Introduce parse_slice that allows value borrowing. Technically this works, but I am happy with precisely NONE of it.

jaarg-nostd/examples/basic_nostd.rs

@@ -6,8 +6,6 @@
 #![no_std]
 #![no_main]
 
-extern crate alloc;
-
 use jaarg::{
   ErrorUsageWriter, ErrorUsageWriterContext, HelpWriter, HelpWriterContext, Opt, Opts,
   ParseControl, ParseResult, StandardErrorUsageWriter, StandardFullHelpWriter
@@ -18,8 +16,8 @@ use jaarg_nostd::{print, println, harness::ExitCode, simplepathbuf::SimplePathBu
 #[allow(improper_ctypes_definitions)]
 extern "C" fn safe_main(args: &[&str]) -> ExitCode {
   // Variables for arguments to fill
-  let mut file = SimplePathBuf::default();
+  let mut file: Option<&str> = None;
-  let mut out: Option<SimplePathBuf> = None;
+  let mut out: Option<&str> = None;
   let mut number = 0;
 
   // Set up arguments table
@@ -35,9 +33,9 @@ extern "C" fn safe_main(args: &[&str]) -> ExitCode {
   ]).with_description("My simple utility.");
 
   // Parse command-line arguments from argv
-  match OPTIONS.parse(
+  match OPTIONS.parse_slice(
     SimplePathBuf::from(*args.first().unwrap()).basename(),
-    args.iter().skip(1), |ctx| {
+    &args[1..], |ctx| {
       match ctx.id {
         Arg::Help => {
           let ctx = HelpWriterContext { options: &OPTIONS, program_name: ctx.program_name };
@@ -45,8 +43,8 @@ extern "C" fn safe_main(args: &[&str]) -> ExitCode {
           return Ok(ParseControl::Quit);
         }
         Arg::Number => { number = str::parse(ctx.arg.unwrap())?; }
-        Arg::File   => { file = ctx.arg.unwrap().into(); }
+        Arg::File   => { file = ctx.arg; }
-        Arg::Out    => { out = Some(ctx.arg.unwrap().into()); }
+        Arg::Out    => { out = ctx.arg; }
       }
       Ok(ParseControl::Continue)
     }, |program_name, error| {
@@ -60,8 +58,9 @@ extern "C" fn safe_main(args: &[&str]) -> ExitCode {
   }
 
   // Print the result variables
+  let file = SimplePathBuf::from(file.unwrap());
   println!("{file} -> {out} (number: {number})",
-    out = out.unwrap_or(file.with_extension("out")));
+    out = out.map_or(file.with_extension("out"), |out| SimplePathBuf::from(out)));
 
   ExitCode::SUCCESS
 }

jaarg/src/alloc.rs

@@ -13,7 +13,7 @@ impl Opts<&'static str> {
   /// Parse an iterator of strings as arguments and return the results in a [`BTreeMap`].
   ///
   /// Requires `features = ["alloc"]`.
-  pub fn parse_map<'a, S: AsRef<str> + 'a, I: Iterator<Item = S>>(&self, program_name: &str, args: I,
+  pub fn parse_map<'opt, 't, S: AsRef<str> + 't, I: Iterator<Item = S>>(&'opt self, program_name: &str, args: I,
     help: impl Fn(&str), error: impl FnOnce(&str, ParseError)
   ) -> ParseMapResult {
     let mut out: BTreeMap<&'static str, String> = BTreeMap::new();
@@ -22,7 +22,7 @@ impl Opts<&'static str> {
         help(program_name);
         Ok(ParseControl::Quit)
       } else {
-        out.insert(ctx.id, ctx.arg.unwrap().to_string());
+        out.insert(ctx.id, ctx.arg.map_or(String::new(), |o| o.to_string()));
         Ok(ParseControl::Continue)
       }
     }, error) {

jaarg/src/argparse.rs

@@ -29,9 +29,9 @@ pub enum ParseControl {
 }
 
 #[derive(Debug)]
-pub struct ParseHandlerContext<'a, ID: 'static> {
+pub struct ParseHandlerContext<'a, 'name, ID: 'static> {
   /// Name of the program, for printing statuses to the user.
-  pub program_name: &'a str,
+  pub program_name: &'name str,
   /// The generic argument ID that was matched.
   pub id: &'a ID,
   /// The option that was matched by the parser.
@@ -47,12 +47,12 @@ pub struct ParseHandlerContext<'a, ID: 'static> {
 pub(crate) type HandlerResult<'a, T> = core::result::Result<T, ParseError<'a>>;
 
