Add zip feature and make zip method conditional

Cargo.toml

@@ -5,8 +5,11 @@ edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[features]
+default = ["zip"]
+zip = ["dep:zip"]
 
 [dependencies]
 serde = { version = "1.0.197", features = ["derive"] }
 serde_json = "1.0.114"
-zip = { version = "0.6.6", default-features = false, features = ["deflate", "time"] }
+zip = { version = "0.6.6", default-features = false, features = ["deflate", "time"], optional = true }

src/virtual_fs.rs

@@ -1,13 +1,9 @@
 //! Virtual file system for creating and manipulating files and folders in memory.
 
-use std::{
-    collections::HashMap,
-    fs,
-    io::{self, Write},
-    path::Path,
-};
+use std::{collections::HashMap, fs, io, path::Path};
 
 use serde::{Deserialize, Serialize};
+#[cfg(feature = "zip")]
 use zip::ZipWriter;
 
 /// Folder representation in virtual file system
@@ -143,8 +139,11 @@ impl VFolder {
         Ok(())
     }
 
+    #[cfg(feature = "zip")]
     /// Zip the folder and its contents into a zip archive.
     pub fn zip(&self, path: &Path) -> io::Result<()> {
+        use io::Write;
+
         let file = fs::File::create(path)?;
         let mut writer = ZipWriter::new(file);
         let virtual_files = self.flatten();
@@ -166,6 +165,7 @@ impl VFolder {
         Ok(())
     }
 
+    #[allow(dead_code)]
     /// Flatten the folder and its contents into a list of files with full paths.
     fn flatten(&self) -> Vec<(String, &VFile)> {
         let mut files = self