remove peekmore dependency

Cargo.toml

@@ -57,7 +57,6 @@ num-traits = "0.2.14"
 once_cell = "1.5.2"
 rand = { version = "0.8", optional = true }
 codemap = "0.1.3"
-peekmore = "1.0"
 wasm-bindgen = { version = "0.2.68", optional = true }
 beef = "0.5"
 phf = { version = "0.9", features = ["macros"] }

src/lexer.rs

@@ -7,20 +7,87 @@ use crate::Token;
 const FORM_FEED: char = '\x0C';
 
 #[derive(Debug, Clone)]
-pub(crate) struct Lexer<'a> {
+pub(crate) struct Lexer {
-    buf: Peekable<Chars<'a>>,
+    buf: Vec<Token>,
-    pos: usize,
+    cursor: usize,
-    file: &'a Arc<File>,
+    amt_peeked: usize,
 }
 
-impl<'a> Iterator for Lexer<'a> {
+impl Lexer {
+    fn peek_cursor(&self) -> usize {
+        self.cursor + self.amt_peeked
+    }
+
+    pub fn peek(&self) -> Option<Token> {
+        self.buf.get(self.peek_cursor()).copied()
+    }
+
+    pub fn reset_cursor(&mut self) {
+        self.amt_peeked = 0;
+    }
+
+    pub fn advance_cursor(&mut self) {
+        self.amt_peeked += 1;
+    }
+
+    pub fn move_cursor_back(&mut self) {
+        self.amt_peeked = self.amt_peeked.saturating_sub(1);
+    }
+
+    pub fn peek_next(&mut self) -> Option<Token> {
+        self.amt_peeked += 1;
+
+        self.peek()
+    }
+
+    pub fn peek_previous(&mut self) -> Option<Token> {
+        self.buf.get(self.peek_cursor() - 1).copied()
+    }
+
+    pub fn peek_forward(&mut self, n: usize) -> Option<Token> {
+        self.amt_peeked += n;
+
+        self.peek()
+    }
+
+    pub fn peek_backward(&mut self, n: usize) -> Option<Token> {
+        self.amt_peeked = self.amt_peeked.checked_sub(n)?;
+
+        self.peek()
+    }
+
+    pub fn truncate_iterator_to_cursor(&mut self) {
+        self.cursor += self.amt_peeked;
+        self.amt_peeked = 0;
+    }
+}
+
+impl Iterator for Lexer {
+    type Item = Token;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.buf.get(self.cursor).copied().map(|tok| {
+            self.cursor += 1;
+            self.amt_peeked = self.amt_peeked.saturating_sub(1);
+            tok
+        })
+    }
+}
+
+struct TokenLexer<'a> {
+    buf: Peekable<Chars<'a>>,
+    cursor: usize,
+    file: Arc<File>,
+}
+
+impl<'a> Iterator for TokenLexer<'a> {
     type Item = Token;
     fn next(&mut self) -> Option<Self::Item> {
         let kind = match self.buf.next()? {
             FORM_FEED => '\n',
             '\r' => {
                 if self.buf.peek() == Some(&'\n') {
-                    self.pos += 1;
+                    self.cursor += 1;
                     self.buf.next();
                 }
                 '\n'
@@ -31,18 +98,29 @@ impl<'a> Iterator for Lexer<'a> {
         let pos = self
             .file
             .span
-            .subspan(self.pos as u64, (self.pos + len) as u64);
+            .subspan(self.cursor as u64, (self.cursor + len) as u64);
-        self.pos += len;
+        self.cursor += len;
         Some(Token { pos, kind })
     }
 }
 
-impl<'a> Lexer<'a> {
+impl Lexer {
-    pub fn new(file: &'a Arc<File>) -> Lexer<'a> {
+    pub fn new_from_file(file: &Arc<File>) -> Self {
-        Lexer {
+        let buf = TokenLexer {
+            file: Arc::clone(file),
             buf: file.source().chars().peekable(),
-            pos: 0,
+            cursor: 0,
-            file,
+        }
+        .collect();
+
+        Self::new(buf)
+    }
+
+    pub fn new(buf: Vec<Token>) -> Lexer {
+        Lexer {
+            buf,
+            cursor: 0,
+            amt_peeked: 0,
         }
     }
 }

src/lib.rs

@@ -101,8 +101,6 @@ pub(crate) use beef::lean::Cow;
 
 use codemap::CodeMap;
 
-use peekmore::PeekMore;
-
 pub use crate::error::{SassError as Error, SassResult as Result};
 pub(crate) use crate::token::Token;
 use crate::{
@@ -288,10 +286,7 @@ pub fn from_path(p: &str, options: &Options) -> Result<String> {
     let empty_span = file.span.subspan(0, 0);
 
     let stmts = Parser {
-        toks: &mut Lexer::new(&file)
+        toks: &mut Lexer::new_from_file(&file),
-            .collect::<Vec<Token>>()
-            .into_iter()
-            .peekmore(),
         map: &mut map,
         path: p.as_ref(),
         scopes: &mut Scopes::new(),
@@ -334,10 +329,7 @@ pub fn from_string(p: String, options: &Options) -> Result<String> {
     let file = map.add_file("stdin".into(), p);
     let empty_span = file.span.subspan(0, 0);
     let stmts = Parser {
-        toks: &mut Lexer::new(&file)
+        toks: &mut Lexer::new_from_file(&file),
-            .collect::<Vec<Token>>()
-            .into_iter()
-            .peekmore(),
         map: &mut map,
         path: Path::new(""),
         scopes: &mut Scopes::new(),
@@ -371,10 +363,7 @@ pub fn from_string(p: String) -> std::result::Result<String, JsValue> {
     let empty_span = file.span.subspan(0, 0);
 
     let stmts = Parser {
-        toks: &mut Lexer::new(&file)
+        toks: &mut Lexer::new_from_file(&file),
-            .collect::<Vec<Token>>()
-            .into_iter()
-            .peekmore(),
         map: &mut map,
         path: Path::new(""),
         scopes: &mut Scopes::new(),

src/output.rs

@@ -410,7 +410,7 @@ impl CompressedFormatter {
     fn write_block_entry(&self, buf: &mut Vec<u8>, styles: &[BlockEntry]) -> SassResult<()> {
         let mut styles = styles.iter();
 
-        while let Some(style) = styles.next() {
+        for style in &mut styles {
             match style {
                 BlockEntry::Style(s) => {
                     let value = s.value.node.to_css_string(s.value.span)?;

src/parse/args.rs

@@ -21,7 +21,7 @@ impl<'a> Parser<'a> {
     pub(super) fn parse_func_args(&mut self) -> SassResult<FuncArgs> {
         let mut args: Vec<FuncArg> = Vec::new();
         let mut close_paren_span: Span = match self.toks.peek() {
-            Some(Token { pos, .. }) => *pos,
+            Some(Token { pos, .. }) => pos,
             None => return Err(("expected \")\".", self.span_before).into()),
         };
 
