Merge pull request #374 from ozwaldorf/feat/not_strict

feat: `ParsePositional::non_strict`

Author: pacak

bpaf_derive/src/attrs.rs

@@ -217,6 +217,7 @@ impl ToTokens for PostParse {
             PostParse::Optional { .. } => quote!(optional()),
             PostParse::Parse { f, .. } => quote!(parse(#f)),
             PostParse::Strict { .. } => quote!(strict()),
+            PostParse::NonStrict { .. } => quote!(non_strict()),
             PostParse::Anywhere { .. } => quote!(anywhere()),
         }
         .to_tokens(tokens);
@@ -256,6 +257,7 @@ pub(crate) enum PostParse {
     Optional { span: Span },
     Parse { span: Span, f: Box<Expr> },
     Strict { span: Span },
+    NonStrict { span: Span },
     Anywhere { span: Span },
 }
 impl PostParse {
@@ -271,6 +273,7 @@ impl PostParse {
             | Self::Optional { span }
             | Self::Parse { span, .. }
             | Self::Strict { span }
+            | Self::NonStrict { span }
             | Self::Anywhere { span } => *span,
         }
     }
@@ -480,6 +483,8 @@ impl PostParse {
             Self::Parse { span, f }
         } else if kw == "strict" {
             Self::Strict { span }
+        } else if kw == "non_strict" {
+            Self::NonStrict { span }
         } else if kw == "some" {
             let msg = parse_arg(input)?;
             Self::Some_ { span, msg }

bpaf_derive/src/field_tests.rs

@@ -485,6 +485,19 @@ fn strict_positional_named_fields() {
     };
     assert_eq!(input.to_token_stream().to_string(), output.to_string());
 }
+
+#[test]
+fn non_strict_positional_named_fields() {
+    let input: NamedField = parse_quote! {
+        #[bpaf(positional("ARG"), non_strict)]
+        name: String
+    };
+    let output = quote! {
+        ::bpaf::positional::<String>("ARG").non_strict()
+    };
+    assert_eq!(input.to_token_stream().to_string(), output.to_string());
+}
+
 #[test]
 fn optional_named_pathed() {
     let input: NamedField = parse_quote! {

src/error.rs

@@ -42,10 +42,14 @@ pub(crate) enum Message {
     // those cannot be caught-------------------------------------------------------------
     /// Parsing failed and this is the final output
     ParseFailure(ParseFailure),
+
     /// Tried to consume a strict positional argument, value was present but was not strictly
     /// positional
     StrictPos(usize, Metavar),
 
+    /// Tried to consume a non-strict positional argument, but the value was strict
+    NonStrictPos(usize, Metavar),
+
     /// Parser provided by user failed to parse a value
     ParseFailed(Option<usize>, String),
 
@@ -87,7 +91,8 @@ impl Message {
             | Message::ParseSome(_)
             | Message::ParseFail(_)
             | Message::Missing(_)
-            | Message::PureFailed(_) => true,
+            | Message::PureFailed(_)
+            | Message::NonStrictPos(_, _) => true,
             Message::StrictPos(_, _)
             | Message::ParseFailed(_, _)
             | Message::GuardFailed(_, _)
@@ -325,6 +330,18 @@ impl Message {
                 doc.token(Token::BlockEnd(Block::TermRef));
             }
 
+            // Error: FOO expected to be on the left side of --
+            Message::NonStrictPos(_ix, metavar) => {
+                doc.text("expected ");
+                doc.token(Token::BlockStart(Block::TermRef));
+                doc.metavar(metavar);
+                doc.token(Token::BlockEnd(Block::TermRef));
+                doc.text(" to be on the left side of ");
+                doc.token(Token::BlockStart(Block::TermRef));
+                doc.literal("--");
+                doc.token(Token::BlockEnd(Block::TermRef));
+            }
+
             // Error: <message from some or fail>
             Message::ParseSome(s) | Message::ParseFail(s) => {
                 doc.text(s);

src/params.rs

@@ -709,21 +709,28 @@ pub(crate) fn build_positional<T>(metavar: &'static str) -> ParsePositional<T> {
     ParsePositional {
         metavar,
         help: None,
-        result_type: PhantomData,
-        strict: false,
+        position: Position::Unrestricted,
+        ty: PhantomData,
     }
 }
 
