异常处理

src/cli.rs

@@ -39,6 +39,14 @@ pub struct App {
     #[arg(short, long, default_value_t = 1)]
     pub padding: usize,
 
+    ///select line between start and end;
+    #[arg(long="start", default_value_t = 0)]
+    pub start_index: usize,
+
+    ///select line between start and end;
+    #[arg(long="end", default_value_t = 0)]
+    pub end_index: usize,
+
     /// Specify global indent for table.
     #[arg(short, long, default_value_t = 0)]
     pub indent: usize,

src/main.rs

@@ -1,14 +1,14 @@
 mod cli;
 mod table;
 mod util;
+mod prehandle;
 
 use anyhow::bail;
 use clap::Parser;
 use cli::App;
 use csv::{ErrorKind, ReaderBuilder};
 use std::{
-    fs::File,
+    io::{self, BufRead, BufWriter, IsTerminal, Read},
-    io::{self, BufRead, BufReader, BufWriter, Cursor, IsTerminal, Read},
     process,
 };
 use table::TablePrinter;
@@ -67,6 +67,8 @@ fn try_main() -> anyhow::Result<()> {
         delimiter,
         filter_str,
         style,
+        start_index,
+        end_index,
         padding,
         indent,
         sniff,
@@ -92,26 +94,7 @@ fn try_main() -> anyhow::Result<()> {
         .has_headers(!no_headers)
         .from_reader(match file {
             Some(path) => {
-                let data = Box::new(File::open(path)?) as Box<dyn Read>;
+                prehandle::handle(path, filter_str, start_index as u32, end_index as u32)
-                if filter_str == "" {
-                    data
-                } else {
-                    let reader = BufReader::new(data);
-                    let filter_data: Vec<u8> = reader
-                        .lines()
-                        .filter_map(|line| {
-                            let line = line.unwrap();
-                            if line.contains(&filter_str) {
-                                Some(line+"\n")
-                            } else {
-                                None
-                            }
-                        })
-                        .flat_map(|str| str.into_bytes())
-                        .collect();
-                    println!("{}", String::from_utf8_lossy(&filter_data));
-                    Box::new(Cursor::new(filter_data)) as Box<dyn Read>
-                }
             }
             None if io::stdin().is_terminal() => bail!("no input file specified (use -h for help)"),
             None => Box::new(io::stdin()),

src/prehandle.rs

@@ -0,0 +1,43 @@
+use std::{io::Read, path::PathBuf};
+use std::fs::File;
+use std::io::{BufRead, BufReader, Cursor};
+use std::ptr::read;
+
+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());
+    result.extend(reader.into_iter().skip(1).filter(|line| line.contains(filter_str)));
+    result
+}
+
+fn take(reader: &mut Vec<String>, start_index: u32, end_index: u32) -> Vec<String> {
+    if end_index < 0 && start_index < 0{
+        panic!("start_index and end_index must be positive");
+    }
+    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 if(end_index < reader.len() as u32){
+        body.append(&mut reader[start_index as usize..end_index as usize].to_owned());
+    }else {
+        body.append(&mut reader[start_index as usize..].to_owned());
+    }
+    body
+}