move all parsing related bits to a separate module

4 files changed, 447 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/parsing/grammar/items/consts.rs b/crates/ra_syntax/src/parsing/grammar/items/consts.rs
new file mode 100644
index 000000000..5a5852f83
--- /dev/null
+++ b/crates/ra_syntax/src/parsing/grammar/items/consts.rs
@@ -0,0 +1,21 @@
+use super::*;
+
+pub(super) fn static_def(p: &mut Parser) {
+    const_or_static(p, STATIC_KW)
+}
+
+pub(super) fn const_def(p: &mut Parser) {
+    const_or_static(p, CONST_KW)
+}
+
+fn const_or_static(p: &mut Parser, kw: SyntaxKind) {
+    assert!(p.at(kw));
+    p.bump();
+    p.eat(MUT_KW); // TODO: validator to forbid const mut
+    name(p);
+    types::ascription(p);
+    if p.eat(EQ) {
+        expressions::expr(p);
+    }
+    p.expect(SEMI);
+}
diff --git a/crates/ra_syntax/src/parsing/grammar/items/nominal.rs b/crates/ra_syntax/src/parsing/grammar/items/nominal.rs
new file mode 100644
index 000000000..ff9b38f9c
--- /dev/null
+++ b/crates/ra_syntax/src/parsing/grammar/items/nominal.rs
@@ -0,0 +1,168 @@
+use super::*;
+
+pub(super) fn struct_def(p: &mut Parser, kind: SyntaxKind) {
+    assert!(p.at(STRUCT_KW) || p.at_contextual_kw("union"));
+    p.bump_remap(kind);
+
+    name_r(p, ITEM_RECOVERY_SET);
+    type_params::opt_type_param_list(p);
+    match p.current() {
+        WHERE_KW => {
+            type_params::opt_where_clause(p);
+            match p.current() {
+                SEMI => {
+                    p.bump();
+                    return;
+                }
+                L_CURLY => named_field_def_list(p),
+                _ => {
+                    //TODO: special case `(` error message
+                    p.error("expected `;` or `{`");
+                    return;
+                }
+            }
+        }
+        SEMI if kind == STRUCT_KW => {
+            p.bump();
+            return;
+        }
+        L_CURLY => named_field_def_list(p),
+        L_PAREN if kind == STRUCT_KW => {
+            pos_field_def_list(p);
+            // test tuple_struct_where
+            // struct Test<T>(T) where T: Clone;
+            // struct Test<T>(T);
+            type_params::opt_where_clause(p);
+            p.expect(SEMI);
+        }
+        _ if kind == STRUCT_KW => {
+            p.error("expected `;`, `{`, or `(`");
+            return;
+        }
+        _ => {
+            p.error("expected `{`");
+            return;
+        }
+    }
+}
+
+pub(super) fn enum_def(p: &mut Parser) {
+    assert!(p.at(ENUM_KW));
+    p.bump();
+    name_r(p, ITEM_RECOVERY_SET);
+    type_params::opt_type_param_list(p);
+    type_params::opt_where_clause(p);
+    if p.at(L_CURLY) {
+        enum_variant_list(p);
+    } else {
+        p.error("expected `{`")
+    }
+}
+
+pub(crate) fn enum_variant_list(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    let m = p.start();
+    p.bump();
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        if p.at(L_CURLY) {
+            error_block(p, "expected enum variant");
+            continue;
+        }
+        let var = p.start();
+        attributes::outer_attributes(p);
+        if p.at(IDENT) {
+            name(p);
+            match p.current() {
+                L_CURLY => named_field_def_list(p),
+                L_PAREN => pos_field_def_list(p),
+                EQ => {
+                    p.bump();
+                    expressions::expr(p);
+                }
+                _ => (),
+            }
+            var.complete(p, ENUM_VARIANT);
+        } else {
+            var.abandon(p);
+            p.err_and_bump("expected enum variant");
+        }
+        if !p.at(R_CURLY) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_CURLY);
+    m.complete(p, ENUM_VARIANT_LIST);
+}
+
+pub(crate) fn named_field_def_list(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    let m = p.start();
+    p.bump();
+    while !p.at(R_CURLY) && !p.at(EOF) {
+        if p.at(L_CURLY) {
+            error_block(p, "expected field");
+            continue;
+        }
+        named_field_def(p);
+        if !p.at(R_CURLY) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_CURLY);
+    m.complete(p, NAMED_FIELD_DEF_LIST);
+
+    fn named_field_def(p: &mut Parser) {
+        let m = p.start();
+        // test field_attrs
+        // struct S {
+        //     #[serde(with = "url_serde")]
+        //     pub uri: Uri,
+        // }
+        attributes::outer_attributes(p);
+        opt_visibility(p);
+        if p.at(IDENT) {
