use peekmore rather than std::iter::Peekable

src/args.rs

@@ -1,8 +1,9 @@
 use std::collections::HashMap;
-use std::iter::Peekable;
 
 use codemap::{Span, Spanned};
 
+use peekmore::PeekMoreIterator;
+
 use crate::error::SassResult;
 use crate::scope::Scope;
 use crate::selector::Selector;
@@ -172,7 +173,7 @@ impl CallArgs {
 }
 
 pub(crate) fn eat_func_args<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<FuncArgs> {
@@ -275,7 +276,7 @@ pub(crate) fn eat_func_args<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn eat_call_args<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<CallArgs> {

src/atrule/for_rule.rs

@@ -1,7 +1,7 @@
-use std::iter::Peekable;
-
 use codemap::{Span, Spanned};
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use num_traits::cast::ToPrimitive;
 
 use super::parse::eat_stmts;
@@ -18,7 +18,7 @@ use crate::value::{Number, Value};
 use crate::Token;
 
 pub(crate) fn parse_for<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &mut Scope,
     super_selector: &Selector,
     span: Span,
@@ -155,7 +155,7 @@ pub(crate) fn parse_for<I: Iterator<Item = Token>>(
             },
         )?;
         stmts.extend(eat_stmts(
-            &mut body.clone().into_iter().peekable(),
+            &mut body.clone().into_iter().peekmore(),
             scope,
             super_selector,
         )?);

src/atrule/function.rs

@@ -1,9 +1,9 @@
-use std::iter::Peekable;
-
 use super::eat_stmts;
 
 use codemap::{Span, Spanned};
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use crate::args::{eat_func_args, CallArgs, FuncArgs};
 use crate::atrule::AtRule;
 use crate::error::SassResult;
@@ -40,7 +40,7 @@ impl Function {
     }
 
     pub fn decl_from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: Scope,
         super_selector: &Selector,
     ) -> SassResult<(String, Function)> {
@@ -84,7 +84,7 @@ impl Function {
                     Some(v) => v?,
                     None => match &arg.default {
                         Some(v) => Value::from_tokens(
-                            &mut v.iter().cloned().peekable(),
+                            &mut v.iter().cloned().peekmore(),
                             scope,
                             super_selector,
                         )?,
@@ -110,7 +110,7 @@ impl Function {
             match stmt.node {
                 Stmt::AtRule(AtRule::Return(toks)) => {
                     return Ok(Value::from_tokens(
-                        &mut toks.into_iter().peekable(),
+                        &mut toks.into_iter().peekmore(),
                         &self.scope,
                         super_selector,
                     )?

src/atrule/if_rule.rs

@@ -1,7 +1,7 @@
-use std::iter::Peekable;
-
 use codemap::Spanned;
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use super::{eat_stmts, AtRule};
 
 use crate::error::SassResult;
@@ -32,7 +32,9 @@ impl Branch {
 }
 
 impl If {
-    pub fn from_tokens<I: Iterator<Item = Token>>(toks: &mut Peekable<I>) -> SassResult<If> {
+    pub fn from_tokens<I: Iterator<Item = Token>>(
+        toks: &mut PeekMoreIterator<I>,
+    ) -> SassResult<If> {
         let mut branches = Vec::new();
         let init_cond = read_until_open_curly_brace(toks);
         toks.next();
@@ -111,7 +113,7 @@ impl If {
         if !found_true {
             toks = self.else_;
         }
-        for stmt in eat_stmts(&mut toks.into_iter().peekable(), scope, super_selector)? {
+        for stmt in eat_stmts(&mut toks.into_iter().peekmore(), scope, super_selector)? {
             match stmt.node {
                 Stmt::AtRule(AtRule::If(i)) => stmts.extend(i.eval(scope, super_selector)?),
                 Stmt::RuleSet(r) if r.selector.is_empty() => stmts.extend(r.rules),

src/atrule/mixin.rs

@@ -1,8 +1,9 @@
-use std::iter::Peekable;
 use std::vec::IntoIter;
 
 use codemap::Spanned;
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use super::eat_stmts;
 
 use crate::args::{eat_call_args, eat_func_args, CallArgs, FuncArgs};
@@ -20,7 +21,7 @@ use crate::{eat_expr, Expr, RuleSet, Stmt, Token};
 pub(crate) struct Mixin {
     scope: Scope,
     args: FuncArgs,
-    body: Peekable<IntoIter<Token>>,
+    body: PeekMoreIterator<IntoIter<Token>>,
     content: Vec<Spanned<Stmt>>,
 }
 
