1 files changed, 77 insertions, 0 deletions

diff --git a/src/grammar/paths.rs b/src/grammar/paths.rs
new file mode 100644
index 000000000..fe69db096
--- /dev/null
+++ b/src/grammar/paths.rs
@@ -0,0 +1,77 @@
+use super::*;
+
+pub(super) fn is_path_start(p: &Parser) -> bool {
+    match p.current() {
+        IDENT | SELF_KW | SUPER_KW | COLONCOLON => true,
+        _ => false,
+    }
+}
+
+pub(super) fn use_path(p: &mut Parser) {
+    path(p, Mode::Use)
+}
+
+pub(super) fn type_path(p: &mut Parser) {
+    path(p, Mode::Type)
+}
+
+pub(super) fn expr_path(p: &mut Parser) {
+    path(p, Mode::Expr)
+}
+
+#[derive(Clone, Copy, Eq, PartialEq)]
+enum Mode {
+    Use,
+    Type,
+    Expr,
+}
+
+fn path(p: &mut Parser, mode: Mode) {
+    if !is_path_start(p) {
+        return;
+    }
+    let path = p.start();
+    path_segment(p, mode, true);
+    let mut qual = path.complete(p, PATH);
+    loop {
+        let use_tree = match p.nth(1) {
+            STAR | L_CURLY => true,
+            _ => false,
+        };
+        if p.at(COLONCOLON) && !use_tree {
+            let path = qual.precede(p);
+            p.bump();
+            path_segment(p, mode, false);
+            let path = path.complete(p, PATH);
+            qual = path;
+        } else {
+            break;
+        }
+    }
+}
+
+fn path_segment(p: &mut Parser, mode: Mode, first: bool) {
+    let segment = p.start();
+    if first {
+        p.eat(COLONCOLON);
+    }
+    match p.current() {
+        IDENT => {
+            name_ref(p);
+            path_generic_args(p, mode);
+        }
+        SELF_KW | SUPER_KW => p.bump(),
+        _ => {
+            p.error("expected identifier");
+        }
+    };
+    segment.complete(p, PATH_SEGMENT);
+}
+
+fn path_generic_args(p: &mut Parser, mode: Mode) {
+    match mode {
+        Mode::Use => return,
+        Mode::Type => type_args::type_arg_list(p, false),
+        Mode::Expr => type_args::type_arg_list(p, true),
+    }
+}