1 files changed, 127 insertions, 0 deletions

diff --git a/crates/libsyntax2/src/grammar/type_params.rs b/crates/libsyntax2/src/grammar/type_params.rs
new file mode 100644
index 000000000..0a3e8fd07
--- /dev/null
+++ b/crates/libsyntax2/src/grammar/type_params.rs
@@ -0,0 +1,127 @@
+use super::*;
+
+pub(super) fn type_param_list(p: &mut Parser) {
+    if !p.at(L_ANGLE) {
+        return;
+    }
+    let m = p.start();
+    p.bump();
+
+    while !p.at(EOF) && !p.at(R_ANGLE) {
+        match p.current() {
+            LIFETIME => lifetime_param(p),
+            IDENT => type_param(p),
+            _ => p.err_and_bump("expected type parameter"),
+        }
+        if !p.at(R_ANGLE) && !p.expect(COMMA) {
+            break;
+        }
+    }
+    p.expect(R_ANGLE);
+    m.complete(p, TYPE_PARAM_LIST);
+
+    fn lifetime_param(p: &mut Parser) {
+        assert!(p.at(LIFETIME));
+        let m = p.start();
+        p.bump();
+        if p.at(COLON) {
+            lifetime_bounds(p);
+        }
+        m.complete(p, LIFETIME_PARAM);
+    }
+
+    fn type_param(p: &mut Parser) {
+        assert!(p.at(IDENT));
+        let m = p.start();
+        name(p);
+        if p.at(COLON) {
+            bounds(p);
+        }
+        // test type_param_default
+        // struct S<T = i32>;
+        if p.at(EQ) {
+            p.bump();
+            types::type_(p)
+        }
+        m.complete(p, TYPE_PARAM);
+    }
+}
+
+// test type_param_bounds
+// struct S<T: 'a + ?Sized + (Copy)>;
+pub(super) fn bounds(p: &mut Parser) {
+    assert!(p.at(COLON));
+    p.bump();
+    bounds_without_colon(p);
+}
+
+fn lifetime_bounds(p: &mut Parser) {
+    assert!(p.at(COLON));
+    p.bump();
+    while p.at(LIFETIME) {
+        p.bump();
+        if !p.eat(PLUS) {
+            break;
+        }
+    }
+}
+
+pub(super) fn bounds_without_colon(p: &mut Parser) {
+    loop {
+        let has_paren = p.eat(L_PAREN);
+        p.eat(QUESTION);
+        if p.at(FOR_KW) {
+            //TODO
+        }
+        if p.at(LIFETIME) {
+            p.bump();
+        } else if paths::is_path_start(p) {
+            paths::type_path(p);
+        } else {
+            break;
+        }
+        if has_paren {
+            p.expect(R_PAREN);
+        }
+        if !p.eat(PLUS) {
+            break;
+        }
+    }
+}
+
+// test where_clause
+// fn foo()
+// where
+//    'a: 'b + 'c,
+//    T: Clone + Copy + 'static,
+//    Iterator::Item: 'a,
+// {}
+pub(super) fn where_clause(p: &mut Parser) {
+    if !p.at(WHERE_KW) {
+        return;
+    }
+    let m = p.start();
+    p.bump();
+    loop {
+        if !(paths::is_path_start(p) || p.current() == LIFETIME) {
+            break
+        }
+        where_predicate(p);
+        if p.current() != L_CURLY && p.current() != SEMI {
+            p.expect(COMMA);
+        }
+    }
+    m.complete(p, WHERE_CLAUSE);
+}
+
+fn where_predicate(p: &mut Parser) {
+    let m = p.start();
+    if p.at(LIFETIME) {
+        p.eat(LIFETIME);
+        lifetime_bounds(p)
+    } else {
+        types::path_type(p);
+        bounds(p);
+    }
+    m.complete(p, WHERE_PRED);
+}