127 lines
4.2 KiB
Rust
127 lines
4.2 KiB
Rust
//
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// imag - the personal information management suite for the commandline
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// Copyright (C) 2015-2018 Matthias Beyer <mail@beyermatthias.de> and contributors
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; version
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// 2.1 of the License.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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//
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use error::EntryUtilError as EUE;
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use error::Result;
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use toml::Value;
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use toml_query::read::TomlValueReadTypeExt;
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use toml_query::insert::TomlValueInsertExt;
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/// Trait to check whether an entry is a certain kind of entry
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///
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/// If an entry is marked with a `bool` flag in the header to contain a certain amount of data (for
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/// example a "wiki" entry may provide some meta information in the `[wiki]` section of its header),
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/// this trait provides a check whether the entry has set the flag to `true` or `false`.
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///
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/// # Note
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///
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/// This trait is solely for library implementations, as convenience functionality for implementing
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/// some function like this:
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///
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/// # Example
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///
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/// ```
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/// # extern crate libimagstore;
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/// # #[macro_use]
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/// # extern crate libimagentryutil;
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///
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/// # use libimagentryutil::error::Result as Result;
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/// use libimagentryutil::isa::IsKindHeaderPathProvider;
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/// use libimagentryutil::isa::Is;
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///
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/// trait WikiArticle {
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/// fn is_wiki_article(&self) -> Result<bool>;
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/// // ...
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/// }
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///
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/// provide_kindflag_path!(IsWikiEntry, "wiki.is_entry");
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///
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/// impl WikiArticle for ::libimagstore::store::Entry {
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/// fn is_wiki_article(&self) -> Result<bool> {
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/// self.is::<IsWikiEntry>()
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/// }
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/// }
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///
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/// # fn main() { }
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/// ```
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///
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/// # See also
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///
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/// * Documentation for `IsKindHeaderPathProvider`
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/// * Helper macro `provide_kindflag_path!()`
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///
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pub trait Is {
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fn is<T: IsKindHeaderPathProvider>(&self) -> Result<bool>;
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fn set_isflag<T: IsKindHeaderPathProvider>(&mut self) -> Result<()>;
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}
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impl Is for ::libimagstore::store::Entry {
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fn is<T: IsKindHeaderPathProvider>(&self) -> Result<bool> {
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let field = T::kindflag_header_location();
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match self.get_header().read_bool(field)? {
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Some(b) => Ok(b),
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None => Err(format!("Field {} not available", field)).map_err(EUE::from),
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}
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}
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fn set_isflag<T: IsKindHeaderPathProvider>(&mut self) -> Result<()> {
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self.get_header_mut()
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.insert(T::kindflag_header_location(), Value::Boolean(true))
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.map_err(EUE::from)
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.map(|_| ())
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}
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}
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/// The IsKindHeaderPathProvider trait provides a function `typeflag_header_location()` which
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/// returns a `toml-query` path.
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///
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/// This path points to a `bool` entry in the header of an entry which marks the entry to be an
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/// entry of a certain kind.
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///
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/// For example, an "Wiki" entry might contain a `true` at `"wiki.is_entry"` in the header.
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/// This trait provides `"wiki.is_entry"`.
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pub trait IsKindHeaderPathProvider {
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fn kindflag_header_location() -> &'static str;
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}
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/// Create (pub/non-pub) type for providing a `kindflag_header_location()` implementation.
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#[macro_export]
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macro_rules! provide_kindflag_path {
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(pub $entry_header_path_provider_type:ident, $path:expr) => {
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pub struct $entry_header_path_provider_type;
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provide_kindflag_path!(impl for $entry_header_path_provider_type, $path);
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};
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($entry_header_path_provider_type:ident, $path:expr) => {
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struct $entry_header_path_provider_type;
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provide_kindflag_path!(impl for $entry_header_path_provider_type, $path);
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};
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(impl for $entry_header_path_provider_type:ident, $path:expr) => {
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impl IsKindHeaderPathProvider for $entry_header_path_provider_type {
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fn kindflag_header_location() -> &'static str {
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$path
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}
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}
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};
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}
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