchik/Code/mdemory/src/compiler/input.mdem")
+	if (err != nil) { 
+		log.Fatalf("Cannot open the input file: %s", err.Error())
+		return
+	}
+	fileContents := string(file)
+
+	tokens, err := tokenize([]rune(fileContents))
+	if (err != nil) {
+		fmt.Printf("%s\n", err.Error())	
+		return
+	}
+
+	automata = parserAutomata()
+	err = validateGrammar()
+	if (err != nil) {
+		log.Fatal(err.Error())
+	}
+
+	questions, err := ParseQuestions(tokens)
+	if (err != nil) {
+		log.Fatal(err.Error())
+	}
 	for _, element := range questions {
 		switch element.(type) {
 		case SingleAnswerQuestion:
@@ -205,13 +252,13 @@ func main() {
 				strings.Trim(element.(SingleAnswerQuestion).question, "\t\n "),
 				strings.Trim(element.(SingleAnswerQuestion).answer, "\t\n "),
 			)
-		case ChoiceQuestion:
+		case MultipleChoiceQuestion:
 			fmt.Printf(
 				"<Multi choice> (%s) %s\n",
-				element.(ChoiceQuestion).section,
-				element.(ChoiceQuestion).question,
+				element.(MultipleChoiceQuestion).section,
+				element.(MultipleChoiceQuestion).question,
 			)
-			for _, el := range element.(ChoiceQuestion).choices {
+			for _, el := range element.(MultipleChoiceQuestion).choices {
 				opener := '-'
 				if (el.isCorrect) {
 					opener = '+'
@@ -223,28 +270,3 @@ func main() {
 
 	log.Println("Compilation completed")
 }
-
-type QuestionElement struct {
-	isDash bool;
-	content string;
-} 
-
-
-type CompilerErr struct {
-	message string;	
-	row	     int32;
-	column   int32;
-}
-
-func (e CompilerErr) Error() string {
-	return fmt.Sprintf("%d:%d - %s", e.row, e.column, e.message)
-}
-
-func contains(s []TokenType, e TokenType) bool {
-    for _, a := range s {
-        if a == e {
-            return true
-        }
-    }
-    return false
-}