attempts at parsing

compiler/parse/src/ast.rs

@@ -4,7 +4,7 @@ use crate::header::{AppHeader, HostedHeader, InterfaceHeader, PlatformHeader};
 use crate::ident::Ident;
 use bumpalo::collections::{String, Vec};
 use bumpalo::Bump;
-use roc_collections::soa::{EitherIndex, Slice};
+use roc_collections::soa::{EitherIndex, Index, Slice};
 use roc_module::called_via::{BinOp, CalledVia, UnaryOp};
 use roc_region::all::{Loc, Position, Region};
 
@@ -334,7 +334,7 @@ pub enum ValueDef<'a> {
     Expect(&'a Loc<Expr<'a>>),
 }
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Default)]
 pub struct Defs<'a> {
     pub tags: std::vec::Vec<EitherIndex<TypeDef<'a>, ValueDef<'a>>>,
     pub regions: std::vec::Vec<Region>,
@@ -346,12 +346,62 @@ pub struct Defs<'a> {
 }
 
 impl<'a> Defs<'a> {
-    pub fn defs(&self) -> impl Iterator<Item = Result<&TypeDef<'a>, &ValueDef<'a>>> {
+    pub fn defs<I>(&self) -> impl Iterator<Item = Result<&TypeDef<'a>, &ValueDef<'a>>> {
         self.tags.iter().map(|tag| match tag.split() {
             Ok(type_index) => Ok(&self.type_defs[type_index.index()]),
             Err(value_index) => Err(&self.value_defs[value_index.index()]),
         })
     }
+
+    pub fn last(&self) -> Option<Result<&TypeDef<'a>, &ValueDef<'a>>> {
+        self.tags.last().map(|tag| match tag.split() {
+            Ok(type_index) => Ok(&self.type_defs[type_index.index()]),
+            Err(value_index) => Err(&self.value_defs[value_index.index()]),
+        })
+    }
+
+    /// NOTE assumes the def itself is pushed already!
+    fn push_def_help(
+        &mut self,
+        tag: EitherIndex<TypeDef<'a>, ValueDef<'a>>,
+        region: Region,
+        spaces_before: &[CommentOrNewline<'a>],
+        spaces_after: &[CommentOrNewline<'a>],
+    ) {
+        self.tags.push(tag);
+
+        self.regions.push(region);
+
+        let before = Slice::extend_new(&mut self.spaces, spaces_before.iter().copied());
+        self.space_before.push(before);
+
+        let after = Slice::extend_new(&mut self.spaces, spaces_after.iter().copied());
+        self.space_after.push(after);
+    }
+
+    pub fn push_value_def(
+        &mut self,
+        value_def: ValueDef<'a>,
+        region: Region,
+        spaces_before: &[CommentOrNewline<'a>],
+        spaces_after: &[CommentOrNewline<'a>],
+    ) {
+        let value_def_index = Index::push_new(&mut self.value_defs, value_def);
+        let tag = EitherIndex::from_right(value_def_index);
+        self.push_def_help(tag, region, spaces_before, spaces_after)
+    }
+
+    pub fn push_type_def(
+        &mut self,
+        type_def: TypeDef<'a>,
+        region: Region,
+        spaces_before: &[CommentOrNewline<'a>],
+        spaces_after: &[CommentOrNewline<'a>],
+    ) {
+        let type_def_index = Index::push_new(&mut self.type_defs, type_def);
+        let tag = EitherIndex::from_left(type_def_index);
+        self.push_def_help(tag, region, spaces_before, spaces_after)
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq)]

compiler/parse/src/expr.rs

@@ -1,6 +1,6 @@
 use crate::ast::{
-    AssignedField, Collection, CommentOrNewline, Def, Derived, Expr, ExtractSpaces, Has, Pattern,
-    Spaceable, TypeAnnotation, TypeDef, TypeHeader, ValueDef,
+    AssignedField, Collection, CommentOrNewline, Def, Defs, Derived, Expr, ExtractSpaces, Has,
+    Pattern, Spaceable, TypeAnnotation, TypeDef, TypeHeader, ValueDef,
 };
 use crate::blankspace::{
     space0_after_e, space0_around_ee, space0_before_e, space0_before_optional_after, space0_e,
@@ -811,6 +811,306 @@ struct DefState<'a> {
     spaces_after: &'a [CommentOrNewline<'a>],
 }
 
