339 lines
15 KiB
Rust
339 lines
15 KiB
Rust
use crate::generate::{FnSelfArg, Generator, StreamBuilder};
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use crate::parse::{EnumVariant, FieldAttribute, Fields};
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use crate::prelude::*;
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use crate::Result;
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const TUPLE_FIELD_PREFIX: &str = "field_";
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pub struct DeriveEnum {
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pub variants: Vec<EnumVariant>,
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}
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impl DeriveEnum {
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fn iter_fields(&self) -> EnumVariantIterator {
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EnumVariantIterator {
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idx: 0,
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last_val: None,
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variants: &self.variants,
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}
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}
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pub fn generate_encode(self, generator: &mut Generator) -> Result<()> {
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generator
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.impl_for("bincode::enc::Encode")
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.unwrap()
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.generate_fn("encode")
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.with_generic("E", ["bincode::enc::Encoder"])
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.with_self_arg(FnSelfArg::RefSelf)
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.with_arg("mut encoder", "E")
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.with_return_type("core::result::Result<(), bincode::error::EncodeError>")
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.body(|fn_body| {
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fn_body.ident_str("match");
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fn_body.ident_str("self");
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fn_body.group(Delimiter::Brace, |match_body| {
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for (variant_index, variant) in self.iter_fields() {
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// Self::Variant
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match_body.ident_str("Self");
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match_body.puncts("::");
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match_body.ident(variant.name.clone());
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// if we have any fields, declare them here
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// Self::Variant { a, b, c }
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if let Some(delimiter) = variant.fields.delimiter() {
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match_body.group(delimiter, |field_body| {
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for (idx, field_name) in
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variant.fields.names().into_iter().enumerate()
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{
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if idx != 0 {
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field_body.punct(',');
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}
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field_body.push(
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field_name.to_token_tree_with_prefix(TUPLE_FIELD_PREFIX),
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);
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}
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});
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}
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// Arrow
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// Self::Variant { a, b, c } =>
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match_body.puncts("=>");
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// Body of this variant
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// Note that the fields are available as locals because of the match destructuring above
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// {
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// encoder.encode_u32(n)?;
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// bincode::enc::Encode::encode(a, &mut encoder)?;
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// bincode::enc::Encode::encode(b, &mut encoder)?;
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// bincode::enc::Encode::encode(c, &mut encoder)?;
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// }
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match_body.group(Delimiter::Brace, |body| {
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// variant index
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body.push_parsed("<u32 as bincode::enc::Encode>::encode")
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.unwrap();
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body.group(Delimiter::Parenthesis, |args| {
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args.punct('&');
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args.group(Delimiter::Parenthesis, |num| num.extend(variant_index));
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args.punct(',');
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args.push_parsed("&mut encoder").unwrap();
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});
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body.punct('?');
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body.punct(';');
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// If we have any fields, encode them all one by one
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for field_name in variant.fields.names() {
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if field_name.has_field_attribute(FieldAttribute::WithSerde) {
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body.push_parsed(format!(
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"bincode::enc::Encode::encode(&bincode::serde::Compat({}), &mut encoder)?;",
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field_name.to_string_with_prefix(TUPLE_FIELD_PREFIX),
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))
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.unwrap();
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} else {
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body.push_parsed(format!(
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"bincode::enc::Encode::encode({}, &mut encoder)?;",
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field_name.to_string_with_prefix(TUPLE_FIELD_PREFIX),
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))
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.unwrap();
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}
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}
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});
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match_body.punct(',');
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}
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});
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fn_body.push_parsed("Ok(())").unwrap();
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})
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.unwrap();
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Ok(())
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}
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/// Build the catch-all case for an int-to-enum decode implementation
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fn invalid_variant_case(&self, enum_name: &str, result: &mut StreamBuilder) {
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// we'll be generating:
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// variant => Err(
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// bincode::error::DecodeError::UnexpectedVariant {
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// found: variant,
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// type_name: <enum_name>
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// allowed: ...,
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// }
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// )
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//
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// Where allowed is either:
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// - bincode::error::AllowedEnumVariants::Range { min: 0, max: <max> }
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// if we have no fixed value variants
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// - bincode::error::AllowedEnumVariants::Allowed(&[<variant1>, <variant2>, ...])