@@ -164,7 +164,7 @@ impl<'a> Parser<'a> {
             }
 
             if let Some(Token { kind: '$', pos }) = self.toks.peek() {
-                span = span.merge(*pos);
+                span = span.merge(pos);
                 self.toks.advance_cursor();
 
                 let v = peek_ident_no_interpolation(self.toks, false, self.span_before)?;
@@ -229,10 +229,9 @@ impl<'a> Parser<'a> {
                     continue;
                 }
                 Some(Token { kind: '.', pos }) => {
-                    let pos = *pos;
                     self.toks.next();
 
-                    if let Some(Token { kind: '.', pos }) = self.toks.peek().copied() {
+                    if let Some(Token { kind: '.', pos }) = self.toks.peek() {
                         if !name.is_empty() {
                             return Err(("expected \")\".", pos).into());
                         }
@@ -324,7 +323,7 @@ impl<'a> Parser<'a> {
                             return Ok(CallArgs(args, span));
                         }
                         Some(Token { kind: ',', pos }) => {
-                            span = span.merge(*pos);
+                            span = span.merge(pos);
                             self.toks.next();
                             self.whitespace_or_comment();
                             continue;
@@ -341,14 +340,14 @@ impl<'a> Parser<'a> {
                             self.expect_char('.')?;
                         }
                         Some(Token { pos, .. }) => {
-                            return Err(("expected \")\".", *pos).into());
+                            return Err(("expected \")\".", pos).into());
                         }
                         None => return Err(("expected \")\".", span).into()),
                     }
                 }
                 Some(Token { pos, .. }) => {
                     value?;
-                    return Err(("expected \")\".", *pos).into());
+                    return Err(("expected \")\".", pos).into());
                 }
                 None => return Err(("expected \")\".", span).into()),
             }

src/parse/control_flow.rs

@@ -1,10 +1,10 @@
 use codemap::Spanned;
 use num_traits::cast::ToPrimitive;
-use peekmore::PeekMore;
 
 use crate::{
     common::Identifier,
     error::SassResult,
+    lexer::Lexer,
     parse::{ContextFlags, Parser, Stmt},
     unit::Unit,
     utils::{
@@ -60,7 +60,7 @@ impl<'a> Parser<'a> {
 
         loop {
             self.whitespace_or_comment();
-            if let Some(Token { kind: '@', pos }) = self.toks.peek().copied() {
+            if let Some(Token { kind: '@', pos }) = self.toks.peek() {
                 self.toks.peek_forward(1);
                 let ident = peek_ident_no_interpolation(self.toks, false, pos)?;
                 if ident.as_str() != "else" {
@@ -72,7 +72,7 @@ impl<'a> Parser<'a> {
                 break;
             }
             self.whitespace_or_comment();
-            if let Some(tok) = self.toks.peek().copied() {
+            if let Some(tok) = self.toks.peek() {
                 match tok.kind {
                     'i' if matches!(
                         self.toks.peek_forward(1),
@@ -182,7 +182,7 @@ impl<'a> Parser<'a> {
             Some(Token { kind: 't', pos })
             | Some(Token { kind: 'T', pos })
             | Some(Token { kind: '\\', pos }) => {
-                let span = *pos;
+                let span = pos;
                 let mut ident = match peek_ident_no_interpolation(toks, false, span) {
                     Ok(s) => s,
                     Err(..) => return false,
@@ -266,7 +266,7 @@ impl<'a> Parser<'a> {
             );
             if self.flags.in_function() {
                 let these_stmts = Parser {
-                    toks: &mut body.clone().into_iter().peekmore(),
+                    toks: &mut Lexer::new(body.clone()),
                     map: self.map,
                     path: self.path,
                     scopes: self.scopes,
@@ -290,7 +290,7 @@ impl<'a> Parser<'a> {
             } else {
                 stmts.append(
                     &mut Parser {
-                        toks: &mut body.clone().into_iter().peekmore(),
+                        toks: &mut Lexer::new(body.clone()),
                         map: self.map,
                         path: self.path,
                         scopes: self.scopes,
@@ -343,7 +343,7 @@ impl<'a> Parser<'a> {
         while val.node.is_true() {
             if self.flags.in_function() {
                 let these_stmts = Parser {
-                    toks: &mut body.clone().into_iter().peekmore(),
+                    toks: &mut Lexer::new(body.clone()),
                     map: self.map,
                     path: self.path,
                     scopes: self.scopes,
@@ -367,7 +367,7 @@ impl<'a> Parser<'a> {
             } else {
                 stmts.append(
                     &mut Parser {
-                        toks: &mut body.clone().into_iter().peekmore(),
+                        toks: &mut Lexer::new(body.clone()),
                         map: self.map,
                         path: self.path,
                         scopes: self.scopes,
@@ -455,7 +455,7 @@ impl<'a> Parser<'a> {
 
             if self.flags.in_function() {
                 let these_stmts = Parser {
-                    toks: &mut body.clone().into_iter().peekmore(),
+                    toks: &mut Lexer::new(body.clone()),
                     map: self.map,
                     path: self.path,
                     scopes: self.scopes,
@@ -479,7 +479,7 @@ impl<'a> Parser<'a> {
             } else {
                 stmts.append(
                     &mut Parser {
-                        toks: &mut body.clone().into_iter().peekmore(),
+                        toks: &mut Lexer::new(body.clone()),
                         map: self.map,
                         path: self.path,
                         scopes: self.scopes,

src/parse/function.rs

@@ -1,11 +1,11 @@
 use codemap::Spanned;
-use peekmore::PeekMore;
 
 use crate::{
     args::CallArgs,
     atrule::Function,
     common::{unvendor, Identifier},
     error::SassResult,
+    lexer::Lexer,
     scope::Scopes,
     utils::{read_until_closing_curly_brace, read_until_semicolon_or_closing_curly_brace},
     value::{SassFunction, Value},
@@ -100,7 +100,7 @@ impl<'a> Parser<'a> {
         };
 
         let mut return_value = Parser {
-            toks: &mut body.into_iter().peekmore(),
+            toks: &mut Lexer::new(body),
             map: self.map,
             path: self.path,
             scopes: if declared_at_root {

src/parse/ident.rs

@@ -20,7 +20,7 @@ impl<'a> Parser<'a> {
             if unit && tok.kind == '-' {
                 // Disallow `-` followed by a dot or a digit digit in units.
                 let second = match self.toks.peek_forward(1) {
-                    Some(v) => *v,
+                    Some(v) => v,
                     None => break,
                 };
 