@@ -31,7 +32,7 @@ impl Mixin {
         body: Vec<Token>,
         content: Vec<Spanned<Stmt>>,
     ) -> Self {
-        let body = body.into_iter().peekable();
+        let body = body.into_iter().peekmore();
         Mixin {
             scope,
             args,
@@ -41,7 +42,7 @@ impl Mixin {
     }
 
     pub fn decl_from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<Spanned<(String, Mixin)>> {
@@ -95,7 +96,7 @@ impl Mixin {
                     Some(v) => v?,
                     None => match &arg.default {
                         Some(v) => Value::from_tokens(
-                            &mut v.iter().cloned().peekable(),
+                            &mut v.iter().cloned().peekmore(),
                             scope,
                             super_selector,
                         )?,
@@ -177,7 +178,7 @@ impl Mixin {
 }
 
 pub(crate) fn eat_include<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<Vec<Spanned<Stmt>>> {

src/atrule/mod.rs

@@ -1,7 +1,7 @@
-use std::iter::Peekable;
-
 use codemap::{Span, Spanned};
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use crate::common::{Brackets, ListSeparator};
 use crate::error::SassResult;
 use crate::scope::Scope;
@@ -50,7 +50,7 @@ impl AtRule {
     pub fn from_tokens<I: Iterator<Item = Token>>(
         rule: &AtRuleKind,
         kind_span: Span,
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &mut Scope,
         super_selector: &Selector,
     ) -> SassResult<Spanned<AtRule>> {
@@ -139,7 +139,7 @@ impl AtRule {
                 let mut selector = &Selector::replace(
                     super_selector,
                     Selector::from_tokens(
-                        &mut read_until_open_curly_brace(toks).into_iter().peekable(),
+                        &mut read_until_open_curly_brace(toks).into_iter().peekmore(),
                         scope,
                         super_selector,
                     )?,
@@ -156,7 +156,7 @@ impl AtRule {
                 devour_whitespace(toks);
                 let mut styles = Vec::new();
                 let raw_stmts = eat_stmts_at_root(
-                    &mut body.into_iter().peekable(),
+                    &mut body.into_iter().peekmore(),
                     scope,
                     selector,
                     0,
@@ -284,7 +284,7 @@ impl AtRule {
                     }
 
                     stmts.extend(eat_stmts(
-                        &mut body.clone().into_iter().peekable(),
+                        &mut body.clone().into_iter().peekmore(),
                         scope,
                         super_selector,
                     )?);
@@ -323,7 +323,7 @@ impl AtRule {
                 let mut val = Value::from_vec(cond.clone(), scope, super_selector)?;
                 while val.node.is_true(val.span)? {
                     stmts.extend(eat_stmts(
-                        &mut body.clone().into_iter().peekable(),
+                        &mut body.clone().into_iter().peekmore(),
                         scope,
                         super_selector,
                     )?);

src/atrule/parse.rs

@@ -1,14 +1,14 @@
-use std::iter::Peekable;
-
 use codemap::Spanned;
 
+use peekmore::PeekMoreIterator;
+
 use crate::error::SassResult;
 use crate::scope::Scope;
 use crate::selector::Selector;
 use crate::{eat_expr, Expr, RuleSet, Stmt, Token};
 
 pub(crate) fn eat_stmts<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &mut Scope,
     super_selector: &Selector,
 ) -> SassResult<Vec<Spanned<Stmt>>> {
@@ -46,7 +46,7 @@ pub(crate) fn eat_stmts<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn eat_stmts_at_root<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &mut Scope,
     super_selector: &Selector,
     mut nesting: usize,

src/atrule/unknown.rs

@@ -1,7 +1,7 @@
-use std::iter::Peekable;
-
 use codemap::{Span, Spanned};
 