+fn parse_toplevel_defs_end<'a>(
+    options: ExprParseOptions,
+    start_column: u32,
+    mut defs: Defs<'a>,
+    arena: &'a Bump,
+    state: State<'a>,
+) -> ParseResult<'a, Defs<'a>, EExpr<'a>> {
+    let min_indent = start_column;
+    let initial = state.clone();
+
+    let mut spaces_before_current = &[] as &[_];
+
+    let state = match space0_e(min_indent, EExpr::IndentStart).parse(arena, state) {
+        Err((MadeProgress, _, s)) => {
+            return Err((MadeProgress, EExpr::DefMissingFinalExpr(s.pos()), s));
+        }
+        Ok((_, spaces, state)) => {
+            spaces_before_current = spaces;
+            state
+        }
+        Err((NoProgress, _, state)) => state,
+    };
+
+    let start = state.pos();
+    let column = state.column();
+
+    match space0_after_e(
+        crate::pattern::loc_pattern_help(min_indent),
+        min_indent,
+        EPattern::IndentEnd,
+    )
+    .parse(arena, state.clone())
+    {
+        Err((NoProgress, _, _)) => {
+            match crate::parser::keyword_e(crate::keyword::EXPECT, EExpect::Expect)
+                .parse(arena, state)
+            {
+                Err((_, _, _)) => {
+                    // a hacky way to get expression-based error messages. TODO fix this
+                    Ok((NoProgress, defs, initial))
+                }
+                Ok((_, _, state)) => {
+                    let parse_def_expr = space0_before_e(
+                        move |a, s| parse_loc_expr(min_indent + 1, a, s),
+                        min_indent,
+                        EExpr::IndentEnd,
+                    );
+
+                    let (_, loc_def_expr, state) = parse_def_expr.parse(arena, state)?;
+
+                    let end = loc_def_expr.region.end();
+                    let region = Region::new(start, end);
+
+                    let value_def = ValueDef::Expect(arena.alloc(loc_def_expr));
+                    defs.push_value_def(value_def, region, spaces_before_current, &[]);
+
+                    parse_toplevel_defs_end(options, column, defs, arena, state)
+                }
+            }
+        }
+        Err((MadeProgress, _, _)) => {
+            // a hacky way to get expression-based error messages. TODO fix this
+            Ok((NoProgress, defs, initial))
+        }
+        Ok((_, loc_pattern, state)) => {
+            // First let's check whether this is an ability definition.
+            let opt_tag_and_args: Option<(&str, Region, &[Loc<Pattern>])> = match loc_pattern.value
+            {
+                Pattern::Apply(
+                    Loc {
+                        value: Pattern::Tag(name),
+                        region,
+                    },
+                    args,
+                ) => Some((name, *region, args)),
+                Pattern::Tag(name) => Some((name, loc_pattern.region, &[])),
+                _ => None,
+            };
+
+            if let Some((name, name_region, args)) = opt_tag_and_args {
+                if let Ok((_, loc_has, state)) =
+                    loc_has_parser(min_indent).parse(arena, state.clone())
+                {
+                    let (_, (type_def, def_region), state) = finish_parsing_ability_def_help(
+                        start_column,
+                        Loc::at(name_region, name),
+                        args,
+                        loc_has,
+                        arena,
+                        state,
+                    )?;
+
+                    defs.push_type_def(type_def, def_region, spaces_before_current, &[]);
+
+                    return parse_toplevel_defs_end(options, column, defs, arena, state);
+                }
+            }
+
+            // Otherwise, this is a def or alias.
+            match operator().parse(arena, state) {
+                Ok((_, BinOp::Assignment, state)) => {
+                    let parse_def_expr = space0_before_e(
+                        move |a, s| parse_loc_expr(min_indent + 1, a, s),
+                        min_indent,
+                        EExpr::IndentEnd,
+                    );
+
+                    let (_, loc_def_expr, state) = parse_def_expr.parse(arena, state)?;
+
+                    {
+                        let region = Region::span_across(&loc_pattern.region, &loc_def_expr.region);
+
+                        if spaces_before_current.len() <= 1 {
+                            match defs.last() {
+                                Some((
+                                    before_ann_spaces,
+                                    Def::Value(ValueDef::Annotation(ann_pattern, ann_type)),
+                                )) => {
+                                    return append_body_definition_help(
+                                        arena,
+                                        defs,
+                                        region,
+                                        before_ann_spaces,
+                                        spaces_before_current,
+                                        loc_pattern,
+                                        loc_def_expr,
+                                        ann_pattern,
+                                        ann_type,
+                                    );
+                                }
+                                Some((
+                                    before_ann_spaces,
+                                    Def::Type(TypeDef::Alias {
+                                        header,
+                                        ann: ann_type,
+                                    }),
+                                )) => {
+                                    // This is a case like
+                                    //   UserId x : [UserId Int]
+                                    //   UserId x = UserId 42
+                                    // We optimistically parsed the first line as an alias; we now turn it
+                                    // into an annotation.
+                                    let loc_name =
+                                        arena.alloc(header.name.map(|x| Pattern::Tag(x)));
+                                    let ann_pattern = Pattern::Apply(loc_name, header.vars);
+                                    let vars_region =
+                                        Region::across_all(header.vars.iter().map(|v| &v.region));
+                                    let region_ann_pattern =
+                                        Region::span_across(&loc_name.region, &vars_region);
+                                    let loc_ann_pattern = Loc::at(region_ann_pattern, ann_pattern);
+
+                                    return append_body_definition_help(
+                                        arena,
+                                        defs,
+                                        region,
+                                        before_ann_spaces,
+                                        spaces_before_current,
+                                        loc_pattern,
+                                        loc_def_expr,
+                                        arena.alloc(loc_ann_pattern),
