error handling and transformation improvements

Added vscode config for easy debug including all modules.

memorybase/faulty.mdem

@@ -0,0 +1,25 @@
+
+
+
+- Another question? >
+    - Answer
+    - Answer
+    - Answer
+    - Answer
+    - Answer
+
+
+    oejcoewjic
+
+- Question? >
+    - Answer
+
+
+
+    fwefew
+
+    dwedew
+    dwe
+
+
+    dee

memorybase/hello.mdem

@@ -1,110 +1,42 @@
-
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 1 What is the capital of Latvia? >
     - Riga 
-
-- [cap_riga] What is the capital of Latvia? >
-    - Riga
-
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 2 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 3 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 4 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 5 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 6 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 7 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 8 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 9 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 10 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 11 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 12 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 13 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 14 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 15 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 16 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 17 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 18 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 19 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 20 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
+- [cap_riga] 21 What is the capital of Latvia? >
     - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-- [cap_riga] What is the capital of Latvia? >
-    - Riga 
-

src/.vscode/launch.json

@@ -0,0 +1,26 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Launch Package",
+            "type": "go",
+            "request": "launch",
+            "mode": "auto",
+            "program": "${fileDirname}"
+        },
+        {
+            "name": "Debug with Build Flags",
+            "type": "go",
+            "request": "launch",
+            "mode": "debug",
+            "program": "${workspaceFolder}/mdemory-app-qt/main.go",
+           // "buildFlags": "-gcflags='all=-N -l'",
+            "args": [],
+            "env": {},
+            "cwd": "${workspaceFolder}"
+        }
+    ]
+}

src/compiler/api/api.go

@@ -1,15 +1,14 @@
 package api
 
 import (
-
 	"github.com/jorenchik/mdemory/src/compiler/lexer"
 	"github.com/jorenchik/mdemory/src/compiler/parser"
 )
 
 func Compile(fileContents string) ([]parser.Question, error) {
 	tokens, err := lexer.TokenizeMdem([]rune(fileContents))
-	if err != nil {
-		return nil, err
+	if (err != nil) {
+        return nil, err
 	}
     questions, err := parser.ParseQuestions(tokens)
 	if (err != nil) {

src/compiler/comperror/comperror.go

@@ -0,0 +1,15 @@
+package comperror 
+
+import (
+    "fmt"
+)
+
+type PositionErr struct {
+	Message string
+	Row     int32
+	Column  int32
+}
+
+func (e PositionErr) Error() string {
+	return fmt.Sprintf("%d:%d - %s", e.Row, e.Column, e.Message)
+}

src/compiler/lexer/lexer.go

@@ -3,14 +3,17 @@ package lexer
 import (
 	"fmt"
 	"strings"
+
+	"github.com/jorenchik/mdemory/src/compiler/comperror"
 )
 
-var buffer         []rune
-var	row              int32
-var	column           int32
-var	previousRow      int32
-var	previousColumn   int32
-var textStarted      bool
+var buffer            []rune
+var	row                 int32
+var	column              int32
+var	previousRow         int32
+var	previousColumn      int32
+var textStarted         bool  = false
+var identifierStarted   bool  = false
 
 type TokenType int
 const (
@@ -91,7 +94,7 @@ func makeTokenWithTokenBuffer(
 	buffer = []rune{}
 }
 
-func TokenizeMdem(fileRunes []rune) ( []Token, error ) {
+func TokenizeMdem(fileRunes []rune) ([]Token, error) {
 	tokens         = []Token{} 
 	buffer         = []rune{} 
     row            = 1
@@ -104,7 +107,6 @@ func TokenizeMdem(fileRunes []rune) ( []Token, error ) {
         return []Token{}, nil
     }
 
-
 	for i := 0; i < len(fileRunes); i++ {
 		c := fileRunes[i]
 
