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kyrenkyren
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Merge pull request #34 from jonas-schievink/better-error
[WIP] Enhanced errors
2 parents c3c7d8c + dd1d335 commit 16f57d1

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6 files changed

+202
-120
lines changed

6 files changed

+202
-120
lines changed

‎examples/repl.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -33,7 +33,7 @@ fn main() {
3333
);
3434
break;
3535
}
36-
Err(Error::IncompleteStatement(_)) => {
36+
Err(Error::SyntaxError { incomplete_input: true, .. }) => {
3737
// continue reading input and append it to `line`
3838
line.push_str("\n"); // separate input lines
3939
prompt = ">> ";

‎src/conversion.rs

+47-29
Original file line numberDiff line numberDiff line change
@@ -39,9 +39,11 @@ impl<'lua> FromLua<'lua> for Table<'lua> {
3939
fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Table<'lua>> {
4040
match value {
4141
Value::Table(table) => Ok(table),
42-
_ => Err(Error::FromLuaConversionError(
43-
"cannot convert lua value to table".to_owned(),
44-
)),
42+
_ => Err(Error::FromLuaConversionError {
43+
from: value.type_name(),
44+
to: "table",
45+
message: None,
46+
}),
4547
}
4648
}
4749
}
@@ -56,9 +58,11 @@ impl<'lua> FromLua<'lua> for Function<'lua> {
5658
fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Function<'lua>> {
5759
match value {
5860
Value::Function(table) => Ok(table),
59-
_ => Err(Error::FromLuaConversionError(
60-
"cannot convert lua value to function".to_owned(),
61-
)),
61+
_ => Err(Error::FromLuaConversionError {
62+
from: value.type_name(),
63+
to: "function",
64+
message: None,
65+
}),
6266
}
6367
}
6468
}
@@ -73,9 +77,11 @@ impl<'lua> FromLua<'lua> for Thread<'lua> {
7377
fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<Thread<'lua>> {
7478
match value {
7579
Value::Thread(t) => Ok(t),
76-
_ => Err(Error::FromLuaConversionError(
77-
"cannot convert lua value to thread".to_owned(),
78-
)),
80+
_ => Err(Error::FromLuaConversionError {
81+
from: value.type_name(),
82+
to: "thread",
83+
message: None,
84+
}),
7985
}
8086
}
8187
}
@@ -90,9 +96,11 @@ impl<'lua> FromLua<'lua> for AnyUserData<'lua> {
9096
fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<AnyUserData<'lua>> {
9197
match value {
9298
Value::UserData(ud) => Ok(ud),
93-
_ => Err(Error::FromLuaConversionError(
94-
"cannot convert lua value to userdata".to_owned(),
95-
)),
99+
_ => Err(Error::FromLuaConversionError {
100+
from: value.type_name(),
101+
to: "userdata",
102+
message: None,
103+
}),
96104
}
97105
}
98106
}
@@ -107,9 +115,11 @@ impl<'lua, T: UserData + Clone> FromLua<'lua> for T {
107115
fn from_lua(value: Value<'lua>, _: &'lua Lua) -> Result<T> {
108116
match value {
109117
Value::UserData(ud) => Ok(ud.borrow::<T>()?.clone()),
110-
_ => Err(Error::FromLuaConversionError(
111-
"cannot convert lua value to userdata".to_owned(),
112-
)),
118+
_ => Err(Error::FromLuaConversionError {
119+
from: value.type_name(),
120+
to: "userdata",
121+
message: None,
122+
}),
113123
}
114124
}
115125
}
@@ -156,12 +166,14 @@ impl<'lua> ToLua<'lua> for LightUserData {
156166
}
157167

