1 files changed, 400 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/grammar/expressions/atom.rs b/crates/ra_syntax/src/grammar/expressions/atom.rs
new file mode 100644
index 000000000..f01df56bc
--- /dev/null
+++ b/crates/ra_syntax/src/grammar/expressions/atom.rs
@@ -0,0 +1,400 @@
+use super::*;
+
+// test expr_literals
+// fn foo() {
+//     let _ = true;
+//     let _ = false;
+//     let _ = 1;
+//     let _ = 2.0;
+//     let _ = b'a';
+//     let _ = 'b';
+//     let _ = "c";
+//     let _ = r"d";
+//     let _ = b"e";
+//     let _ = br"f";
+// }
+pub(crate) const LITERAL_FIRST: TokenSet =
+    token_set![TRUE_KW, FALSE_KW, INT_NUMBER, FLOAT_NUMBER, BYTE, CHAR,
+               STRING, RAW_STRING, BYTE_STRING, RAW_BYTE_STRING];
+
+pub(crate) fn literal(p: &mut Parser) -> Option<CompletedMarker> {
+    if !p.at_ts(LITERAL_FIRST) {
+        return None;
+    }
+    let m = p.start();
+    p.bump();
+    Some(m.complete(p, LITERAL))
+}
+
+pub(super) const ATOM_EXPR_FIRST: TokenSet =
+    token_set_union![
+        LITERAL_FIRST,
+        token_set![L_CURLY, L_PAREN, L_BRACK, PIPE, MOVE_KW, IF_KW, WHILE_KW, MATCH_KW, UNSAFE_KW,
+                   RETURN_KW, IDENT, SELF_KW, SUPER_KW, COLONCOLON, BREAK_KW, CONTINUE_KW, LIFETIME ],
+    ];
+
+const EXPR_RECOVERY_SET: TokenSet =
+    token_set![LET_KW];
+
+pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<CompletedMarker> {
+    match literal(p) {
+        Some(m) => return Some(m),
+        None => (),
+    }
+    if paths::is_path_start(p) || p.at(L_ANGLE) {
+        return Some(path_expr(p, r));
+    }
+    let la = p.nth(1);
+    let done = match p.current() {
+        L_PAREN => tuple_expr(p),
+        L_BRACK => array_expr(p),
+        PIPE => lambda_expr(p),
+        MOVE_KW if la == PIPE => lambda_expr(p),
+        IF_KW => if_expr(p),
+
+        LOOP_KW => loop_expr(p, None),
+        FOR_KW => for_expr(p, None),
+        WHILE_KW => while_expr(p, None),
+        LIFETIME if la == COLON => {
+            let m = p.start();
+            label(p);
+            match p.current() {
+                LOOP_KW => loop_expr(p, Some(m)),
+                FOR_KW => for_expr(p, Some(m)),
+                WHILE_KW => while_expr(p, Some(m)),
+                L_CURLY => block_expr(p, Some(m)),
+                _ => {
+                    // test misplaced_label_err
+                    // fn main() {
+                    //     'loop: impl
+                    // }
+                    p.error("expected a loop");
+                    m.complete(p, ERROR);
+                    return None;
+                }
+            }
+        }
+
+        MATCH_KW => match_expr(p),
+        UNSAFE_KW if la == L_CURLY => {
+            let m = p.start();
+            p.bump();
+            block_expr(p, Some(m))
+        },
+        L_CURLY => block_expr(p, None),
+        RETURN_KW => return_expr(p),
+        CONTINUE_KW => continue_expr(p),
+        BREAK_KW => break_expr(p),
+        _ => {
+            p.err_recover("expected expression", EXPR_RECOVERY_SET);
+            return None;
+        }
+    };
+    Some(done)
+}
+
+// test tuple_expr
+// fn foo() {
+//     ();
+//     (1);
+//     (1,);
+// }
+fn tuple_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(L_PAREN));
+    let m = p.start();
+    p.expect(L_PAREN);
+
+    let mut saw_comma = false;
+    let mut saw_expr = false;
+    while !p.at(EOF) && !p.at(R_PAREN) {
+        saw_expr = true;
+        if !p.at_ts(EXPR_FIRST) {
+            p.error("expected expression");
+            break;
+        }
+        expr(p);
+        if !p.at(R_PAREN) {
+            saw_comma = true;
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_PAREN);
+    m.complete(p, if saw_expr && !saw_comma { PAREN_EXPR } else { TUPLE_EXPR })
+}
+
+// test array_expr
+// fn foo() {
+//     [];
+//     [1];
+//     [1, 2,];
+//     [1; 2];
+// }
+fn array_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(L_BRACK));
+    let m = p.start();
+    p.bump();
+    if p.eat(R_BRACK) {
+        return m.complete(p, ARRAY_EXPR);
+    }
+    expr(p);
+    if p.eat(SEMI) {
+        expr(p);
+        p.expect(R_BRACK);
+        return m.complete(p, ARRAY_EXPR);
+    }
+    while !p.at(EOF) && !p.at(R_BRACK) {
+        p.expect(COMMA);
+        if p.at(R_BRACK) {
+            break;
+        }
+        if !p.at_ts(EXPR_FIRST) {
+            p.error("expected expression");
+            break;
+        }
+        expr(p);
+    }
+    p.expect(R_BRACK);
+    m.complete(p, ARRAY_EXPR)
+}
+
+// test lambda_expr
+// fn foo() {
+//     || ();
+//     || -> i32 { 92 };
+//     |x| x;
+//     move |x: i32,| x;
+// }
+fn lambda_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(PIPE) || (p.at(MOVE_KW) && p.nth(1) == PIPE));
+    let m = p.start();
+    p.eat(MOVE_KW);
+    params::param_list_opt_types(p);