@@ -59,7 +59,7 @@ impl<'a> Parser<'a> {
                     buf.push_str(&self.escape(false)?);
                 }
                 '#' => {
-                    if let Some(Token { kind: '{', .. }) = self.toks.peek_forward(1).copied() {
+                    if let Some(Token { kind: '{', .. }) = self.toks.peek_forward(1) {
                         self.toks.next();
                         self.toks.next();
                         // TODO: if ident, interpolate literally
@@ -136,7 +136,6 @@ impl<'a> Parser<'a> {
         let Token { kind, pos } = self
             .toks
             .peek()
-            .copied()
             .ok_or(("Expected identifier.", self.span_before))?;
         let mut text = String::new();
         if kind == '-' {
@@ -163,7 +162,7 @@ impl<'a> Parser<'a> {
         }
 
         let Token { kind: first, pos } = match self.toks.peek() {
-            Some(v) => *v,
+            Some(v) => v,
             None => return Err(("Expected identifier.", self.span_before).into()),
         };
 
@@ -205,7 +204,7 @@ impl<'a> Parser<'a> {
             .peek()
             .ok_or(("Expected identifier.", self.span_before))?;
         let mut text = String::new();
-        if kind == &'-' {
+        if kind == '-' {
             self.toks.next();
             text.push('-');
 
@@ -264,7 +263,7 @@ impl<'a> Parser<'a> {
                 }
                 '#' => {
                     if let Some(Token { kind: '{', pos }) = self.toks.peek() {
-                        self.span_before = self.span_before.merge(*pos);
+                        self.span_before = self.span_before.merge(pos);
                         self.toks.next();
                         let interpolation = self.parse_interpolation()?;
                         match interpolation.node {

src/parse/import.rs

@@ -1,7 +1,6 @@
 use std::{ffi::OsStr, fs, path::Path, path::PathBuf};
 
 use codemap::{Span, Spanned};
-use peekmore::PeekMore;
 
 use crate::{
     common::{ListSeparator::Comma, QuoteKind},
@@ -104,10 +103,7 @@ impl<'a> Parser<'a> {
                 String::from_utf8(fs::read(&name)?)?,
             );
             return Parser {
-                toks: &mut Lexer::new(&file)
+                toks: &mut Lexer::new_from_file(&file),
-                    .collect::<Vec<Token>>()
-                    .into_iter()
-                    .peekmore(),
                 map: self.map,
                 path: &name,
                 scopes: self.scopes,
@@ -141,7 +137,7 @@ impl<'a> Parser<'a> {
             Some(Token { kind: '\'', .. })
             | Some(Token { kind: '"', .. })
             | Some(Token { kind: 'u', .. }) => {}
-            Some(Token { pos, .. }) => return Err(("Expected string.", *pos).into()),
+            Some(Token { pos, .. }) => return Err(("Expected string.", pos).into()),
             None => return Err(("expected more input.", self.span_before).into()),
         };
         let Spanned {

src/parse/keyframes.rs

@@ -1,10 +1,9 @@
 use std::fmt;
 
-use peekmore::PeekMore;
-
 use crate::{
     atrule::keyframes::{Keyframes, KeyframesSelector},
     error::SassResult,
+    lexer::Lexer,
     parse::Stmt,
     utils::eat_whole_number,
     Token,
@@ -34,7 +33,7 @@ impl<'a, 'b> KeyframesSelectorParser<'a, 'b> {
     fn parse_keyframes_selector(&mut self) -> SassResult<Vec<KeyframesSelector>> {
         let mut selectors = Vec::new();
         self.parser.whitespace_or_comment();
-        while let Some(tok) = self.parser.toks.peek().copied() {
+        while let Some(tok) = self.parser.toks.peek() {
             match tok.kind {
                 't' | 'T' => {
                     let mut ident = self.parser.parse_identifier()?;
@@ -128,7 +127,7 @@ impl<'a> Parser<'a> {
             span = span.merge(tok.pos());
             match tok.kind {
                 '#' => {
-                    if let Some(Token { kind: '{', .. }) = self.toks.peek().copied() {
+                    if let Some(Token { kind: '{', .. }) = self.toks.peek() {
                         self.toks.next();
                         string.push_str(&self.parse_interpolation()?.to_css_string(span)?);
                     } else {
@@ -154,13 +153,11 @@ impl<'a> Parser<'a> {
                     string.push(' ');
                 }
                 '{' => {
-                    // we must collect here because the parser is not generic over iterator
-                    #[allow(clippy::needless_collect)]
                     let sel_toks: Vec<Token> =
                         string.chars().map(|x| Token::new(span, x)).collect();
 
                     let selector = KeyframesSelectorParser::new(&mut Parser {
-                        toks: &mut sel_toks.into_iter().peekmore(),
+                        toks: &mut Lexer::new(sel_toks),
                         map: self.map,
                         path: self.path,
                         scopes: self.scopes,

src/parse/media.rs

@@ -98,7 +98,7 @@ impl<'a> Parser<'a> {
             return Ok(buf);
         }
 
-        let next_tok = self.toks.peek().copied();
+        let next_tok = self.toks.peek();
         let is_angle = next_tok.map_or(false, |t| t.kind == '<' || t.kind == '>');
         if is_angle || matches!(next_tok, Some(Token { kind: '=', .. })) {
             buf.push(' ');

src/parse/mixin.rs

@@ -2,12 +2,11 @@ use std::mem;
 
 use codemap::Spanned;
 
-use peekmore::PeekMore;
-
 use crate::{
     args::{CallArgs, FuncArgs},
     atrule::mixin::{Content, Mixin, UserDefinedMixin},
     error::SassResult,
+    lexer::Lexer,
     scope::Scopes,
     utils::read_until_closing_curly_brace,
     Token,
@@ -124,7 +123,7 @@ impl<'a> Parser<'a> {
 
             let mut toks = read_until_closing_curly_brace(self.toks)?;
             if let Some(tok) = self.toks.peek() {
-                toks.push(*tok);
+                toks.push(tok);
                 self.toks.next();
             }
             Some(toks)
@@ -167,7 +166,7 @@ impl<'a> Parser<'a> {
         });
 
         let body = Parser {
-            toks: &mut body.into_iter().peekmore(),
+            toks: &mut Lexer::new(body),
             map: self.map,
             path: self.path,
             scopes: self.scopes,
@@ -234,7 +233,7 @@ impl<'a> Parser<'a> {
 
             let stmts = if let Some(body) = content.content.clone() {
                 Parser {
-                    toks: &mut body.into_iter().peekmore(),
+                    toks: &mut Lexer::new(body),
                     map: self.map,
                     path: self.path,
                     scopes: &mut scope_at_decl,

src/parse/mod.rs

@@ -1,7 +1,6 @@
-use std::{convert::TryFrom, path::Path, vec::IntoIter};
+use std::{convert::TryFrom, path::Path};
 