+                                        ann_type,
+                                    );
+                                }
+                                _ => {
+                                    defs.extend(last);
+                                }
+                            }
+                        }
+
+                        // the previous and current def can't be joined up
+                        let mut loc_def = Loc::at(
+                            region,
+                            Def::Value(ValueDef::Body(
+                                arena.alloc(loc_pattern),
+                                &*arena.alloc(loc_def_expr),
+                            )),
+                        );
+
+                        if !spaces_before_current.is_empty() {
+                            loc_def = arena
+                                .alloc(loc_def.value)
+                                .with_spaces_before(spaces_before_current, loc_def.region);
+                        }
+
+                        defs.push(arena.alloc(loc_def));
+                    };
+
+                    parse_toplevel_defs_end(options, column, defs, arena, state)
+                }
+                Ok((_, BinOp::IsAliasType, state)) => {
+                    let (_, ann_type, state) =
+                        alias_signature_with_space_before(min_indent + 1).parse(arena, state)?;
+
+                    let region = Region::span_across(&loc_pattern.region, &ann_type.region);
+
+                    // the previous and current def can't be joined up
+                    match &loc_pattern.value {
+                        Pattern::Apply(
+                            Loc {
+                                value: Pattern::Tag(name),
+                                ..
+                            },
+                            alias_arguments,
+                        ) => {
+                            let name = Loc::at(loc_pattern.region, *name);
+                            let header = TypeHeader {
+                                name,
+                                vars: alias_arguments,
+                            };
+
+                            let type_def = TypeDef::Alias {
+                                header,
+                                ann: ann_type,
+                            };
+
+                            defs.push_type_def(type_def, region, spaces_before_current, &[]);
+                        }
+                        Pattern::Tag(name) => {
+                            let name = Loc::at(loc_pattern.region, *name);
+                            let pattern_arguments: &'a [Loc<Pattern<'a>>] = &[];
+                            let header = TypeHeader {
+                                name,
+                                vars: pattern_arguments,
+                            };
+
+                            let type_def = TypeDef::Alias {
+                                header,
+                                ann: ann_type,
+                            };
+
+                            defs.push_type_def(type_def, region, spaces_before_current, &[]);
+                        }
+                        _ => {
+                            let value_def = ValueDef::Annotation(loc_pattern, ann_type);
+                            defs.push_value_def(value_def, region, spaces_before_current, &[]);
+                        }
+                    };
+
+                    parse_toplevel_defs_end(options, column, defs, arena, state)
+                }
+                Ok((_, BinOp::IsOpaqueType, state)) => {
+                    let (_, (signature, derived), state) =
+                        opaque_signature_with_space_before(min_indent + 1).parse(arena, state)?;
+
+                    let region = Region::span_across(&loc_pattern.region, &signature.region);
+
+                    // the previous and current def can't be joined up
+                    match &loc_pattern.value {
+                        Pattern::Apply(
+                            Loc {
+                                value: Pattern::Tag(name),
+                                ..
+                            },
+                            alias_arguments,
+                        ) => {
+                            let name = Loc::at(loc_pattern.region, *name);
+                            let header = TypeHeader {
+                                name,
+                                vars: alias_arguments,
+                            };
+
+                            let type_def = TypeDef::Opaque {
+                                header,
+                                typ: signature,
+                                derived,
+                            };
+
+                            defs.push_type_def(type_def, region, spaces_before_current, &[]);
+                        }
+                        Pattern::Tag(name) => {
+                            let name = Loc::at(loc_pattern.region, *name);
+                            let pattern_arguments: &'a [Loc<Pattern<'a>>] = &[];
+                            let header = TypeHeader {
+                                name,
+                                vars: pattern_arguments,
+                            };
+
+                            let type_def = TypeDef::Opaque {
+                                header,
+                                typ: signature,
+                                derived,
+                            };
+
+                            defs.push_type_def(type_def, region, spaces_before_current, &[]);
+                        }
+                        _ => {
+                            let value_def = ValueDef::Annotation(loc_pattern, signature);
+                            defs.push_value_def(value_def, region, spaces_before_current, &[]);
+                        }
+                    };
+
+                    parse_toplevel_defs_end(options, column, defs, arena, state)
+                }
+
+                _ => Ok((MadeProgress, defs, initial)),
+            }
+        }
+    }
+}
+
 fn parse_defs_end<'a>(
     options: ExprParseOptions,
     start_column: u32,
@@ -1309,6 +1609,32 @@ fn finish_parsing_ability_def<'a>(
     arena: &'a Bump,
     state: State<'a>,
 ) -> ParseResult<'a, &'a Loc<Def<'a>>, EExpr<'a>> {
+    let (_, (type_def, def_region), state) =
+        finish_parsing_ability_def_help(start_column, name, args, loc_has, arena, state)?;
+
+    let def = Def::Type(type_def);
+
+    let loc_def = &*(if spaces_before.is_empty() {
+        arena.alloc(Loc::at(def_region, def))
+    } else {
+        arena.alloc(
+            arena
+                .alloc(def)
+                .with_spaces_before(spaces_before, def_region),
+        )
+    });
+
+    Ok((MadeProgress, loc_def, state))
+}
+
+fn finish_parsing_ability_def_help<'a>(
+    start_column: u32,
+    name: Loc<&'a str>,
+    args: &'a [Loc<Pattern<'a>>],
+    loc_has: Loc<Has<'a>>,
+    arena: &'a Bump,
+    state: State<'a>,
+) -> ParseResult<'a, (TypeDef<'a>, Region), EExpr<'a>> {
     let mut demands = Vec::with_capacity_in(2, arena);
 
