refactor: Use strum for filter plugin type determination

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/filter_plugin/mod.rs

@@ -1,4 +1,6 @@
 use std::io::{Result, Read, Write};
+use std::str::FromStr;
+use strum::{EnumString, EnumVariantNames};
 
 pub mod head;
 pub mod tail;
@@ -11,6 +13,19 @@ pub trait FilterPlugin: Send {
     fn filter(&mut self, reader: Box<&mut dyn Read>, writer: Box<&mut dyn Write>) -> Result<()>;
 }
 
+#[derive(Debug, EnumString, EnumVariantNames)]
+#[strum(serialize_all = "snake_case")]
+enum FilterType {
+    HeadBytes,
+    HeadLines,
+    TailBytes,
+    TailLines,
+    SkipBytes,
+    SkipLines,
+    Grep,
+    StripAnsi,
+}
+
 pub struct FilterChain {
     plugins: Vec<Box<dyn FilterPlugin>>,
 }
@@ -72,39 +87,70 @@ pub fn parse_filter_string(filter_str: &str) -> Result<FilterChain> {
             continue;
         }
 
-        // Define a macro to reduce duplication in filter parsing
-        macro_rules! parse_filter {
-            ($prefix:expr, $suffix:expr, $constructor:expr) => {{
-                if let Some(stripped) = part.strip_prefix($prefix).and_then(|s| s.strip_suffix($suffix)) {
-                    let count = utils::parse_number(stripped)?;
-                    chain.add_plugin(Box::new($constructor(count)));
+        // Parse the filter type
+        if let Ok(filter_type) = FilterType::from_str(part) {
+            match filter_type {
+                FilterType::StripAnsi => {
+                    chain.add_plugin(Box::new(strip_ansi::StripAnsiFilter::new()));
                     continue;
                 }
-            }};
+                _ => {
+                    return Err(std::io::Error::new(
+                        std::io::ErrorKind::InvalidInput,
+                        format!("Filter '{}' requires parameters", part)
+                    ));
+                }
+            }
         }
 
-        // Handle strip_ansi filter
-        if part == "strip_ansi" {
-            chain.add_plugin(Box::new(strip_ansi::StripAnsiFilter::new()));
-            continue;
+        // Handle filters with parameters
+        // Extract the filter name and parameters
+        if let Some((filter_name, params)) = part.split_once('(') {
+            if let Some(params) = params.strip_suffix(')') {
+                if let Ok(filter_type) = FilterType::from_str(filter_name) {
+                    match filter_type {
+                        FilterType::Grep => {
+                            // Remove quotes if present
+                            let pattern = params.trim_matches(|c| c == '\'' || c == '"');
+                            chain.add_plugin(Box::new(grep::GrepFilter::new(pattern.to_string())?));
+                        }
+                        FilterType::HeadBytes => {
+                            let count = utils::parse_number(params)?;
+                            chain.add_plugin(Box::new(head::HeadBytesFilter::new(count)));
+                        }
+                        FilterType::HeadLines => {
+                            let count = utils::parse_number(params)?;
+                            chain.add_plugin(Box::new(head::HeadLinesFilter::new(count)));
+                        }
+                        FilterType::TailBytes => {
+                            let count = utils::parse_number(params)?;
+                            chain.add_plugin(Box::new(tail::TailBytesFilter::new(count)));
+                        }
+                        FilterType::TailLines => {
+                            let count = utils::parse_number(params)?;
+                            chain.add_plugin(Box::new(tail::TailLinesFilter::new(count)));
+                        }
+                        FilterType::SkipBytes => {
+                            let count = utils::parse_number(params)?;
+                            chain.add_plugin(Box::new(skip::SkipBytesFilter::new(count)));
+                        }
+                        FilterType::SkipLines => {
+                            let count = utils::parse_number(params)?;
+                            chain.add_plugin(Box::new(skip::SkipLinesFilter::new(count)));
+                        }
+                        FilterType::StripAnsi => {
+                            // This should not happen as strip_ansi doesn't take parameters
+                            return Err(std::io::Error::new(
+                                std::io::ErrorKind::InvalidInput,
+                                "strip_ansi filter doesn't take parameters"
+                            ));
+                        }
+                    }
+                    continue;
+                }
+            }
         }
 
-        // Handle grep filter
-        if let Some(stripped) = part.strip_prefix("grep(").and_then(|s| s.strip_suffix(')')) {
-            // Remove quotes if present
-            let pattern = stripped.trim_matches(|c| c == '\'' || c == '"');
-            chain.add_plugin(Box::new(grep::GrepFilter::new(pattern.to_string())?));
-            continue;
-        }
-
-        // Handle other filters using the macro
-        parse_filter!("head_bytes(", ")", head::HeadBytesFilter::new);
-        parse_filter!("head_lines(", ")", head::HeadLinesFilter::new);
-        parse_filter!("tail_bytes(", ")", tail::TailBytesFilter::new);
-        parse_filter!("tail_lines(", ")", tail::TailLinesFilter::new);
-        parse_filter!("skip_bytes(", ")", skip::SkipBytesFilter::new);
-        parse_filter!("skip_lines(", ")", skip::SkipLinesFilter::new);
-
         // If we get here, the filter wasn't recognized
         return Err(std::io::Error::new(
             std::io::ErrorKind::InvalidInput,