reduce usage of std::process::exit

src/error.rs

@@ -7,7 +7,7 @@ use crate::common::Pos;
 
 pub type SassResult<T> = Result<T, SassError>;
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Eq, PartialEq)]
 pub struct SassError {
     message: String,
     pos: Pos,

src/lexer.rs

@@ -285,8 +285,7 @@ impl<'a> Lexer<'a> {
             if c == &'=' {
                 return TokenKind::Symbol(Symbol::Dollar);
             } else if !c.is_alphabetic() && c != &'-' && c != &'_' {
-                eprintln!("Error: Expected identifier.");
-                std::process::exit(1)
+                return TokenKind::Error("Expected identifier.".into());
             } else {
                 self.pos.next_char();
                 name.push(*c);

src/lib.rs

@@ -121,10 +121,6 @@ mod unit;
 mod utils;
 mod value;
 
-pub(crate) fn error<E: Into<String>>(msg: E) -> ! {
-    eprintln!("Error: {}", msg.into());
-    std::process::exit(1);
-}
 /// Represents a parsed SASS stylesheet with nesting
 #[derive(Debug, Clone)]
 pub struct StyleSheet(Vec<Stmt>);
@@ -325,11 +321,13 @@ impl<'a> StyleSheetParser<'a> {
                     GLOBAL_SCOPE.with(|s| {
                         if !default || s.borrow().get_var(&name).is_err() {
                             match s.borrow_mut().insert_var(&name, val) {
-                                Ok(..) => {},
-                                Err(e) => error(e),
+                                Ok(..) => Ok(()),
+                                Err(e) => Err(e),
                             }
+                        } else {
+                            Ok(())
                         }
-                    })
+                    })?
                 }
                 TokenKind::MultilineComment(_) => {
                     let comment = match self

src/token.rs

@@ -2,6 +2,7 @@ use std::fmt;
 
 use crate::atrule::AtRuleKind;
 use crate::common::{Keyword, Op, Pos, Symbol, Whitespace};
+use crate::error::SassError;
 use crate::utils::{IsComment, IsWhitespace};
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -82,6 +83,7 @@ pub(crate) enum TokenKind {
     Op(Op),
     MultilineComment(String),
     Interpolation,
+    Error(SassError),
 }
 
 impl TokenKind {
@@ -102,7 +104,7 @@ impl fmt::Display for TokenKind {
             TokenKind::Keyword(kw) => write!(f, "{}", kw),
             TokenKind::MultilineComment(s) => write!(f, "/*{}*/", s),
             TokenKind::Variable(s) => write!(f, "{}", s),
-            TokenKind::Interpolation => {
+            TokenKind::Interpolation | TokenKind::Error(..) => {
                 panic!("we don't want to format TokenKind::Interpolation using Display")
             }
         }

src/value/parse.rs

@@ -293,6 +293,7 @@ impl Value {
             TokenKind::Keyword(Keyword::Through(s)) => Ok(Value::Ident(s, QuoteKind::None)),
             TokenKind::Keyword(Keyword::To(s)) => Ok(Value::Ident(s, QuoteKind::None)),
             TokenKind::AtRule(_) => Err("expected \";\".".into()),
+            TokenKind::Error(e) => return Err(e),
             TokenKind::Op(Op::Plus) | TokenKind::Symbol(Symbol::Plus) => {
                 devour_whitespace_or_comment(toks);
                 let v = Self::_from_tokens(toks, scope, super_selector)?;