添加预处理相关逻辑, 将筛选逻辑移进预处理逻辑, 添加根据Start, End截取功能

src/prehandle.rs

@@ -0,0 +1,41 @@
+use std::{io::Read, path::PathBuf};
+use std::fs::File;
+use std::io::{BufRead, BufReader, Cursor};
+
+pub fn handle(path: PathBuf,filter_str:String, start_index: u32, end_index: u32) -> Box<dyn Read>{
+    let reader = BufReader::new(File::open(path).unwrap());
+    let mut lines = reader.lines().collect::<Result<Vec<_>, _>>().unwrap();
+    lines = filter_by_string(lines, filter_str.as_str());
+    lines = take(&mut lines, start_index, end_index);
+
+    Box::new(Cursor::new(lines.join("\n").into_bytes())) as Box<dyn Read>
+}
+
+fn filter_by_string(reader: Vec<String>, filter_str: &str) ->Vec<String>{
+    if filter_str == "" {
+        return reader
+    }
+    let mut result: Vec<String> = Vec::new();
+    result.push(reader[0].clone());
+    for line in reader[1..].iter(){
+        if line.contains(filter_str){
+            result.push(line.to_string());
+        }
+    }
+    return result;
+}
+
+fn take(reader: &mut Vec<String>, start_index: u32, end_index: u32) -> Vec<String> {
+    if end_index == 0 && start_index == 0{
+        return reader.to_owned();
+    }
+    let header = reader[0].clone();
+    let mut body= Vec::new();
+    body.push(header);
+    if end_index == 0{
+        body.append(&mut reader[start_index as usize..].to_owned());
+    }else{
+        body.append(&mut reader[start_index as usize..end_index as usize].to_owned());
+    }
+    body
+}