From a750135a0ac5a42035a1baa808e0af8ae562cd72 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Wed, 1 Aug 2018 00:14:26 +0300
Subject: If expr

---
 src/grammar.ron               |  2 ++
 src/grammar/expressions.rs    | 35 ++++++++++++++++++++++++++++++-----
 src/syntax_kinds/generated.rs |  6 ++++++
 3 files changed, 38 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/grammar.ron b/src/grammar.ron
index a9a3847c9..9912f9698 100644
--- a/src/grammar.ron
+++ b/src/grammar.ron
@@ -60,6 +60,7 @@ Grammar(
         "loop",
         "while",
         "if",
+        "else",
         "match",
         "const",
         "static",
@@ -134,6 +135,7 @@ Grammar(
         "LAMBDA_EXPR",
         "STRUCT_LIT",
         "STRUCT_LIT_FIELD",
+        "IF_EXPR",
 
         "EXTERN_BLOCK",
         "ENUM_VARIANT",
diff --git a/src/grammar/expressions.rs b/src/grammar/expressions.rs
index e2be13a77..ed9236b02 100644
--- a/src/grammar/expressions.rs
+++ b/src/grammar/expressions.rs
@@ -145,14 +145,16 @@ fn atom_expr(p: &mut Parser) -> Option<CompletedMarker> {
         return Some(path_expr(p));
     }
 
-    match p.current() {
-        L_PAREN => Some(tuple_expr(p)),
-        PIPE => Some(lambda_expr(p)),
+    let done = match p.current() {
+        L_PAREN => tuple_expr(p),
+        PIPE => lambda_expr(p),
+        IF_KW => if_expr(p),
         _ => {
             p.err_and_bump("expected expression");
-            None
+            return None;
         }
-    }
+    };
+    Some(done)
 }
 
 fn tuple_expr(p: &mut Parser) -> CompletedMarker {
@@ -182,6 +184,29 @@ fn lambda_expr(p: &mut Parser) -> CompletedMarker {
     m.complete(p, LAMBDA_EXPR)
 }
 
+// test if_expr
+// fn foo() {
+//     if true {};
+//     if true {} else {};
+//     if true {} else if false {} else {}
+// }
+fn if_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(IF_KW));
+    let m = p.start();
+    p.bump();
+    expr(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 call_expr
 // fn foo() {
 //     let _ = f();
diff --git a/src/syntax_kinds/generated.rs b/src/syntax_kinds/generated.rs
index 2f7c29008..35d9640fa 100644
--- a/src/syntax_kinds/generated.rs
+++ b/src/syntax_kinds/generated.rs
@@ -61,6 +61,7 @@ pub enum SyntaxKind {
     LOOP_KW,
     WHILE_KW,
     IF_KW,
+    ELSE_KW,
     MATCH_KW,
     CONST_KW,
     STATIC_KW,
@@ -125,6 +126,7 @@ pub enum SyntaxKind {
     LAMBDA_EXPR,
     STRUCT_LIT,
     STRUCT_LIT_FIELD,
+    IF_EXPR,
     EXTERN_BLOCK,
     ENUM_VARIANT,
     NAMED_FIELD,
@@ -223,6 +225,7 @@ impl SyntaxKind {
             LOOP_KW => &SyntaxInfo { name: "LOOP_KW" },
             WHILE_KW => &SyntaxInfo { name: "WHILE_KW" },
             IF_KW => &SyntaxInfo { name: "IF_KW" },
+            ELSE_KW => &SyntaxInfo { name: "ELSE_KW" },
             MATCH_KW => &SyntaxInfo { name: "MATCH_KW" },
             CONST_KW => &SyntaxInfo { name: "CONST_KW" },
             STATIC_KW => &SyntaxInfo { name: "STATIC_KW" },
@@ -287,6 +290,7 @@ impl SyntaxKind {
             LAMBDA_EXPR => &SyntaxInfo { name: "LAMBDA_EXPR" },
             STRUCT_LIT => &SyntaxInfo { name: "STRUCT_LIT" },
             STRUCT_LIT_FIELD => &SyntaxInfo { name: "STRUCT_LIT_FIELD" },
+            IF_EXPR => &SyntaxInfo { name: "IF_EXPR" },
             EXTERN_BLOCK => &SyntaxInfo { name: "EXTERN_BLOCK" },
             ENUM_VARIANT => &SyntaxInfo { name: "ENUM_VARIANT" },
             NAMED_FIELD => &SyntaxInfo { name: "NAMED_FIELD" },
@@ -344,6 +348,7 @@ impl SyntaxKind {
             "loop" => LOOP_KW,
             "while" => WHILE_KW,
             "if" => IF_KW,
+            "else" => ELSE_KW,
             "match" => MATCH_KW,
             "const" => CONST_KW,
             "static" => STATIC_KW,
@@ -445,6 +450,7 @@ impl SyntaxKind {
             LOOP_KW => "loop",
             WHILE_KW => "while",
             IF_KW => "if",
+            ELSE_KW => "else",
             MATCH_KW => "match",
             CONST_KW => "const",
             STATIC_KW => "static",
-- 
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