arraygen 0.3.2

Derive macro for generating arrays from struct fields.
Documentation 
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use syn::parse::{ParseStream, Result};
use syn::token;
use syn::{bracketed, parenthesized, Ident, Path, Token, Type, Visibility};

use crate::parse_attribute::single_parse_outer_attribute;
use crate::parse_decorator::{CastKind, Decorator};
use crate::FIELD_SELECTOR_NAME;

#[derive(PartialEq)]
pub enum InArrayElementKind {
    Implicit,
    InArray,
}

pub struct InArrayElement {
    pub ident: Ident,
    pub ty: Type,
    pub cast: Option<CastKind>,
    pub kind: InArrayElementKind,
}

pub struct InArrayAttributeEntry {
    pub ident: Ident,
    pub decorator: Decorator,
}

pub struct InArrayAttribute {
    pub entries: Vec<InArrayAttributeEntry>,
}

pub struct InArrayField {
    pub attrs: Vec<InArrayAttribute>,
    pub ident: Ident,
    pub ty: Type,
}

pub fn parse_in_array_fields(input: ParseStream) -> Result<InArrayField> {
    let attrs: Vec<InArrayAttribute> = input.call(parse_in_array_attributes)?;
    let _: Visibility = input.parse()?;
    let ident: Ident = input.parse()?;
    let _: Option<token::Colon> = Some(input.parse()?);
    let ty: Type = input.parse()?;
    Ok(InArrayField { attrs, ident, ty })
}

pub fn is_in_array_attribute(input: ParseStream) -> Result<bool> {
    let content;
    let _: Token![#] = input.parse()?;
    let _: token::Bracket = bracketed!(content in input);
    let path: Path = content.call(Path::parse_mod_style)?;

    Ok(!path.segments.is_empty() && path.segments[0].ident == FIELD_SELECTOR_NAME)
}

pub fn parse_in_array_attributes(input: ParseStream) -> Result<Vec<InArrayAttribute>> {
    let mut ret = vec![];
    while input.peek(Token![#]) {
        if let Ok(true) = is_in_array_attribute(&input.fork()) {
            ret.push(input.call(parse_single_in_array_attribute_header)?);
        } else {
            input.call(single_parse_outer_attribute)?;
        }
    }
    Ok(ret)
}

pub fn parse_single_in_array_attribute_header(input: ParseStream) -> Result<InArrayAttribute> {
    let content;
    let _: Token![#] = input.parse()?;
    let _: token::Bracket = bracketed!(content in input);
    let path: Path = content.call(Path::parse_mod_style)?;

    if path.segments.len() != 1 {
        return Err(input.error(format!("Wrong syntax for {}", FIELD_SELECTOR_NAME)));
    }

    content.call(parse_single_in_array_attribute_body)
}

pub fn parse_single_in_array_attribute_body(input: ParseStream) -> Result<InArrayAttribute> {
    let content;
    let _ = parenthesized!(content in input);
    Ok(InArrayAttribute {
        entries: content
            .parse_terminated::<InArrayAttributeEntry, Token![,]>(parse_attribute_entry)?
            .into_iter()
            .collect(),
    })
}

pub fn parse_attribute_entry(input: ParseStream) -> Result<InArrayAttributeEntry> {
    Ok(InArrayAttributeEntry {
        ident: input.parse()?,
        decorator: input.parse()?,
    })
}