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//! Contexts that might not include a driver
use super::framework::*;
use GeneralContext as GC;
use GeneralContextBuf as GCB;
//==================== types ====================
pub type FullContextResult<'s, 'c> = Result<
&'s Context<'c>, //
MissingContextError<'c>,
>;
/// Cheap type that embodies a failed requirement for a driver
///
/// This can be pre-obtained and bound to a local `ctx`, and then
/// converted conveniently to `syn::Error` with `ctx?` when actually
/// needed.
#[derive(Clone, Copy)]
pub struct MissingContextError<'c> {
span: Span,
error_handler: ErrorGenerator<'c>,
}
/// Probably a `Context`, but might not be - there might be no driver
///
/// Definitely contains a `DefinitionsContext`.
#[derive(Clone, Copy)]
pub enum GeneralContext<'c> {
Full(&'c Context<'c>),
NoDriver(&'c DriverlessContext<'c>),
}
/// Probably a `Context`, but might not be - there might be no driver
///
/// Definitely contains a `DefinitionsContext`.
#[derive(Clone, Copy)]
pub enum GeneralContextBuf<'c> {
Full(Context<'c>),
NoDriver(DriverlessContext<'c>),
}
#[derive(Clone, Copy)]
pub struct DriverlessContext<'c> {
pub defs: DefinitionsContext<'c>,
pub driver_needed: ErrorGenerator<'c>,
}
//==================== methods on GeneralContext ====================
impl<'c> GeneralContext<'c> {
pub fn full_ctx_raw(&self) -> Result<&Context<'c>, ErrorGenerator<'c>> {
match self {
GC::Full(ctx) => Ok(ctx),
GC::NoDriver(dc) => Err(dc.driver_needed),
}
}
/// Obtain a full `Context`, in situations where a driver is needed
pub fn full_ctx(&self, span: Span) -> FullContextResult<'_, 'c> {
self.full_ctx_raw()
.map_err(move |error_handler| MissingContextError {
span,
error_handler,
})
}
/// Convenience method.
///
/// We could use `.as_ref()` but that is less clear (and risks
/// future inference failures).
///
/// We don't bother with `defs_mut`.
pub fn defs(&self) -> &DefinitionsContext<'c> {
self.as_ref()
}
pub fn error_loc(&self) -> Option<ErrorLoc<'c>> {
match self {
GC::Full(ctx) => Some(ctx.error_loc()),
GC::NoDriver { .. } => None,
}
}
pub fn prepend_error_loc(
&self,
rest: &'_ [ErrorLoc<'c>],
) -> Vec<ErrorLoc<'c>> {
chain!(
self.error_loc(), //
rest.iter().copied(),
)
.collect_vec()
}
pub fn clone_buf(&self) -> GeneralContextBuf<'c> {
match self {
GC::Full(ctx) => GCB::Full((*ctx).clone()),
GC::NoDriver(dc) => GCB::NoDriver((*dc).clone()),
}
}
}
impl<'c> AsRef<DefinitionsContext<'c>> for GeneralContext<'c> {
fn as_ref(&self) -> &DefinitionsContext<'c> {
match self {
GC::Full(ctx) => &ctx.defs,
GC::NoDriver(dc) => &dc.defs,
}
}
}
impl<'c> AsMut<DefinitionsContext<'c>> for GeneralContextBuf<'c> {
fn as_mut(&mut self) -> &mut DefinitionsContext<'c> {
match self {
GCB::Full(ctx) => &mut ctx.defs,
GCB::NoDriver(dc) => &mut dc.defs,
}
}
}
//==================== display_for_dbg ====================
struct ContextDbgDisplayAdapter<'a>(Option<&'a Context<'a>>);
impl Display for ContextDbgDisplayAdapter<'_> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let ctx = match self.0 {
Some(y) => y,
None => return write!(f, "[no driver]"),
};
write!(f, "for {}", &ctx.top.ident)?;
if let Some(wv) = &ctx.variant {
if let Some(v) = &wv.variant {
write!(f, "::{}", &v.ident)?;
}
}
if let Some(wf) = &ctx.field {
// we're just using the Display impl, any span will do
let span = Span::call_site();
write!(f, ".{}", &wf.fname(span))?;
}
if let Some(templ) = &ctx.template_name {
let templ = templ.to_token_stream().to_string();
write!(f, " from {}", templ)?;
}
Ok::<_, fmt::Error>(())
}
}
impl<'c> Context<'c> {
pub fn display_for_dbg(&self) -> impl Display + '_ {
ContextDbgDisplayAdapter(Some(self))
}
}
impl<'c> GeneralContext<'c> {
pub fn display_for_dbg(&self) -> impl Display + '_ {
ContextDbgDisplayAdapter(match &self {
GC::Full(ctx) => Some(ctx),
GC::NoDriver { .. } => None,
})
}
}
//==================== conversions to/from Context ====================
impl<'c> Context<'c> {
pub fn as_general(&'c self) -> GeneralContext<'c> {
GC::Full(self)
}
}
impl<'c> GeneralContextBuf<'c> {
pub fn as_ref(&'c self) -> GeneralContext<'c> {
match self {
GCB::Full(ctx) => GC::Full(ctx),
GCB::NoDriver(dc) => GC::NoDriver(dc),
}
}
}
//==================== remaining impl(s) ====================
impl<'c> From<MissingContextError<'c>> for syn::Error {
fn from(e: MissingContextError<'c>) -> syn::Error {
(e.error_handler)(e.span)
}
}
|