+use peekmore::PeekMoreIterator;
+
 use super::parse::eat_stmts;
 use crate::error::SassResult;
 use crate::scope::Scope;
@@ -19,7 +19,7 @@ pub(crate) struct UnknownAtRule {
 
 impl UnknownAtRule {
     pub fn from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         name: &str,
         scope: &mut Scope,
         super_selector: &Selector,

src/lib.rs

@@ -83,11 +83,13 @@ grass input.scss
 use std::fmt::{self, Display};
 use std::fs;
 use std::io::Write;
-use std::iter::{Iterator, Peekable};
+use std::iter::Iterator;
 use std::path::Path;
 
 use codemap::{CodeMap, Span, Spanned};
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use crate::atrule::{eat_include, AtRule, AtRuleKind, Function, Mixin};
 pub use crate::error::{SassError, SassResult};
 use crate::format::PrettyPrinter;
@@ -220,7 +222,7 @@ impl StyleSheet {
         let file = map.add_file("stdin".into(), input);
         Css::from_stylesheet(StyleSheet(
             StyleSheetParser {
-                lexer: Lexer::new(&file).peekable(),
+                lexer: Lexer::new(&file).peekmore(),
                 nesting: 0,
                 map: &map,
             }
@@ -255,7 +257,7 @@ impl StyleSheet {
         let file = map.add_file(p.clone().into(), String::from_utf8(fs::read(p.as_ref())?)?);
         Css::from_stylesheet(StyleSheet(
             StyleSheetParser {
-                lexer: Lexer::new(&file).peekable(),
+                lexer: Lexer::new(&file).peekmore(),
                 nesting: 0,
                 map: &map,
             }
@@ -275,7 +277,7 @@ impl StyleSheet {
         let mut map = CodeMap::new();
         let file = map.add_file(p.clone().into(), String::from_utf8(fs::read(p.as_ref())?)?);
         Ok(StyleSheetParser {
-            lexer: Lexer::new(&file).peekable(),
+            lexer: Lexer::new(&file).peekmore(),
             nesting: 0,
             map: &map,
         }
@@ -288,7 +290,7 @@ impl StyleSheet {
 }
 
 struct StyleSheetParser<'a> {
-    lexer: Peekable<Lexer<'a>>,
+    lexer: PeekMoreIterator<Lexer<'a>>,
     nesting: u32,
     map: &'a CodeMap,
 }
@@ -520,7 +522,7 @@ impl<'a> StyleSheetParser<'a> {
 }
 
 pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &mut Scope,
     super_selector: &Selector,
 ) -> SassResult<Option<Spanned<Expr>>> {
@@ -537,7 +539,7 @@ pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
                 let tok = toks.next();
                 if devour_whitespace(toks) {
                     let prop = Style::parse_property(
-                        &mut values.into_iter().peekable(),
+                        &mut values.into_iter().peekmore(),
                         scope,
                         super_selector,
                         String::new(),
@@ -555,7 +557,7 @@ pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
                 devour_whitespace(toks);
                 // special edge case where there was no space between the colon
                 // in a style, e.g. `color:red`. todo: refactor
-                let mut v = values.into_iter().peekable();
+                let mut v = values.into_iter().peekmore();
                 devour_whitespace(&mut v);
                 if v.peek().is_none() {
                     devour_whitespace(toks);
@@ -587,7 +589,7 @@ pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
                     // special edge case where there was no space between the colon
                     // and no semicolon following the style
                     // in a style `color:red`. todo: refactor
-                    let mut v = values.into_iter().peekable();
+                    let mut v = values.into_iter().peekmore();
                     let property =
                         Style::parse_property(&mut v, scope, super_selector, String::new())?;
                     let value = Style::parse_value(&mut v, scope, super_selector)?;
@@ -602,7 +604,7 @@ pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
                 devour_whitespace(toks);
                 return Ok(Some(Spanned {
                     node: Expr::Selector(Selector::from_tokens(
-                        &mut values.into_iter().peekable(),
+                        &mut values.into_iter().peekmore(),
                         scope,
                         super_selector,
                     )?),
@@ -713,7 +715,7 @@ pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
     Ok(None)
 }
 
-fn eat_interpolation<I: Iterator<Item = Token>>(toks: &mut Peekable<I>) -> Vec<Token> {
+fn eat_interpolation<I: Iterator<Item = Token>>(toks: &mut PeekMoreIterator<I>) -> Vec<Token> {
     let mut vals = Vec::new();
     let mut n = 1;
     for tok in toks {

src/selector/attribute.rs

@@ -1,5 +1,6 @@
 use std::fmt::{self, Display};
-use std::iter::Peekable;
+
+use peekmore::PeekMoreIterator;
 
 use codemap::Span;
 