 #[derive(Debug)]
-pub enum ParseError<'a> {
+pub enum ParseError<'t> {
-  UnknownOption(&'a str),
+  UnknownOption(&'t str),
-  UnexpectedToken(&'a str),
+  UnexpectedToken(&'t str),
-  ExpectArgument(&'a str),
+  ExpectArgument(&'t str),
-  UnexpectedArgument(&'a str),
+  UnexpectedArgument(&'t str),
-  ArgumentError(&'static str, &'a str, ParseErrorKind),
+  ArgumentError(&'static str, &'t str, ParseErrorKind),
   //TODO
   //Exclusive(&'static str, &'a str),
   RequiredPositional(&'static str),
@@ -154,6 +154,30 @@ impl<ID: 'static> Opts<ID> {
     self.validate_state(program_name, state, error)
   }
 
+  /// Parses a slice of strings as argument tokens.
+  /// Like [Opts::parse] but allows borrowing argument tokens outside the handler.
+  pub fn parse_slice<'opts, 't, S: AsRef<str>>(&'opts self, program_name: &str, args: &'t [S],
+    mut handler: impl FnMut(ParseHandlerContext<'opts, '_, ID>) -> HandlerResult<'opts, ParseControl>,
+    error: impl FnOnce(&str, ParseError),
+  ) -> ParseResult where 't: 'opts {
+    let mut state = ParserState::default();
+    for arg in args {
+      // Fetch the next token
+      match self.next_borrow(&mut state, arg.as_ref(), program_name, &mut handler) {
+        Ok(ParseControl::Continue) => {}
+        Ok(ParseControl::Stop) => { break; }
+        Ok(ParseControl::Quit) => { return ParseResult::ExitSuccess; }
+        Err(err) => {
+          // Call the error handler
+          error(program_name, err);
+          return ParseResult::ExitFailure;
+        }
+      }
+    }
+
+    self.validate_state(program_name, state, error)
+  }
+
   fn validate_state(&self, program_name: &str, mut state: ParserState<ID>, error: impl FnOnce(&str, ParseError)
   ) -> ParseResult {
     // Ensure that value options are provided a value
@@ -184,10 +208,10 @@ impl<ID: 'static> Opts<ID> {
     ParseResult::ContinueSuccess
   }
 
-  /// Parse the next token in the argument stream
+  /// Parse the next token in the argument stream.
-  fn next<'a, 'b>(&self, state: &mut ParserState<ID>, token: &'b str, program_name: &str,
+  fn next<'r, 't>(&self, state: &mut ParserState<ID>, token: &'t str, program_name: &str,
-    handler: &mut impl FnMut(ParseHandlerContext<ID>) -> HandlerResult<'a, ParseControl>
+    handler: &mut impl FnMut(ParseHandlerContext<ID>) -> HandlerResult<'r, ParseControl>
-  ) -> HandlerResult<'b, ParseControl> where 'a: 'b {
+  ) -> HandlerResult<'t, ParseControl> where 'r: 't {
     let mut call_handler = |option: &Opt<ID>, name, value| {
       match handler(ParseHandlerContext{ program_name, id: &option.id, option, name, arg: value }) {
         // HACK: Ensure the string fields are set properly, because coerced
@@ -261,17 +285,90 @@ impl<ID: 'static> Opts<ID> {
       }
     }
   }
+
+  /// I absolutely hate that this needs to be DUPLICATED
+  fn next_borrow<'opts, 't>(&'opts self, state: &mut ParserState<ID>, token: &'t str, program_name: &str,
+    handler: &mut impl FnMut(ParseHandlerContext<'opts, '_, ID>) -> HandlerResult<'opts, ParseControl>
+  ) -> HandlerResult<'opts, ParseControl> where 't: 'opts {
+    let mut call_handler = |option: &'opts Opt<ID>, name, value| {
+      match handler(ParseHandlerContext{ program_name, id: &option.id, option, name, arg: value }) {
+        // HACK: Ensure the string fields are set properly, because coerced
+        //       ParseIntError/ParseFloatError will have the string fields blanked.
+        Err(ParseError::ArgumentError("", "", kind))
+          => Err(ParseError::ArgumentError(name, value.unwrap(), kind)),
+        Err(err) => Err(err),
+        Ok(ctl) => Ok(ctl),
+      }
+    };
+
+    // If the previous token is expecting an argument, ie: value a value option
+    //  was matched and didn't have an equals sign separating a value,
+    //  then call the handler here.
+    if let Some((name, option)) = state.expects_arg.take() {
+      call_handler(option, name, Some(token))
+    } else {
+      // Check if the next argument token starts with an option flag
+      if self.flag_chars.chars().any(|c| token.starts_with(c)) {
+        // Value options can have their value delineated by an equals sign or with whitespace.
+        // In the latter case; the value will be in the next token.
+        let (option_str, value_str) = token.split_once("=")
+          .map_or((token, None), |(k, v)| (k, Some(v)));
+
+        // Keep track of how many required options we've seen
+        let mut required_idx = 0;
+
+        // Match a suitable option by name (ignoring the first flag character & skipping positional arguments)
+        let (name, option) = self.iter()
+          .filter(|opt| matches!(opt.r#type, OptType::Flag | OptType::Value)).find_map(|opt| {
+            if let Some(name) = opt.match_name(option_str, 1) {
+              Some((name, opt))
+            } else {
+              if opt.is_required() {
+                required_idx += 1
+              }
+              None
+            }
+          }).ok_or(ParseError::UnknownOption(option_str))?;
+
+        // Mark required option as visited
+        if option.is_required() {
+          state.required_param_presences.insert(required_idx, true);
+        }
+
+        match (&option.r#type, value_str) {
+          // Call handler for flag-only options
+          (OptType::Flag, None) => call_handler(option, name, None),
+          // Value was provided this token, so call the handler right now
+          (OptType::Value, Some(value)) => call_handler(option, name, Some(value)),
+          // No value available in this token, delay handling to next token
+          (OptType::Value, None) => {
+            state.expects_arg = Some((name, option));
+            Ok(ParseControl::Continue)
+          }
+          // Flag-only options do not support arguments
+          (OptType::Flag, Some(_)) => Err(ParseError::UnexpectedArgument(option_str)),
+          // Positional arguments are filtered out so this is impossible
+          (OptType::Positional, _) => unreachable!("Won't parse a positional argument as an option"),
+        }
+      } else {
+        // Find the next positional argument
+        for (i, option) in self.options[state.positional_index..].iter().enumerate() {
+          if matches!(option.r#type, OptType::Positional) {
+            call_handler(option, option.first_name(), Some(token))?;
+            state.positional_index += i + 1;
+            return Ok(ParseControl::Continue);
+          }
+        }
+        Err(ParseError::UnexpectedToken(token))
+      }
+    }
+  }
 }
 
