derive: properly display error locations

rinja_derive/Cargo.toml

@@ -26,6 +26,7 @@ with-warp = []
 
 [dependencies]
 parser = { package = "rinja_parser", version = "0.2.0", path = "../rinja_parser" }
+annotate-snippets = "0.11.4"
 basic-toml = { version = "0.1.1", optional = true }
 memchr = "2"
 mime = "0.3"

rinja_derive/src/input.rs

@@ -149,7 +149,21 @@ impl TemplateInput<'_> {
         let mut dependency_graph = Vec::new();
         let mut check = vec![(Arc::clone(&self.path), source, source_path)];
         while let Some((path, source, source_path)) = check.pop() {
-            let parsed = self.syntax.parse(source, source_path)?;
+            let parsed = match self.syntax.parse(Arc::clone(&source), source_path) {
+                Ok(parsed) => parsed,
+                Err(err) => {
+                    let msg = err
+                        .message
+                        .unwrap_or_else(|| "failed to parse template source".into());
+                    let file_path = err
+                        .file_path
+                        .as_deref()
+                        .unwrap_or(Path::new("<source attribute>"));
+                    let file_info =
+                        FileInfo::new(file_path, Some(&source), Some(&source[err.offset..]));
+                    return Err(CompileError::new(msg, Some(file_info)));
+                }
+            };
 
             let mut top = true;
             let mut nested = vec![parsed.nodes()];

rinja_derive/src/lib.rs

@@ -14,11 +14,12 @@ use std::collections::HashMap;
 use std::fmt;
 use std::path::Path;
 
+use annotate_snippets::{Level, Renderer, Snippet};
 use config::{read_config_file, Config};
 use generator::{Generator, MapChain};
 use heritage::{Context, Heritage};
 use input::{Print, TemplateArgs, TemplateInput};
-use parser::{generate_error_info, strip_common, ErrorInfo, ParseError, Parsed, WithSpan};
+use parser::{strip_common, Parsed, WithSpan};
 #[cfg(not(feature = "__standalone"))]
 use proc_macro::TokenStream as TokenStream12;
 #[cfg(feature = "__standalone")]
@@ -188,14 +189,46 @@ struct CompileError {
 
 impl CompileError {
     fn new<S: fmt::Display>(msg: S, file_info: Option<FileInfo<'_>>) -> Self {
+        let span = Span::call_site();
+
+        if let Some(FileInfo {
+            path,
+            source: Some(source),
+            node_source: Some(node_source),
+        }) = file_info
+        {
+            if source
+                .as_bytes()
+                .as_ptr_range()
+                .contains(&node_source.as_ptr())
+            {
+                let label = msg.to_string();
+                let path = match std::env::current_dir() {
+                    Ok(cwd) => strip_common(&cwd, path),
+                    Err(_) => path.display().to_string(),
+                };
+
+                let start = node_source.as_ptr() as usize - source.as_ptr() as usize;
+                let annotation = Level::Error.span(start..start).label("close to this token");
+                let snippet = Snippet::source(source)
+                    .origin(&path)
+                    .fold(true)
+                    .annotation(annotation);
+                let message = Level::Error.title(&label).snippet(snippet);
+
+                let mut msg = Renderer::styled().render(message).to_string();
+                if let Some((prefix, _)) = msg.split_once(' ') {
+                    msg.replace_range(..=prefix.len(), "");
+                }
+                return Self { msg, span };
+            }
+        }
+
         let msg = match file_info {
             Some(file_info) => format!("{msg}{file_info}"),
             None => msg.to_string(),
         };
-        Self {
-            msg,
-            span: Span::call_site(),
-        }
+        Self { msg, span }
     }
 
     fn no_file_info<S: fmt::Display>(msg: S) -> Self {
@@ -219,14 +252,7 @@ impl fmt::Display for CompileError {
     }
 }
 
