move db basics to ra_db

This should allow to move hir to a separate crate

crates/ra_db/src/input.rs

@@ -0,0 +1,73 @@
+use std::sync::Arc;
+
+use rustc_hash::FxHashMap;
+use rustc_hash::FxHashSet;
+use salsa;
+
+use crate::file_resolver::FileResolverImp;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct FileId(pub u32);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct CrateId(pub u32);
+
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub struct CrateGraph {
+    pub(crate) crate_roots: FxHashMap<CrateId, FileId>,
+}
+
+impl CrateGraph {
+    pub fn crate_root(&self, crate_id: CrateId) -> FileId {
+        self.crate_roots[&crate_id]
+    }
+    pub fn add_crate_root(&mut self, file_id: FileId) -> CrateId {
+        let crate_id = CrateId(self.crate_roots.len() as u32);
+        let prev = self.crate_roots.insert(crate_id, file_id);
+        assert!(prev.is_none());
+        crate_id
+    }
+    pub fn crate_id_for_crate_root(&self, file_id: FileId) -> Option<CrateId> {
+        let (&crate_id, _) = self
+            .crate_roots
+            .iter()
+            .find(|(_crate_id, &root_id)| root_id == file_id)?;
+        Some(crate_id)
+    }
+}
+
+salsa::query_group! {
+    pub trait FilesDatabase: salsa::Database {
+        fn file_text(file_id: FileId) -> Arc<String> {
+            type FileTextQuery;
+            storage input;
+        }
+        fn file_source_root(file_id: FileId) -> SourceRootId {
+            type FileSourceRootQuery;
+            storage input;
+        }
+        fn source_root(id: SourceRootId) -> Arc<SourceRoot> {
+            type SourceRootQuery;
+            storage input;
+        }
+        fn libraries() -> Arc<Vec<SourceRootId>> {
+            type LibrariesQuery;
+            storage input;
+        }
+        fn crate_graph() -> Arc<CrateGraph> {
+            type CrateGraphQuery;
+            storage input;
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct SourceRootId(pub u32);
+
+#[derive(Default, Clone, Debug, PartialEq, Eq)]
+pub struct SourceRoot {
+    pub file_resolver: FileResolverImp,
+    pub files: FxHashSet<FileId>,
+}
+
+pub const WORKSPACE: SourceRootId = SourceRootId(0);