protto_derive 0.6.0

Automatically derive Protobuf and Rust conversions.
Documentation 
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use crate::analysis::{attribute_parser, expect_analysis::ExpectMode};

/// Comprehensive analysis of error requirements for a struct
pub struct ErrorRequirements {
    pub needs_try_from: bool,
    pub needs_default_error: bool,
    pub needs_error_conversions: bool,
}

pub fn analyze_error_requirements(
    fields: &syn::punctuated::Punctuated<syn::Field, syn::token::Comma>,
    struct_level_error_type: &Option<syn::Type>,
) -> ErrorRequirements {
    let needs_try_from = requires_try_from(fields);
    let needs_default_error = requires_default_error_type(fields, struct_level_error_type);
    let needs_error_conversions =
        needs_try_from && needs_default_error && struct_level_error_type.is_none();

    ErrorRequirements {
        needs_try_from,
        needs_default_error,
        needs_error_conversions,
    }
}

/// Analyzes fields to determine if TryFrom trait is needed
fn requires_try_from(fields: &syn::punctuated::Punctuated<syn::Field, syn::token::Comma>) -> bool {
    fields.iter().any(|field| {
        if attribute_parser::has_proto_ignore(field) {
            false
        } else {
            let proto_meta =
                attribute_parser::ProtoFieldMeta::from_field(field).unwrap_or_default();
            let expect_mode = ExpectMode::from_field_meta(field, &proto_meta);
            matches!(expect_mode, ExpectMode::Error)
        }
    })
}

/// Analyzes fields to determine if default error type generation is needed
fn requires_default_error_type(
    fields: &syn::punctuated::Punctuated<syn::Field, syn::token::Comma>,
    struct_level_error_type: &Option<syn::Type>,
) -> bool {
    fields.iter().any(|field| {
        if attribute_parser::has_proto_ignore(field) {
            return false;
        }
        let proto_meta = attribute_parser::ProtoFieldMeta::from_field(field).unwrap_or_default();
        if matches!(
            ExpectMode::from_field_meta(field, &proto_meta),
            ExpectMode::Error
        ) {
            let effective_error_type =
                get_effective_error_type(&proto_meta, struct_level_error_type);
            effective_error_type.is_none()
        } else {
            false
        }
    })
}

/// Determines the effective error type for a field
fn get_effective_error_type(
    proto_meta: &attribute_parser::ProtoFieldMeta,
    struct_level_error_type: &Option<syn::Type>,
) -> Option<syn::Type> {
    if let Some(field_error_type) = &proto_meta.error_type {
        return Some(
            syn::parse_str(field_error_type).expect("Failed to parse field-level error_type"),
        );
    }

    struct_level_error_type.clone()
}