 #[cfg(test)]
 mod tests {
   use super::*;
 
-  #[test]
-  fn test_parse() {
-    extern crate alloc;
-    use alloc::string::String;
-
   enum ArgID { One, Two, Three, Four, Five }
   const OPTIONS: Opts<ArgID> = Opts::new(&[
     Opt::positional(ArgID::One, "one"),
@@ -282,7 +379,11 @@ mod tests {
   ]);
   const ARGUMENTS: &[&str] = &["one", "--two", "--three=three", "--five=", "--four", "four"];
 
-    //TODO: currently needs alloc to deal with arguments not being able to escape handler
+  #[test]
+  fn test_parse() {
+    extern crate alloc;
+    use alloc::string::String;
+
     let mut one: Option<String> = None;
     let mut two = false;
     let mut three: Option<String> = None;
@@ -307,4 +408,31 @@ mod tests {
     assert_eq!(four, Some("four".into()));
     assert_eq!(five, Some("".into()));
   }
+
+  #[test]
+  fn test_parse_slice() {
+    let mut one: Option<&str> = None;
+    let mut two = false;
+    let mut three: Option<&str> = None;
+    let mut four: Option<&str> = None;
+    let mut five: Option<&str> = None;
+    assert!(matches!(OPTIONS.parse_slice("", &ARGUMENTS, |ctx| {
+      match ctx.id {
+        ArgID::One =>   { one = ctx.arg; }
+        ArgID::Two =>   { two = true; }
+        ArgID::Three => { three = ctx.arg; }
+        ArgID::Four =>  { four = ctx.arg; }
+        ArgID::Five =>  { five = ctx.arg; }
+      }
+      Ok(ParseControl::Continue)
+    }, |_, error| {
+      panic!("unreachable: {error:?}");
+    }), ParseResult::ContinueSuccess));
+
+    assert_eq!(one, Some("one"));
+    assert!(two);
+    assert_eq!(three, Some("three"));
+    assert_eq!(four, Some("four"));
+    assert_eq!(five, Some(""));
+  }
 }

jaarg/src/std.rs

@@ -18,7 +18,7 @@ impl<ID: 'static> Opts<ID> {
   /// The errors are formatted in a standard user-friendly format.
   ///
   /// Requires `features = ["std"]`.
-  pub fn parse_easy<'a>(&self, handler: impl FnMut(ParseHandlerContext<ID>) -> HandlerResult<'a, ParseControl>
+  pub fn parse_easy<'a>(&'static self, handler: impl FnMut(ParseHandlerContext<ID>) -> HandlerResult<'a, ParseControl>
   ) -> ParseResult {
     let (program_name, argv) = Self::easy_args();
     self.parse(&program_name, argv, handler,
@@ -69,7 +69,7 @@ impl Opts<&'static str> {
   /// Help and errors are formatted in a standard user-friendly format.
   ///
   /// Requires `features = ["std"]`.
-  pub fn parse_map_easy(&self) -> ParseMapResult {
+  pub fn parse_map_easy(&'static self) -> ParseMapResult {
     let (program_name, argv) = Self::easy_args();
     self.parse_map(&program_name, argv,
       |name| self.print_full_help(name),