-impl From<ParseError> for CompileError {
-    #[inline]
-    fn from(e: ParseError) -> Self {
-        // It already has the correct message so no need to do anything.
-        Self::no_file_info(e)
-    }
-}
-
+#[derive(Debug, Clone, Copy)]
 struct FileInfo<'a> {
     path: &'a Path,
     source: Option<&'a str>,
@@ -255,18 +281,13 @@ impl fmt::Display for FileInfo<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match (self.source, self.node_source) {
             (Some(source), Some(node_source)) => {
-                let (
-                    ErrorInfo {
-                        row,
-                        column,
-                        source_after,
-                    },
-                    file_path,
-                ) = generate_error_info(source, node_source, self.path);
+                let (error_info, file_path) = generate_error_info(source, node_source, self.path);
                 write!(
                     f,
                     "\n  --> {file_path}:{row}:{column}\n{source_after}",
-                    row = row + 1
+                    row = error_info.row,
+                    column = error_info.column,
+                    source_after = &error_info.source_after,
                 )
             }
             _ => {
@@ -280,6 +301,40 @@ impl fmt::Display for FileInfo<'_> {
     }
 }
 
+struct ErrorInfo {
+    row: usize,
+    column: usize,
+    source_after: String,
+}
+
+fn generate_row_and_column(src: &str, input: &str) -> ErrorInfo {
+    let offset = src.len() - input.len();
+    let (source_before, source_after) = src.split_at(offset);
+
+    let source_after = match source_after.char_indices().enumerate().take(41).last() {
+        Some((80, (i, _))) => format!("{:?}...", &source_after[..i]),
+        _ => format!("{source_after:?}"),
+    };
+
+    let (row, last_line) = source_before.lines().enumerate().last().unwrap_or_default();
+    let column = last_line.chars().count();
+    ErrorInfo {
+        row,
+        column,
+        source_after,
+    }
+}
+
+/// Return the error related information and its display file path.
+fn generate_error_info(src: &str, input: &str, file_path: &Path) -> (ErrorInfo, String) {
+    let file_path = match std::env::current_dir() {
+        Ok(cwd) => strip_common(&cwd, file_path),
+        Err(_) => file_path.display().to_string(),
+    };
+    let error_info = generate_row_and_column(src, input);
+    (error_info, file_path)
+}
+
 struct MsgValidEscapers<'a>(&'a [(Vec<Cow<'a, str>>, Cow<'a, str>)]);
 
 impl fmt::Display for MsgValidEscapers<'_> {

rinja_derive_standalone/Cargo.toml

@@ -25,6 +25,7 @@ with-warp = []
 
 [dependencies]
 parser = { package = "rinja_parser", version = "0.2.0", path = "../rinja_parser" }
+annotate-snippets = "0.11.4"
 basic-toml = { version = "0.1.1", optional = true }
 memchr = "2"
 mime = "0.3"

rinja_parser/src/lib.rs

@@ -12,7 +12,7 @@ use std::{fmt, str};
 use nom::branch::alt;
 use nom::bytes::complete::{escaped, is_not, tag, take_till, take_while_m_n};
 use nom::character::complete::{anychar, char, one_of, satisfy};
-use nom::combinator::{cut, eof, map, not, opt, recognize};
+use nom::combinator::{complete, cut, eof, map, not, opt, recognize};
 use nom::error::{Error, ErrorKind, FromExternalError};
 use nom::multi::{many0_count, many1};
 use nom::sequence::{delimited, pair, preceded, terminated, tuple};
@@ -110,31 +110,18 @@ impl<'a> Ast<'a> {
         syntax: &Syntax<'_>,
     ) -> Result<Self, ParseError> {
         let parse = |i: &'a str| Node::many(i, &State::new(syntax));
-        let (input, message) = match terminated(parse, cut(eof))(src) {
+        let (input, message) = match complete(terminated(parse, cut(eof)))(src) {
             Ok(("", nodes)) => return Ok(Self { nodes }),
             Ok(_) => unreachable!("eof() is not eof?"),
+            Err(nom::Err::Incomplete(_)) => unreachable!("complete() is not complete?"),
             Err(
                 nom::Err::Error(ErrorContext { input, message, .. })
                 | nom::Err::Failure(ErrorContext { input, message, .. }),
             ) => (input, message),
-            Err(nom::Err::Incomplete(_)) => return Err(ParseError::Incomplete),
         };
-
-        let offset = src.len() - input.len();
-        let (source_before, source_after) = src.split_at(offset);
-
-        let source_after = match source_after.char_indices().enumerate().take(41).last() {
-            Some((40, (i, _))) => format!("{:?}...", &source_after[..i]),
-            _ => format!("{source_after:?}"),
-        };
-
-        let (row, last_line) = source_before.lines().enumerate().last().unwrap_or_default();
-        let column = last_line.chars().count();
-        Err(ParseError::Details {
+        Err(ParseError {
             message,
-            row,
-            column,
-            source_after,
+            offset: src.len() - input.len(),
             file_path,
         })
     }
@@ -198,89 +185,39 @@ impl<'a, T: PartialEq> PartialEq for WithSpan<'a, T> {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub enum ParseError {
-    Incomplete,
-    Details {
-        message: Option<Cow<'static, str>>,
-        row: usize,
-        column: usize,
-        source_after: String,
-        file_path: Option<Arc<Path>>,
-    },
+pub struct ParseError {
+    pub message: Option<Cow<'static, str>>,
+    pub offset: usize,
+    pub file_path: Option<Arc<Path>>,
 }
 
