in midst of refactor

orchid-base/src/system.rs

@@ -0,0 +1,70 @@
+//! Unified extension struct instances of which are catalogued by
+//! [super::loader::Loader]. Language extensions must implement [IntoSystem].
+
+use crate::error::{ErrorPosition, ProjectError};
+use crate::gen::tree::ConstTree;
+use crate::interpreter::handler::HandlerTable;
+use crate::name::VName;
+use crate::parse::lex_plugin::LexerPlugin;
+use crate::parse::parse_plugin::ParseLinePlugin;
+use crate::pipeline::load_project::Prelude;
+use crate::virt_fs::DeclTree;
+
+/// A description of every point where an external library can hook into Orchid.
+/// Intuitively, this can be thought of as a plugin
+pub struct System<'a> {
+  /// An identifier for the system used eg. in error reporting.
+  pub name: &'a str,
+  /// External functions and other constant values defined in AST form
+  pub constants: ConstTree,
+  /// Orchid libraries defined by this system
+  pub code: DeclTree,
+  /// Prelude lines to be added to the head of files to expose the
+  /// functionality of this system. A glob import from the first path is
+  /// added to every file outside the prefix specified by the second path
+  pub prelude: Vec<Prelude>,
+  /// Handlers for actions defined in this system
+  pub handlers: HandlerTable<'a>,
+  /// Custom lexer for the source code representation atomic data.
+  /// These take priority over builtin lexers so the syntax they
+  /// match should be unambiguous
+  pub lexer_plugins: Vec<Box<dyn LexerPlugin + 'a>>,
+  /// Parser that processes custom line types into their representation in the
+  /// module tree
+  pub line_parsers: Vec<Box<dyn ParseLinePlugin>>,
+}
+impl<'a> System<'a> {
+  /// Intern the name of the system so that it can be used as an Orchid
+  /// namespace
+  #[must_use]
+  pub fn vname(&self) -> VName {
+    VName::parse(self.name).expect("Systems must have a non-empty name")
+  }
+}
+
+/// An error raised when a system fails to load a path. This usually means that
+/// another system the current one depends on did not get loaded
+#[derive(Debug)]
+struct MissingSystemCode {
+  path: VName,
+  system: Vec<String>,
+  referrer: VName,
+}
+impl ProjectError for MissingSystemCode {
+  const DESCRIPTION: &'static str = "A system tried to import a path that doesn't exist";
+  fn message(&self) -> String {
+    format!(
+      "Path {} imported by {} is not defined by {} or any system before it",
+      self.path,
+      self.referrer,
+      self.system.join("::")
+    )
+  }
+  fn positions(&self) -> impl IntoIterator<Item = ErrorPosition> { [] }
+}
+
+/// Trait for objects that can be converted into a [System].
+pub trait IntoSystem<'a> {
+  /// Convert this object into a system using an interner
+  fn into_system(self) -> System<'a>;
+}