158168
impl<'lua> FromLua<'lua> for LightUserData {
159-
fn from_lua(v: Value, _: &'lua Lua) -> Result<Self> {
160-
match v {
169+
fn from_lua(value: Value, _: &'lua Lua) -> Result<Self> {
170+
match value {
161171
Value::LightUserData(ud) => Ok(ud),
162-
_ => Err(Error::FromLuaConversionError(
163-
"cannot convert lua value to lightuserdata".to_owned(),
164-
)),
172+
_ => Err(Error::FromLuaConversionError {
173+
from: value.type_name(),
174+
to: "light userdata",
175+
message: None,
176+
}),
165177
}
166178
}
167179
}
@@ -241,9 +253,11 @@ impl<'lua, T: FromLua<'lua>> FromLua<'lua> for Vec<T> {
241253
if let Value::Table(table) = value {
242254
table.sequence_values().collect()
243255
} else {
244-
Err(Error::FromLuaConversionError(
245-
"cannot convert lua value to table for Vec".to_owned(),
246-
))
256+
Err(Error::FromLuaConversionError {
257+
from: value.type_name(),
258+
to: "Vec",
259+
message: Some("expected table".to_string()),
260+
})
247261
}
248262
}
249263
}
@@ -259,9 +273,11 @@ impl<'lua, K: Eq + Hash + FromLua<'lua>, V: FromLua<'lua>> FromLua<'lua> for Has
259273
if let Value::Table(table) = value {
260274
table.pairs().collect()
261275
} else {
262-
Err(Error::FromLuaConversionError(
263-
"cannot convert lua value to table for HashMap".to_owned(),
264-
))
276+
Err(Error::FromLuaConversionError {
277+
from: value.type_name(),
278+
to: "HashMap",
279+
message: Some("expected table".to_string()),
280+
})
265281
}
266282
}
267283
}
@@ -277,9 +293,11 @@ impl<'lua, K: Ord + FromLua<'lua>, V: FromLua<'lua>> FromLua<'lua> for BTreeMap<
277293
if let Value::Table(table) = value {
278294
table.pairs().collect()
279295
} else {
280-
Err(Error::FromLuaConversionError(
281-
"cannot convert lua value to table for BTreeMap".to_owned(),
282-
))
296+
Err(Error::FromLuaConversionError {
297+
from: value.type_name(),
298+
to: "BTreeMap",
299+
message: Some("expected table".to_string()),
300+
})
283301
}
284302
}
285303
}