 use codemap::{CodeMap, Span, Spanned};
-use peekmore::{PeekMore, PeekMoreIterator};
 
 use crate::{
     atrule::{
@@ -12,6 +11,7 @@ use crate::{
     },
     builtin::modules::{ModuleConfig, Modules},
     error::SassResult,
+    lexer::Lexer,
     scope::{Scope, Scopes},
     selector::{
         ComplexSelectorComponent, ExtendRule, ExtendedSelector, Extender, Selector, SelectorParser,
@@ -68,7 +68,7 @@ pub(crate) enum Stmt {
 /// hit (if there is one) is not important for now.
 // todo: merge at_root and at_root_has_selector into an enum
 pub(crate) struct Parser<'a> {
-    pub toks: &'a mut PeekMoreIterator<IntoIter<Token>>,
+    pub toks: &'a mut Lexer,
     pub map: &'a mut CodeMap,
     pub path: &'a Path,
     pub global_scope: &'a mut Scope,
@@ -114,19 +114,19 @@ impl<'a> Parser<'a> {
 
     pub fn expect_char(&mut self, c: char) -> SassResult<()> {
         match self.toks.peek() {
-            Some(Token { kind, pos }) if *kind == c => {
+            Some(Token { kind, pos }) if kind == c => {
-                self.span_before = *pos;
+                self.span_before = pos;
                 self.toks.next();
                 Ok(())
             }
-            Some(Token { pos, .. }) => Err((format!("expected \"{}\".", c), *pos).into()),
+            Some(Token { pos, .. }) => Err((format!("expected \"{}\".", c), pos).into()),
             None => Err((format!("expected \"{}\".", c), self.span_before).into()),
         }
     }
 
     pub fn consume_char_if_exists(&mut self, c: char) -> bool {
         if let Some(Token { kind, .. }) = self.toks.peek() {
-            if *kind == c {
+            if kind == c {
                 self.toks.next();
                 return true;
             }
@@ -150,7 +150,7 @@ impl<'a> Parser<'a> {
             if self.flags.in_function() && !stmts.is_empty() {
                 return Ok(stmts);
             }
-            self.span_before = *pos;
+            self.span_before = pos;
             match kind {
                 '@' => {
                     self.toks.next();
@@ -207,7 +207,7 @@ impl<'a> Parser<'a> {
                             } = self.parse_value(false, &|_| false)?;
                             span.merge(kind_string.span);
                             if let Some(Token { kind: ';', pos }) = self.toks.peek() {
-                                kind_string.span.merge(*pos);
+                                kind_string.span.merge(pos);
                                 self.toks.next();
                             }
                             self.warn(&Spanned {
@@ -222,7 +222,7 @@ impl<'a> Parser<'a> {
                             } = self.parse_value(false, &|_| false)?;
                             span.merge(kind_string.span);
                             if let Some(Token { kind: ';', pos }) = self.toks.peek() {
-                                kind_string.span.merge(*pos);
+                                kind_string.span.merge(pos);
                                 self.toks.next();
                             }
                             self.debug(&Spanned {
@@ -287,14 +287,14 @@ impl<'a> Parser<'a> {
                     }
                 }
                 '\u{0}'..='\u{8}' | '\u{b}'..='\u{1f}' => {
-                    return Err(("expected selector.", *pos).into())
+                    return Err(("expected selector.", pos).into())
                 }
                 '}' => {
                     self.toks.next();
                     break;
                 }
                 // dart-sass seems to special-case the error message here?
-                '!' | '{' => return Err(("expected \"}\".", *pos).into()),
+                '!' | '{' => return Err(("expected \"}\".", pos).into()),
                 _ => {
                     if self.flags.in_function() {
                         return Err((
@@ -403,7 +403,7 @@ impl<'a> Parser<'a> {
             span = span.merge(pos);
             match kind {
                 '#' => {
-                    if let Some(Token { kind: '{', .. }) = self.toks.peek().copied() {
+                    if let Some(Token { kind: '{', .. }) = self.toks.peek() {
                         self.toks.next();
                         string.push_str(&self.parse_interpolation()?.to_css_string(span)?);
                     } else {
@@ -447,15 +447,13 @@ impl<'a> Parser<'a> {
             return Err(("expected \"{\".", span).into());
         }
 
-        // we must collect here because the parser isn't generic over the iterator
-        #[allow(clippy::needless_collect)]
         let sel_toks: Vec<Token> = string.chars().map(|x| Token::new(span, x)).collect();
 
-        let mut iter = sel_toks.into_iter().peekmore();
+        let mut lexer = Lexer::new(sel_toks);
 
         let selector = SelectorParser::new(
             &mut Parser {
-                toks: &mut iter,
+                toks: &mut lexer,
                 map: self.map,
                 path: self.path,
                 scopes: self.scopes,
@@ -635,7 +633,7 @@ impl<'a> Parser<'a> {
                 '{' => break,
                 '#' => {
                     if let Some(Token { kind: '{', pos }) = self.toks.peek() {
-                        self.span_before = self.span_before.merge(*pos);
+                        self.span_before = self.span_before.merge(pos);
                         self.toks.next();
                         params.push_str(&self.parse_interpolation_as_string()?);
                     } else {
@@ -780,9 +778,7 @@ impl<'a> Parser<'a> {
         //     return Err(("@extend may only be used within style rules.", self.span_before).into());
         // }
         let (value, is_optional) = Parser {
-            toks: &mut read_until_semicolon_or_closing_curly_brace(self.toks)?
+            toks: &mut Lexer::new(read_until_semicolon_or_closing_curly_brace(self.toks)?),
-                .into_iter()
-                .peekmore(),
             map: self.map,
             path: self.path,
             scopes: self.scopes,
@@ -888,7 +884,7 @@ impl<'a> Parser<'a> {
             match tok.kind {
                 '{' => break,
                 '#' => {
-                    if let Some(Token { kind: '{', pos }) = self.toks.peek().copied() {
+                    if let Some(Token { kind: '{', pos }) = self.toks.peek() {
                         self.toks.next();
                         self.span_before = pos;
                         let interpolation = self.parse_interpolation()?;

src/parse/module.rs

@@ -1,7 +1,6 @@
 use std::{convert::TryFrom, fs};
 
 use codemap::Spanned;
-use peekmore::PeekMore;
 
 use crate::{
     atrule::AtRuleKind,
@@ -116,10 +115,7 @@ impl<'a> Parser<'a> {
                         .add_file(name.to_owned(), String::from_utf8(fs::read(&import)?)?);
 
                     let stmts = Parser {
-                        toks: &mut Lexer::new(&file)
+                        toks: &mut Lexer::new_from_file(&file),
-                            .collect::<Vec<Token>>()
-                            .into_iter()
-                            .peekmore(),
                         map: self.map,
                         path: &import,
                         scopes: self.scopes,

src/parse/style.rs

@@ -27,36 +27,36 @@ impl<'a> Parser<'a> {
                     return None;
                 }
                 '(' => {
-                    toks.push(*tok);
+                    toks.push(tok);
                     self.toks.peek_forward(1);
                     let mut scope = 0;
                     while let Some(tok) = self.toks.peek() {
                         match tok.kind {
                             ')' => {
                                 if scope == 0 {
-                                    toks.push(*tok);
+                                    toks.push(tok);
                                     self.toks.peek_forward(1);
                                     break;
                                 }
 
