nac3/nac3parser/src/error.rs

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//! Define internal parse error types
//! The goal is to provide a matching and a safe error API, maksing errors from LALR
use lalrpop_util::ParseError as LalrpopError;
use crate::ast::Location;
use crate::token::Tok;
use std::error::Error;
use std::fmt;
/// Represents an error during lexical scanning.
#[derive(Debug, PartialEq)]
pub struct LexicalError {
pub error: LexicalErrorType,
pub location: Location,
}
#[derive(Debug, PartialEq)]
pub enum LexicalErrorType {
StringError,
UnicodeError,
NestingError,
IndentationError,
TabError,
TabsAfterSpaces,
DefaultArgumentError,
PositionalArgumentError,
DuplicateKeywordArgumentError,
UnrecognizedToken { tok: char },
FStringError(FStringErrorType),
LineContinuationError,
Eof,
OtherError(String),
}
impl fmt::Display for LexicalErrorType {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
LexicalErrorType::StringError => write!(f, "Got unexpected string"),
LexicalErrorType::FStringError(error) => write!(f, "Got error in f-string: {}", error),
LexicalErrorType::UnicodeError => write!(f, "Got unexpected unicode"),
LexicalErrorType::NestingError => write!(f, "Got unexpected nesting"),
LexicalErrorType::IndentationError => {
write!(f, "unindent does not match any outer indentation level")
}
LexicalErrorType::TabError => {
write!(f, "inconsistent use of tabs and spaces in indentation")
}
LexicalErrorType::TabsAfterSpaces => {
write!(f, "Tabs not allowed as part of indentation after spaces")
}
LexicalErrorType::DefaultArgumentError => {
write!(f, "non-default argument follows default argument")
}
LexicalErrorType::DuplicateKeywordArgumentError => {
write!(f, "keyword argument repeated")
}
LexicalErrorType::PositionalArgumentError => {
write!(f, "positional argument follows keyword argument")
}
LexicalErrorType::UnrecognizedToken { tok } => {
write!(f, "Got unexpected token {}", tok)
}
LexicalErrorType::LineContinuationError => {
write!(f, "unexpected character after line continuation character")
}
LexicalErrorType::Eof => write!(f, "unexpected EOF while parsing"),
LexicalErrorType::OtherError(msg) => write!(f, "{}", msg),
}
}
}
// TODO: consolidate these with ParseError
#[derive(Debug, PartialEq)]
pub struct FStringError {
pub error: FStringErrorType,
pub location: Location,
}
#[derive(Debug, PartialEq)]
pub enum FStringErrorType {
UnclosedLbrace,
UnopenedRbrace,
ExpectedRbrace,
InvalidExpression(Box<ParseErrorType>),
InvalidConversionFlag,
EmptyExpression,
MismatchedDelimiter,
ExpressionNestedTooDeeply,
}
impl fmt::Display for FStringErrorType {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
FStringErrorType::UnclosedLbrace => write!(f, "Unclosed '{{'"),
FStringErrorType::UnopenedRbrace => write!(f, "Unopened '}}'"),
FStringErrorType::ExpectedRbrace => write!(f, "Expected '}}' after conversion flag."),
FStringErrorType::InvalidExpression(error) => {
write!(f, "Invalid expression: {}", error)
}
FStringErrorType::InvalidConversionFlag => write!(f, "Invalid conversion flag"),
FStringErrorType::EmptyExpression => write!(f, "Empty expression"),
FStringErrorType::MismatchedDelimiter => write!(f, "Mismatched delimiter"),
FStringErrorType::ExpressionNestedTooDeeply => {
write!(f, "expressions nested too deeply")
}
}
}
}
impl From<FStringError> for LalrpopError<Location, Tok, LexicalError> {
fn from(err: FStringError) -> Self {
lalrpop_util::ParseError::User {
error: LexicalError {
error: LexicalErrorType::FStringError(err.error),
location: err.location,
},
}
}
}
/// Represents an error during parsing
#[derive(Debug, PartialEq)]
pub struct ParseError {
pub error: ParseErrorType,
pub location: Location,
}
#[derive(Debug, PartialEq)]
pub enum ParseErrorType {
/// Parser encountered an unexpected end of input
Eof,
/// Parser encountered an extra token
ExtraToken(Tok),
/// Parser encountered an invalid token
InvalidToken,
/// Parser encountered an unexpected token
UnrecognizedToken(Tok, Option<String>),
/// Maps to `User` type from `lalrpop-util`
Lexical(LexicalErrorType),
}
/// Convert `lalrpop_util::ParseError` to our internal type
impl From<LalrpopError<Location, Tok, LexicalError>> for ParseError {
fn from(err: LalrpopError<Location, Tok, LexicalError>) -> Self {
match err {
// TODO: Are there cases where this isn't an EOF?
LalrpopError::InvalidToken { location } => ParseError {
error: ParseErrorType::Eof,
location,
},
LalrpopError::ExtraToken { token } => ParseError {
error: ParseErrorType::ExtraToken(token.1),
location: token.0,
},
LalrpopError::User { error } => ParseError {
error: ParseErrorType::Lexical(error.error),
location: error.location,
},
LalrpopError::UnrecognizedToken { token, expected } => {
// Hacky, but it's how CPython does it. See PyParser_AddToken,
// in particular "Only one possible expected token" comment.
let expected = if expected.len() == 1 {
Some(expected[0].clone())
} else {
None
};
ParseError {
error: ParseErrorType::UnrecognizedToken(token.1, expected),
location: token.0,
}
}
LalrpopError::UnrecognizedEOF { location, .. } => ParseError {
error: ParseErrorType::Eof,
location,
},
}
}
}
impl fmt::Display for ParseError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{} at {}", self.error, self.location)
}
}
impl fmt::Display for ParseErrorType {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
ParseErrorType::Eof => write!(f, "Got unexpected EOF"),
ParseErrorType::ExtraToken(ref tok) => write!(f, "Got extraneous token: {:?}", tok),
ParseErrorType::InvalidToken => write!(f, "Got invalid token"),
ParseErrorType::UnrecognizedToken(ref tok, ref expected) => {
if *tok == Tok::Indent {
write!(f, "unexpected indent")
} else if expected.as_deref() == Some("Indent") {
write!(f, "expected an indented block")
} else {
write!(f, "Got unexpected token {}", tok)
}
}
ParseErrorType::Lexical(ref error) => write!(f, "{}", error),
}
}
}
impl Error for ParseErrorType {}
impl ParseErrorType {
pub fn is_indentation_error(&self) -> bool {
match self {
ParseErrorType::Lexical(LexicalErrorType::IndentationError) => true,
ParseErrorType::UnrecognizedToken(token, expected) => {
*token == Tok::Indent || expected.clone() == Some("Indent".to_owned())
}
_ => false,
}
}
pub fn is_tab_error(&self) -> bool {
matches!(
self,
ParseErrorType::Lexical(LexicalErrorType::TabError)
| ParseErrorType::Lexical(LexicalErrorType::TabsAfterSpaces)
)
}
}
impl std::ops::Deref for ParseError {
type Target = ParseErrorType;
fn deref(&self) -> &Self::Target {
&self.error
}
}
impl Error for ParseError {
fn source(&self) -> Option<&(dyn Error + 'static)> {
None
}
}