@@ -131,43 +133,53 @@ func TokenizeMdem(fileRunes []rune) ( []Token, error ) {
 		switch c {
 		case '[':
 			makeTokenWithTokenBuffer(IdentifierStart, 1, TextFragment)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
+            identifierStarted = true
 		case ']':
+            if !identifierStarted {
+                return []Token{}, comperror.PositionErr{
+                    Message: "Cannot end identifier if it is not started",
+                    Row:     row,
+                    Column:  column,
+                } 
+
+            }
 			makeTokenWithTokenBuffer(IdentifierEnd, 1, Identifier)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
+            identifierStarted = false
 		case '#':
 			makeTokenWithTokenBuffer(SectionIdentifierStart, 1, TextFragment)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
 		case '{':
 			makeTokenWithTokenBuffer(SectionStart, 1, Identifier)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
 		case '}':
 			makeTokenWithTokenBuffer(SectionEnd, 1, TextFragment)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
 		case '-':
 			makeTokenWithTokenBuffer(ElementDashStart, 1, TextFragment)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
 		case '>':
 			makeTokenWithTokenBuffer(QuestionEnd, 1, TextFragment)
 			previousRow = row
 			previousColumn = column
 		case '+':
 			makeTokenWithTokenBuffer(ElementPlusStart, 1, TextFragment)
-			previousRow = row
-			previousColumn = column
-			textStarted = false
+			previousRow       = row
+			previousColumn    = column
+			textStarted       = false
 		}
 		column += 1
 	}
@@ -187,17 +199,17 @@ func TokenizeMdem(fileRunes []rune) ( []Token, error ) {
 
 func ToString (ttype *TokenType) string {
 	switch *ttype {
-        case TextFragment:           return "TextFragment"
-        case QuestionEnd:            return "QuestionEnd"               
-        case ElementDashStart:       return "ElementDashStart"          
-        case ElementPlusStart:       return "ElementPlusStart"          
-        case Identifier:             return "Identifier"                
-        case IdentifierStart:        return "IdentifierStart"            
-        case IdentifierEnd:          return "IdentifierEnd"             
-        case SectionIdentifierStart: return "SectionIdentifierStart"             
-        case SectionStart:           return "SectionStart"             
-        case SectionEnd:             return "SectionEnd"             
-        case EOF:                    return "EndOfFile"             
-        default:                     return "NOT_RECOGNIZED"
+        case TextFragment:           return "text fragment"
+        case QuestionEnd:            return "question end symbol"
+        case ElementDashStart:       return "dash element start"
+        case ElementPlusStart:       return "plus element start"
+        case Identifier:             return "identifier"
+        case IdentifierStart:        return "start of identifier"
+        case IdentifierEnd:          return "end of identifier"
+        case SectionIdentifierStart: return "identifier"
+        case SectionStart:           return "start of a section"
+        case SectionEnd:             return "end of a section"
+        case EOF:                    return "end of a file"
+        default:                     return "unrecognized token"
 	}
 }

src/compiler/parser/parser.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/jorenchik/mdemory/src/compiler/comperror"
 	"github.com/jorenchik/mdemory/src/compiler/lexer"
 )
 
@@ -32,8 +33,8 @@ type MultipleChoiceQuestion struct {
 
 func (question SingleAnswerQuestion) ToString() string {
 	return fmt.Sprintf(
-        "%20s: section: %-10s id: %-10s %-30s: %-30s",
-        "<Single choice>",
+		"%20s: section: %-10s id: %-10s %-30s: %-30s",
+		"<Single choice>",
 		question.Section,
 		question.ID,
 		strings.Trim(question.Question, "\t\n "),
@@ -44,8 +45,8 @@ func (question SingleAnswerQuestion) ToString() string {
 func (question MultipleChoiceQuestion) ToString() string {
 	acc := ""
 	acc += fmt.Sprintf(
-        "%20s: section: %-10s id: %-10s %-30s",
-        "<Multi choice>",
+		"%20s: section: %-10s id: %-10s %-30s",
+		"<Multi choice>",
 		question.Section,
 		question.ID,
 		question.Question,
@@ -67,16 +68,6 @@ type QuestionElement struct {
 