@@ -21,7 +22,7 @@ pub(crate) struct Attribute {
 
 impl Attribute {
     pub fn from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
         mut start: Span,

src/selector/mod.rs

@@ -1,5 +1,6 @@
 use std::fmt::{self, Display, Write};
-use std::iter::Peekable;
+
+use peekmore::{PeekMore, PeekMoreIterator};
 
 use crate::error::SassResult;
 use crate::scope::Scope;
@@ -26,7 +27,7 @@ struct SelectorPart {
 
 impl Display for SelectorPart {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut iter = self.inner.iter().peekable();
+        let mut iter = self.inner.iter().peekmore();
         devour_whitespace(&mut iter);
         while let Some(s) = iter.next() {
             write!(f, "{}", s)?;
@@ -176,7 +177,7 @@ fn is_selector_name_char(c: char) -> bool {
 
 impl Selector {
     pub fn from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<Selector> {
@@ -252,7 +253,7 @@ impl Selector {
             tok
         }));
 
-        let mut iter = sel_toks.into_iter().peekable();
+        let mut iter = sel_toks.into_iter().peekmore();
 
         while let Some(tok) = iter.peek() {
             inner.push(match tok.kind {
@@ -360,7 +361,7 @@ impl Selector {
     }
 
     fn consume_pseudo_selector<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<SelectorKind> {
@@ -378,7 +379,7 @@ impl Selector {
                     let mut inner_toks = read_until_closing_paren(toks);
                     inner_toks.pop();
                     let inner = Selector::from_tokens(
-                        &mut inner_toks.into_iter().peekable(),
+                        &mut inner_toks.into_iter().peekmore(),
                         scope,
                         super_selector,
                     )?;

src/style.rs

@@ -1,4 +1,4 @@
-use std::iter::Peekable;
+use peekmore::PeekMoreIterator;
 
 use codemap::Spanned;
 
@@ -21,7 +21,7 @@ pub(crate) struct Style {
 
 impl Style {
     pub fn parse_property<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
         super_property: String,
@@ -48,7 +48,7 @@ impl Style {
     }
 
     pub fn parse_value<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<Spanned<Value>> {
@@ -56,7 +56,7 @@ impl Style {
     }
 
     pub fn from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
         super_property: String,
@@ -80,7 +80,7 @@ impl<'a> StyleParser<'a> {
 
     pub(crate) fn parse_style_value<I: Iterator<Item = Token>>(
         &self,
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
     ) -> SassResult<Spanned<Value>> {
         devour_whitespace(toks);
@@ -93,7 +93,7 @@ impl<'a> StyleParser<'a> {
 
     pub(crate) fn eat_style_group<I: Iterator<Item = Token>>(
         &self,
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         super_property: String,
         scope: &Scope,
     ) -> SassResult<Expr> {
@@ -199,7 +199,7 @@ impl<'a> StyleParser<'a> {
 
     pub(crate) fn parse_property<I: Iterator<Item = Token>>(
         &self,
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         mut super_property: String,
     ) -> SassResult<String> {
         devour_whitespace(toks);

src/utils.rs

@@ -1,7 +1,9 @@
-use std::iter::{Iterator, Peekable};
+use std::iter::Iterator;
 
 use codemap::{Span, Spanned};
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use crate::common::QuoteKind;
 use crate::error::SassResult;
 use crate::selector::Selector;
@@ -19,7 +21,7 @@ impl IsWhitespace for char {
 }
 
 pub(crate) fn devour_whitespace<I: Iterator<Item = W>, W: IsWhitespace>(
-    s: &mut Peekable<I>,
+    s: &mut PeekMoreIterator<I>,
 ) -> bool {
     let mut found_whitespace = false;
     while let Some(w) = s.peek() {
@@ -37,7 +39,7 @@ pub(crate) trait IsComment {
 }
 
