feat: add option to list all builtin functions in info command

src/filterx/src/args.rs

@@ -192,5 +192,9 @@ pub struct GFFCommand {
 #[derive(Debug, Clone, Parser)]
 pub struct InfoArgs {
     /// builtin function name
-    pub name: String,
+    pub name: Option<String>,
+
+    /// list all builtin functions
+    #[clap(long, default_value = "false", action = ArgAction::SetTrue)]
+    pub list: Option<bool>
 }

src/filterx/src/info.rs

@@ -1,11 +1,39 @@
 use crate::args::InfoArgs;
-use filterx_core::FilterxResult;
-use filterx_engine::eval::call::functions::get_function;
+use filterx_core::{hint::Colorize, FilterxResult, Hint};
+use filterx_engine::eval::call::functions::{get_function, list_functions};
 use filterx_info::render;
 
+fn list_and_print() -> FilterxResult<()> {
+    let functions = list_functions();
+    for (index, func) in functions.iter().enumerate() {
+        println!("{:2} {}", (index + 1), func.name.cyan().bold());
+    }
+    println!();
+    let mut h = Hint::new();
+    h.white("Use ")
+        .green("filterx info <function_name>")
+        .bold()
+        .white(" to get more information about a function.")
+        .print_and_clear();
+    Ok(())
+}
+
 pub fn filterx_info(info: InfoArgs) -> FilterxResult<()> {
-    let InfoArgs { name } = info;
-    let f = get_function(&name);
+    let InfoArgs { name, list } = info;
+
+    let list = list.unwrap();
+
+    if !list && name.is_none() {
+        println!("filterx info {}", "<name>".cyan());
+        return Ok(());
+    }
+
+    if list {
+        list_and_print()?;
+        return Ok(());
+    }
+
+    let f = get_function(&name.unwrap());
     render::render_markdown_help(f.doc)?;
     render::render_alias_function(&f.alias)?;
     Ok(())