+            name(p);
+            p.expect(COLON);
+            types::type_(p);
+            m.complete(p, NAMED_FIELD_DEF);
+        } else {
+            m.abandon(p);
+            p.err_and_bump("expected field declaration");
+        }
+    }
+}
+
+fn pos_field_def_list(p: &mut Parser) {
+    assert!(p.at(L_PAREN));
+    let m = p.start();
+    if !p.expect(L_PAREN) {
+        return;
+    }
+    while !p.at(R_PAREN) && !p.at(EOF) {
+        let m = p.start();
+        // test pos_field_attrs
+        // struct S (
+        //     #[serde(with = "url_serde")]
+        //     pub Uri,
+        // );
+        //
+        // enum S {
+        //     Uri(#[serde(with = "url_serde")] Uri),
+        // }
+        attributes::outer_attributes(p);
+        opt_visibility(p);
+        if !p.at_ts(types::TYPE_FIRST) {
+            p.error("expected a type");
+            m.complete(p, ERROR);
+            break;
+        }
+        types::type_(p);
+        m.complete(p, POS_FIELD_DEF);
+
+        if !p.at(R_PAREN) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_PAREN);
+    m.complete(p, POS_FIELD_DEF_LIST);
+}
diff --git a/crates/ra_syntax/src/parsing/grammar/items/traits.rs b/crates/ra_syntax/src/parsing/grammar/items/traits.rs
new file mode 100644
index 000000000..d5a8ccd98
--- /dev/null
+++ b/crates/ra_syntax/src/parsing/grammar/items/traits.rs
@@ -0,0 +1,137 @@
+use super::*;
+
+// test trait_item
+// trait T<U>: Hash + Clone where U: Copy {}
+pub(super) fn trait_def(p: &mut Parser) {
+    assert!(p.at(TRAIT_KW));
+    p.bump();
+    name_r(p, ITEM_RECOVERY_SET);
+    type_params::opt_type_param_list(p);
+    if p.at(COLON) {
+        type_params::bounds(p);
+    }
+    type_params::opt_where_clause(p);
+    if p.at(L_CURLY) {
+        trait_item_list(p);
+    } else {
+        p.error("expected `{`");
+    }
+}
+
+// test trait_item_list
+// impl F {
+//     type A: Clone;
+//     const B: i32;
+//     fn foo() {}
+//     fn bar(&self);
+// }
+pub(crate) fn trait_item_list(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    let m = p.start();
+    p.bump();
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        if p.at(L_CURLY) {
+            error_block(p, "expected an item");
+            continue;
+        }
+        item_or_macro(p, true, ItemFlavor::Trait);
+    }
+    p.expect(R_CURLY);
+    m.complete(p, ITEM_LIST);
+}
+
+// test impl_block
+// impl Foo {}
+pub(super) fn impl_block(p: &mut Parser) {
+    assert!(p.at(IMPL_KW));
+    p.bump();
+    if choose_type_params_over_qpath(p) {
+        type_params::opt_type_param_list(p);
+    }
+
+    // TODO: never type
+    // impl ! {}
+
+    // test impl_block_neg
+    // impl !Send for X {}
+    p.eat(EXCL);
+    impl_type(p);
+    if p.eat(FOR_KW) {
+        impl_type(p);
+    }
+    type_params::opt_where_clause(p);
+    if p.at(L_CURLY) {
+        impl_item_list(p);
+    } else {
+        p.error("expected `{`");
+    }
+}
+
+// test impl_item_list
+// impl F {
+//     type A = i32;
+//     const B: i32 = 92;
+//     fn foo() {}
+//     fn bar(&self) {}
+// }
+pub(crate) fn impl_item_list(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    let m = p.start();
+    p.bump();
+    // test impl_inner_attributes
+    // enum F{}
+    // impl F {
+    //      //! This is a doc comment
+    //      #![doc("This is also a doc comment")]
+    // }
+    attributes::inner_attributes(p);
+
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        if p.at(L_CURLY) {
+            error_block(p, "expected an item");
+            continue;
+        }
+        item_or_macro(p, true, ItemFlavor::Mod);
+    }
+    p.expect(R_CURLY);
+    m.complete(p, ITEM_LIST);
+}
+
+fn choose_type_params_over_qpath(p: &Parser) -> bool {
+    // There's an ambiguity between generic parameters and qualified paths in impls.
+    // If we see `<` it may start both, so we have to inspect some following tokens.
+    // The following combinations can only start generics,
+    // but not qualified paths (with one exception):
+    //     `<` `>` - empty generic parameters
+    //     `<` `#` - generic parameters with attributes
+    //     `<` (LIFETIME|IDENT) `>` - single generic parameter
+    //     `<` (LIFETIME|IDENT) `,` - first generic parameter in a list
+    //     `<` (LIFETIME|IDENT) `:` - generic parameter with bounds
+    //     `<` (LIFETIME|IDENT) `=` - generic parameter with a default
+    // The only truly ambiguous case is
+    //     `<` IDENT `>` `::` IDENT ...
