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error.rs
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error.rs
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use std::borrow::Cow;
use std::fmt;
/// Represents template errors.
///
/// If debug mode is enabled a template error contains additional debug
/// information that can be displayed by formatting an error with the
/// alternative formatting (``format!("{:#}", err)``). That information
/// is also shown for the [`Debug`] display where the extended information
/// is hidden when the alternative formatting is used.
///
/// Since MiniJinja takes advantage of chained errors it's recommended
/// to render the entire chain to better understand the causes.
///
/// # Example
///
/// Here is an example of you might want to render errors:
///
/// ```rust
/// # let mut env = minijinja::Environment::new();
/// # env.add_template("", "");
/// # let template = env.get_template("").unwrap(); let ctx = ();
/// match template.render(ctx) {
/// Ok(result) => println!("{}", result),
/// Err(err) => {
/// eprintln!("Could not render template: {:#}", err);
/// // render causes as well
/// let mut err = &err as &dyn std::error::Error;
/// while let Some(next_err) = err.source() {
/// eprintln!();
/// eprintln!("caused by: {:#}", next_err);
/// err = next_err;
/// }
/// }
/// }
/// ```
pub struct Error {
kind: ErrorKind,
detail: Option<Cow<'static, str>>,
name: Option<String>,
lineno: usize,
span: Option<Span>,
source: Option<Box<dyn std::error::Error + Send + Sync>>,
#[cfg(feature = "debug")]
pub(crate) debug_info: Option<DebugInfo>,
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut err = f.debug_struct("Error");
err.field("kind", &self.kind);
if let Some(ref detail) = self.detail {
err.field("detail", detail);
}
if let Some(ref name) = self.name {
err.field("name", name);
}
if self.lineno > 0 {
err.field("line", &self.lineno);
}
if let Some(ref source) = self.source {
err.field("source", source);
}
err.finish()?;
// so this is a bit questionablem, but because of how commonly errors are just
// unwrapped i think it's sensible to spit out the debug info following the
// error struct dump.
#[cfg(feature = "debug")]
{
if !f.alternate() {
if let Some(info) = self.debug_info() {
writeln!(f)?;
render_debug_info(f, self.kind, self.line(), self.span, info)?;
writeln!(f)?;
}
}
}
Ok(())
}
}
/// An enum describing the error kind.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum ErrorKind {
/// A non primitive value was encountered where one was expected.
NonPrimitive,
/// A value is not valid for a key in a map.
NonKey,
/// An impossible operation was attempted.
ImpossibleOperation,
/// The template has a syntax error
SyntaxError,
/// A template was not found.
TemplateNotFound,
/// Too many arguments were passed to a function.
TooManyArguments,
/// A expected argument was missing
MissingArgument,
/// A filter is unknown
UnknownFilter,
/// A test is unknown
UnknownTest,
/// A function is unknown
UnknownFunction,
/// A bad escape sequence in a string was encountered.
BadEscape,
/// An operation on an undefined value was attempted.
UndefinedError,
/// Impossible to serialize this value.
BadSerialization,
/// An error happened in an include.
BadInclude,
/// An error happened in a super block.
EvalBlock,
/// Unable to unpack a value.
CannotUnpack,
/// Failed writing output.
WriteFailure,
}
impl ErrorKind {
fn description(self) -> &'static str {
match self {
ErrorKind::NonPrimitive => "not a primitive",
ErrorKind::NonKey => "not a key type",
ErrorKind::ImpossibleOperation => "impossible operation",
ErrorKind::SyntaxError => "syntax error",
ErrorKind::TemplateNotFound => "template not found",
ErrorKind::TooManyArguments => "too many arguments",
ErrorKind::MissingArgument => "missing argument",
ErrorKind::UnknownFilter => "unknown filter",
ErrorKind::UnknownFunction => "unknown function",
ErrorKind::UnknownTest => "unknown test",
ErrorKind::BadEscape => "bad string escape",
ErrorKind::UndefinedError => "undefined value",
ErrorKind::BadSerialization => "could not serialize to internal format",
ErrorKind::BadInclude => "could not render an included template",
ErrorKind::EvalBlock => "could not render block",
ErrorKind::CannotUnpack => "cannot unpack",
ErrorKind::WriteFailure => "failed to write output",
}
}
}
impl fmt::Display for ErrorKind {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.description())
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(ref detail) = self.detail {
write!(f, "{}: {}", self.kind, detail)?;
} else {
write!(f, "{}", self.kind)?;
}
if let Some(ref filename) = self.name {
write!(f, " (in {}:{})", filename, self.lineno)?
}
#[cfg(feature = "debug")]
{
if f.alternate() {
if let Some(info) = self.debug_info() {
render_debug_info(f, self.kind, self.line(), self.span, info)?;
}
}
}
Ok(())
}
}
impl Error {
/// Creates a new error with kind and detail.
pub fn new<D: Into<Cow<'static, str>>>(kind: ErrorKind, detail: D) -> Error {
Error {
kind,
detail: Some(detail.into()),
name: None,
lineno: 0,
span: None,
source: None,
#[cfg(feature = "debug")]
debug_info: None,
}
}
pub(crate) fn set_filename_and_line(&mut self, filename: &str, lineno: usize) {
self.name = Some(filename.into());
self.lineno = lineno;
}
pub(crate) fn set_filename_and_span(&mut self, filename: &str, span: Span) {
self.name = Some(filename.into());
self.span = Some(span);
self.lineno = span.start_line;
}
pub(crate) fn new_not_found(name: &str) -> Error {
Error::new(
ErrorKind::TemplateNotFound,
format!("template {:?} does not exist", name),
)
}
/// Attaches another error as source to this error.
