feat: ternary syntax

docs/language/control-flow.md

@@ -65,3 +65,37 @@ elif condition {
 ```
 
 ![](../assets/ifelif.png){width="200"}
+
+## Ternary Expressions
+
+Embed conditional logic directly inside expressions.
+
+### Syntax
+
+```goboscript
+if (<condition>) <true_value> else <false_value>
+```
+
+### Examples
+
+```goboscript
+say if (score > 100) "winner" else "loser";
+```
+
+Ternaries can be nested — an `else` branch can itself be a ternary:
+
+```goboscript
+say if (condition_A) "A_true"
+    else if (condition_B) "B_true"
+    else "false";
+```
+
+When used as a condition, a ternary must be wrapped in parentheses:
+
+```goboscript
+say if (if (condition_A) true else false) "yes" else "no";
+```
+
+### Compilation
+
+Ternaries are desugared at compile time into `if`/`else` branches. Each branch receives a copy of the surrounding statement with the ternary substituted for the appropriate value.

src/ast/expr.rs

@@ -64,6 +64,11 @@ pub enum Expr {
         property: SmolStr,
         span: Span,
     },
+    Ternary {
+        condition: Box<Expr>,
+        tvalue: Box<Expr>,
+        fvalue: Box<Expr>,
+    },
 }
 
 impl Expr {
@@ -79,6 +84,7 @@ impl Expr {
             Self::BinOp { span, .. } => span.clone(),
             Self::StructLiteral { span, .. } => span.clone(),
             Self::Property { span, .. } => span.clone(),
+            Self::Ternary { condition, .. } => condition.span(),
         }
     }
 }

src/codegen/build.rs

@@ -130,6 +130,7 @@ pub fn build_impl<T: Write + Seek>(
             block_count: 0,
         });
     }
+    visitor::ternary::visit_project(&mut project);
     {
         let mut fs = fs.borrow_mut();
         visitor::pass0::visit_project(

src/codegen/sb3.rs

@@ -1305,6 +1305,7 @@ impl Sb3 {
                 property,
                 span,
             } => self.property(s, d, this_id, parent_id, object, property, span),
+            Expr::Ternary { .. } => unreachable!(),
         }
     }
 }

src/visitor.rs

@@ -3,4 +3,5 @@ pub mod pass1;
 pub mod pass2;
 pub mod pass3;
 pub mod pass4;
+pub mod ternary;
 mod transformations;

src/visitor/pass0.rs

@@ -14,6 +14,7 @@ use crate::{
     diagnostic::SpriteDiagnostics,
     misc::SmolStr,
     vfs::VFS,
+    visitor::ternary::extract_ternary_from_stmts,
 };
 
 struct V<'a> {
@@ -58,6 +59,7 @@ fn visit_sprite(
             .proc_locals
             .insert(proc.name.clone(), Default::default());
         let proc_definition = sprite.proc_definitions.get_mut(&proc.name).unwrap();
+        extract_ternary_from_stmts(proc_definition);
         visit_stmts(
             proc_definition,
             &mut V {
@@ -86,6 +88,7 @@ fn visit_sprite(
             );
         }
         let func_definition = sprite.func_definitions.get_mut(&func.name).unwrap();
+        extract_ternary_from_stmts(func_definition);
         visit_stmts(
             func_definition,
             &mut V {
@@ -96,6 +99,7 @@ fn visit_sprite(
         );
     }
     for event in &mut sprite.events {
+        extract_ternary_from_stmts(&mut event.body);
         visit_stmts(
             &mut event.body,
             &mut V {

src/visitor/pass1.rs

@@ -325,6 +325,7 @@ fn visit_expr(expr: &mut Expr, before: &mut Vec<Stmt>, s: &mut S) {
             visit_expr(object, before, s);
             None
         }
+        Expr::Ternary { .. } => unreachable!(),
     };
     if let Some(replace) = replace {
         *expr = replace;

src/visitor/pass2.rs

@@ -395,6 +395,7 @@ fn visit_expr(expr: &mut Expr, s: S, d: D) {
         Expr::Property { object, .. } => {
             visit_expr(object, s, d);
         }
+        Expr::Ternary { .. } => unreachable!(),
     }
     transformations::apply(expr, |expr| transformations::enum_field_access(expr, s, d));
     transformations::apply(expr, transformations::minus);

src/visitor/pass3.rs

@@ -242,5 +242,6 @@ fn visit_expr(expr: &Expr, s: &mut S) {
         } => {
             visit_expr(object, s);
         }
+        Expr::Ternary { .. } => unreachable!(),
     }
 }