 var automata map[lexer.TokenType][]lexer.TokenType
 
-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 []lexer.TokenType, e lexer.TokenType) bool {
 	for _, a := range s {
 		if a == e {
@@ -99,18 +90,18 @@ func parserAutomata() map[lexer.TokenType][]lexer.TokenType {
 	}
 	automata[lexer.QuestionEnd] = []lexer.TokenType{
 		lexer.ElementDashStart,
-        lexer.ElementPlusStart,
+		lexer.ElementPlusStart,
 	}
 	automata[lexer.ElementDashStart] = []lexer.TokenType{
 		lexer.IdentifierStart,
-        lexer.TextFragment,
+		lexer.TextFragment,
 	}
 	automata[lexer.ElementPlusStart] = []lexer.TokenType{
 		lexer.TextFragment,
 	}
 	automata[lexer.Identifier] = []lexer.TokenType{
 		lexer.IdentifierEnd,
-        lexer.SectionStart,
+		lexer.SectionStart,
 	}
 	automata[lexer.IdentifierStart] = []lexer.TokenType{
 		lexer.Identifier,
@@ -123,37 +114,49 @@ func parserAutomata() map[lexer.TokenType][]lexer.TokenType {
 	}
 	automata[lexer.SectionStart] = []lexer.TokenType{
 		lexer.ElementDashStart,
-        lexer.SectionIdentifierStart,
-        lexer.EOF,
+		lexer.SectionIdentifierStart,
+		lexer.EOF,
 	}
 	automata[lexer.SectionEnd] = []lexer.TokenType{
 		lexer.SectionIdentifierStart,
-        lexer.ElementDashStart,
-        lexer.EOF,
+		lexer.ElementDashStart,
+		lexer.EOF,
 	}
 	automata[lexer.SOF] = []lexer.TokenType{
 		lexer.ElementDashStart,
-        lexer.SectionIdentifierStart,
-        lexer.EOF,
+		lexer.SectionIdentifierStart,
+		lexer.EOF,
 	}
 	automata[lexer.EOF] = []lexer.TokenType{}
 	return automata
 }
 
+func capitalize(str string) string {
+	if len(str) <= 0 {
+		return str
+	}
+	firstCapital := strings.ToUpper(str[0:1])
+    if len(str) == 1 {
+        return firstCapital
+    } else {
+        return firstCapital + str[1:]
+    }
+}
+
 func ValidateGrammar(tokens []lexer.Token) error {
 	automata = parserAutomata()
-	for i := 0; i < len(tokens) - 1; i++ {
+	for i := 0; i < len(tokens)-1; i++ {
 		token := tokens[i]
 		nextToken := tokens[i+1]
 		if !contains(automata[token.TokenType], nextToken.TokenType) {
-			return CompilerErr{
-				message: fmt.Sprintf(
-					"Token %s cannot precede %s\n",
-					lexer.ToString(&token.TokenType),
+			return comperror.PositionErr{
+				Message: fmt.Sprintf(
+					"%s cannot precede %s",
+					capitalize(lexer.ToString(&token.TokenType)),
 					lexer.ToString(&nextToken.TokenType),
 				),
-				row:    token.Row,
-				column: token.Column,
+				Row:    token.Row,
+				Column: token.Column,
 			}
 		}
 	}
@@ -163,76 +166,76 @@ func ValidateGrammar(tokens []lexer.Token) error {
 var DEBUG bool = true
 
 func ParseQuestions(tokens []lexer.Token) ([]Question, error) {
-    err := ValidateGrammar(tokens)
+	err := ValidateGrammar(tokens)
 	if err != nil {
-        return nil, err
+		return nil, err
 	}
 
 	questions := []Question{}
 	section := ""
 	i := 0
-    if DEBUG {
-        fmt.Printf("Parser output:\n")
-    }
+	if DEBUG {
+		fmt.Printf("Parser output:\n")
+	}
 	for {
 		if i >= len(tokens) {
 			break
 		}
-        // - [identifier] question_token > 
+		// - [identifier] question_token >
 		if tokens[i].TokenType == lexer.ElementDashStart {
-            var id string
-            var question string
-            var questionElements []QuestionElement
+			var id string
+			var question string
+			var questionElements []QuestionElement
 
