From be40cd61c403160f402d446d7af4dcaebcf47274 Mon Sep 17 00:00:00 2001
From: Ryan Chandler <ryangjchandler@gmail.com>
Date: Mon, 25 Jul 2022 20:16:18 +0100
Subject: [PATCH] parser: support basic math ops

---
 trunk_lexer/src/lexer.rs       | 11 +++++++++++
 trunk_parser/src/ast.rs        |  4 ++++
 trunk_parser/src/parser/mod.rs | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/trunk_lexer/src/lexer.rs b/trunk_lexer/src/lexer.rs
index 7778035..25a9012 100644
--- a/trunk_lexer/src/lexer.rs
+++ b/trunk_lexer/src/lexer.rs
@@ -496,6 +496,17 @@ impl Lexer {
                     TokenKind::Comment(buffer)
                 }
             },
+            '*' => {
+                self.col += 1;
+
+                if let Some('*') = it.peek() {
+                    self.col += 1;
+                    it.next();
+                    TokenKind::Pow
+                } else {
+                    TokenKind::Asterisk
+                }
+            },
             '|' => {
                 self.col += 1;
                 // TODO: Handle boolean or || tokens.
diff --git a/trunk_parser/src/ast.rs b/trunk_parser/src/ast.rs
index 3f82321..3f65e05 100644
--- a/trunk_parser/src/ast.rs
+++ b/trunk_parser/src/ast.rs
@@ -243,6 +243,8 @@ pub struct ArrayItem {
 pub enum InfixOp {
     Add,
     Sub,
+    Div,
+    Mul,
     LessThan,
 }
 
@@ -251,6 +253,8 @@ impl From<TokenKind> for InfixOp {
         match k {
             TokenKind::Plus => Self::Add,
             TokenKind::Minus => Self::Sub,
+            TokenKind::Asterisk => Self::Mul,
+            TokenKind::Slash => Self::Div,
             TokenKind::LessThan => Self::LessThan,
             _ => unreachable!()
         }
diff --git a/trunk_parser/src/parser/mod.rs b/trunk_parser/src/parser/mod.rs
index 5c1b80d..7395c51 100644
--- a/trunk_parser/src/parser/mod.rs
+++ b/trunk_parser/src/parser/mod.rs
@@ -911,6 +911,7 @@ fn infix(lhs: Expression, op: TokenKind, rhs: Expression) -> Expression {
 
 fn infix_binding_power(t: &TokenKind) -> Option<(u8, u8)> {
     Some(match t {
+        TokenKind::Asterisk | TokenKind::Slash => (13, 14),
         TokenKind::Plus | TokenKind::Minus => (11, 12),
         TokenKind::LessThan => (9, 10),
         TokenKind::Equals => (2, 1),
@@ -1011,6 +1012,14 @@ mod tests {
         };
     }
 
+    macro_rules! expr {
+        ($expr:expr) => {
+            Statement::Expression {
+                expr: $expr,
+            }
+        };
+    }
+
     #[test]
     fn paren_expression() {
         assert_ast("<?php (1 + 2);", &[
@@ -1022,6 +1031,29 @@ mod tests {
         ]);
     }
 
+    #[test]
+    fn math_precedence() {
+        assert_ast("<?php 1 + 2 * 3 / 4 - 5;", &[
+            expr!(Expression::Infix(
+                Box::new(Expression::Infix(
+                    Box::new(Expression::Int(1)),
+                    InfixOp::Add,
+                    Box::new(Expression::Infix(
+                        Box::new(Expression::Infix(
+                            Box::new(Expression::Int(2)),
+                            InfixOp::Mul,
+                            Box::new(Expression::Int(3))
+                        )),
+                        InfixOp::Div,
+                        Box::new(Expression::Int(4))
+                    ))
+                )),
+                InfixOp::Sub,
+                Box::new(Expression::Int(5))
+            ))
+        ]);
+    }
+
     #[test]
     fn empty_fn() {
         assert_ast("<?php function foo() {}", &[