Support Luau floor division (//) (#291)

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
+### Added
+- Added support for parsing Luau's floor division `//`
+
 ### Changed
 - Flattened `Expression::Value` to all be variants of `Expression` directly, as this was not used anywhere else. The extra `type_assertion` field has been moved into a new variant `Expression::TypeAssertion`. None of these variants are boxed.
 - The following fields/variants have been changed from `Expression` to `Box<Expression>`: `Prefix::Expression`, `Var::Expression`, `IfExpression::condition`, `IfExpression::if_expression`, `IfExpression::else_expression`.

full-moon/src/ast/mod.rs

@@ -2028,7 +2028,7 @@ make_op!(BinOp,
         TwoEqual,
         #[cfg(feature = "lua53")]
         Ampersand,
-        #[cfg(feature = "lua53")]
+        #[cfg(any(feature = "roblox", feature = "lua53"))]
         DoubleSlash,
         #[cfg(feature = "lua53")]
         DoubleLessThan,
@@ -2049,6 +2049,8 @@ impl BinOp {
         match *self {
             BinOp::Caret(_) => 8,
             BinOp::Star(_) | BinOp::Slash(_) | BinOp::Percent(_) => 6,
+            #[cfg(feature = "roblox")]
+            BinOp::DoubleSlash(_) => 6,
             BinOp::Plus(_) | BinOp::Minus(_) => 5,
             BinOp::TwoDots(_) => 4,
             BinOp::GreaterThan(_)
@@ -2110,9 +2112,10 @@ impl BinOp {
             | BinOp::TildeEqual(token)
             | BinOp::TwoDots(token)
             | BinOp::TwoEqual(token) => token,
+            #[cfg(any(feature = "roblox", feature = "lua53"))]
+            BinOp::DoubleSlash(token) => token,
             #[cfg(feature = "lua53")]
             BinOp::Ampersand(token)
-            | BinOp::DoubleSlash(token)
             | BinOp::DoubleLessThan(token)
             | BinOp::Pipe(token)
             | BinOp::DoubleGreaterThan(token)

full-moon/src/ast/parsers.rs

@@ -2221,12 +2221,16 @@ define_parser!(ParseBinOp, BinOp, |_, state| {
     } else if let Ok((state, operator)) = ParseSymbol(Symbol::TwoEqual).parse(state) {
         Ok((state, BinOp::TwoEqual(operator)))
     } else {
+        // Luau & Lua 5.3
+        #[cfg(any(feature = "roblox", feature = "lua53"))]
+        if let Ok((state, operator)) = ParseSymbol(Symbol::DoubleSlash).parse(state) {
+            return Ok((state, BinOp::DoubleSlash(operator)));
+        }
+
         // Lua 5.3
         #[cfg(feature = "lua53")]
         if let Ok((state, operator)) = ParseSymbol(Symbol::Ampersand).parse(state) {
             return Ok((state, BinOp::Ampersand(operator)));
-        } else if let Ok((state, operator)) = ParseSymbol(Symbol::DoubleSlash).parse(state) {
-            return Ok((state, BinOp::DoubleSlash(operator)));
         } else if let Ok((state, operator)) = ParseSymbol(Symbol::DoubleLessThan).parse(state) {
             return Ok((state, BinOp::DoubleLessThan(operator)));
         } else if let Ok((state, operator)) = ParseSymbol(Symbol::Pipe).parse(state) {

full-moon/src/atom.rs

@@ -356,7 +356,7 @@ pub(crate) enum Atom {
     #[token("/")]
     Slash,
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "roblox", feature = "lua53"))]
     #[token("//")]
     DoubleSlash,
 

full-moon/src/tokenizer.rs

@@ -172,7 +172,7 @@ pub enum Symbol {
     #[cfg_attr(feature = "serde", serde(rename = "/"))]
     Slash,
 
-    #[cfg(feature = "lua53")]
+    #[cfg(any(feature = "roblox", feature = "lua53"))]
     #[cfg_attr(feature = "serde", serde(rename = "//"))]
     DoubleSlash,
 