-            if tokens[i + 1].TokenType == lexer.IdentifierStart {
-                id               = tokens[i + 2].Content
-                question         = tokens[i + 4].Content
-                questionElements = []QuestionElement{}
-                i += 6
-            } else {
-                id               = ""
-                question         = tokens[i + 1].Content
-                questionElements = []QuestionElement{}
-                i += 3
-            }
+			if tokens[i+1].TokenType == lexer.IdentifierStart {
+				id = tokens[i+2].Content
+				question = tokens[i+4].Content
+				questionElements = []QuestionElement{}
+				i += 6
+			} else {
+				id = ""
+				question = tokens[i+1].Content
+				questionElements = []QuestionElement{}
+				i += 3
+			}
 
 			for {
-                // Pointer is on the start of an element
-                //   - a_question >
-                //   - [identifier] a_question >
-                //   - an_element
-                // terminate if we encounter a question.
-				if i + 3 < len(tokens) &&
-                   tokens[i + 3].TokenType != lexer.EOF {
+				// Pointer is on the start of an element
+				//   - a_question >
+				//   - [identifier] a_question >
+				//   - an_element
+				// terminate if we encounter a question.
+				if i+3 < len(tokens) &&
+					tokens[i+3].TokenType != lexer.EOF {
 
-                    offset := 0
-                    if tokens[i + 1].TokenType == lexer.IdentifierStart {
-                        offset = 5
-                    } else {
-                        offset = 2
-                    }
-                    if i + offset < len(tokens) &&
-                       tokens[i + offset].TokenType == lexer.QuestionEnd {
-                        break
-                    }
-                    if offset == 5 && tokens[i + 5].TokenType != lexer.QuestionEnd {
-                        return nil, CompilerErr{
-                            message: "Cannot have an identifier here",
-                            row:     tokens[i].Row,
-                            column:  tokens[i].Column,
-                        }
-                    }
-                }
-                if (i + 2 >= len(tokens)) {
-                    break;
-                }
+					offset := 0
+					if tokens[i+1].TokenType == lexer.IdentifierStart {
+						offset = 5
+					} else {
+						offset = 2
+					}
+					if i+offset < len(tokens) &&
+						tokens[i+offset].TokenType == lexer.QuestionEnd {
+						break
+					}
+					if offset == 5 && tokens[i+5].TokenType != lexer.QuestionEnd {
+						return nil, comperror.PositionErr{
+							Message: "Cannot have an identifier here",
+							Row:     tokens[i].Row,
+							Column:  tokens[i].Column,
+						}
+					}
+				}
+				if i+2 >= len(tokens) {
+					break
+				}
 				questionElement := QuestionElement{}
 				if tokens[i].TokenType == lexer.ElementDashStart {
 					questionElement.isDash = true
 				} else {
 					questionElement.isDash = false
 				}
-				questionElement.content = tokens[i + 1].Content
+				questionElement.content = tokens[i+1].Content
 				questionElements = append(questionElements, questionElement)
 				i += 2
 			}
@@ -253,9 +256,9 @@ func ParseQuestions(tokens []lexer.Token) ([]Question, error) {
 				}
 				question.Choices = choices
 				questions = append(questions, question)
-                if DEBUG {
-                    fmt.Printf("%s", question.ToString())
-                }
+				if DEBUG {
+					fmt.Printf("%s", question.ToString())
+				}
 			} else if len(questionElements) == 1 {
 				question := SingleAnswerQuestion{
 					ID:       id,
@@ -266,32 +269,32 @@ func ParseQuestions(tokens []lexer.Token) ([]Question, error) {
 					question.Section = section
 				}
 				questions = append(questions, question)
-                if DEBUG {
-                    fmt.Printf("%s\n", question.ToString())
-                }
+				if DEBUG {
+					fmt.Printf("%s\n", question.ToString())
+				}
 			}
 		} else if tokens[i].TokenType == lexer.SectionIdentifierStart {
-			section = tokens[i + 1].Content
+			section = tokens[i+1].Content
 			i += 3
-            if DEBUG {
-                fmt.Printf("Started section: %s\n", section)
-            }
+			if DEBUG {
+				fmt.Printf("Started section: %s\n", section)
+			}
 		} else if tokens[i].TokenType == lexer.SectionEnd {
 			section = ""
 			i += 1
-            if DEBUG {
-                fmt.Printf("Section ended: %s\n", section)
-            }
+			if DEBUG {
+				fmt.Printf("Section ended: %s\n", section)
+			}
 		} else if tokens[i].TokenType == lexer.EOF {
-            if DEBUG {
-                fmt.Printf("File terminated: EOF\n")
-            }
+			if DEBUG {
+				fmt.Printf("File terminated: EOF\n")
+			}
 			break
 		} else {
-			return nil, CompilerErr{
-				message: "Unexpeced token: %s",
-				row:     tokens[i].Row,
-				column:  tokens[i].Column,
+			return nil, comperror.PositionErr{
+				Message: "Unexpeced token",
+				Row:     tokens[i].Row,
+				Column:  tokens[i].Column,
 			}
 		}
 	}

