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use proc_macro2::TokenStream;
use quote::TokenStreamExt;
use crate::attributes::*;
use crate::DeriveContext;
use crate::*;
use derive_builder::Builder;
use quote::format_ident;
#[derive(Builder, Clone, Debug, PartialEq)]
pub(crate) struct SequentialFieldContext {
member_ident: syn::Ident,
ty: syn::Type,
require_attrs: Vec<RequireAttribute>,
conversion_attr: ConvertAttribute,
skip_if_fail: bool,
}
impl StructFieldContext for SequentialFieldContext {
fn from_syn_field(field: &syn::Field) -> Self {
let basic_attributes = BasicAttribute::from_syn_attributes(&field.attrs);
SequentialFieldContextBuilder::default()
.member_ident(field.ident.clone().unwrap())
.ty(field.ty.clone())
.conversion_attr(
basic_attributes
.iter()
.find_map(|attr| {
if let BasicAttribute::Convert(c) = attr {
Some(c)
} else {
None
}
})
.unwrap_or(&ConvertAttribute::Auto)
.clone(),
)
.require_attrs(
basic_attributes
.clone()
.into_iter()
.filter_map(|attr| {
if let BasicAttribute::Require(req) = attr {
Some(req)
} else {
None
}
})
.collect(),
)
.skip_if_fail(BasicAttribute::is_skippable(&basic_attributes))
.build()
.expect("failed to build sequential field context")
}
}
impl SequentialFieldContext {
// pub fn condition(&self) -> TokenStream {}
pub fn check(&self, ctx: &DeriveContext) -> TokenStream {
let field_value_ident = format_ident!("{}_{}_value", &ctx.ident, self.member_ident);
let rule_ident = &ctx.rule_ident.segments[0].ident;
// let field_ident = format_ident!("{}_{}_check_pair", &ctx.ident, self.member_ident);
let checks = self
.require_attrs
.iter()
.map(|req| req.check(&ctx, ("e! { convert_pair }).into()));
let expr = self
.conversion_attr
.expression(&self.ty, Some("e! { convert_pair }));
if !self.skip_if_fail {
quote! {
let context = closure_ctx.clone();
// let #field_ident = inner.next().expect("impossible: Pairs length was checked");
let convert_pair = {
if previous_was_used {
inner.next().expect("incorrect pair count?")
}
else {
convert_pair
}
};
#(#checks)*
let #field_value_ident = #expr;
let previous_was_used = true;
}
} else {
// probably an option<>
quote! {
let context = closure_ctx.clone();
let potential_convert_pair = {
if previous_was_used {
inner.next()
}
else {
Some(convert_pair.clone())
}
};
let mut previous_was_used = true; // temporary value
let mut #field_value_ident = Option::None; //todo fix stupid error
if let Some(convert_pair) = potential_convert_pair {
let potential_field_value_ident = move || -> Result<_,TreeError<#rule_ident>> {
#(#checks)*
return Ok(#expr);
}();
previous_was_used = potential_field_value_ident.is_ok();
let potential_field_value_ident_unwrapped = potential_field_value_ident.unwrap();
if previous_was_used {
// just to make sure this is not an Ok(None)
if potential_field_value_ident_unwrapped.is_none() {
previous_was_used = false;
}
}
#field_value_ident = potential_field_value_ident_unwrapped;
}
else {
// there are no more items (either the rest are empty Option<>s, or we have an error)
// convert_pair isn't shadowed, so we won't have type errors.
}
// future fix: potentially convert option::None to some user specified type
}
}
}
pub fn field_pair(&self, ctx: &DeriveContext) -> TokenStream {
let field_value_ident = format_ident!("{}_{}_value", &ctx.ident, self.member_ident);
// let field_ident = format_ident!("{}_{}_check_pair", &ctx.ident, self.member_ident);
let ident = &self.member_ident;
quote! {
#ident: #field_value_ident,
}
}
}
/// Rules for strategy::Sequential are:
/// 1. Any number of overall requirements on the pair
/// 2. Any number of fields. The overall pair should contain a Pairs, which contains many [`pest::Pair`].
/// Each [`pest::Pair`] matches to one field.