#[allow(unused)]
pub fn with_source<E: std::error::Error + Send + Sync + 'static>(mut self, source: E) -> Self {
self.source = Some(Box::new(source));
self
}
/// Returns the error kind
pub fn kind(&self) -> ErrorKind {
self.kind
}
/// Returns the filename.
pub fn name(&self) -> Option<&str> {
self.name.as_deref()
}
/// Returns the line.
pub fn line(&self) -> Option<usize> {
self.name.as_ref().map(|_| self.lineno)
}
/// Returns the template debug information is available.
///
/// The debug info snapshot is only embedded into the error if the debug
/// mode is enabled on the environment
/// ([`Environment::set_debug`](crate::Environment::set_debug)).
#[cfg(feature = "debug")]
#[cfg_attr(docsrs, doc(cfg(feature = "debug")))]
pub(crate) fn debug_info(&self) -> Option<&DebugInfo> {
self.debug_info.as_ref()
}
}
impl std::error::Error for Error {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
self.source.as_ref().map(|err| err.as_ref() as _)
}
}
impl From<ErrorKind> for Error {
fn from(kind: ErrorKind) -> Self {
Error {
kind,
detail: None,
name: None,
lineno: 0,
span: None,
source: None,
#[cfg(feature = "debug")]
debug_info: None,
}
}
}
impl From<fmt::Error> for Error {
fn from(_: fmt::Error) -> Self {
Error::new(ErrorKind::WriteFailure, "formatting failed")
}
}
impl serde::ser::Error for Error {
fn custom<T>(msg: T) -> Self
where
T: fmt::Display,
{
Error::new(ErrorKind::BadSerialization, msg.to_string())
}
}
#[cfg(feature = "debug")]
mod debug_info {
use super::*;
use crate::value::Value;
/// This is a snapshot of the debug information.
#[cfg_attr(docsrs, doc(cfg(feature = "debug")))]
#[derive(Default)]
pub(crate) struct DebugInfo {
pub(crate) template_source: Option<String>,
pub(crate) context: Option<Value>,
pub(crate) referenced_names: Option<Vec<String>>,
}
struct VarPrinter<'x>(Value, &'x [String]);
impl<'x> fmt::Debug for VarPrinter<'x> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut m = f.debug_struct("Referenced variables:");
for var in self.1 {
match self.0.get_attr(var) {
Ok(val) => m.field(var, &val),
Err(_) => m.field(var, &Value::UNDEFINED),
};
}
m.finish()
}
}
impl DebugInfo {
/// If available this contains a reference to the source string.
pub fn source(&self) -> Option<&str> {
self.template_source.as_deref()
}
/// Provides access to a snapshot of the context.
///
/// The context is created at the time the error was created if that error
/// happened during template rendering.
pub fn context(&self) -> Option<Value> {
self.context.clone()
}
/// Returns a narrowed down set of referenced names from the context
/// where the error happened.
///
/// This function is currently internal and only used for the default
/// error printing. This could be exposed but it's a highly specific
/// API.
pub(crate) fn referenced_names(&self) -> Option<&[String]> {
self.referenced_names.as_deref()
}
}
pub(super) fn render_debug_info(
f: &mut fmt::Formatter,
kind: ErrorKind,
line: Option<usize>,
span: Option<Span>,
info: &DebugInfo,
) -> fmt::Result {
if let Some(source) = info.source() {
writeln!(f)?;
writeln!(f, "{:-^1$}", " Template Source ", 74).unwrap();
let lines: Vec<_> = source.lines().enumerate().collect();
let idx = line.unwrap_or(1).saturating_sub(1);
let skip = idx.saturating_sub(3);
let pre = lines.iter().skip(skip).take(3.min(idx)).collect::<Vec<_>>();
let post = lines.iter().skip(idx + 1).take(3).collect::<Vec<_>>();
for (idx, line) in pre {
writeln!(f, "{:>4} | {}", idx + 1, line).unwrap();
}
writeln!(f, "{:>4} > {}", idx + 1, lines[idx].1).unwrap();
if let Some(span) = span {
if span.start_line == span.end_line {
writeln!(
f,
" i {}{} {}",
" ".repeat(span.start_col),
"^".repeat(span.end_col - span.start_col),
kind,
)?;
}
}
for (idx, line) in post {
writeln!(f, "{:>4} | {}", idx + 1, line).unwrap();
}
write!(f, "{:-^1$}", "", 74).unwrap();
}
if let Some(ctx) = info.context() {
if let Some(vars) = info.referenced_names() {
writeln!(f)?;
writeln!(f, "{:#?}", VarPrinter(ctx, vars))?;
}
write!(f, "{:-^1$}", "", 74).unwrap();
}
Ok(())
}
}
pub fn attach_basic_debug_info<T>(rv: Result<T, Error>, source: &str) -> Result<T, Error> {
#[cfg(feature = "debug")]
{
match rv {
Ok(rv) => Ok(rv),
Err(mut err) => {
err.debug_info = Some(crate::error::DebugInfo {
template_source: Some(source.to_string()),
..Default::default()
});
Err(err)
}
}
}
#[cfg(not(feature = "debug"))]
{
let _source = source;
rv
}
}
use crate::compiler::tokens::Span;
#[cfg(feature = "debug")]
pub(crate) use self::debug_info::*;