feat: improve error message

cmd/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/bangumi/wiki-parser-go"
+)
+
+func main() {
+	_, err := wiki.Parse(`{{Infobox animanga/Manga
+|中文名= 坐在旁边的家伙用这种眼神看着我
+|别名={邻座的家伙用瑟瑟的眼神盯着我的故事
+}
+|作者= mmk
+|作画= 
+}}`)
+	if err == nil {
+		panic("expecting error")
+	}
+
+	fmt.Println(err.Error())
+
+	se := err.(*wiki.SyntaxError)
+
+	fmt.Println(se.ReadableError())
+}

error.go

@@ -14,17 +14,41 @@
 
 package wiki
 
-import "strconv"
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
 
 var _ interface {
 	Error() string
 	Unwrap() error
 } = (*SyntaxError)(nil)
 
 type SyntaxError struct {
-	Err  error
-	Line string
-	Lino int
+	Err     error
+	Line    string
+	Lino    int
+	infobox string
+}
+
+func (w *SyntaxError) ReadableError() string {
+	fmt.Println(w.Lino)
+
+	lines := strings.Split(w.infobox, "\n")
+	show := lines[max(w.Lino-3, 0) : w.Lino-1]
+
+	var buf strings.Builder
+	for _, line := range show {
+		buf.WriteString(line)
+		buf.WriteRune('\n')
+	}
+
+	buf.WriteString(strings.Repeat("^", len(lines[w.Lino-1])))
+	buf.WriteRune('\n')
+
+	buf.WriteString(w.Err.Error())
+	return buf.String()
 }
 
 func (p *SyntaxError) Error() string {
@@ -35,10 +59,11 @@ func (p *SyntaxError) Unwrap() error {
 	return p.Err
 }
 
-func wrapError(err error, lino int, line string) error {
+func wrapError(err error, lino int, line string, infobox string) error {
 	return &SyntaxError{
-		Line: line,
-		Lino: lino,
-		Err:  err,
+		Line:    line,
+		Lino:    lino,
+		Err:     err,
+		infobox: infobox,
 	}
 }

parser.go

@@ -46,20 +46,29 @@ const suffix = "}}"
 
 //nolint:funlen,gocognit,gocyclo
 func Parse(s string) (Wiki, error) {
+	var originalInput = s
 	var w = Wiki{}
 	s, lineOffset := processInput(s)
 	if s == "" {
 		return w, nil
 	}
 
 	if !strings.HasPrefix(s, prefix) {
-		return Wiki{}, ErrGlobalPrefix
+		return Wiki{}, &SyntaxError{
+			Err:     ErrGlobalPrefix,
+			Lino:    lineOffset,
+			infobox: originalInput,
+		}
 	}
 
 	eolCount := strings.Count(s, "\n")
 
 	if !strings.HasSuffix(s, suffix) {
-		return Wiki{}, ErrGlobalSuffix
+		return Wiki{}, &SyntaxError{
+			Err:     ErrGlobalSuffix,
+			Lino:    lineOffset + eolCount,
+			infobox: originalInput,
+		}
 	}
 
 	w.Type = readType(s)
@@ -96,7 +105,7 @@ func Parse(s string) (Wiki, error) {
 			// can't find next line
 			if inArray {
 				// array should be close have read all contents
-				return Wiki{}, wrapError(ErrArrayNoClose, lino+1, s[secondLastEOL:lastEOL])
+				return Wiki{}, wrapError(ErrArrayNoClose, lino+1, s[secondLastEOL:lastEOL], originalInput)
 			}
 
 			break
@@ -112,12 +121,12 @@ func Parse(s string) (Wiki, error) {
 			// new field
 			currentField = Field{}
 			if inArray {
-				return Wiki{}, wrapError(ErrArrayNoClose, lino, line)
+				return Wiki{}, wrapError(ErrArrayNoClose, lino, line, originalInput)
 			}
 
 			key, value, err := readStartLine(trimLeftSpace(line[1:])) // read "key = value"
 			if err != nil {
-				return Wiki{}, wrapError(err, lino, line)
+				return Wiki{}, wrapError(err, lino, line, originalInput)
 			}
 
 			switch value {
@@ -150,7 +159,7 @@ func Parse(s string) (Wiki, error) {
 			// array item
 			key, value, err := readArrayItem(line)
 			if err != nil {
-				return Wiki{}, wrapError(err, lino, line)
+				return Wiki{}, wrapError(err, lino, line, originalInput)
 			}
 			itemContainer = append(itemContainer, Item{
 				Key:   key,
@@ -159,7 +168,7 @@ func Parse(s string) (Wiki, error) {
 		}
 
 		if !inArray {
-			return Wiki{}, wrapError(ErrExpectingNewField, lino, line)
+			return Wiki{}, wrapError(ErrExpectingNewField, lino, line, originalInput)
 		}
 	}