+    if opt_fn_ret_type(p) {
+        if !p.at(L_CURLY) {
+            p.error("expected `{`");
+        }
+    }
+    expr(p);
+    m.complete(p, LAMBDA_EXPR)
+}
+
+// test if_expr
+// fn foo() {
+//     if true {};
+//     if true {} else {};
+//     if true {} else if false {} else {};
+//     if S {};
+// }
+fn if_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(IF_KW));
+    let m = p.start();
+    p.bump();
+    cond(p);
+    block(p);
+    if p.at(ELSE_KW) {
+        p.bump();
+        if p.at(IF_KW) {
+            if_expr(p);
+        } else {
+            block(p);
+        }
+    }
+    m.complete(p, IF_EXPR)
+}
+
+// test label
+// fn foo() {
+//     'a: loop {}
+//     'b: while true {}
+//     'c: for x in () {}
+// }
+fn label(p: &mut Parser) {
+    assert!(p.at(LIFETIME) && p.nth(1) == COLON);
+    let m = p.start();
+    p.bump();
+    p.bump();
+    m.complete(p, LABEL);
+}
+
+// test loop_expr
+// fn foo() {
+//     loop {};
+// }
+fn loop_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
+    assert!(p.at(LOOP_KW));
+    let m = m.unwrap_or_else(|| p.start());
+    p.bump();
+    block(p);
+    m.complete(p, LOOP_EXPR)
+}
+
+// test while_expr
+// fn foo() {
+//     while true {};
+//     while let Some(x) = it.next() {};
+// }
+fn while_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
+    assert!(p.at(WHILE_KW));
+    let m = m.unwrap_or_else(|| p.start());
+    p.bump();
+    cond(p);
+    block(p);
+    m.complete(p, WHILE_EXPR)
+}
+
+// test for_expr
+// fn foo() {
+//     for x in [] {};
+// }
+fn for_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
+    assert!(p.at(FOR_KW));
+    let m = m.unwrap_or_else(|| p.start());
+    p.bump();
+    patterns::pattern(p);
+    p.expect(IN_KW);
+    expr_no_struct(p);
+    block(p);
+    m.complete(p, FOR_EXPR)
+}
+
+// test cond
+// fn foo() { if let Some(_) = None {} }
+fn cond(p: &mut Parser) {
+    let m = p.start();
+    if p.eat(LET_KW) {
+        patterns::pattern(p);
+        p.expect(EQ);
+    }
+    expr_no_struct(p);
+    m.complete(p, CONDITION);
+}
+
+// test match_expr
+// fn foo() {
+//     match () { };
+//     match S {};
+// }
+fn match_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(MATCH_KW));
+    let m = p.start();
+    p.bump();
+    expr_no_struct(p);
+    if p.at(L_CURLY) {
+        match_arm_list(p);
+    } else {
+        p.error("expected `{`")
+    }
+    m.complete(p, MATCH_EXPR)
+}
+
+pub(crate) fn match_arm_list(p: &mut Parser) {
+    assert!(p.at(L_CURLY));
+    let m = p.start();
+    p.eat(L_CURLY);
+    while !p.at(EOF) && !p.at(R_CURLY) {
+        if p.at(L_CURLY) {
+            error_block(p, "expected match arm");
+            continue;
+        }
+        // test match_arms_commas
+        // fn foo() {
+        //     match () {
+        //         _ => (),
+        //         _ => {}
+        //         _ => ()
+        //     }
+        // }
+        if match_arm(p).is_block() {
+            p.eat(COMMA);
+        } else if !p.at(R_CURLY) {
+            p.expect(COMMA);
+        }
+    }
+    p.expect(R_CURLY);
+    m.complete(p, MATCH_ARM_LIST);
+}
+
+// test match_arm
+// fn foo() {
+//     match () {
+//         _ => (),
+//         X | Y if Z => (),
+//     };
+// }
+fn match_arm(p: &mut Parser) -> BlockLike {
+    let m = p.start();
+    patterns::pattern_r(p, TokenSet::EMPTY);
+    while p.eat(PIPE) {
+        patterns::pattern(p);
+    }
+    if p.eat(IF_KW) {
+        expr_no_struct(p);
+    }
+    p.expect(FAT_ARROW);
+    let ret = expr_stmt(p);
+    m.complete(p, MATCH_ARM);
+    ret
+}
+
+// test block_expr
+// fn foo() {
+//     {};
+//     unsafe {};
+//     'label: {};
+// }
+fn block_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
+    assert!(p.at(L_CURLY));
+    let m = m.unwrap_or_else(|| p.start());
+    block(p);
+    m.complete(p, BLOCK_EXPR)
+}
+
+// test return_expr
+// fn foo() {
+//     return;
+//     return 92;
+// }
+fn return_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(RETURN_KW));
+    let m = p.start();
+    p.bump();
+    if p.at_ts(EXPR_FIRST) {
+        expr(p);
+    }
+    m.complete(p, RETURN_EXPR)
+}
+
+// test continue_expr
+// fn foo() {
+//     loop {
+//         continue;
+//         continue 'l;
+//     }
+// }
+fn continue_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(CONTINUE_KW));
+    let m = p.start();
+    p.bump();
+    p.eat(LIFETIME);
+    m.complete(p, CONTINUE_EXPR)
+}
+
+// test break_expr
+// fn foo() {
+//     loop {
+//         break;
+//         break 'l;
+//         break 92;
+//         break 'l 92;
+//     }
+// }
+fn break_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(BREAK_KW));
+    let m = p.start();
+    p.bump();
+    p.eat(LIFETIME);
+    if p.at_ts(EXPR_FIRST) {
+        expr(p);
+    }
+    m.complete(p, BREAK_EXPR)
+}