/// Every [`pest::Pair`] is "consumed" when that field is converted
///
#[derive(Builder, Debug, PartialEq)]
pub(crate) struct SequentialStructContext {
ctx: DeriveContext,
fields: Vec<SequentialFieldContext>,
require_attrs: Vec<RequireAttribute>,
}
impl StructContext for SequentialStructContext {
fn from_syn_item_struct(item_struct: syn::ItemStruct) -> Self {
let basic_attributes = BasicAttribute::from_syn_attributes(&item_struct.attrs);
let derive_context = DeriveContextBuilder::default()
.ident(item_struct.ident)
.struct_enum_token(Ident::new("struct", proc_macro2::Span::call_site()))
.rule_ident(
BasicAttribute::search_for_rule_in_attrs(&basic_attributes)
.expect("A Rule requirement must be supplied for sequential matches"),
)
.build()
.unwrap();
SequentialStructContextBuilder::default()
.ctx(derive_context)
.fields(
item_struct
.fields
.iter()
.map(SequentialFieldContext::from_syn_field)
.collect(),
)
.require_attrs(
basic_attributes
.into_iter()
.filter_map(|attr| {
if let BasicAttribute::Require(req) = attr {
Some(req)
} else {
None
}
})
.collect(),
)
.build()
.unwrap()
}
fn to_impl(&self) -> TokenStream {
let ident = &self.ctx.ident;
let rule_ident = &self.ctx.rule_ident.segments[0].ident;
let overall_require_checks: Vec<_> = self
.require_attrs
.iter()
.map(|req| req.check(&self.ctx, None))
.collect();
let fields = &self.fields;
let expected_count = fields.len();
let field_checks = self.fields.iter().map(|f| f.check(&self.ctx));
let field_pairs = self.fields.iter().map(|f| f.field_pair(&self.ctx));
// panic!("{}", field_checks.clone().next().unwrap().to_string());
quote! {
#[allow(non_snake_case)]
impl PestTree<#rule_ident> for #ident {
fn with_pair(
pair: pest::iterators::Pair<'_, #rule_ident>,
context: std::rc::Rc<ParsingContext>,
) -> Result<Self, TreeError<#rule_ident>>
where
Self: Sized,
{
// checks for the overall pair
let check_pair = pair.clone();
let backup_pair = pair.clone();
let backup_ctx = context.clone();
let closure_ctx = context.clone();
let conversion_result = move || -> Result<Self, pest_tree::TreeError<'_, #rule_ident>> {
#(#overall_require_checks)*
// expand the members
let mut inner = pair.clone().into_inner();
// check if there's a correct number of Pair in the Pairs
let inner_cloned_for_length = inner.clone();
let count_found = inner_cloned_for_length.count();
if #expected_count < count_found {
return Err(PairCountError::as_tree_error(
check_pair,
context,
#expected_count,
count_found
))
}
let previous_was_used = false;
let convert_pair = inner.next().expect("incorrect pair count?");
#(#field_checks)*
// TODO: finish code for expanding the "inner" Pairs (go write the code for the wrong pair )
return Ok(#ident {
#(#field_pairs)*
});
}();
conversion_result.map_err(|err| {
SequentialMatchError::as_tree_error(
backup_pair,
backup_ctx,
err
)
})
}
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn derive_sequential_struct() {
let item_struct: syn::ItemStruct = parse_quote! {
#[derive(PestTree)]
#[pest_tree(strategy(Sequential))]
#[pest_tree(require(rule(Rule::abc)))]
struct ABC {
a: A,
b: B,
c: C
}
};
let implementation = SequentialStructContext::from_syn_item_struct(item_struct);
let expected = quote! {
#[allow(non_snake_case)]
impl PestTree<Rule> for ABC {
fn with_pair(
pair: pest::iterators::Pair<'_, Rule>,
context: std::rc::Rc<ParsingContext>,
) -> Result<Self, TreeError<Rule>>
where
Self: Sized,
{
let check_pair = pair.clone();
let backup_pair = pair.clone();
let backup_ctx = context.clone();
let conversion_result = move || -> Result<Self, pest_tree::TreeError<'_, Rule>> {
if !(check_pair.as_rule() == Rule::abc) {
return Err(
pest_tree::DirectMatchError::as_tree_error(
check_pair.clone(),
context.clone(),
stringify!(ABC).to_string(),
stringify!(Rule::abc).to_string(),
),
);
}
let mut inner = pair.clone().into_inner();
let inner_cloned_for_length = inner.clone();
let count_found = inner_cloned_for_length.count();
if 3usize != count_found {
return Err(
PairCountError::as_tree_error(check_pair, context, 3usize, count_found),
);
}
let ABC_a_check_pair = inner
.next()
.expect("impossible: Pairs length was checked");
let ABC_b_check_pair = inner
.next()
.expect("impossible: Pairs length was checked");
let ABC_c_check_pair = inner
.next()
.expect("impossible: Pairs length was checked");
return Ok(ABC {
a: <A>::with_pair(ABC_a_check_pair, context.clone())?,
b: <B>::with_pair(ABC_b_check_pair, context.clone())?,
c: <C>::with_pair(ABC_c_check_pair, context.clone())?,
});
}();
conversion_result
.map_err(|err| {
SequentialMatchError::as_tree_error(backup_pair, backup_ctx, err)
})
}
}
};
use syn::ItemImpl;
let expected: ItemImpl = syn::parse2(expected).unwrap();
let generated: ItemImpl = syn::parse2(implementation.to_impl()).unwrap();
assert_eq!(
pretty_print(&expected.to_token_stream()),
pretty_print(&generated.to_token_stream())
);
}
}