‎src/error.rs

+61-41
Original file line numberDiff line numberDiff line change
@@ -6,25 +6,40 @@ use std::result::Result as StdResult;
66
/// Error type returned by rlua methods.
77
#[derive(Debug, Clone)]
88
pub enum Error {
9-
/// Lua syntax error, aka `LUA_ERRSYNTAX` that is NOT an incomplete statement.
10-
SyntaxError(String),
11-
/// Lua syntax error that IS an incomplete statement. Useful for implementing a REPL.
12-
IncompleteStatement(String),
9+
/// Syntax error while parsing Lua source code.
10+
SyntaxError {
11+
/// The error message as returned by Lua.
12+
message: String,
13+
/// `true` if the error can likely be fixed by appending more input to the source code.
14+
///
15+
/// This is useful for implementing REPLs as they can query the user for more input if this
16+
/// is set.
17+
incomplete_input: bool,
18+
},
1319
/// Lua runtime error, aka `LUA_ERRRUN`.
1420
///
1521
/// The Lua VM returns this error when a builtin operation is performed on incompatible types.
1622
/// Among other things, this includes invoking operators on wrong types (such as calling or
1723
/// indexing a `nil` value).
1824
RuntimeError(String),
19-
/// Lua error from inside an error handler, aka `LUA_ERRERR`.
20-
///
21-
/// To prevent an infinite recursion when invoking an error handler, this error will be returned
22-
/// instead of invoking the error handler.
23-
ErrorError(String),
2425
/// A Rust value could not be converted to a Lua value.
25-
ToLuaConversionError(String),
26+
ToLuaConversionError {
27+
/// Name of the Rust type that could not be converted.
28+
from: &'static str,
29+
/// Name of the Lua type that could not be created.
30+
to: &'static str,
31+
/// A message indicating why the conversion failed in more detail.
32+
message: Option<String>,
33+
},
2634
/// A Lua value could not be converted to the expected Rust type.
27-
FromLuaConversionError(String),
35+
FromLuaConversionError {
36+
/// Name of the Lua type that could not be converted.
37+
from: &'static str,
38+
/// Name of the Rust type that could not be created.
39+
to: &'static str,
40+
/// A string containing more detailed error information.
41+
message: Option<String>,
42+
},
2843
/// [`Thread::resume`] was called on an inactive coroutine.
2944
///
3045
/// A coroutine is inactive if its main function has returned or if an error has occured inside
@@ -64,9 +79,12 @@ pub enum Error {
6479
/// [`UserData`]: trait.UserData.html
6580
UserDataBorrowMutError,
6681
/// A Rust callback returned `Err`, raising the contained `Error` as a Lua error.
67-
///
68-
/// The first field is the Lua traceback, the second field holds the original error.
69-
CallbackError(String, Arc<Error>),
82+
CallbackError {
83+
/// Lua call stack backtrace.
84+
traceback: String,
85+
/// Original error returned by the Rust code.
86+
cause: Arc<Error>,
87+
},
7088
/// A custom error.
7189
///
7290
/// This can be used for returning user-defined errors from callbacks.
@@ -83,23 +101,27 @@ pub type Result<T> = StdResult<T, Error>;
83101
impl fmt::Display for Error {
84102
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
85103
match *self {
86-
Error::SyntaxError(ref msg) => write!(fmt, "Lua syntax error: {}", msg),
87-
Error::IncompleteStatement(ref msg) => {
88-
write!(fmt, "Lua syntax error (incomplete statement): {}", msg)
89-
}
90-
Error::RuntimeError(ref msg) => write!(fmt, "Lua runtime error: {}", msg),
91-
Error::ErrorError(ref msg) => write!(fmt, "Lua error in error handler: {}", msg),
92-
Error::ToLuaConversionError(ref msg) => {
93-
write!(fmt, "Error converting rust type to lua: {}", msg)
104+
Error::SyntaxError { ref message, .. } => write!(fmt, "syntax error: {}", message),
105+
Error::RuntimeError(ref msg) => write!(fmt, "runtime error: {}", msg),
106+
Error::ToLuaConversionError { from, to, ref message } => {
107+
write!(fmt, "error converting {} to Lua {}", from, to)?;
108+
match *message {
109+
None => Ok(()),
110+
Some(ref message) => write!(fmt, " ({})", message),
111+
}
94112
}
95-
Error::FromLuaConversionError(ref msg) => {
96-
write!(fmt, "Error converting lua type to rust: {}", msg)
113+
Error::FromLuaConversionError { from, to, ref message } => {
114+
write!(fmt, "error converting Lua {} to {}", from, to)?;
115+
match *message {
116+
None => Ok(()),
117+
Some(ref message) => write!(fmt, " ({})", message),
118+
}
97119
}
98-
Error::CoroutineInactive => write!(fmt, "Cannot resume inactive coroutine"),
99-
Error::UserDataTypeMismatch => write!(fmt, "Userdata not expected type"),
100-
Error::UserDataBorrowError => write!(fmt, "Userdata already mutably borrowed"),
101-
Error::UserDataBorrowMutError => write!(fmt, "Userdata already borrowed"),
102-
Error::CallbackError(ref msg, _) => write!(fmt, "Error during lua callback: {}", msg),
120+
Error::CoroutineInactive => write!(fmt, "cannot resume inactive coroutine"),
121+
Error::UserDataTypeMismatch => write!(fmt, "userdata is not expected type"),
122+
Error::UserDataBorrowError => write!(fmt, "userdata already mutably borrowed"),
123+
Error::UserDataBorrowMutError => write!(fmt, "userdata already borrowed"),
124+
Error::CallbackError { ref cause, .. } => write!(fmt, "{}", cause),
103125
Error::ExternalError(ref err) => err.fmt(fmt),
104126
}
105127
}
@@ -108,24 +130,22 @@ impl fmt::Display for Error {
108130
impl StdError for Error {
109131
fn description(&self) -> &str {
110132
match *self {
111-
Error::SyntaxError(_) => "lua syntax error",
112-
Error::IncompleteStatement(_) => "lua incomplete statement",
113-
Error::RuntimeError(_) => "lua runtime error",
114-
Error::ErrorError(_) => "lua error handling error",
115-
Error::ToLuaConversionError(_) => "conversion error to lua",
116-
Error::FromLuaConversionError(_) => "conversion error from lua",
117-
Error::CoroutineInactive => "lua coroutine inactive",
118-
Error::UserDataTypeMismatch => "lua userdata type mismatch",
119-
Error::UserDataBorrowError => "lua userdata already mutably borrowed",
120-
Error::UserDataBorrowMutError => "lua userdata already borrowed",
121-
Error::CallbackError(_, _) => "lua callback error",
133+
Error::SyntaxError { .. } => "syntax error",
134+
Error::RuntimeError(_) => "runtime error",
135+
Error::ToLuaConversionError { .. } => "conversion error to lua",
136+
Error::FromLuaConversionError { .. } => "conversion error from lua",
137+
Error::CoroutineInactive => "attempt to resume inactive coroutine",
138+
Error::UserDataTypeMismatch => "userdata type mismatch",
139+
Error::UserDataBorrowError => "userdata already mutably borrowed",
140+
Error::UserDataBorrowMutError => "userdata already borrowed",
141+
Error::CallbackError { ref cause, .. } => cause.description(),
122142
Error::ExternalError(ref err) => err.description(),
123143
}
124144
}
125145

126146
fn cause(&self) -> Option<&StdError> {
127147
match *self {
128-
Error::CallbackError(_, ref cause) => Some(cause.as_ref()),
148+
Error::CallbackError { ref cause, .. } => Some(cause.as_ref()),
129149
Error::ExternalError(ref err) => err.cause(),
130150
_ => None,
131151
}

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