 pub(crate) fn devour_whitespace_or_comment<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> SassResult<bool> {
     let mut found_whitespace = false;
     while let Some(tok) = toks.peek() {
@@ -63,7 +65,7 @@ pub(crate) fn devour_whitespace_or_comment<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn parse_interpolation<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<Spanned<Value>> {
@@ -95,7 +97,7 @@ impl VariableDecl {
 //
 // Does not consume the open curly brace
 pub(crate) fn read_until_open_curly_brace<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> Vec<Token> {
     let mut val = Vec::new();
     let mut n = 0;
@@ -123,7 +125,7 @@ pub(crate) fn read_until_open_curly_brace<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn read_until_closing_curly_brace<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> Vec<Token> {
     let mut t = Vec::new();
     let mut nesting = 0;
@@ -161,7 +163,7 @@ pub(crate) fn read_until_closing_curly_brace<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn read_until_closing_quote<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     q: char,
 ) -> Vec<Token> {
     let mut t = Vec::new();
@@ -194,7 +196,7 @@ pub(crate) fn read_until_closing_quote<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn read_until_semicolon_or_closing_curly_brace<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> Vec<Token> {
     let mut t = Vec::new();
     let mut nesting = 0;
@@ -240,7 +242,7 @@ pub(crate) fn read_until_semicolon_or_closing_curly_brace<I: Iterator<Item = Tok
 }
 
 pub(crate) fn read_until_semicolon_or_open_or_closing_curly_brace<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> Vec<Token> {
     let mut t = Vec::new();
     let mut nesting = 0;
@@ -299,7 +301,7 @@ pub(crate) fn read_until_semicolon_or_open_or_closing_curly_brace<I: Iterator<It
 }
 
 pub(crate) fn eat_variable_value<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<VariableDecl> {
@@ -308,7 +310,7 @@ pub(crate) fn eat_variable_value<I: Iterator<Item = Token>>(
     let mut global = false;
     let mut raw = read_until_semicolon_or_closing_curly_brace(toks)
         .into_iter()
-        .peekable();
+        .peekmore();
     if toks.peek().is_some() && toks.peek().unwrap().kind == ';' {
         toks.next();
     }
@@ -348,7 +350,7 @@ pub(crate) fn eat_variable_value<I: Iterator<Item = Token>>(
 }
 
 fn ident_body<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     unit: bool,
     mut span: Span,
 ) -> SassResult<Spanned<String>> {
@@ -356,8 +358,8 @@ fn ident_body<I: Iterator<Item = Token>>(
     while let Some(tok) = toks.peek() {
         span = span.merge(tok.pos());
         if unit && tok.kind == '-' {
-            todo!()
+            // Disallow `-` followed by a dot or a digit digit in units.
-        // Disallow `-` followed by a dot or a digit digit in units.
+            toks.next();
         // var second = scanner.peekChar(1);
         // if (second != null && (second == $dot || isDigit(second))) break;
         // text.writeCharCode(scanner.readChar());
@@ -374,7 +376,7 @@ fn ident_body<I: Iterator<Item = Token>>(
 }
 
 fn interpolated_ident_body<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
     mut span: Span,
@@ -419,7 +421,7 @@ fn is_name_start(c: char) -> bool {
 }
 
 fn escape<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     identifier_start: bool,
 ) -> SassResult<String> {
     let mut value = 0;
@@ -475,7 +477,7 @@ fn escape<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn eat_ident<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<Spanned<String>> {
@@ -532,7 +534,7 @@ pub(crate) fn eat_ident<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn eat_ident_no_interpolation<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     unit: bool,
 ) -> SassResult<Spanned<String>> {
     let mut span = toks.peek().unwrap().pos();
@@ -569,7 +571,7 @@ pub(crate) fn eat_ident_no_interpolation<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn eat_number<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> SassResult<Spanned<String>> {
     let mut whole = String::new();
     let mut span = if let Some(tok) = toks.peek() {
@@ -621,7 +623,7 @@ pub(crate) fn eat_number<I: Iterator<Item = Token>>(
 /// We only have to check for \n as the lexing step normalizes all newline characters
 ///
 /// The newline is consumed
-pub(crate) fn read_until_newline<I: Iterator<Item = Token>>(toks: &mut Peekable<I>) {
+pub(crate) fn read_until_newline<I: Iterator<Item = Token>>(toks: &mut PeekMoreIterator<I>) {
     for tok in toks {
         if tok.kind == '\n' {
             break;
@@ -635,7 +637,7 @@ pub(crate) fn read_until_newline<I: Iterator<Item = Token>>(toks: &mut Peekable<
 /// The entirety of the comment, including the ending "*/" is consumed.
 /// Note that the ending "*/" is not included in the output.
 pub(crate) fn eat_comment<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<Spanned<String>> {
@@ -676,7 +678,7 @@ fn as_hex(c: u32) -> u32 {
 }
 