-/// Parse a positional item, created with [`positional`]
+/// Parse a positional item, created with [`positional`](crate::positional)
 ///
-/// You can add extra information to positional parsers with [`help`](Self::help)
-/// and [`strict`](Self::strict) on this struct.
+/// You can add extra information to positional parsers with [`help`](Self::help),
+/// [`strict`](Self::strict), or [`non_strict`](Self::non_strict) on this struct.
 #[derive(Clone)]
 pub struct ParsePositional<T> {
     metavar: &'static str,
     help: Option<Doc>,
-    result_type: PhantomData<T>,
-    strict: bool,
+    position: Position,
+    ty: PhantomData<T>,
+}
+
+#[derive(Clone, PartialEq, Eq)]
+enum Position {
+    Unrestricted,
+    Strict,
+    NonStrict,
 }
 
 impl<T> ParsePositional<T> {
@@ -769,39 +776,59 @@ impl<T> ParsePositional<T> {
     /// `bpaf` would display such positional elements differently in usage line as well.
     #[cfg_attr(not(doctest), doc = include_str!("docs2/positional_strict.md"))]
     #[must_use]
-    pub fn strict(mut self) -> Self {
-        self.strict = true;
+    #[inline(always)]
+    pub fn strict(mut self) -> ParsePositional<T> {
+        self.position = Position::Strict;
+        self
+    }
+
+    /// Changes positional parser to be a "not strict" positional
+    ///
+    /// Ensures the parser always rejects "strict" positions to the right of the separator, `--`.
+    /// Essentially the inverse operation to [`ParsePositional::strict`], which can be used to ensure
+    /// adjacent strict and nonstrict args never conflict with eachother.
+    #[must_use]
+    #[inline(always)]
+    pub fn non_strict(mut self) -> Self {
+        self.position = Position::NonStrict;
         self
     }
 
+    #[inline(always)]
     fn meta(&self) -> Meta {
         let meta = Meta::from(Item::Positional {
             metavar: Metavar(self.metavar),
             help: self.help.clone(),
         });
-        if self.strict {
-            Meta::Strict(Box::new(meta))
-        } else {
-            meta
+        match self.position {
+            Position::Strict => Meta::Strict(Box::new(meta)),
+            _ => meta,
         }
     }
 }
 
 fn parse_pos_word(
     args: &mut State,
-    strict: bool,
-    metavar: &'static str,
+    metavar: Metavar,
     help: &Option<Doc>,
+    position: &Position,
 ) -> Result<OsString, Error> {
-    let metavar = Metavar(metavar);
     match args.take_positional_word(metavar) {
         Ok((ix, is_strict, word)) => {
-            if strict && !is_strict {
-                #[cfg(feature = "autocomplete")]
-                args.push_pos_sep();
-
-                return Err(Error(Message::StrictPos(ix, metavar)));
+            match position {
+                &Position::Strict if !is_strict => {
+                    #[cfg(feature = "autocomplete")]
+                    args.push_pos_sep();
+                    return Err(Error(Message::StrictPos(ix, metavar)));
+                }
+                &Position::NonStrict if is_strict => {
+                    #[cfg(feature = "autocomplete")]
+                    args.push_pos_sep();
+                    return Err(Error(Message::NonStrictPos(ix, metavar)));
+                }
+                _ => {}
             }
+
             #[cfg(feature = "autocomplete")]
             if args.touching_last_remove() && !args.check_no_pos_ahead() {
                 args.push_metavar(metavar.0, help, false);
@@ -826,13 +853,14 @@ where
     <T as std::str::FromStr>::Err: std::fmt::Display,
 {
     fn eval(&self, args: &mut State) -> Result<T, Error> {
-        let os = parse_pos_word(args, self.strict, self.metavar, &self.help)?;
+        let os = parse_pos_word(args, Metavar(self.metavar), &self.help, &self.position)?;
         match parse_os_str::<T>(os) {
             Ok(ok) => Ok(ok),
             Err(err) => Err(Error(Message::ParseFailed(args.current, err))),
         }
     }
 
+    #[inline(always)]
     fn meta(&self) -> Meta {
         self.meta()
     }

tests/positionals.rs

@@ -144,3 +144,17 @@ fn strictly_positional() {
     let r = parser.run_inner(&["--"]).unwrap_err().unwrap_stderr();
     assert_eq!(r, "expected `A`, pass `--help` for usage information");
 }
+
+#[test]
+fn non_strictly_positional() {
+    let parser = positional::<String>("A").non_strict().to_options();
+
+    let r = parser.run_inner(&["a"]).unwrap();
+    assert_eq!(r, "a");
+
+    let r = parser.run_inner(&["--", "a"]).unwrap_err().unwrap_stderr();
+    assert_eq!(r, "expected `A` to be on the left side of `--`");
+
+    let r = parser.run_inner(&["--"]).unwrap_err().unwrap_stderr();
+    assert_eq!(r, "expected `A`, pass `--help` for usage information");
+}