src/mdemory-app-qt/main.go

@@ -1,23 +1,16 @@
 package main
 
-// iter: 1
-// [1] 2 3 4 5 6 7
-
-// 2
-// press 4
-//  1 2 3 [4] 5 6 7
-// 4 (page num) - 2
-
-
 import (
 	"fmt"
+	"math/rand"
 	"os"
+	"regexp"
+	"strconv"
 	"strings"
 	"time"
-    "strconv"
-    "math/rand"
 
 	"github.com/jorenchik/mdemory/src/compiler/api"
+	"github.com/jorenchik/mdemory/src/compiler/comperror"
 	"github.com/jorenchik/mdemory/src/compiler/parser"
 	"github.com/therecipe/qt/core"
 	"github.com/therecipe/qt/widgets"
@@ -42,6 +35,12 @@ var questions         [] parser.Question
 var paginationButtons []*widgets.QToolButton
 var paginationLabel     *widgets.QLabel
 
+var errorBox            *widgets.QWidget
+var errorLabel          *widgets.QLabel 
+
+
+var multispacePattern   *regexp.Regexp = regexp.MustCompile(`\s\s+`)
+
 // var currentPage = 0
 var PER_PAGE = 10
 var pages []Page
@@ -156,13 +155,7 @@ func CreateMdem() *Mdem {
 }
 
 func CreateMdems(questions *[]parser.Question) {
-	if spacerInitialized {
-		hMdemScroll.RemoveItem(mdemSpacer)
-	} else {
-		mdemSpacer = widgets.NewQSpacerItem(
-			0, 0, widgets.QSizePolicy__Maximum, widgets.QSizePolicy__Minimum,
-		)
-	}
+    hMdemScroll.RemoveItem(mdemSpacer)
 
 	for i := range mdems {
         if mdems[i].wMdem.IsVisible() {
@@ -179,6 +172,12 @@ func CreateMdems(questions *[]parser.Question) {
     }
 
 	// destroy widgets
+    transformAnswer := func(answer string) string {
+        answer = strings.ReplaceAll(answer, "\t", " ")
+        answer = strings.ReplaceAll(answer, "\n", " ")
+        answer = multispacePattern.ReplaceAllString(answer, ` `)
+        return answer 
+    }
 	for i := range *questions {
 		question := (*questions)[i]
 		switch question.(type) {
@@ -186,10 +185,10 @@ func CreateMdems(questions *[]parser.Question) {
 			mdems[i].wFrontText.SetText(
 				question.(parser.SingleAnswerQuestion).Question,
 			)
-            answer := strings.Trim(
-                question.(parser.SingleAnswerQuestion).Answer, " \t\n",
-            ) 
-			mdems[i].backLabels[0].SetText(fmt.Sprintf("- %s", answer))
+            answer := question.(parser.SingleAnswerQuestion).Answer 
+            answer = transformAnswer(answer)
+            answer = fmt.Sprintf("- %s", answer)
+			mdems[i].backLabels[0].SetText(answer)
             if mdems[i].wBack.IsVisible() {
                 mdems[i].wBack.Hide()
             }
@@ -200,11 +199,13 @@ func CreateMdems(questions *[]parser.Question) {
 				question.(parser.MultipleChoiceQuestion).Question,
 			)
 			for k := range choices {
-                answer := strings.Trim(choices[k].Answer, " \t\n") 
+                answer := choices[k].Answer
+                answer = transformAnswer(answer)
+                answer = fmt.Sprintf("- %s", answer)
 				if k < len(mdems[i].backLabels) {
 					mdems[i].backLabels[k].SetText(answer)
 				} else {
-					label := widgets.NewQLabel2(fmt.Sprintf("- %s", answer), nil, 0)
+					label := widgets.NewQLabel2(answer, nil, 0)
 					mdems[i].backLabels = append(
 						mdems[i].backLabels,
 						label,
@@ -219,15 +220,6 @@ func CreateMdems(questions *[]parser.Question) {
         }
 	}
 
