From c62b73a2477b9fa625285e9c2ca1e51c2bcb8024 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Thu, 14 Jan 2021 23:53:47 -0800
Subject: Add branching primitives

---
 src/com/craftinginterpreters/lox/Parser.java | 42 +++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

(limited to 'src/com/craftinginterpreters/lox/Parser.java')

diff --git a/src/com/craftinginterpreters/lox/Parser.java b/src/com/craftinginterpreters/lox/Parser.java
index f044feb..1643129 100644
--- a/src/com/craftinginterpreters/lox/Parser.java
+++ b/src/com/craftinginterpreters/lox/Parser.java
@@ -43,6 +43,8 @@ class Parser {
     }
 
     private Stmt statement() {
+        if (match(IF))
+            return ifStatement();
         if (match(PRINT))
             return printStatement();
         if (match(LEFT_BRACE))
@@ -51,6 +53,20 @@ class Parser {
         return expressionStatement();
     }
 
+    private Stmt ifStatement() {
+        consume(LEFT_PAREN, "Expect '(' after 'if'.");
+        Expr condition = expression();
+        consume(RIGHT_PAREN, "Expect ')' after if condition.");
+
+        Stmt thenBranch = statement();
+        Stmt elseBranch = null;
+        if (match(ELSE)) {
+            elseBranch = statement();
+        }
+
+        return new Stmt.If(condition, thenBranch, elseBranch);
+    }
+
     private Stmt printStatement() {
         Expr value = expression();
         consume(SEMICOLON, "Expect ';' after value.");
@@ -87,7 +103,7 @@ class Parser {
     }
 
     private Expr assignment() {
-        Expr expr = equality();
+        Expr expr = or();
 
         if (match(EQUAL)) {
             Token equals = previous();
@@ -104,6 +120,30 @@ class Parser {
         return expr;
     }
 
+    private Expr or() {
+        Expr expr = and();
+
+        while (match(OR)) {
+            Token operator = previous();
+            Expr right = and();
+            expr = new Expr.Logical(expr, operator, right);
+        }
+
+        return expr;
+    }
+
+    private Expr and() {
+        Expr expr = equality();
+
+        while (match(AND)) {
+            Token operator = previous();
+            Expr right = equality();
+            expr = new Expr.Logical(expr, operator, right);
+        }
+
+        return expr;
+    }
+
     private Expr equality() {
         Expr expr = comparison();
 
-- 
cgit v1.2.3-54-g00ecf