differentiate named and positional args

src/args.rs

@@ -28,16 +28,26 @@ impl FuncArgs {
     }
 }
 
-#[derive(Debug, Clone, std::default::Default)]
+#[derive(Debug, Clone)]
-pub(crate) struct CallArgs(pub HashMap<String, Value>);
+pub(crate) struct CallArgs(HashMap<CallArg, Value>);
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq)]
+enum CallArg {
+    Named(String),
+    Positional(usize),
+}
 
 impl CallArgs {
     pub fn new() -> Self {
         CallArgs(HashMap::new())
     }
 
-    pub fn get(&self, val: &str) -> Option<&Value> {
+    pub fn get_named(&self, val: String) -> Option<&Value> {
-        self.0.get(val)
+        self.0.get(&CallArg::Named(val))
+    }
+
+    pub fn get_positional(&self, val: usize) -> Option<&Value> {
+        self.0.get(&CallArg::Positional(val))
     }
 
     pub fn len(&self) -> usize {
@@ -48,8 +58,12 @@ impl CallArgs {
         self.0.len() == 0
     }
 
-    pub fn remove(&mut self, s: &str) -> Option<Value> {
+    pub fn remove_named(&mut self, s: String) -> Option<Value> {
-        self.0.remove(s)
+        self.0.remove(&CallArg::Named(s))
+    }
+
+    pub fn remove_positional(&mut self, s: usize) -> Option<Value> {
+        self.0.remove(&CallArg::Positional(s))
     }
 }
 
@@ -174,9 +188,9 @@ pub(crate) fn eat_call_args<I: Iterator<Item = Token>>(
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<CallArgs> {
-    let mut args: HashMap<String, Value> = HashMap::new();
+    let mut args: HashMap<CallArg, Value> = HashMap::new();
     devour_whitespace_or_comment(toks)?;
-    let mut name: String;
+    let mut name = String::new();
     let mut val: Vec<Token> = Vec::new();
     loop {
         match toks.peek().unwrap().kind {
@@ -190,14 +204,14 @@ pub(crate) fn eat_call_args<I: Iterator<Item = Token>>(
                 } else {
                     val.push(Token::new(Pos::new(), '$'));
                     val.extend(v.chars().map(|x| Token::new(Pos::new(), x)));
-                    name = args.len().to_string();
+                    name.clear();
                 }
             }
             ')' => {
                 toks.next();
                 return Ok(CallArgs(args));
             }
-            _ => name = args.len().to_string(),
+            _ => name.clear(),
         }
         devour_whitespace_or_comment(toks)?;
 
@@ -205,7 +219,11 @@ pub(crate) fn eat_call_args<I: Iterator<Item = Token>>(
             match tok.kind {
                 ')' => {
                     args.insert(
-                        name.replace('_', "-"),
+                        if name.is_empty() {
+                            CallArg::Positional(args.len())
+                        } else {
+                            CallArg::Named(name.replace('_', "-"))
+                        },
                         Value::from_tokens(&mut val.into_iter().peekable(), scope, super_selector)?,
                     );
                     return Ok(CallArgs(args));
@@ -228,7 +246,11 @@ pub(crate) fn eat_call_args<I: Iterator<Item = Token>>(
         }
 
         args.insert(
-            name.replace('_', "-"),
+            if name.is_empty() {
+                CallArg::Positional(args.len())
+            } else {
+                CallArg::Named(name.replace('_', "-"))
+            },
             Value::from_tokens(
                 &mut val.clone().into_iter().peekable(),
                 scope,

src/atrule/function.rs

@@ -45,9 +45,9 @@ impl Function {
 
     pub fn args(mut self, args: &mut CallArgs) -> SassResult<Function> {
         for (idx, arg) in self.args.0.iter().enumerate() {
-            let val = match args.remove(&format!("{}", idx)) {
+            let val = match args.remove_positional(idx) {
                 Some(v) => v,
-                None => match args.remove(&arg.name) {
+                None => match args.remove_named(arg.name.clone()) {
                     Some(v) => v,
                     None => match &arg.default {
                         Some(v) => v.clone(),

src/atrule/mixin.rs

@@ -61,9 +61,9 @@ impl Mixin {
 
     pub fn args(mut self, args: &mut CallArgs) -> SassResult<Mixin> {
         for (idx, arg) in self.args.0.iter().enumerate() {
-            let val = match args.remove(&format!("{}", idx)) {
+            let val = match args.remove_positional(idx) {
                 Some(v) => v,
-                None => match args.remove(&arg.name) {
+                None => match args.remove_named(arg.name.clone()) {
                     Some(v) => v,
                     None => match &arg.default {
                         Some(v) => v.clone(),