                                 scope -= 1;
-                                toks.push(*tok);
+                                toks.push(tok);
                                 self.toks.peek_forward(1);
                             }
                             '(' => {
-                                toks.push(*tok);
+                                toks.push(tok);
                                 self.toks.peek_forward(1);
                                 scope += 1;
                             }
                             _ => {
-                                toks.push(*tok);
+                                toks.push(tok);
                                 self.toks.peek_forward(1);
                             }
                         }
                     }
                 }
                 _ => {
-                    toks.push(*tok);
+                    toks.push(tok);
                     self.toks.peek_forward(1);
                 }
             }
@@ -123,7 +123,7 @@ impl<'a> Parser<'a> {
                             property.push(':');
                             SelectorOrStyle::Selector(property)
                         }
-                        c if is_name(*c) => {
+                        c if is_name(c) => {
                             if let Some(toks) =
                                 self.parse_style_value_when_no_space_after_semicolon()
                             {
@@ -201,7 +201,7 @@ impl<'a> Parser<'a> {
     ) -> SassResult<Vec<Style>> {
         let mut styles = Vec::new();
         self.whitespace();
-        while let Some(tok) = self.toks.peek().copied() {
+        while let Some(tok) = self.toks.peek() {
             match tok.kind {
                 '{' => {
                     self.toks.next();

src/parse/value/css_function.rs

@@ -27,7 +27,7 @@ impl<'a> Parser<'a> {
                 }
                 '#' => {
                     if let Some(Token { kind: '{', pos }) = self.toks.peek() {
-                        self.span_before = *pos;
+                        self.span_before = pos;
                         self.toks.next();
                         let interpolation = self.parse_interpolation()?;
                         buf.push_str(&interpolation.node.to_css_string(interpolation.span)?);
@@ -315,7 +315,7 @@ impl<'a> Parser<'a> {
             }
             buf.push_str(&num);
         } else {
-            self.toks.move_cursor_back().unwrap();
+            self.toks.move_cursor_back();
         }
 
         let next = match self.toks.peek() {
@@ -365,7 +365,7 @@ impl<'a> Parser<'a> {
     fn peek_escape(&mut self) -> SassResult<String> {
         let mut value = 0;
         let first = match self.toks.peek() {
-            Some(t) => *t,
+            Some(t) => t,
             None => return Ok(String::new()),
         };
         let mut span = first.pos;

src/parse/value/parse.rs

@@ -1,4 +1,4 @@
-use std::{iter::Iterator, mem, vec::IntoIter};
+use std::{iter::Iterator, mem};
 
 use num_bigint::BigInt;
 use num_rational::{BigRational, Rational64};
@@ -6,13 +6,12 @@ use num_traits::{pow, One, ToPrimitive};
 
 use codemap::{Span, Spanned};
 
-use peekmore::{PeekMore, PeekMoreIterator};
-
 use crate::{
     builtin::GLOBAL_FUNCTIONS,
     color::{Color, NAMED_COLORS},
     common::{unvendor, Brackets, Identifier, ListSeparator, Op, QuoteKind},
     error::SassResult,
+    lexer::Lexer,
     unit::Unit,
     utils::{eat_whole_number, is_name, IsWhitespace, ParsedNumber},
     value::{Number, SassFunction, SassMap, Value},
@@ -53,7 +52,7 @@ impl<'a> Parser<'a> {
     pub(crate) fn parse_value(
         &mut self,
         in_paren: bool,
-        predicate: &dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
+        predicate: &dyn Fn(&mut Lexer) -> bool,
     ) -> SassResult<Spanned<Value>> {
         self.whitespace();
 
@@ -62,7 +61,7 @@ impl<'a> Parser<'a> {
             | Some(Token { kind: ';', .. })
             | Some(Token { kind: '{', .. })
             | None => return Err(("Expected expression.", self.span_before).into()),
-            Some(Token { pos, .. }) => *pos,
+            Some(Token { pos, .. }) => pos,
         };
 
         if predicate(self.toks) {
@@ -173,7 +172,7 @@ impl<'a> Parser<'a> {
         in_paren: bool,
     ) -> SassResult<Spanned<Value>> {
         Parser {
-            toks: &mut toks.into_iter().peekmore(),
+            toks: &mut Lexer::new(toks),
             map: self.map,
             path: self.path,
             scopes: self.scopes,
@@ -291,7 +290,7 @@ impl<'a> Parser<'a> {
 
     fn parse_ident_value(
         &mut self,
-        predicate: &dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
+        predicate: &dyn Fn(&mut Lexer) -> bool,
     ) -> SassResult<Spanned<IntermediateValue>> {
         let Spanned { node: mut s, span } = self.parse_identifier()?;
 
@@ -363,7 +362,7 @@ impl<'a> Parser<'a> {
 
     fn parse_number(
         &mut self,
-        predicate: &dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
+        predicate: &dyn Fn(&mut Lexer) -> bool,
     ) -> SassResult<Spanned<ParsedNumber>> {
         let mut span = self.toks.peek().unwrap().pos;
         let mut whole = eat_whole_number(self.toks);
@@ -375,7 +374,7 @@ impl<'a> Parser<'a> {
             });
         }
 
-        let next_tok = *self.toks.peek().unwrap();
+        let next_tok = self.toks.peek().unwrap();
 
         let dec_len = if next_tok.kind == '.' {
             self.toks.next();
@@ -395,7 +394,7 @@ impl<'a> Parser<'a> {
         let mut times_ten = String::new();
         let mut times_ten_is_postive = true;
         if let Some(Token { kind: 'e', .. }) | Some(Token { kind: 'E', .. }) = self.toks.peek() {
-            if let Some(&tok) = self.toks.peek_next() {
+            if let Some(tok) = self.toks.peek_next() {
                 if tok.kind == '-' {
                     self.toks.next();
                     times_ten_is_postive = false;
@@ -404,13 +403,11 @@ impl<'a> Parser<'a> {
                     times_ten = eat_whole_number(self.toks);
 
                     if times_ten.is_empty() {
-                        return Err(
+                        return Err(("Expected digit.", self.toks.peek().unwrap_or(tok).pos).into());
-                            ("Expected digit.", self.toks.peek().unwrap_or(&tok).pos).into()
-                        );
                     } else if times_ten.len() > 2 {
                         return Err((
                             "Exponent too negative.",
-                            self.toks.peek().unwrap_or(&tok).pos,
+                            self.toks.peek().unwrap_or(tok).pos,
                         )
                             .into());
                     }
@@ -420,15 +417,15 @@ impl<'a> Parser<'a> {
 
                     if times_ten.len() > 2 {
                         return Err(
-                            ("Exponent too large.", self.toks.peek().unwrap_or(&tok).pos).into(),
+                            ("Exponent too large.", self.toks.peek().unwrap_or(tok).pos).into()
                         );
                     }
                 }
             }
         }
 