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// if we have fixed value variants
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result.ident_str("variant");
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result.puncts("=>");
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result.ident_str("Err");
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result.group(Delimiter::Parenthesis, |err_inner| {
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err_inner
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.push_parsed("bincode::error::DecodeError::UnexpectedVariant")
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.unwrap();
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err_inner.group(Delimiter::Brace, |variant_inner| {
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variant_inner.ident_str("found");
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variant_inner.punct(':');
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variant_inner.ident_str("variant");
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variant_inner.punct(',');
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variant_inner.ident_str("type_name");
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variant_inner.punct(':');
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variant_inner.lit_str(enum_name);
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variant_inner.punct(',');
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variant_inner.ident_str("allowed");
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variant_inner.punct(':');
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if self.variants.iter().any(|i| i.has_fixed_value()) {
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// we have fixed values, implement AllowedEnumVariants::Allowed
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variant_inner
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.push_parsed("bincode::error::AllowedEnumVariants::Allowed")
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.unwrap();
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variant_inner.group(Delimiter::Parenthesis, |allowed_inner| {
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allowed_inner.punct('&');
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allowed_inner.group(Delimiter::Bracket, |allowed_slice| {
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for (idx, (ident, _)) in self.iter_fields().enumerate() {
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if idx != 0 {
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allowed_slice.punct(',');
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}
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allowed_slice.extend(ident);
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}
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});
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});
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} else {
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// no fixed values, implement a range
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variant_inner
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.push_parsed(format!(
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"bincode::error::AllowedEnumVariants::Range {{ min: 0, max: {} }}",
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self.variants.len() - 1
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))
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.unwrap();
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}
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})
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});
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}
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pub fn generate_decode(&self, generator: &mut Generator) -> Result<()> {
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// Remember to keep this mostly in sync with generate_borrow_decode
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let enum_name = generator.target_name().to_string();
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generator
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.impl_for("bincode::Decode")
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.unwrap()
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.generate_fn("decode")
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.with_generic("D", ["bincode::de::Decoder"])
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.with_arg("mut decoder", "D")
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.with_return_type("core::result::Result<Self, bincode::error::DecodeError>")
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.body(|fn_builder| {
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fn_builder
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.push_parsed(
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"let variant_index = <u32 as bincode::Decode>::decode(&mut decoder)?;",
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)
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.unwrap();
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fn_builder.push_parsed("match variant_index").unwrap();
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fn_builder.group(Delimiter::Brace, |variant_case| {
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for (mut variant_index, variant) in self.iter_fields() {
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// idx => Ok(..)
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if variant_index.len() > 1 {
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variant_case.push_parsed("x if x == ").unwrap();
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variant_case.extend(variant_index);
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} else {
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variant_case.push(variant_index.remove(0));
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}
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variant_case.puncts("=>");
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variant_case.ident_str("Ok");
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variant_case.group(Delimiter::Parenthesis, |variant_case_body| {
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// Self::Variant { }
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// Self::Variant { 0: ..., 1: ... 2: ... },
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// Self::Variant { a: ..., b: ... c: ... },
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variant_case_body.ident_str("Self");
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variant_case_body.puncts("::");
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variant_case_body.ident(variant.name.clone());
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variant_case_body.group(Delimiter::Brace, |variant_body| {
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let is_tuple = matches!(variant.fields, Fields::Tuple(_));
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for (idx, field) in variant.fields.names().into_iter().enumerate() {
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if is_tuple {
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variant_body.lit_usize(idx);
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} else {
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variant_body.ident(field.unwrap_ident().clone());
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}
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variant_body.punct(':');
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if field.has_field_attribute(FieldAttribute::WithSerde) {
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variant_body
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.push_parsed("<bincode::serde::Compat<_> as bincode::Decode>::decode(&mut decoder)?.0,")
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.unwrap();
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} else {
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variant_body
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.push_parsed("bincode::Decode::decode(&mut decoder)?,")
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.unwrap();
