feat(parselib): implement ArgMatcher for named and positional args

Implement `on_match_one` and `on_match_all` for `ArgMatcher`,
supporting named flags (with eq-mode and short flags), positional
arguments, end-of-options marker (`--`), and case-insensitive matching

1 files changed, 142 insertions, 9 deletions

diff --git a/mingling_picker/src/parselib/arg_matcher.rs b/mingling_picker/src/parselib/arg_matcher.rs
index e8be999..931652a 100644
--- a/mingling_picker/src/parselib/arg_matcher.rs
+++ b/mingling_picker/src/parselib/arg_matcher.rs
@@ -1,21 +1,154 @@
-use crate::matcher_needed::*;
+use crate::{matcher_needed::*, parselib::build_possible_flags};
 
+/// `ArgMatcher` is used for parameters that carry a single value.
+///
+/// It handles two scenarios:
+///
+/// **Named** — `--name Alice` or `--name=Alice`.
+///   Each flag occurrence consumes **one** following argument as its value,
+///   regardless of what it is (even if it looks like a flag).
+///   This ensures the mask correctly claims the value slot; validation is
+///   the `Pickable`'s responsibility.
+///
+/// **Positional** — no flag prefix, matched by position.
+///
+/// # Examples
+///
+/// | Input | `on_match_one` | `on_match_all` |
+/// |-------|----------------|----------------|
+/// | `--name Alice` | `[0, 1]` (via Pickable tag) | `[0, 1]` |
+/// | `--name=Alice` | `[0]` | `[0]` |
+/// | `--val a --val b` | `[0, 1]` | `[0, 1, 2, 3]` |
+///
+/// Args after `--` are ignored.
 pub struct ArgMatcher;
 
+impl ArgMatcher {
+    /// Check whether `raw` matches `flag_str` (exact or eq-separated).
+    #[inline(always)]
+    fn matches(raw: &str, flag_str: &str, case_sensitive: bool) -> bool {
+        if case_sensitive {
+            raw == flag_str
+                || raw.starts_with(flag_str) && raw.as_bytes().get(flag_str.len()) == Some(&b'=')
+        } else {
+            raw.eq_ignore_ascii_case(flag_str)
+                || (raw.len() > flag_str.len()
+                    && raw[..flag_str.len()].eq_ignore_ascii_case(flag_str)
+                    && raw.as_bytes()[flag_str.len()] == b'=')
+        }
+    }
+
+    /// Check whether the argument at the given position (in the masked slice)
+    /// contains its value inline (eq mode), so no extra slot is needed.
+    #[inline(always)]
+    fn is_eq_mode(raw: &str, flag_str: &str) -> bool {
+        raw.len() > flag_str.len() && raw.as_bytes().get(flag_str.len()) == Some(&b'=')
+    }
+}
+
 impl Matcher for ArgMatcher {
     fn on_match_one(
-        _args: &[MaskedArg],
-        _style: &ParserStyle,
-        _arg_info: &PickerArgInfo,
+        args: &[MaskedArg],
+        style: &ParserStyle,
+        arg_info: &PickerArgInfo,
     ) -> Option<usize> {
-        todo!()
+        if arg_info.positional {
+            // Positional: first available position.
+            return args.first().map(|a| a.raw_idx);
+        }
+
+        let possible_flags = build_possible_flags(style, arg_info);
+        let end = seek_end_of_options(args, style);
+
+        for arg in args {
+            // Stop at end-of-options marker.
+            if end.is_some_and(|e| arg.raw_idx >= e) {
+                break;
+            }
+
+            let matched = possible_flags
+                .iter()
+                .any(|f| Self::matches(arg.raw, f, style.case_sensitive));
+            if matched {
+                return Some(arg.raw_idx);
+            }
+        }
+
+        None
     }
 
     fn on_match_all(
-        _args: &[MaskedArg],
-        _style: &ParserStyle,
-        _arg_info: &PickerArgInfo,
+        args: &[MaskedArg],
+        style: &ParserStyle,
+        arg_info: &PickerArgInfo,
     ) -> Vec<usize> {
-        todo!()
+        if arg_info.positional {
+            // Positional: all available positions before `--`.
+            let end = seek_end_of_options(args, style);
+            return args
+                .iter()
+                .take_while(|a| end.is_none_or(|e| a.raw_idx < e))
+                .map(|a| a.raw_idx)
+                .collect();
+        }
+
+        let possible_flags = build_possible_flags(style, arg_info);
+        let end = seek_end_of_options(args, style);
+
+        let mut result = Vec::new();
+        let mut i = 0;
+        while i < args.len() {
+            // Stop at end-of-options marker.
+            if end.is_some_and(|e| args[i].raw_idx >= e) {
+                break;
+            }
+
+            let matched = possible_flags
+                .iter()
+                .any(|f| Self::matches(args[i].raw, f, style.case_sensitive));
+
+            if matched {
+                // Find which flag matched to check eq mode.
+                let flag_str = possible_flags
+                    .iter()
+                    .find(|f| Self::matches(args[i].raw, f, style.case_sensitive))
+                    .expect("already matched");
+
+                result.push(args[i].raw_idx); // flag position
+
+                if !Self::is_eq_mode(args[i].raw, flag_str) {
+                    // Non-eq mode: the next argument is the value.
+                    // Always tag it — even if it looks like a flag — so that
+                    // the mask reserves it. Validation is the Pickable's job.
+                    if i + 1 < args.len() {
+                        result.push(args[i + 1].raw_idx);
+                        i += 2; // skip flag + value
+                        continue;
+                    }
+                    // No value available: tag just the flag.
+                    i += 1;
+                    continue;
+                }
+                // eq mode: value is inline, no extra slot.
+                i += 1;
+                continue;
+            }
+            i += 1;
+        }
+
+        result
     }
 }
+
+/// Locate the end-of-options marker (`--`) in the argument list.
+fn seek_end_of_options(args: &[MaskedArg], style: &ParserStyle) -> Option<usize> {
+    args.iter()
+        .find(|arg| {
+            if style.case_sensitive {
+                arg.raw == style.end_of_options
+            } else {
+                arg.raw.eq_ignore_ascii_case(style.end_of_options)
+            }
+        })
+        .map(|arg| arg.raw_idx)
+}