// Abstract semantic graph (ASG) errors
//
// Copyright (C) 2014-2022 Ryan Specialty Group, LLC.
//
// This file is part of TAME.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see .
//! Errors resulting from operations on the ASG.
use std::{
error::Error,
fmt::{self, Display},
};
use crate::{
diagnose::{Annotate, AnnotatedSpan, Diagnostic},
span::Span,
};
use super::TransitionError;
/// An error from an ASG operation.
#[derive(Debug, PartialEq)]
pub enum AsgError {
/// An object could not change state in the manner requested.
IdentTransition(TransitionError),
/// An expresion is not reachable by any other expression or
/// identifier.
///
/// A dangling expression has no incoming edge from any other object and
/// can therefore not be referenced.
///
/// Since the expression is dangling,
/// it must be anonymous,
/// and can therefore only be identified meaningfully to the user by
/// its span.
/// The span should encompass the entirety of the expression.
DanglingExpr(Span),
}
impl Display for AsgError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use AsgError::*;
match self {
IdentTransition(err) => Display::fmt(&err, f),
DanglingExpr(_) => write!(f, "dangling expression"),
}
}
}
impl Error for AsgError {
fn source(&self) -> Option<&(dyn Error + 'static)> {
use AsgError::*;
match self {
IdentTransition(err) => err.source(),
DanglingExpr(_) => None,
}
}
}
impl From for AsgError {
fn from(err: TransitionError) -> Self {
Self::IdentTransition(err)
}
}
impl Diagnostic for AsgError {
fn describe(&self) -> Vec {
use AsgError::*;
match self {
// TODO: need spans
IdentTransition(_) => vec![],
DanglingExpr(span) => vec![
span.error("expression has no parent or identifier"),
span.help("an expression must either be the child of another "),
span.help(
" expression or be assigned an identifier, otherwise ",
),
span.help(" its value cannot referenced."),
],
}
}
}