rust/src/libsyntax/attr.rs

// Functions dealing with attributes and meta_items

use std::map;
use std::map::HashMap;
use either::Either;
use diagnostic::span_handler;
use ast_util::{spanned, dummy_spanned};
use parse::comments::{doc_comment_style, strip_doc_comment_decoration};

// Constructors
export mk_name_value_item_str;
export mk_name_value_item;
export mk_list_item;
export mk_word_item;
export mk_attr;
export mk_sugared_doc_attr;

// Conversion
export attr_meta;
export attr_metas;
export desugar_doc_attr;

// Accessors
export get_attr_name;
export get_meta_item_name;
export get_meta_item_value_str;
export get_meta_item_list;
export get_name_value_str_pair;

// Searching
export find_attrs_by_name;
export find_meta_items_by_name;
export contains;
export contains_name;
export attrs_contains_name;
export first_attr_value_str_by_name;
export last_meta_item_value_str_by_name;
export last_meta_item_list_by_name;

// Higher-level applications
export sort_meta_items;
export remove_meta_items_by_name;
export find_linkage_attrs;
export find_linkage_metas;
export foreign_abi;
export inline_attr;
export find_inline_attr;
export require_unique_names;

/* Constructors */

fn mk_name_value_item_str(name: ~str, +value: ~str) ->
    @ast::meta_item {
    let value_lit = dummy_spanned(ast::lit_str(@value));
    return mk_name_value_item(name, value_lit);
}

fn mk_name_value_item(name: ~str, +value: ast::lit)
        -> @ast::meta_item {
    return @dummy_spanned(ast::meta_name_value(name, value));
}

fn mk_list_item(name: ~str, +items: ~[@ast::meta_item]) ->
   @ast::meta_item {
    return @dummy_spanned(ast::meta_list(name, items));
}

fn mk_word_item(name: ~str) -> @ast::meta_item {
    return @dummy_spanned(ast::meta_word(name));
}

fn mk_attr(item: @ast::meta_item) -> ast::attribute {
    return dummy_spanned({style: ast::attr_inner, value: *item,
                       is_sugared_doc: false});
}

fn mk_sugared_doc_attr(text: ~str, lo: uint, hi: uint) -> ast::attribute {
    let lit = spanned(lo, hi, ast::lit_str(@text));
    let attr = {
        style: doc_comment_style(text),
        value: spanned(lo, hi, ast::meta_name_value(~"doc", lit)),
        is_sugared_doc: true
    };
    return spanned(lo, hi, attr);
}

/* Conversion */

fn attr_meta(attr: ast::attribute) -> @ast::meta_item { @attr.node.value }

// Get the meta_items from inside a vector of attributes
fn attr_metas(attrs: ~[ast::attribute]) -> ~[@ast::meta_item] {
    let mut mitems = ~[];
    for attrs.each |a| { vec::push(mitems, attr_meta(*a)); }
    return mitems;
}

fn desugar_doc_attr(attr: ast::attribute) -> ast::attribute {
    if attr.node.is_sugared_doc {
        let comment = get_meta_item_value_str(@attr.node.value).get();
        let meta = mk_name_value_item_str(~"doc",
                                     strip_doc_comment_decoration(comment));
        return mk_attr(meta);
    } else {
        attr
    }
}

/* Accessors */

fn get_attr_name(attr: ast::attribute) -> ~str {
    get_meta_item_name(@attr.node.value)
}

fn get_meta_item_name(meta: @ast::meta_item) -> ~str {
    match meta.node {
      ast::meta_word(n) => n,
      ast::meta_name_value(n, _) => n,
      ast::meta_list(n, _) => n
    }
}

/**
 * Gets the string value if the meta_item is a meta_name_value variant
 * containing a string, otherwise none
 */
fn get_meta_item_value_str(meta: @ast::meta_item) -> Option<~str> {
    match meta.node {
        ast::meta_name_value(_, v) => match v.node {
            ast::lit_str(s) => option::Some(*s),
            _ => option::None
        },
        _ => option::None
    }
}