-        if let Ok(Some(Token { pos, .. })) = self.toks.peek_previous() {
+        if let Some(Token { pos, .. }) = self.toks.peek_previous() {
-            span = span.merge(*pos);
+            span = span.merge(pos);
         }
 
         self.toks.reset_cursor();
@@ -445,7 +442,7 @@ impl<'a> Parser<'a> {
         self.whitespace_or_comment();
 
         Ok(if let Some(Token { kind: ']', pos }) = self.toks.peek() {
-            span = span.merge(*pos);
+            span = span.merge(pos);
             self.toks.next();
             IntermediateValue::Value(HigherIntermediateValue::Literal(Value::List(
                 Vec::new(),
@@ -473,14 +470,14 @@ impl<'a> Parser<'a> {
 
     fn parse_dimension(
         &mut self,
-        predicate: &dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
+        predicate: &dyn Fn(&mut Lexer) -> bool,
     ) -> SassResult<Spanned<IntermediateValue>> {
         let Spanned {
             node: val,
             mut span,
         } = self.parse_number(predicate)?;
         let unit = if let Some(tok) = self.toks.peek() {
-            let Token { kind, .. } = *tok;
+            let Token { kind, .. } = tok;
             match kind {
                 'a'..='z' | 'A'..='Z' | '_' | '\\' | '\u{7f}'..=std::char::MAX => {
                     let u = self.parse_identifier_no_interpolation(true)?;
@@ -488,7 +485,7 @@ impl<'a> Parser<'a> {
                     Unit::from(u.node)
                 }
                 '-' => {
-                    if let Some(Token { kind, .. }) = self.toks.peek_next().copied() {
+                    if let Some(Token { kind, .. }) = self.toks.peek_next() {
                         self.toks.reset_cursor();
                         if matches!(kind, 'a'..='z' | 'A'..='Z' | '_' | '\\' | '\u{7f}'..=std::char::MAX)
                         {
@@ -679,7 +676,7 @@ impl<'a> Parser<'a> {
     fn in_interpolated_identifier_body(&mut self) -> bool {
         match self.toks.peek() {
             Some(Token { kind: '\\', .. }) => true,
-            Some(Token { kind, .. }) if is_name(*kind) => true,
+            Some(Token { kind, .. }) if is_name(kind) => true,
             Some(Token { kind: '#', .. }) => {
                 let next_is_curly = matches!(self.toks.peek_next(), Some(Token { kind: '{', .. }));
                 self.toks.reset_cursor();
@@ -701,9 +698,9 @@ impl<'a> Parser<'a> {
         for _ in 0..6 {
             if let Some(Token { kind, pos }) = self.toks.peek() {
                 if kind.is_ascii_hexdigit() {
-                    span = span.merge(*pos);
+                    span = span.merge(pos);
-                    self.span_before = *pos;
+                    self.span_before = pos;
-                    buf.push(*kind);
+                    buf.push(kind);
                     self.toks.next();
                 } else {
                     break;
@@ -715,8 +712,8 @@ impl<'a> Parser<'a> {
             buf.push('?');
             for _ in 0..(8_usize.saturating_sub(buf.len())) {
                 if let Some(Token { kind: '?', pos }) = self.toks.peek() {
-                    span = span.merge(*pos);
+                    span = span.merge(pos);
-                    self.span_before = *pos;
+                    self.span_before = pos;
                     buf.push('?');
                     self.toks.next();
                 } else {
@@ -743,9 +740,9 @@ impl<'a> Parser<'a> {
                 found_hex_digit = true;
                 if let Some(Token { kind, pos }) = self.toks.peek() {
                     if kind.is_ascii_hexdigit() {
-                        span = span.merge(*pos);
+                        span = span.merge(pos);
-                        self.span_before = *pos;
+                        self.span_before = pos;
-                        buf.push(*kind);
+                        buf.push(kind);
                         self.toks.next();
                     } else {
                         break;
@@ -773,7 +770,7 @@ impl<'a> Parser<'a> {
 
     fn parse_intermediate_value(
         &mut self,
-        predicate: &dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
+        predicate: &dyn Fn(&mut Lexer) -> bool,
     ) -> Option<SassResult<Spanned<IntermediateValue>>> {
         if predicate(self.toks) {
             return None;
@@ -832,7 +829,7 @@ impl<'a> Parser<'a> {
             }
             '#' => {
                 if let Some(Token { kind: '{', pos }) = self.toks.peek_forward(1) {
-                    self.span_before = *pos;
+                    self.span_before = pos;
                     self.toks.reset_cursor();
                     return Some(self.parse_ident_value(predicate));
                 }
@@ -1048,7 +1045,7 @@ impl<'a> Parser<'a> {
 struct IntermediateValueIterator<'a, 'b: 'a> {
     parser: &'a mut Parser<'b>,
     peek: Option<SassResult<Spanned<IntermediateValue>>>,
-    predicate: &'a dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
+    predicate: &'a dyn Fn(&mut Lexer) -> bool,
 }
 
 impl<'a, 'b: 'a> Iterator for IntermediateValueIterator<'a, 'b> {
@@ -1063,10 +1060,7 @@ impl<'a, 'b: 'a> Iterator for IntermediateValueIterator<'a, 'b> {
 }
 
 impl<'a, 'b: 'a> IntermediateValueIterator<'a, 'b> {
-    pub fn new(
+    pub fn new(parser: &'a mut Parser<'b>, predicate: &'a dyn Fn(&mut Lexer) -> bool) -> Self {
-        parser: &'a mut Parser<'b>,
-        predicate: &'a dyn Fn(&mut PeekMoreIterator<IntoIter<Token>>) -> bool,
-    ) -> Self {
         Self {
             parser,
             peek: None,

src/selector/attribute.rs

@@ -141,7 +141,7 @@ impl Attribute {
         };
         parser.whitespace();
 
-        let modifier = match parser.toks.peek().copied() {
+        let modifier = match parser.toks.peek() {
             Some(Token {
                 kind: c @ 'a'..='z',
                 ..

