Add While statement

src/main/ExprGenerator.ws.kts

@@ -55,6 +55,7 @@ val stmtTypes = listOf(
     "Expression : Expr expression",
     "If         : Expr condition, Stmt thenBranch, Stmt? elseBranch",
     "Print      : Expr expression",
-    "Var        : Token name, Expr? initializer"
+    "Var        : Token name, Expr? initializer",
+    "While      : Expr condition, Stmt body"
 )
 defineAst("Stmt", stmtTypes)

src/main/fr/celticinfo/lox/Interpreter.kt

@@ -52,6 +52,12 @@ class Interpreter: ExprVisitor<Any?>, StmtVisitor<Unit>{
         }
     }
 
+    override fun visitWhile(stmt: While) {
+        while (isTruthy(evaluate(stmt.condition))) {
+            execute(stmt.body)
+        }
+    }
+
     override fun visitPrint(stmt: Print) {
         val value = evaluate(stmt.expression)
         println(stringify(value))

src/main/fr/celticinfo/lox/Parser.kt

@@ -43,11 +43,20 @@ class Parser(private val tokens: List<Token>) {
         return Var(name, initializer)
     }
 
+    private fun whileStatement(): Stmt {
+        consume(LEFT_PAREN, "Expect '(' after 'while'.")
+        val condition = expression()
+        consume(RIGHT_PAREN, "Expect ')' after condition.")
+        val body = statement()
+
+        return While(condition, body)
+    }
 
     private fun statement(): Stmt {
         return when {
             match(IF) -> ifStatement()
             match(PRINT) -> printStatement()
+            match(WHILE) -> whileStatement()
             match(LEFT_BRACE) -> Block(blockStatement())
             else -> expressionStatement()
         }

src/main/fr/celticinfo/lox/Stmt.kt

@@ -8,7 +8,8 @@ interface StmtVisitor<R> {
     fun visitExpression(stmt: Expression): R
     fun visitIf(stmt: If): R
     fun visitPrint(stmt: Print): R
-    fun visitVar(stmt: Var): R    
+    fun visitVar(stmt: Var): R
+    fun visitWhile(stmt: While): R
 }
 
 /**
@@ -58,4 +59,13 @@ data class Var(
     override fun <R> accept(visitor: StmtVisitor<R>): R {
         return visitor.visitVar(this)
     }
+}
+
+data class While(
+    val condition: Expr,
+    val body: Stmt
+) : Stmt() {
+    override fun <R> accept(visitor: StmtVisitor<R>): R {
+        return visitor.visitWhile(this)
+    }
 }