add: rewriter logic and tests

Cargo.lock

@@ -61,6 +61,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.97"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcfed56ad506cb2c684a14971b8861fdc3baaaae314b9e5f9bb532cbe3ba7a4f"
+
 [[package]]
 name = "clap"
 version = "4.5.34"
@@ -384,6 +390,7 @@ dependencies = [
 name = "skubelb"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "clap",
  "dir-diff",
  "env_logger",

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+anyhow = "1.0.97"
 clap = { version = "4.5.34", features = ["derive"] }
 dir-diff = "0.3.3"
 env_logger = "0.11.7"

src/main.rs

@@ -12,13 +12,19 @@ use rewriter::Rewriter;
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
 struct Args {
-    /// Name of the person to greet
+    /// The needle that will be replaced. Anytime a line
+    /// is encountered with this needle, the line is dropped
+    /// and instead N lines (one per replacement) is added to
+    /// the output.
     #[arg(short, long)]
     rewrite_string: String,
 
+    /// The folder which contains the templates that
+    /// will be be searched for the needle.
     #[arg(short, long)]
     source_folder: String,
 
+    /// Where to write the replaced lines.
     #[arg(short, long)]
     dest_folder: String,
 }

src/rewriter.rs

@@ -1,8 +1,9 @@
+use anyhow::Result;
 use std::collections::HashSet;
 use std::path::Path;
 use std::{
     fs::{self, File},
-    io::{self, BufReader, prelude::*},
+    io::{BufReader, prelude::*},
 };
 
 pub struct Rewriter {
@@ -26,7 +27,7 @@ impl Rewriter {
         self.replacements.remove(replacement);
     }
 
-    pub fn rewrite_folder(&self, src: &str, dst: &str) -> Result<(), io::Error> {
+    pub fn rewrite_folder(&self, src: &str, dst: &str) -> Result<()> {
         // Make sure we are deterministic; construct a list of strings and sort
         // them
         let mut replacements: Vec<String> = self.replacements.iter().map(|s| s.clone()).collect();
@@ -43,7 +44,7 @@ impl Rewriter {
                 // First, calculate the 'relative' path after we trim the
                 // the src prefix, then join that with the dst prefix
                 let src_path = entry.path();
-                let src_part_path = src_path.strip_prefix(&src).unwrap();
+                let src_part_path = src_path.strip_prefix(&src)?;
                 let dst_path = dst_base.join(src_part_path);
 
                 if metadata.is_dir() {
@@ -96,9 +97,7 @@ mod tests {
     #[test]
     fn basic_test() {
         let testdata = TempDir::new("").unwrap();
-        TEST_FILES
-            .extract(testdata.path())
-            .unwrap();
+        TEST_FILES.extract(testdata.path()).unwrap();
         let src = testdata.path().join("testsrc");
         let dst = TempDir::new("").unwrap();
 
@@ -115,6 +114,8 @@ mod tests {
             .unwrap();
 
         // Validate that everything matches
-        assert!(dir_diff::is_different(testdata.path().join("testdst"), dst.path()).unwrap() == false);
+        assert!(
+            dir_diff::is_different(testdata.path().join("testdst"), dst.path()).unwrap() == false
+        );
     }
 }