Initial attempt at implementing switch support

Author: Gui-Yom

data/Switch.hx

@@ -0,0 +1,26 @@
+class Switch {
+    static function main() {
+        var a = 3;
+        var b = switch (a) {
+            case 0: a * 2;
+            case 3: a - 1;
+            default: a << 2;
+        }
+        switch (b) {
+            case 0: b += 1;
+            case 1: b += 1;
+            case 2: b += 1;
+            //case 4: b += 1;
+        }
+        /*
+        switch (a) {
+            case -1: b += 1;
+            case -5: b += 1;
+        }
+        var c = "hello";
+        switch (c) {
+            case "hello": a += 1;
+            case "world": a += 1;
+        }*/
+    }
+}

src/decompiler/ast.rs

@@ -258,12 +258,10 @@ pub enum Statement {
         variable: Expr,
         assign: Expr,
     },
-    // Call a void function (no assignment)
-    Call(Call),
-    /// Return an expression
-    Return(Expr),
-    /// Return nothing / early return
-    ReturnVoid,
+    /// Expression statement
+    ExprStatement(Expr),
+    /// Return an expression or nothing (void)
+    Return(Option<Expr>),
     /// If statement
     If {
         cond: Expr,
@@ -273,6 +271,11 @@ pub enum Statement {
     Else {
         stmts: Vec<Statement>,
     },
+    Switch {
+        arg: Expr,
+        default: Vec<Statement>,
+        cases: Vec<(Expr, Vec<Statement>)>,
+    },
     /// While statement
     While {
         cond: Expr,
@@ -282,3 +285,8 @@ pub enum Statement {
     Continue,
     Throw(Expr),
 }
+
+/// Create an expression statement
+pub fn stmt(e: Expr) -> Statement {
+    Statement::ExprStatement(e)
+}

src/decompiler/fmt.rs

@@ -2,7 +2,7 @@ use std::fmt;
 use std::fmt::{Display, Formatter};
 
 use crate::decompiler::ast::{
-    Call, Class, Constant, ConstructorCall, Expr, Method, Operation, Statement,
+    Class, Constant, ConstructorCall, Expr, Method, Operation, Statement,
 };
 use crate::types::{Function, RefField, Type};
 use crate::Bytecode;
@@ -245,13 +245,12 @@ impl Statement {
                 } => {
                     if *declaration { "var " } else { "" }{disp!(variable)}" = "{disp!(assign)}";"
                 }
-                Statement::Call(Call { fun, args }) => {
-                    {disp!(fun)}"("{fmtools::join(", ", args.iter().map(|e| disp!(e)))}");"
+                Statement::ExprStatement(expr) => {
+                    {disp!(expr)}";"
                 }
                 Statement::Return(expr) => {
-                    "return "{disp!(expr)}";"
+                    "return" if let Some(e) = expr { " "{disp!(e)} } ";"
                 }
-                Statement::ReturnVoid => "return;",
                 Statement::If { cond, stmts } => {
                     "if ("{disp!(cond)}") {\n"
                     let indent2 = indent.inc_nesting();
@@ -268,6 +267,24 @@ impl Statement {
                     }
                     {indent}"}"
                 }
+                Statement::Switch {arg, default, cases} => {
+                    "switch ("{disp!(arg)}") {\n"
+                    let indent2 = indent.inc_nesting();
+                    let indent3 = indent2.inc_nesting();
+                    if !default.is_empty() {
+                        {indent2}"default:\n"
+                        for stmt in default {
+                            {indent3}{stmt.display(&indent3, code, f)}"\n"
+                        }
+                    }
+                    for (pattern, stmts) in cases {
+                        {indent2}"case "{disp!(pattern)}":\n"
+                        for stmt in stmts {
+                            {indent3}{stmt.display(&indent3, code, f)}"\n"
+                        }
+                    }
+                    {indent}"}"
+                }
                 Statement::While { cond, stmts } => {
                     "while ("{disp!(cond)}") {\n"
                     let indent2 = indent.inc_nesting();