src/selector/parse.rs

@@ -198,7 +198,7 @@ impl<'a, 'b> SelectorParser<'a, 'b> {
         let mut components = vec![self.parse_simple_selector(None)?];
 
         while let Some(Token { kind, .. }) = self.parser.toks.peek() {
-            if !is_simple_selector_start(*kind) {
+            if !is_simple_selector_start(kind) {
                 break;
             }
 
@@ -219,13 +219,13 @@ impl<'a, 'b> SelectorParser<'a, 'b> {
     /// [the CSS algorithm]: https://drafts.csswg.org/css-syntax-3/#would-start-an-identifier
     fn looking_at_identifier(&mut self) -> bool {
         match self.parser.toks.peek() {
-            Some(Token { kind, .. }) if is_name_start(*kind) || kind == &'\\' => return true,
+            Some(Token { kind, .. }) if is_name_start(kind) || kind == '\\' => return true,
             Some(Token { kind: '-', .. }) => {}
             Some(..) | None => return false,
         }
 
         match self.parser.toks.peek_forward(1) {
-            Some(Token { kind, .. }) if is_name_start(*kind) || kind == &'-' || kind == &'\\' => {
+            Some(Token { kind, .. }) if is_name_start(kind) || kind == '-' || kind == '\\' => {
                 self.parser.toks.reset_cursor();
                 true
             }
@@ -391,7 +391,7 @@ impl<'a, 'b> SelectorParser<'a, 'b> {
 
         match self.parser.toks.peek() {
             Some(Token { kind: '*', pos }) => {
-                self.parser.span_before = self.parser.span_before.merge(*pos);
+                self.parser.span_before = self.parser.span_before.merge(pos);
                 self.parser.toks.next();
                 if let Some(Token { kind: '|', .. }) = self.parser.toks.peek() {
                     self.parser.toks.next();
@@ -409,7 +409,7 @@ impl<'a, 'b> SelectorParser<'a, 'b> {
                 return Ok(SimpleSelector::Universal(Namespace::None));
             }
             Some(Token { kind: '|', pos }) => {
-                self.parser.span_before = self.parser.span_before.merge(*pos);
+                self.parser.span_before = self.parser.span_before.merge(pos);
                 self.parser.toks.next();
                 match self.parser.toks.peek() {
                     Some(Token { kind: '*', .. }) => {

src/utils/comment_whitespace.rs

@@ -1,8 +1,4 @@
-use std::vec::IntoIter;
+use crate::{lexer::Lexer, Token};
-
-use peekmore::PeekMoreIterator;
-
-use crate::Token;
 
 use super::peek_until_newline;
 
@@ -16,9 +12,7 @@ impl IsWhitespace for char {
     }
 }
 
-pub(crate) fn devour_whitespace<I: Iterator<Item = W>, W: IsWhitespace>(
+pub(crate) fn devour_whitespace(s: &mut Lexer) -> bool {
-    s: &mut PeekMoreIterator<I>,
-) -> bool {
     let mut found_whitespace = false;
     while let Some(w) = s.peek() {
         if !w.is_whitespace() {
@@ -30,7 +24,7 @@ pub(crate) fn devour_whitespace<I: Iterator<Item = W>, W: IsWhitespace>(
     found_whitespace
 }
 
-pub(crate) fn peek_whitespace(s: &mut PeekMoreIterator<IntoIter<Token>>) -> bool {
+pub(crate) fn peek_whitespace(s: &mut Lexer) -> bool {
     let mut found_whitespace = false;
     while let Some(w) = s.peek() {
         if !w.is_whitespace() {
@@ -42,7 +36,7 @@ pub(crate) fn peek_whitespace(s: &mut PeekMoreIterator<IntoIter<Token>>) -> bool
     found_whitespace
 }
 
-pub(crate) fn peek_whitespace_or_comment(s: &mut PeekMoreIterator<IntoIter<Token>>) -> bool {
+pub(crate) fn peek_whitespace_or_comment(s: &mut Lexer) -> bool {
     let mut found_whitespace = false;
     while let Some(w) = s.peek() {
         match w.kind {
@@ -83,7 +77,7 @@ pub(crate) fn peek_whitespace_or_comment(s: &mut PeekMoreIterator<IntoIter<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 PeekMoreIterator<I>) {
+pub(crate) fn read_until_newline(toks: &mut Lexer) {
     for tok in toks {
         if tok.kind == '\n' {
             return;

src/utils/number.rs

@@ -1,8 +1,4 @@
-use std::vec::IntoIter;
+use crate::lexer::Lexer;
-
-use peekmore::PeekMoreIterator;
-
-use crate::Token;
 
 #[derive(Debug)]
 pub(crate) struct ParsedNumber {
@@ -46,7 +42,7 @@ impl ParsedNumber {
     }
 }
 
-pub(crate) fn eat_whole_number(toks: &mut PeekMoreIterator<IntoIter<Token>>) -> String {
+pub(crate) fn eat_whole_number(toks: &mut Lexer) -> String {
     let mut buf = String::new();
     while let Some(c) = toks.peek() {
         if !c.kind.is_ascii_digit() {

src/utils/peek_until.rs

@@ -1,19 +1,13 @@
-use std::vec::IntoIter;
-
 use codemap::{Span, Spanned};
 
-use peekmore::PeekMoreIterator;
+use crate::{error::SassResult, lexer::Lexer, Token};
-
-use crate::{error::SassResult, Token};
 
 use super::{as_hex, hex_char_for, is_name, is_name_start, peek_whitespace};
 
-pub(crate) fn peek_until_closing_curly_brace(
+pub(crate) fn peek_until_closing_curly_brace(toks: &mut Lexer) -> SassResult<Vec<Token>> {
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
-) -> SassResult<Vec<Token>> {
     let mut t = Vec::new();
     let mut nesting = 0;
-    while let Some(tok) = toks.peek().copied() {
+    while let Some(tok) = toks.peek() {
         match tok.kind {
             q @ '"' | q @ '\'' => {
                 t.push(tok);
@@ -35,7 +29,7 @@ pub(crate) fn peek_until_closing_curly_brace(
                 toks.advance_cursor();
             }
             '/' => {
-                let next = *toks
+                let next = toks
                     .peek_forward(1)
                     .ok_or(("Expected expression.", tok.pos))?;
                 match toks.peek() {
@@ -54,12 +48,9 @@ pub(crate) fn peek_until_closing_curly_brace(
     Ok(t)
 }
 