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}
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}
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});
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});
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variant_case.punct(',');
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}
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// invalid idx
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self.invalid_variant_case(&enum_name, variant_case);
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});
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})
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.unwrap();
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Ok(())
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}
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pub fn generate_borrow_decode(self, generator: &mut Generator) -> Result<()> {
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// Remember to keep this mostly in sync with generate_decode
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let enum_name = generator.target_name().to_string();
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generator.impl_for_with_de_lifetime("bincode::de::BorrowDecode<'__de>")
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.unwrap()
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.generate_fn("borrow_decode")
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.with_generic("D", ["bincode::de::BorrowDecoder<'__de>"])
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.with_arg("mut decoder", "D")
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.with_return_type("core::result::Result<Self, bincode::error::DecodeError>")
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.body(|fn_builder| {
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fn_builder
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.push_parsed("let variant_index = <u32 as bincode::Decode>::decode(&mut decoder)?;").unwrap();
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fn_builder.push_parsed("match variant_index").unwrap();
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fn_builder.group(Delimiter::Brace, |variant_case| {
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for (mut variant_index, variant) in self.iter_fields() {
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// idx => Ok(..)
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if variant_index.len() > 1 {
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variant_case.push_parsed("x if x == ").unwrap();
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variant_case.extend(variant_index);
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} else {
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variant_case.push(variant_index.remove(0));
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}
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variant_case.puncts("=>");
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variant_case.ident_str("Ok");
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variant_case.group(Delimiter::Parenthesis, |variant_case_body| {
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// Self::Variant { }
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// Self::Variant { 0: ..., 1: ... 2: ... },
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// Self::Variant { a: ..., b: ... c: ... },
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variant_case_body.ident_str("Self");
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variant_case_body.puncts("::");
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variant_case_body.ident(variant.name.clone());
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variant_case_body.group(Delimiter::Brace, |variant_body| {
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let is_tuple = matches!(variant.fields, Fields::Tuple(_));
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for (idx, field) in variant.fields.names().into_iter().enumerate() {
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if is_tuple {
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variant_body.lit_usize(idx);
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} else {
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variant_body.ident(field.unwrap_ident().clone());
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}
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variant_body.punct(':');
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if field.has_field_attribute(FieldAttribute::WithSerde) {
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variant_body
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.push_parsed("<bincode::serde::BorrowCompat<_> as bincode::BorrowDecode>::borrow_decode(&mut decoder)?.0,")
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.unwrap();
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} else {
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variant_body.push_parsed("bincode::de::BorrowDecode::borrow_decode(&mut decoder)?,").unwrap();
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}
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}
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});
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});
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variant_case.punct(',');
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}
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// invalid idx
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self.invalid_variant_case(&enum_name, variant_case);
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});
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}).unwrap();
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Ok(())
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}
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}
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struct EnumVariantIterator<'a> {
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variants: &'a [EnumVariant],
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idx: usize,
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last_val: Option<(Literal, u32)>,
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}
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impl<'a> Iterator for EnumVariantIterator<'a> {
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type Item = (Vec<TokenTree>, &'a EnumVariant);
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fn next(&mut self) -> Option<Self::Item> {
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let idx = self.idx;
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let variant = self.variants.get(self.idx)?;
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self.idx += 1;
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let tokens = if let Fields::Integer(lit) = &variant.fields {
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let tree = TokenTree::Literal(lit.clone());
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self.last_val = Some((lit.clone(), 0));
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vec![tree]
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} else if let Some((lit, add)) = self.last_val.as_mut() {
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*add += 1;
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vec![
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TokenTree::Literal(lit.clone()),
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TokenTree::Punct(Punct::new('+', Spacing::Alone)),
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TokenTree::Literal(Literal::u32_suffixed(*add)),
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]
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} else {
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vec![TokenTree::Literal(Literal::u32_suffixed(idx as u32))]
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};
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Some((tokens, variant))
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}
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}
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