 impl std::error::Error for ParseError {}
 
 impl fmt::Display for ParseError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let (message, mut row, column, source, path) = match self {
-            ParseError::Incomplete => return write!(f, "parsing incomplete"),
-            ParseError::Details {
-                message,
-                row,
-                column,
-                source_after,
-                file_path,
-            } => (message, *row, column, source_after, file_path),
-        };
+        let ParseError {
+            message,
+            file_path,
+            offset,
+        } = self;
 
         if let Some(message) = message {
             writeln!(f, "{}", message)?;
         }
 
-        let path = path
+        let path = file_path
             .as_ref()
             .and_then(|path| Some(strip_common(&current_dir().ok()?, path)));
-
-        row += 1;
         match path {
-            Some(path) => f.write_fmt(format_args!(
-                "failed to parse template source\n  --> {path}:{row}:{column}\n{source}",
-            )),
-            None => f.write_fmt(format_args!(
-                "failed to parse template source at row {row}, column {column} near:\n{source}",
-            )),
+            Some(path) => write!(f, "failed to parse template source\n  --> {path}@{offset}"),
+            None => write!(f, "failed to parse template source near offset {offset}"),
         }
     }
 }
 
 pub(crate) type ParseErr<'a> = nom::Err<ErrorContext<'a>>;
 pub(crate) type ParseResult<'a, T = &'a str> = Result<(&'a str, T), ParseErr<'a>>;
 
-pub struct ErrorInfo {
-    pub row: usize,
-    pub column: usize,
-    pub source_after: String,
-}
-
-pub fn generate_row_and_column(src: &str, input: &str) -> ErrorInfo {
-    let offset = src.len() - input.len();
-    let (source_before, source_after) = src.split_at(offset);
-
-    let source_after = match source_after.char_indices().enumerate().take(41).last() {
-        Some((40, (i, _))) => format!("{:?}...", &source_after[..i]),
-        _ => format!("{source_after:?}"),
-    };
-
-    let (row, last_line) = source_before.lines().enumerate().last().unwrap_or_default();
-    let column = last_line.chars().count();
-    ErrorInfo {
-        row,
-        column,
-        source_after,
-    }
-}
-
-/// Return the error related information and its display file path.
-pub fn generate_error_info(src: &str, input: &str, file_path: &Path) -> (ErrorInfo, String) {
-    let file_path = match std::env::current_dir() {
-        Ok(cwd) => strip_common(&cwd, file_path),
-        Err(_) => file_path.display().to_string(),
-    };
-    let error_info = generate_row_and_column(src, input);
-    (error_info, file_path)
-}
-
 /// This type is used to handle `nom` errors and in particular to add custom error messages.
 /// It used to generate `ParserError`.
 ///
@@ -801,7 +738,7 @@ pub fn strip_common(base: &Path, path: &Path) -> String {
     if path_parts.is_empty() {
         path.display().to_string()
     } else {
-        path_parts.join("/")
+        path_parts.join(std::path::MAIN_SEPARATOR_STR)
     }
 }
 

rinja_parser/src/tests.rs

@@ -360,7 +360,7 @@ fn test_rust_macro() {
         &*Ast::from_str("{{a.b.c!( hello )}}", None, &syntax)
             .unwrap_err()
             .to_string(),
-        "failed to parse template source at row 1, column 7 near:\n\"!( hello )}}\"",
+        "failed to parse template source near offset 7",
     );
 }
 
@@ -908,7 +908,7 @@ fn test_missing_space_after_kw() {
     let err = Ast::from_str("{%leta=b%}", None, &syntax).unwrap_err();
     assert!(matches!(
         &*err.to_string(),
-        "failed to parse template source at row 1, column 0 near:\n\"{%leta=b%}\"",
+        "failed to parse template source near offset 0",
     ));
 }