/// Gets a list of inner meta items from a list meta_item type
fn get_meta_item_list(meta: @ast::meta_item) -> Option<~[@ast::meta_item]> {
    match meta.node {
      ast::meta_list(_, l) => option::Some(/* FIXME (#2543) */ copy l),
      _ => option::None
    }
}

/**
 * If the meta item is a nam-value type with a string value then returns
 * a tuple containing the name and string value, otherwise `none`
 */
fn get_name_value_str_pair(item: @ast::meta_item) -> Option<(~str, ~str)> {
    match attr::get_meta_item_value_str(item) {
      Some(value) => {
        let name = attr::get_meta_item_name(item);
        Some((name, value))
      }
      None => None
    }
}


/* Searching */

/// Search a list of attributes and return only those with a specific name
fn find_attrs_by_name(attrs: ~[ast::attribute], name: ~str) ->
   ~[ast::attribute] {
    let filter = (
        fn@(a: ast::attribute) -> Option<ast::attribute> {
            if get_attr_name(a) == name {
                option::Some(a)
            } else { option::None }
        }
    );
    return vec::filter_map(attrs, filter);
}

/// Searcha list of meta items and return only those with a specific name
fn find_meta_items_by_name(metas: ~[@ast::meta_item], name: ~str) ->
   ~[@ast::meta_item] {
    let filter = fn@(&&m: @ast::meta_item) -> Option<@ast::meta_item> {
        if get_meta_item_name(m) == name {
            option::Some(m)
        } else { option::None }
    };
    return vec::filter_map(metas, filter);
}

/**
 * Returns true if a list of meta items contains another meta item. The
 * comparison is performed structurally.
 */
fn contains(haystack: ~[@ast::meta_item], needle: @ast::meta_item) -> bool {
    for haystack.each |item| {
        if eq(*item, needle) { return true; }
    }
    return false;
}

fn eq(a: @ast::meta_item, b: @ast::meta_item) -> bool {
    return match a.node {
          ast::meta_word(na) => match b.node {
            ast::meta_word(nb) => na == nb,
            _ => false
          },
          ast::meta_name_value(na, va) => match b.node {
            ast::meta_name_value(nb, vb) => na == nb && va.node == vb.node,
            _ => false
          },
          ast::meta_list(*) => {

            // ~[Fixme-sorting]
            // FIXME (#607): Needs implementing
            // This involves probably sorting the list by name and
            // meta_item variant
            fail ~"unimplemented meta_item variant"
          }
        }
}

fn contains_name(metas: ~[@ast::meta_item], name: ~str) -> bool {
    let matches = find_meta_items_by_name(metas, name);
    return vec::len(matches) > 0u;
}

fn attrs_contains_name(attrs: ~[ast::attribute], name: ~str) -> bool {
    vec::is_not_empty(find_attrs_by_name(attrs, name))
}

fn first_attr_value_str_by_name(attrs: ~[ast::attribute], name: ~str)
    -> Option<~str> {

    let mattrs = find_attrs_by_name(attrs, name);
    if vec::len(mattrs) > 0u {
        return get_meta_item_value_str(attr_meta(mattrs[0]));
    }
    return option::None;
}

fn last_meta_item_by_name(items: ~[@ast::meta_item], name: ~str)
    -> Option<@ast::meta_item> {

    let items = attr::find_meta_items_by_name(items, name);
    vec::last_opt(items)
}

fn last_meta_item_value_str_by_name(items: ~[@ast::meta_item], name: ~str)
    -> Option<~str> {

    match last_meta_item_by_name(items, name) {
      Some(item) => match attr::get_meta_item_value_str(item) {
        Some(value) => Some(value),
        None => None
      },
      None => None
    }
}

fn last_meta_item_list_by_name(items: ~[@ast::meta_item], name: ~str)
    -> Option<~[@ast::meta_item]> {

    match last_meta_item_by_name(items, name) {
      Some(item) => attr::get_meta_item_list(item),
      None => None
    }
}