@@ -265,7 +265,7 @@ impl TryFrom<Atom> for Symbol {
             Atom::RightParen => Symbol::RightParen,
             Atom::Semicolon => Symbol::Semicolon,
             Atom::Slash => Symbol::Slash,
-            #[cfg(feature = "lua53")]
+            #[cfg(any(feature = "roblox", feature = "lua53"))]
             Atom::DoubleSlash => Symbol::DoubleSlash,
             Atom::Star => Symbol::Star,
             #[cfg(feature = "lua53")]
@@ -349,7 +349,7 @@ impl Display for Symbol {
             Symbol::RightParen => ")",
             Symbol::Semicolon => ";",
             Symbol::Slash => "/",
-            #[cfg(feature = "lua53")]
+            #[cfg(any(feature = "roblox", feature = "lua53"))]
             Symbol::DoubleSlash => "//",
             Symbol::Star => "*",
             #[cfg(feature = "lua53")]

full-moon/tests/roblox_cases/pass/floor_division/ast.snap

@@ -0,0 +1,173 @@
+---
+source: full-moon/tests/pass_cases.rs
+expression: ast.nodes()
+---
+stmts:
+  - - LocalAssignment:
+        local_token:
+          leading_trivia: []
+          token:
+            start_position:
+              bytes: 0
+              line: 1
+              character: 1
+            end_position:
+              bytes: 5
+              line: 1
+              character: 6
+            token_type:
+              type: Symbol
+              symbol: local
+          trailing_trivia:
+            - start_position:
+                bytes: 5
+                line: 1
+                character: 6
+              end_position:
+                bytes: 6
+                line: 1
+                character: 7
+              token_type:
+                type: Whitespace
+                characters: " "
+        name_list:
+          pairs:
+            - End:
+                leading_trivia: []
+                token:
+                  start_position:
+                    bytes: 6
+                    line: 1
+                    character: 7
+                  end_position:
+                    bytes: 7
+                    line: 1
+                    character: 8
+                  token_type:
+                    type: Identifier
+                    identifier: x
+                trailing_trivia:
+                  - start_position:
+                      bytes: 7
+                      line: 1
+                      character: 8
+                    end_position:
+                      bytes: 8
+                      line: 1
+                      character: 9
+                    token_type:
+                      type: Whitespace
+                      characters: " "
+        equal_token:
+          leading_trivia: []
+          token:
+            start_position:
+              bytes: 8
+              line: 1
+              character: 9
+            end_position:
+              bytes: 9
+              line: 1
+              character: 10
+            token_type:
+              type: Symbol
+              symbol: "="
+          trailing_trivia:
+            - start_position:
+                bytes: 9
+                line: 1
+                character: 10
+              end_position:
+                bytes: 10
+                line: 1
+                character: 11
+              token_type:
+                type: Whitespace
+                characters: " "
+        expr_list:
+          pairs:
+            - End:
+                BinaryOperator:
+                  lhs:
+                    Number:
+                      leading_trivia: []
+                      token:
+                        start_position:
+                          bytes: 10
+                          line: 1
+                          character: 11
+                        end_position:
+                          bytes: 11
+                          line: 1
+                          character: 12
+                        token_type:
+                          type: Number
+                          text: "1"
+                      trailing_trivia:
+                        - start_position:
+                            bytes: 11
+                            line: 1
+                            character: 12
+                          end_position:
+                            bytes: 12
+                            line: 1
+                            character: 13
+                          token_type:
+                            type: Whitespace
+                            characters: " "
+                  binop:
+                    DoubleSlash:
+                      leading_trivia: []
+                      token:
+                        start_position:
+                          bytes: 12
+                          line: 1
+                          character: 13
+                        end_position:
+                          bytes: 14
+                          line: 1
+                          character: 15
+                        token_type:
+                          type: Symbol
+                          symbol: //
+                      trailing_trivia:
+                        - start_position:
+                            bytes: 14
+                            line: 1
+                            character: 15
+                          end_position:
+                            bytes: 15
+                            line: 1
+                            character: 16
+                          token_type:
+                            type: Whitespace
+                            characters: " "
+                  rhs:
+                    Number:
+                      leading_trivia: []
+                      token:
+                        start_position:
+                          bytes: 15
+                          line: 1
+                          character: 16
+                        end_position:
+                          bytes: 16
+                          line: 1
+                          character: 17
+                        token_type:
+                          type: Number
+                          text: "2"
+                      trailing_trivia:
+                        - start_position:
+                            bytes: 16
+                            line: 1
+                            character: 17
+                          end_position:
+                            bytes: 17
+                            line: 1
+                            character: 17
+                          token_type:
+                            type: Whitespace
+                            characters: "\n"
+    - ~
+

full-moon/tests/roblox_cases/pass/floor_division/source.lua

@@ -0,0 +1 @@
+local x = 1 // 2