-	if !spacerInitialized {
-		mdemSpacer = widgets.NewQSpacerItem(
-			40,
-			40,
-			widgets.QSizePolicy__Minimum,
-			widgets.QSizePolicy__Expanding,
-		)
-		spacerInitialized = true
-	}
 	hMdemScroll.AddItem(mdemSpacer)
 }
 
@@ -313,6 +305,9 @@ func OpenModelFile(
     if model.IsDir(index) {
         return
     }
+    if errorBox.IsVisible() {
+        errorBox.Hide()
+    }
     filePath := model.FilePath(index)
     fileContents, err := os.ReadFile(filePath)
     if err != nil {
@@ -329,13 +324,25 @@ func OpenModelFile(
     start := time.Now().UnixMicro()
     questions, err = api.Compile(string(fileContents))
     if err != nil {
-        widgets.QMessageBox_Critical(
-            nil,
-            "Compilation error",
-            err.Error(),
-            widgets.QMessageBox__Ok,
-            widgets.QMessageBox__Ok,
-        )
+        var errText string
+        switch err.(type) {
+            case comperror.PositionErr:
+                errText = fmt.Sprintf(
+                    "%s on line %d, column %d",
+                    err.(comperror.PositionErr).Message,
+                    err.(comperror.PositionErr).Row,
+                    err.(comperror.PositionErr).Column,
+                )
+            default:
+                errText = err.Error()
+        }
+        errorLabel.SetText(errText)
+        errorBox.Show()
+        for i := range(mdems) {
+            if mdems[i].wMdem.IsVisible() {
+                mdems[i].wMdem.Hide()
+            }
+        }
         return
     }
     duration := float32(time.Now().UnixMicro()-start) / 1000
@@ -420,6 +427,24 @@ func main() {
 	mdemScroll.SetWidgetResizable(true)
 	mdemContainer.SetLayout(hMdemScroll)
 
+    errorBox = widgets.NewQWidget(nil, 0)
+    hErrorBox := widgets.NewQHBoxLayout2(nil)
+    errorBox.SetLayout(hErrorBox)
+    errorLabel = widgets.NewQLabel(nil, 0)
+    errorLabel.SetText("Error")
+    errorBox.Layout().AddWidget(errorLabel)
+    hErrorBox.AddStretch(1)
+    hMdemScroll.AddWidget(errorBox, 0, 0)
+    errorBox.SetObjectName("error")
+    errorBox.SetStyleSheet(`
+        QWidget#error {
+            border: 1px solid #dc143c;
+            background-color: white;
+            padding: 10px 0px;
+        }
+    `)
+    errorBox.Hide()
+
 	for i := 0; i < 40; i++ {
         mdem := CreateMdem()
 		mdems = append(
@@ -428,6 +453,13 @@ func main() {
 		)
         hMdemScroll.AddWidget(mdem.wMdem, 0, 0)
 	}
+    mdemSpacer = widgets.NewQSpacerItem(
+        40,
+        40,
+        widgets.QSizePolicy__Minimum,
+        widgets.QSizePolicy__Expanding,
+    )
+    hMdemScroll.AddItem(mdemSpacer)
 
 	// CreateMdems
 	rightLayout.AddWidget(mdemScroll, 1, 0)