     let min_indent_for_demand = start_column + 1;
@@ -1347,23 +1673,13 @@ fn finish_parsing_ability_def<'a>(
     }
 
     let def_region = Region::span_across(&name.region, &demands.last().unwrap().typ.region);
-    let def = Def::Type(TypeDef::Ability {
+    let type_def = TypeDef::Ability {
         header: TypeHeader { name, vars: args },
         loc_has,
         members: demands.into_bump_slice(),
-    });
+    };
 
-    let loc_def = &*(if spaces_before.is_empty() {
-        arena.alloc(Loc::at(def_region, def))
-    } else {
-        arena.alloc(
-            arena
-                .alloc(def)
-                .with_spaces_before(spaces_before, def_region),
-        )
-    });
-
-    Ok((MadeProgress, loc_def, state))
+    Ok((MadeProgress, (type_def, def_region), state))
 }
 
 fn finish_parsing_ability<'a>(
@@ -1960,6 +2276,30 @@ fn assigned_expr_field_to_pattern_help<'a>(
     })
 }
 
+pub fn toplevel_defs<'a>(min_indent: u32) -> impl Parser<'a, Defs<'a>, EExpr<'a>> {
+    move |arena, state: State<'a>| {
+        let (_, initial_space, state) =
+            space0_e(min_indent, EExpr::IndentEnd).parse(arena, state)?;
+
+        let start_column = state.column();
+
+        let options = ExprParseOptions {
+            accept_multi_backpassing: false,
+            check_for_arrow: true,
+        };
+
+        let output = Defs::default();
+
+        let (_, output, state) =
+            parse_toplevel_defs_end(options, start_column, output, arena, state)?;
+
+        let (_, final_space, state) =
+            space0_e(start_column, EExpr::IndentEnd).parse(arena, state)?;
+
+        Ok((MadeProgress, output, state))
+    }
+}
+
 pub fn defs<'a>(min_indent: u32) -> impl Parser<'a, Vec<'a, Loc<Def<'a>>>, EExpr<'a>> {
     move |arena, state: State<'a>| {
         let def_state = DefState {