 pub(crate) fn parse_quoted_string<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     q: char,
     super_selector: &Selector,
@@ -753,7 +755,7 @@ pub(crate) fn parse_quoted_string<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn read_until_closing_paren<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> Vec<Token> {
     let mut v = Vec::new();
     let mut scope = 0;
@@ -781,7 +783,7 @@ pub(crate) fn read_until_closing_paren<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn read_until_closing_square_brace<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
 ) -> Vec<Token> {
     let mut v = Vec::new();
     let mut scope = 0;
@@ -809,7 +811,7 @@ pub(crate) fn read_until_closing_square_brace<I: Iterator<Item = Token>>(
 }
 
 pub(crate) fn read_until_char<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     c: char,
 ) -> Vec<Token> {
     let mut v = Vec::new();

src/value/css_function.rs

@@ -1,4 +1,4 @@
-use std::iter::Peekable;
+use peekmore::PeekMoreIterator;
 
 use crate::error::SassResult;
 use crate::scope::Scope;
@@ -7,7 +7,7 @@ use crate::utils::{devour_whitespace, parse_interpolation};
 use crate::Token;
 
 pub(crate) fn eat_calc_args<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<String> {
@@ -57,7 +57,7 @@ pub(crate) fn is_special_function(s: &str) -> bool {
 }
 
 pub(crate) fn eat_progid<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
 ) -> SassResult<String> {

src/value/parse.rs

@@ -1,5 +1,5 @@
 use std::convert::TryFrom;
-use std::iter::{Iterator, Peekable};
+use std::iter::Iterator;
 use std::mem;
 
 use num_bigint::BigInt;
@@ -8,6 +8,8 @@ use num_traits::pow;
 
 use codemap::{Span, Spanned};
 
+use peekmore::{PeekMore, PeekMoreIterator};
+
 use super::css_function::{eat_calc_args, eat_progid};
 
 use crate::args::eat_call_args;
@@ -30,7 +32,7 @@ use super::map::SassMap;
 use super::number::Number;
 
 fn parse_hex<I: Iterator<Item = Token>>(
-    toks: &mut Peekable<I>,
+    toks: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
     mut span: Span,
@@ -140,7 +142,7 @@ fn parse_paren(
         return Ok(());
     }
 
-    let paren_toks = &mut t.node.into_iter().peekable();
+    let paren_toks = &mut t.node.into_iter().peekmore();
 
     let mut map = SassMap::new();
     let key = Value::from_vec(read_until_char(paren_toks, ':'), scope, super_selector)?;
@@ -188,7 +190,7 @@ fn parse_paren(
 }
 
 fn eat_op<I: Iterator<Item = IntermediateValue>>(
-    iter: &mut Peekable<I>,
+    iter: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
     op: Spanned<Op>,
@@ -300,7 +302,7 @@ fn eat_op<I: Iterator<Item = IntermediateValue>>(
 }
 
 fn single_value<I: Iterator<Item = IntermediateValue>>(
-    iter: &mut Peekable<I>,
+    iter: &mut PeekMoreIterator<I>,
     scope: &Scope,
     super_selector: &Selector,
     span: Span,
@@ -363,7 +365,7 @@ fn single_value<I: Iterator<Item = IntermediateValue>>(
 
 impl Value {
     pub fn from_tokens<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<Spanned<Self>> {
@@ -379,7 +381,7 @@ impl Value {
         let mut last_was_whitespace = false;
         let mut space_separated = Vec::new();
         let mut comma_separated = Vec::new();
-        let mut iter = intermediate_values.into_iter().peekable();
+        let mut iter = intermediate_values.into_iter().peekmore();
         while let Some(val) = iter.next() {
             match val {
                 IntermediateValue::Value(v) => {
@@ -484,11 +486,11 @@ impl Value {
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<Spanned<Value>> {
-        Self::from_tokens(&mut toks.into_iter().peekable(), scope, super_selector)
+        Self::from_tokens(&mut toks.into_iter().peekmore(), scope, super_selector)
     }
 
     fn ident<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<IntermediateValue> {
@@ -583,7 +585,7 @@ impl Value {
     }
 
     fn parse_intermediate_value<I: Iterator<Item = Token>>(
-        toks: &mut Peekable<I>,
+        toks: &mut PeekMoreIterator<I>,
         scope: &Scope,
         super_selector: &Selector,
     ) -> SassResult<IntermediateValue> {