Convert errors to strings for pretty printing

src/css.rs

@@ -1,7 +1,7 @@
 //! # Convert from SCSS AST to CSS
-use crate::{RuleSet, Selector, Stmt, Style, StyleSheet};
+use crate::{RuleSet, SassResult, Selector, Stmt, Style, StyleSheet};
 use std::fmt;
-use std::io::{self, Write};
+use std::io::Write;
 
 #[derive(Debug, Clone)]
 pub enum Toplevel {
@@ -94,7 +94,7 @@ impl Css {
         self
     }
 
-    pub fn pretty_print<W: Write>(self, buf: &mut W) -> io::Result<()> {
+    pub fn pretty_print<W: Write>(self, buf: &mut W) -> SassResult<()> {
         for block in self.blocks {
             match block {
                 Toplevel::RuleSet(selector, styles) => {

src/error.rs

@@ -2,6 +2,7 @@ use crate::common::Pos;
 use std::error::Error;
 use std::fmt::{self, Display};
 use std::io;
+use std::string::FromUtf8Error;
 
 #[derive(Debug)]
 pub struct SassError {
@@ -16,13 +17,6 @@ impl SassError {
             pos,
         }
     }
-
-    pub fn unexpected_eof(pos: Pos) -> Self {
-        SassError {
-            message: String::from("unexpected eof"),
-            pos,
-        }
-    }
 }
 
 impl Display for SassError {
@@ -40,6 +34,21 @@ impl From<io::Error> for SassError {
     }
 }
 
+impl From<FromUtf8Error> for SassError {
+    fn from(error: FromUtf8Error) -> Self {
+        SassError {
+            pos: Pos::new(),
+            message: format!("Invalid UTF-8 character \"\\x{:X?}\"", error.as_bytes()[0]),
+        }
+    }
+}
+
+impl From<SassError> for String {
+    fn from(error: SassError) -> String {
+        error.message
+    }
+}
+
 impl Error for SassError {
     fn description(&self) -> &'static str {
         "SASS parsing error"

src/format.rs

@@ -1,6 +1,6 @@
-use std::io::{self, Write};
+use std::io::Write;
 
-use crate::{RuleSet, Stmt, StyleSheet};
+use crate::{RuleSet, SassResult, Stmt, StyleSheet};
 
 pub(crate) struct PrettyPrinter<W: Write> {
     buf: W,
@@ -14,7 +14,7 @@ impl<W: Write> PrettyPrinter<W> {
 
     /// Pretty print `crate::Stmt`
     /// Throws away super selectors and variables
-    fn pretty_print_stmt(&mut self, stmt: &Stmt) -> io::Result<()> {
+    fn pretty_print_stmt(&mut self, stmt: &Stmt) -> SassResult<()> {
         let padding = vec![' '; self.scope * 2].iter().collect::<String>();
         match stmt {
             Stmt::MultilineComment(s) => writeln!(self.buf, "{}/*{}*/", padding, s)?,
@@ -40,7 +40,7 @@ impl<W: Write> PrettyPrinter<W> {
     ///
     /// The result should be an exact copy of the SCSS input
     /// Empty rules are included
-    pub fn pretty_print(&mut self, s: &StyleSheet) -> io::Result<()> {
+    pub fn pretty_print(&mut self, s: &StyleSheet) -> SassResult<()> {
         for rule in &s.0 {
             self.pretty_print_stmt(rule)?;
         }
@@ -49,7 +49,7 @@ impl<W: Write> PrettyPrinter<W> {
 
     /// Pretty print `crate::Stmt`
     /// Keeps super selectors
-    fn pretty_print_stmt_preserve_super_selectors(&mut self, stmt: &Stmt) -> io::Result<()> {
+    fn pretty_print_stmt_preserve_super_selectors(&mut self, stmt: &Stmt) -> SassResult<()> {
         let padding = vec![' '; self.scope * 2].iter().collect::<String>();
         match stmt {
             Stmt::MultilineComment(s) => writeln!(self.buf, "/*{}*/", s)?,
@@ -79,7 +79,7 @@ impl<W: Write> PrettyPrinter<W> {
     pub(crate) fn pretty_print_preserve_super_selectors(
         &mut self,
         s: &StyleSheet,
-    ) -> io::Result<()> {
+    ) -> SassResult<()> {
         for rule in &s.0 {
             self.pretty_print_stmt_preserve_super_selectors(rule)?;
         }

src/lib.rs

@@ -43,7 +43,7 @@
 // todo! handle erroring on styles at the toplevel
 use std::fmt::{self, Display};
 use std::fs;
-use std::io::{self, Write};
+use std::io::Write;
 use std::iter::{Iterator, Peekable};
 use std::path::Path;
 
@@ -209,10 +209,12 @@ impl StyleSheet {
     }
 
     pub fn from_path<P: AsRef<Path> + Into<String>>(p: P) -> SassResult<StyleSheet> {
+        let s = String::from_utf8(fs::read(p.as_ref())?)?;
+        dbg!(&s);
         Ok(StyleSheet(
             StyleSheetParser {
                 global_scope: Scope::new(),
-                lexer: Lexer::new(&fs::read_to_string(p.as_ref())?).peekable(),
+                lexer: Lexer::new(&s).peekable(),
                 rules: Vec::new(),
                 scope: 0,
                 file: p.into(),
@@ -241,17 +243,17 @@ impl StyleSheet {
     /// to pure CSS
     ///
     /// Used mainly in debugging, but can at times be useful
-    pub fn pretty_print<W: Write>(&self, buf: W) -> io::Result<()> {
+    pub fn pretty_print<W: Write>(&self, buf: W) -> SassResult<()> {
         PrettyPrinter::new(buf).pretty_print(self)
     }
 
     #[allow(dead_code)]
-    fn pretty_print_selectors<W: Write>(&self, buf: W) -> io::Result<()> {
+    fn pretty_print_selectors<W: Write>(&self, buf: W) -> SassResult<()> {
         PrettyPrinter::new(buf).pretty_print_preserve_super_selectors(self)
     }
 
     /// Write the internal representation as CSS to `buf`
-    pub fn print_as_css<W: Write>(self, buf: &mut W) -> io::Result<()> {
+    pub fn print_as_css<W: Write>(self, buf: &mut W) -> SassResult<()> {
         Css::from_stylesheet(self).pretty_print(buf)
     }
 }

src/main.rs

@@ -1,9 +1,9 @@
 use clap::{App, Arg};
-use std::io::{BufWriter, stdout};
+use std::io::{stdout, BufWriter};
 
-use grass::{SassResult, StyleSheet};
+use grass::StyleSheet;
 
-fn main() -> SassResult<()> {
+fn main() -> Result<(), String> {
     let matches = App::new("grass")
         .version(env!("CARGO_PKG_VERSION"))
         .about("SCSS Compiler in rust")