/* Higher-level applications */

// FIXME (#607): This needs to sort by meta_item variant in addition to
// the item name (See [Fixme-sorting])
fn sort_meta_items(+items: ~[@ast::meta_item]) -> ~[@ast::meta_item] {
    pure fn lteq(ma: &@ast::meta_item, mb: &@ast::meta_item) -> bool {
        pure fn key(m: &ast::meta_item) -> ~str {
            match m.node {
              ast::meta_word(name) => name,
              ast::meta_name_value(name, _) => name,
              ast::meta_list(name, _) => name
            }
        }
        key(*ma) <= key(*mb)
    }

    // This is sort of stupid here, converting to a vec of mutables and back
    let v: ~[mut @ast::meta_item] = vec::to_mut(items);
    std::sort::quick_sort(lteq, v);
    vec::from_mut(move v)
}

fn remove_meta_items_by_name(items: ~[@ast::meta_item], name: ~str) ->
   ~[@ast::meta_item] {

    return vec::filter_map(items, |item| {
        if get_meta_item_name(item) != name {
            option::Some(/* FIXME (#2543) */ copy item)
        } else {
            option::None
        }
    });
}

/**
 * From a list of crate attributes get only the meta_items that affect crate
 * linkage
 */
fn find_linkage_metas(attrs: ~[ast::attribute]) -> ~[@ast::meta_item] {
    do find_attrs_by_name(attrs, ~"link").flat_map |attr| {
        match attr.node.value.node {
            ast::meta_list(_, items) => /* FIXME (#2543) */ copy items,
            _ => ~[]
        }
    }
}

fn foreign_abi(attrs: ~[ast::attribute]) -> Either<~str, ast::foreign_abi> {
    return match attr::first_attr_value_str_by_name(attrs, ~"abi") {
      option::None => {
        either::Right(ast::foreign_abi_cdecl)
      }
      option::Some(~"rust-intrinsic") => {
        either::Right(ast::foreign_abi_rust_intrinsic)
      }
      option::Some(~"cdecl") => {
        either::Right(ast::foreign_abi_cdecl)
      }
      option::Some(~"stdcall") => {
        either::Right(ast::foreign_abi_stdcall)
      }
      option::Some(t) => {
        either::Left(~"unsupported abi: " + t)
      }
    };
}

enum inline_attr {
    ia_none,
    ia_hint,
    ia_always,
    ia_never,
}

#[cfg(stage0)]
impl inline_attr : cmp::Eq {
    pure fn eq(&&other: inline_attr) -> bool {
        (self as uint) == (other as uint)
    }
    pure fn ne(&&other: inline_attr) -> bool { !self.eq(other) }
}
#[cfg(stage1)]
#[cfg(stage2)]
impl inline_attr : cmp::Eq {
    pure fn eq(other: &inline_attr) -> bool {
        (self as uint) == ((*other) as uint)
    }
    pure fn ne(other: &inline_attr) -> bool { !self.eq(other) }
}

/// True if something like #[inline] is found in the list of attrs.
fn find_inline_attr(attrs: ~[ast::attribute]) -> inline_attr {
    // FIXME (#2809)---validate the usage of #[inline] and #[inline(always)]
    do vec::foldl(ia_none, attrs) |ia,attr| {
        match attr.node.value.node {
          ast::meta_word(~"inline") => ia_hint,
          ast::meta_list(~"inline", items) => {
            if !vec::is_empty(find_meta_items_by_name(items, ~"always")) {
                ia_always
            } else if !vec::is_empty(
                find_meta_items_by_name(items, ~"never")) {
                ia_never
            } else {
                ia_hint
            }
          }
          _ => ia
        }
    }
}


fn require_unique_names(diagnostic: span_handler,
                        metas: ~[@ast::meta_item]) {
    let map = map::HashMap();
    for metas.each |meta| {
        let name = get_meta_item_name(*meta);

        // FIXME: How do I silence the warnings? --pcw (#2619)
        if map.contains_key(name) {
            diagnostic.span_fatal(meta.span,
                                  fmt!("duplicate meta item `%s`", name));
        }
        map.insert(name, ());
    }
}

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//