chore: implement escaping character node

plugin/gomark/parser/escaping_character.go

@@ -0,0 +1,41 @@
+package parser
+
+import (
+	"errors"
+
+	"github.com/usememos/memos/plugin/gomark/ast"
+	"github.com/usememos/memos/plugin/gomark/parser/tokenizer"
+)
+
+type EscapingCharacterParser struct{}
+
+func NewEscapingCharacterParser() *EscapingCharacterParser {
+	return &EscapingCharacterParser{}
+}
+
+func (*EscapingCharacterParser) Match(tokens []*tokenizer.Token) (int, bool) {
+	if len(tokens) == 0 {
+		return 0, false
+	}
+	if tokens[0].Type != tokenizer.Backslash {
+		return 0, false
+	}
+	if len(tokens) == 1 {
+		return 0, false
+	}
+	if tokens[1].Type == tokenizer.Newline || tokens[1].Type == tokenizer.Space || tokens[1].Type == tokenizer.Text || tokens[1].Type == tokenizer.Number {
+		return 0, false
+	}
+	return 2, true
+}
+
+func (p *EscapingCharacterParser) Parse(tokens []*tokenizer.Token) (ast.Node, error) {
+	size, ok := p.Match(tokens)
+	if size == 0 || !ok {
+		return nil, errors.New("not matched")
+	}
+
+	return &ast.EscapingCharacter{
+		Symbol: tokens[1].Value,
+	}, nil
+}