-fn peek_until_closing_quote(
+fn peek_until_closing_quote(toks: &mut Lexer, q: char) -> SassResult<Vec<Token>> {
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
-    q: char,
-) -> SassResult<Vec<Token>> {
     let mut t = Vec::new();
-    while let Some(tok) = toks.peek().copied() {
+    while let Some(tok) = toks.peek() {
         match tok.kind {
             '"' if q == '"' => {
                 t.push(tok);
@@ -74,7 +65,7 @@ fn peek_until_closing_quote(
             '\\' => {
                 t.push(tok);
                 t.push(match toks.peek_forward(1) {
-                    Some(tok) => *tok,
+                    Some(tok) => tok,
                     None => return Err((format!("Expected {}.", q), tok.pos).into()),
                 });
             }
@@ -85,7 +76,7 @@ fn peek_until_closing_quote(
                     None => return Err((format!("Expected {}.", q), tok.pos).into()),
                 };
                 if next.kind == '{' {
-                    t.push(*next);
+                    t.push(next);
                     toks.peek_forward(1);
                     t.append(&mut peek_until_closing_curly_brace(toks)?);
                 }
@@ -97,7 +88,7 @@ fn peek_until_closing_quote(
     Ok(t)
 }
 
-pub(crate) fn peek_until_newline(toks: &mut PeekMoreIterator<IntoIter<Token>>) {
+pub(crate) fn peek_until_newline(toks: &mut Lexer) {
     while let Some(tok) = toks.peek() {
         if tok.kind == '\n' {
             break;
@@ -106,10 +97,10 @@ pub(crate) fn peek_until_newline(toks: &mut PeekMoreIterator<IntoIter<Token>>) {
     }
 }
 
-pub(crate) fn peek_escape(toks: &mut PeekMoreIterator<IntoIter<Token>>) -> SassResult<String> {
+pub(crate) fn peek_escape(toks: &mut Lexer) -> SassResult<String> {
     let mut value = 0;
     let first = match toks.peek() {
-        Some(t) => *t,
+        Some(t) => t,
         None => return Ok(String::new()),
     };
     let mut span = first.pos;
@@ -155,7 +146,7 @@ pub(crate) fn peek_escape(toks: &mut PeekMoreIterator<IntoIter<Token>>) -> SassR
 }
 
 pub(crate) fn peek_ident_no_interpolation(
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
+    toks: &mut Lexer,
     unit: bool,
     span_before: Span,
 ) -> SassResult<Spanned<String>> {
@@ -200,7 +191,7 @@ pub(crate) fn peek_ident_no_interpolation(
 }
 
 fn peek_ident_body_no_interpolation(
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
+    toks: &mut Lexer,
     unit: bool,
     mut span: Span,
 ) -> SassResult<Spanned<String>> {
@@ -210,7 +201,7 @@ fn peek_ident_body_no_interpolation(
         if unit && tok.kind == '-' {
             // Disallow `-` followed by a dot or a digit digit in units.
             let second = match toks.peek_forward(1) {
-                Some(v) => *v,
+                Some(v) => v,
                 None => break,
             };
 

src/utils/read_until.rs

@@ -1,17 +1,11 @@
-use std::vec::IntoIter;
+use crate::{error::SassResult, lexer::Lexer, Token};
-
-use peekmore::PeekMoreIterator;
-
-use crate::{error::SassResult, Token};
 
 use super::{devour_whitespace, read_until_newline};
 
 // Eat tokens until an open curly brace
 //
 // Does not consume the open curly brace
-pub(crate) fn read_until_open_curly_brace(
+pub(crate) fn read_until_open_curly_brace(toks: &mut Lexer) -> SassResult<Vec<Token>> {
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
-) -> SassResult<Vec<Token>> {
     let mut t = Vec::new();
     let mut n = 0;
     while let Some(tok) = toks.peek() {
@@ -49,9 +43,7 @@ pub(crate) fn read_until_open_curly_brace(
     Ok(t)
 }
 
-pub(crate) fn read_until_closing_curly_brace(
+pub(crate) fn read_until_closing_curly_brace(toks: &mut Lexer) -> SassResult<Vec<Token>> {
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
-) -> SassResult<Vec<Token>> {
     let mut buf = Vec::new();
     let mut nesting = 0;
     while let Some(tok) = toks.peek() {
@@ -104,10 +96,7 @@ pub(crate) fn read_until_closing_curly_brace(
 /// Read tokens into a vector until a matching closing quote is found
 ///
 /// The closing quote is included in the output
-pub(crate) fn read_until_closing_quote(
+pub(crate) fn read_until_closing_quote(toks: &mut Lexer, q: char) -> SassResult<Vec<Token>> {
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
-    q: char,
-) -> SassResult<Vec<Token>> {
     let mut t = Vec::new();
     while let Some(tok) = toks.next() {
         match tok.kind {
@@ -130,7 +119,7 @@ pub(crate) fn read_until_closing_quote(
                 t.push(tok);
                 match toks.peek() {
                     Some(tok @ Token { kind: '{', .. }) => {
-                        t.push(*tok);
+                        t.push(tok);
                         toks.next();
                         t.append(&mut read_until_closing_curly_brace(toks)?);
                     }
@@ -151,7 +140,7 @@ pub(crate) fn read_until_closing_quote(
 }
 
 pub(crate) fn read_until_semicolon_or_closing_curly_brace(
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
+    toks: &mut Lexer,
 ) -> SassResult<Vec<Token>> {
     let mut t = Vec::new();
     let mut nesting = 0;
@@ -202,9 +191,7 @@ pub(crate) fn read_until_semicolon_or_closing_curly_brace(
     Ok(t)
 }
 
-pub(crate) fn read_until_closing_paren(
+pub(crate) fn read_until_closing_paren(toks: &mut Lexer) -> SassResult<Vec<Token>> {
-    toks: &mut PeekMoreIterator<IntoIter<Token>>,
-) -> SassResult<Vec<Token>> {
     let mut t = Vec::new();
     let mut scope = 0;
     while let Some(tok) = toks.next() {

src/value/mod.rs

@@ -1,13 +1,12 @@
 use std::cmp::Ordering;
 
-use peekmore::PeekMore;
-
 use codemap::{Span, Spanned};
 
 use crate::{
     color::Color,
     common::{Brackets, ListSeparator, Op, QuoteKind},
     error::SassResult,
+    lexer::Lexer,
     parse::Parser,
     selector::Selector,
     unit::Unit,
@@ -511,12 +510,12 @@ impl Value {
             None => return Err((format!("${}: {} is not a valid selector: it must be a string, a list of strings, or a list of lists of strings.", name, self.inspect(parser.span_before)?), parser.span_before).into()),
         };
         Ok(Parser {
-            toks: &mut string
+            toks: &mut Lexer::new(
+                string
                     .chars()
                     .map(|c| Token::new(parser.span_before, c))
-                .collect::<Vec<Token>>()
+                    .collect::<Vec<Token>>(),
-                .into_iter()
+            ),
-                .peekmore(),
             map: parser.map,
             path: parser.path,
             scopes: parser.scopes,