From 86bb611905ce16c315f2de14bf2beff9cc603697 Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvark@fastmail.com>
Date: Thu, 11 Feb 2021 15:25:20 -0500
Subject: [PATCH] [wgsl] support select()

---
 src/front/wgsl/conv.rs  |  1 +
 src/front/wgsl/mod.rs   | 13 +++++++++++++
 src/front/wgsl/tests.rs | 18 +++++++++++++++---
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/front/wgsl/conv.rs b/src/front/wgsl/conv.rs
index c159684849..a9362f3e58 100644
--- a/src/front/wgsl/conv.rs
+++ b/src/front/wgsl/conv.rs
@@ -99,6 +99,7 @@ pub fn get_scalar_type(word: &str) -> Option<(crate::ScalarKind, crate::Bytes)>
         "f32" => Some((crate::ScalarKind::Float, 4)),
         "i32" => Some((crate::ScalarKind::Sint, 4)),
         "u32" => Some((crate::ScalarKind::Uint, 4)),
+        "bool" => Some((crate::ScalarKind::Bool, 1)),
         _ => None,
     }
 }
diff --git a/src/front/wgsl/mod.rs b/src/front/wgsl/mod.rs
index 32123deece..38aaf4095b 100644
--- a/src/front/wgsl/mod.rs
+++ b/src/front/wgsl/mod.rs
@@ -443,6 +443,19 @@ impl Parser {
                 arg1,
                 arg2,
             })
+        } else if name == "select" {
+            lexer.expect(Token::Paren('('))?;
+            let accept = self.parse_general_expression(lexer, ctx.reborrow())?;
+            lexer.expect(Token::Separator(','))?;
+            let reject = self.parse_general_expression(lexer, ctx.reborrow())?;
+            lexer.expect(Token::Separator(','))?;
+            let condition = self.parse_general_expression(lexer, ctx.reborrow())?;
+            lexer.expect(Token::Paren(')'))?;
+            Some(crate::Expression::Select {
+                condition,
+                accept,
+                reject,
+            })
         } else {
             // texture sampling
             match name {
diff --git a/src/front/wgsl/tests.rs b/src/front/wgsl/tests.rs
index 72238dc1ae..c0408415e1 100644
--- a/src/front/wgsl/tests.rs
+++ b/src/front/wgsl/tests.rs
@@ -197,7 +197,19 @@ fn parse_texture_query() {
 
 #[test]
 fn parse_postfix() {
-    parse_str("fn foo() { const x: f32 = vec4<f32>(1.0, 2.0, 3.0, 4.0).xyz.rgbr.aaaa.wz.g; }")
-        .unwrap();
-    parse_str("fn foo() { const x: f32 = fract(vec2<f32>(0.5, 1.0)).x; }").unwrap();
+    parse_str(
+        "fn foo() {
+        const x: f32 = vec4<f32>(1.0, 2.0, 3.0, 4.0).xyz.rgbr.aaaa.wz.g;
+        const y: f32 = fract(vec2<f32>(0.5, x)).x;
+    }",
+    )
+    .unwrap();
+}
+
+#[test]
+fn parse_expressions() {
+    parse_str("fn foo() {
+        const x: f32 = select(0.0, 1.0, true);
+        const y: vec2<f32> = select(vec2<f32>(1.0, 1.0), vec2<f32>(x, x), vec2<bool>(x < 0.5, x > 0.5));
+    }").unwrap();
 }