From d497e1956428e022555f6c86e48faa970099ac19 Mon Sep 17 00:00:00 2001
From: Nick Krichevsky <nick@ollien.com>
Date: Tue, 21 May 2024 15:23:53 -0400
Subject: [PATCH] Move token matching into a macro

---
 src/parse.rs | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/parse.rs b/src/parse.rs
index ef6c165..c4e50ae 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -41,6 +41,21 @@ pub fn parse_program<I: Iterator<Item = Token>, F: FnMut(ScriptError)>(
     statements
 }
 
+macro_rules! match_token_kind {
+    ($tokens_peekable: expr, $($p:pat),+) => {{
+        match $tokens_peekable.peek().map(|token| token.kind()) {
+            $(
+                Some($p) => {
+                    // consume the peeked token
+                    let token = $tokens_peekable.next().unwrap();
+                    Some(token)
+                }
+            )+
+            _ => None
+        }
+    }};
+}
+
 // To be used later?
 fn synchronize_to_next_statement<I: Iterator<Item = Token>>(iter: &mut I) {
     for item in iter {
@@ -51,7 +66,7 @@ fn synchronize_to_next_statement<I: Iterator<Item = Token>>(iter: &mut I) {
 }
 
 fn parse_statement<I: Iterator<Item = Token>>(iter: &mut Peekable<I>) -> Result<Stmt, ParseError> {
-    if match_token(iter, &[TokenKind::Print]).is_some() {
+    if match_token_kind!(iter, TokenKind::Print).is_some() {
         parse_statement_containing_expression(iter, |expression| Stmt::Print { expression })
     } else {
         parse_statement_containing_expression(iter, |expression| Stmt::Expression { expression })
@@ -65,7 +80,7 @@ fn parse_statement_containing_expression<I: Iterator<Item = Token>, F: Fn(Expr)
     // Snatch the next token before we parse it, so we have line information
     let next_token_line = iter.peek().map(Token::line);
     let expression = parse_expression(iter)?;
-    if match_token(iter, &[TokenKind::SemiColon]).is_some() {
+    if match_token_kind!(iter, TokenKind::SemiColon).is_some() {
         Ok(make_statement(expression))
     } else {
         Err(ParseError {
@@ -117,7 +132,7 @@ fn parse_binary<I: Iterator<Item = Token>, F: Fn(&mut Peekable<I>) -> Result<Exp
 ) -> Result<Expr, ParseError> {
     let mut expr = parse_operand(iter)?;
 
-    while let Some(token) = match_token(iter, valid_operators) {
+    while let Some(token) = match_token_kind_eq(iter, valid_operators) {
         let operator = token;
         let right = parse_operand(iter)?;
         expr = Expr::Binary {
@@ -131,7 +146,7 @@ fn parse_binary<I: Iterator<Item = Token>, F: Fn(&mut Peekable<I>) -> Result<Exp
 }
 
 fn parse_unary<I: Iterator<Item = Token>>(iter: &mut Peekable<I>) -> Result<Expr, ParseError> {
-    if let Some(token) = match_token(iter, &[TokenKind::Bang, TokenKind::Minus]) {
+    if let Some(token) = match_token_kind!(iter, TokenKind::Bang, TokenKind::Minus) {
         let operator = token;
         let right = parse_unary(iter)?;
         Ok(Expr::Unary {
@@ -178,7 +193,7 @@ fn parse_primary<I: Iterator<Item = Token>>(iter: &mut Peekable<I>) -> Result<Ex
             // consume the left paren
             iter.next();
             let expr = parse_expression(iter)?;
-            if match_token(iter, &[TokenKind::RightParen]).is_some() {
+            if match_token_kind!(iter, TokenKind::RightParen).is_some() {
                 Ok(Expr::Grouping {
                     expr: Box::new(expr),
                 })
@@ -197,7 +212,7 @@ fn parse_primary<I: Iterator<Item = Token>>(iter: &mut Peekable<I>) -> Result<Ex
     }
 }
 
-fn match_token<I: Iterator<Item = Token>>(
+fn match_token_kind_eq<I: Iterator<Item = Token>>(
     iter: &mut Peekable<I>,
     valid_kinds: &[TokenKind],
 ) -> Option<Token> {