+    // we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
+    // because this is what almost always expected in practice, qualified paths in impls
+    // (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
+    if !p.at(L_ANGLE) {
+        return false;
+    }
+    if p.nth(1) == POUND || p.nth(1) == R_ANGLE {
+        return true;
+    }
+    (p.nth(1) == LIFETIME || p.nth(1) == IDENT)
+        && (p.nth(2) == R_ANGLE || p.nth(2) == COMMA || p.nth(2) == COLON || p.nth(2) == EQ)
+}
+
+// test_err impl_type
+// impl Type {}
+// impl Trait1 for T {}
+// impl impl NotType {}
+// impl Trait2 for impl NotType {}
+pub(crate) fn impl_type(p: &mut Parser) {
+    if p.at(IMPL_KW) {
+        p.error("expected trait or type");
+        return;
+    }
+    types::type_(p);
+}
diff --git a/crates/ra_syntax/src/parsing/grammar/items/use_item.rs b/crates/ra_syntax/src/parsing/grammar/items/use_item.rs
new file mode 100644
index 000000000..5111d37eb
--- /dev/null
+++ b/crates/ra_syntax/src/parsing/grammar/items/use_item.rs
@@ -0,0 +1,121 @@
+use super::*;
+
+pub(super) fn use_item(p: &mut Parser) {
+    assert!(p.at(USE_KW));
+    p.bump();
+    use_tree(p);
+    p.expect(SEMI);
+}
+
+/// Parse a use 'tree', such as `some::path` in `use some::path;`
+/// Note that this is called both by `use_item` and `use_tree_list`,
+/// so handles both `some::path::{inner::path}` and `inner::path` in
+/// `use some::path::{inner::path};`
+fn use_tree(p: &mut Parser) {
+    let la = p.nth(1);
+    let m = p.start();
+    match (p.current(), la) {
+        // Finish the use_tree for cases of e.g.
+        // `use some::path::{self, *};` or `use *;`
+        // This does not handle cases such as `use some::path::*`
+        // N.B. in Rust 2015 `use *;` imports all from crate root
+        // however in Rust 2018 `use *;` errors: ('cannot glob-import all possible crates')
+        // TODO: Add this error (if not out of scope)
+
+        // test use_star
+        // use *;
+        // use ::*;
+        // use some::path::{*};
+        // use some::path::{::*};
+        (STAR, _) => p.bump(),
+        (COLONCOLON, STAR) => {
+            // Parse `use ::*;`, which imports all from the crate root in Rust 2015
+            // This is invalid inside a use_tree_list, (e.g. `use some::path::{::*}`)
+            // but still parses and errors later: ('crate root in paths can only be used in start position')
+            // TODO: Add this error (if not out of scope)
+            // In Rust 2018, it is always invalid (see above)
+            p.bump();
+            p.bump();
+        }
+        // Open a use tree list
+        // Handles cases such as `use {some::path};` or `{inner::path}` in
+        // `use some::path::{{inner::path}, other::path}`
+
+        // test use_tree_list
+        // use {crate::path::from::root, or::path::from::crate_name}; // Rust 2018 (with a crate named `or`)
+        // use {path::from::root}; // Rust 2015
+        // use ::{some::arbritrary::path}; // Rust 2015
+        // use ::{{{crate::export}}}; // Nonsensical but perfectly legal nestnig
+        (L_CURLY, _) | (COLONCOLON, L_CURLY) => {
+            if p.at(COLONCOLON) {
+                p.bump();
+            }
+            use_tree_list(p);
+        }
+        // Parse a 'standard' path.
+        // Also handles aliases (e.g. `use something as something_else`)
+
+        // test use_path
+        // use ::crate_name; // Rust 2018 - All flavours
+        // use crate_name; // Rust 2018 - Anchored paths
+        // use item_in_scope_or_crate_name; // Rust 2018 - Uniform Paths
+        //
+        // use self::module::Item;
+        // use crate::Item;
+        // use self::some::Struct;
+        // use crate_name::some_item;
+        _ if paths::is_path_start(p) => {
+            paths::use_path(p);
+            match p.current() {
+                AS_KW => {
+                    // test use_alias
+                    // use some::path as some_name;
+                    // use some::{
+                    //  other::path as some_other_name,
+                    //  different::path as different_name,
+                    //  yet::another::path,
+                    //  running::out::of::synonyms::for_::different::*
+                    // };
+                    opt_alias(p);
+                }
+                COLONCOLON => {
+                    p.bump();
+                    match p.current() {
+                        STAR => {
+                            p.bump();
+                        }
+                        // test use_tree_list_after_path
+                        // use crate::{Item};
+                        // use self::{Item};
+                        L_CURLY => use_tree_list(p),
+                        _ => {
+                            // is this unreachable?
+                            p.error("expected `{` or `*`");
+                        }
+                    }
+                }
+                _ => (),
+            }
+        }
+        _ => {
+            m.abandon(p);
+            p.err_and_bump("expected one of `*`, `::`, `{`, `self`, `super` or an indentifier");
+            return;
+        }
+    }
+    m.complete(p, USE_TREE);
+}
+
+pub(crate) fn use_tree_list(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    let m = p.start();
+    p.bump();
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        use_tree(p);
+        if !p.at(R_CURLY) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_CURLY);
+    m.complete(p, USE_TREE_LIST);
+}