From fd21c650c238e1846ed48920ba332bf77aad456f Mon Sep 17 00:00:00 2001
From: Olivier Abrivard <olivier@abrivard.fr>
Date: Sat, 17 Aug 2024 08:33:52 -0400
Subject: [PATCH] Add Logical Operators handling for control flow

---
 .idea/scala_compiler.xml                  |  6 ++++++
 src/main/ExprGenerator.ws.kts             |  1 +
 src/main/fr/celticinfo/lox/Expr.kt        | 11 ++++++++++
 src/main/fr/celticinfo/lox/Interpreter.kt | 12 +++++++++++
 src/main/fr/celticinfo/lox/Parser.kt      | 26 ++++++++++++++++++++++-
 5 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 .idea/scala_compiler.xml

diff --git a/.idea/scala_compiler.xml b/.idea/scala_compiler.xml
new file mode 100644
index 0000000..3c0e0f6
--- /dev/null
+++ b/.idea/scala_compiler.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ScalaCompilerConfiguration">
+    <option name="separateProdTestSources" value="false" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/src/main/ExprGenerator.ws.kts b/src/main/ExprGenerator.ws.kts
index a2ea20b..08352a8 100644
--- a/src/main/ExprGenerator.ws.kts
+++ b/src/main/ExprGenerator.ws.kts
@@ -44,6 +44,7 @@ val exprTypes = listOf(
     "Binary   : Expr left, Token operator, Expr right",
     "Grouping : Expr expression",
     "Literal  : Any? value",
+    "Logical  : Expr left, Token operator, Expr right",
     "Unary    : Token operator, Expr right",
     "Variable : Token name"
 )
diff --git a/src/main/fr/celticinfo/lox/Expr.kt b/src/main/fr/celticinfo/lox/Expr.kt
index a213d3f..3f75a65 100644
--- a/src/main/fr/celticinfo/lox/Expr.kt
+++ b/src/main/fr/celticinfo/lox/Expr.kt
@@ -8,6 +8,7 @@ interface ExprVisitor<R> {
     fun visitBinary(expr: Binary): R
     fun visitGrouping(expr: Grouping): R
     fun visitLiteral(expr: Literal): R
+    fun visitLogical(expr: Logical): R
     fun visitUnary(expr: Unary): R
     fun visitVariable(expr: Variable): R
 }
@@ -52,6 +53,16 @@ data class Literal(
     }
 }
 
+data class Logical(
+    val left: Expr,
+    val operator: Token,
+    val right: Expr
+) : Expr() {
+    override fun <R> accept(visitor: ExprVisitor<R>): R {
+        return visitor.visitLogical(this)
+    }
+}
+
 data class Unary(
     val operator: Token, val right: Expr
 ) : Expr() {
diff --git a/src/main/fr/celticinfo/lox/Interpreter.kt b/src/main/fr/celticinfo/lox/Interpreter.kt
index 8809f9a..99cadc5 100644
--- a/src/main/fr/celticinfo/lox/Interpreter.kt
+++ b/src/main/fr/celticinfo/lox/Interpreter.kt
@@ -127,6 +127,18 @@ class Interpreter: ExprVisitor<Any?>, StmtVisitor<Unit>{
         return expr.value
     }
 
+    override fun visitLogical(expr: Logical): Any? {
+        val left = evaluate(expr.left)
+
+        if (expr.operator.type == OR) {
+            if (isTruthy(left)) return left
+        } else {
+            if (!isTruthy(left)) return left
+        }
+
+        return evaluate(expr.right)
+    }
+
     override fun visitUnary(expr: Unary): Any? {
         val right = evaluate(expr.right)
 
diff --git a/src/main/fr/celticinfo/lox/Parser.kt b/src/main/fr/celticinfo/lox/Parser.kt
index 2b7407a..7ea68c0 100644
--- a/src/main/fr/celticinfo/lox/Parser.kt
+++ b/src/main/fr/celticinfo/lox/Parser.kt
@@ -96,7 +96,7 @@ class Parser(private val tokens: List<Token>) {
     }
 
     private fun assignment(): Expr {
-        val expr = equality()
+        val expr = or()
 
         if (match(EQUAL)) {
             val equals = previous()
@@ -113,6 +113,30 @@ class Parser(private val tokens: List<Token>) {
         return expr
     }
 
+    private fun or(): Expr {
+        var expr = and()
+
+        while (match(OR)) {
+            val operator = previous()
+            val right = and()
+            expr = Logical(expr, operator, right)
+        }
+
+        return expr
+    }
+
+    private fun and(): Expr {
+        var expr = equality()
+
+        while (match(AND)) {
+            val operator = previous()
+            val right = equality()
+            expr = Logical(expr, operator, right)
+        }
+
+        return expr
+    }
+
     private fun equality(): Expr {
         var expr = comparison()