src/builtin/color/other.rs

@@ -11,7 +11,7 @@ use crate::value::{Number, Value};
 macro_rules! opt_rgba {
     ($args:ident, $name:ident, $arg:literal, $low:literal, $high:literal) => {
         let x = $low;
-        let $name = match arg!($args, -1, $arg = Value::Null) {
+        let $name = match named_arg!($args, $arg = Value::Null) {
             Value::Dimension(n, u) => Some(bound!($arg, n, u, x, $high)),
             Value::Null => None,
             v => return Err(format!("${}: {} is not a number.", $arg, v).into()),
@@ -22,7 +22,7 @@ macro_rules! opt_rgba {
 macro_rules! opt_hsl {
     ($args:ident, $name:ident, $arg:literal, $low:literal, $high:literal) => {
         let x = $low;
-        let $name = match arg!($args, -1, $arg = Value::Null) {
+        let $name = match named_arg!($args, $arg = Value::Null) {
             Value::Dimension(n, u) => Some(bound!($arg, n, u, x, $high) / Number::from(100)),
             Value::Null => None,
             v => return Err(format!("${}: {} is not a number.", $arg, v).into()),
@@ -32,7 +32,7 @@ macro_rules! opt_hsl {
 
 pub(crate) fn register(f: &mut HashMap<String, Builtin>) {
     f.insert("change-color".to_owned(), Box::new(|args, _| {
-        if args.get("1").is_some() {
+        if args.get_positional(1).is_some() {
             return Err("Only one positional argument is allowed. All other arguments must be passed by name.".into());
         }
 
@@ -50,7 +50,7 @@ pub(crate) fn register(f: &mut HashMap<String, Builtin>) {
             return Ok(Value::Color(Color::from_rgba(red.unwrap_or(color.red()), green.unwrap_or(color.green()), blue.unwrap_or(color.blue()), alpha.unwrap_or(color.alpha()))))
         }
 
-        let hue = match arg!(args, -1, "hue"=Value::Null) {
+        let hue = match named_arg!(args, "hue"=Value::Null) {
             Value::Dimension(n, _) => Some(n),
             Value::Null => None,
             v => return Err(format!("$hue: {} is not a number.", v).into()),
@@ -93,7 +93,7 @@ pub(crate) fn register(f: &mut HashMap<String, Builtin>) {
                 )));
             }
 
-            let hue = match arg!(args, -1, "hue" = Value::Null) {
+            let hue = match named_arg!(args, "hue" = Value::Null) {
                 Value::Dimension(n, _) => Some(n),
                 Value::Null => None,
                 v => return Err(format!("$hue: {} is not a number.", v).into()),
@@ -132,7 +132,7 @@ pub(crate) fn register(f: &mut HashMap<String, Builtin>) {
             macro_rules! opt_scale_arg {
                 ($args:ident, $name:ident, $arg:literal, $low:literal, $high:literal) => {
                     let x = $low;
-                    let $name = match arg!($args, -1, $arg = Value::Null) {
+                    let $name = match named_arg!($args, $arg = Value::Null) {
                         Value::Dimension(n, Unit::Percent) => {
                             Some(bound!($arg, n, Unit::Percent, x, $high) / Number::from(100))
                         }

src/builtin/macros.rs

@@ -1,17 +1,17 @@
 macro_rules! arg {
     ($args:ident, $idx:literal, $name:literal) => {
-        match $args.remove(stringify!($idx)) {
+        match $args.remove_positional($idx) {
             Some(v) => v.eval()?,
-            None => match $args.remove($name) {
+            None => match $args.remove_named($name.to_owned()) {
                 Some(v) => v.eval()?,
                 None => return Err(concat!("Missing argument $", $name, ".").into()),
             },
         };
     };
     ($args:ident, $idx:literal, $name:literal=$default:expr) => {
-        match $args.remove(stringify!($idx)) {
+        match $args.remove_positional($idx) {
             Some(v) => v.eval()?,
-            None => match $args.remove($name) {
+            None => match $args.remove_named($name.to_owned()) {
                 Some(v) => v.eval()?,
                 None => $default,
             },
@@ -19,6 +19,21 @@ macro_rules! arg {
     };
 }
 
+macro_rules! named_arg {
+    ($args:ident, $name:literal) => {
+        match $args.remove_named($name.to_owned()) {
+            Some(v) => v.eval()?,
+            None => return Err(concat!("Missing argument $", $name, ".").into()),
+        };
+    };
+    ($args:ident, $name:literal=$default:expr) => {
+        match $args.remove_named($name.to_owned()) {
+            Some(v) => v.eval()?,
+            None => $default,
+        };
+    };
+}
+
 macro_rules! max_args {
     ($args:ident, $count:literal) => {
         if $args.len() > $count {