feat: manually mirror opencoze's code from bytedance

Change-Id: I09a73aadda978ad9511264a756b2ce51f5761adf

backend/infra/impl/document/parser/builtin/parse_text.go

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2025 coze-dev Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package builtin
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"github.com/cloudwego/eino/components/document/parser"
+	"github.com/cloudwego/eino/schema"
+
+	contract "github.com/coze-dev/coze-studio/backend/infra/contract/document/parser"
+)
+
+func parseText(config *contract.Config) parseFn {
+	return func(ctx context.Context, reader io.Reader, opts ...parser.Option) (docs []*schema.Document, err error) {
+		content, err := io.ReadAll(reader)
+		if err != nil {
+			return nil, err
+		}
+
+		switch config.ChunkingStrategy.ChunkType {
+		case contract.ChunkTypeCustom, contract.ChunkTypeDefault:
+			docs, err = chunkCustom(ctx, string(content), config, opts...)
+		default:
+			return nil, fmt.Errorf("[parseText] chunk type not support, type=%d", config.ChunkingStrategy.ChunkType)
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		return docs, nil
+	}
+}