1 files changed, 121 insertions, 0 deletions

diff --git a/crates/libanalysis/src/db.rs b/crates/libanalysis/src/db.rs
new file mode 100644
index 000000000..335c79e76
--- /dev/null
+++ b/crates/libanalysis/src/db.rs
@@ -0,0 +1,121 @@
+use std::{
+    hash::Hash,
+    sync::Arc,
+};
+use libsyntax2::{File};
+use im;
+use {
+    FileId,
+    imp::{FileResolverImp},
+};
+
+#[derive(Clone)]
+pub(crate) struct Db {
+    file_resolver: FileResolverImp,
+    files: im::HashMap<FileId, Arc<String>>,
+}
+
+impl Db {
+    pub(crate) fn new() -> Db {
+        Db {
+            file_resolver: FileResolverImp::default(),
+            files: im::HashMap::new(),
+        }
+    }
+    pub(crate) fn change_file(&mut self, file_id: FileId, text: Option<String>) {
+        match text {
+            None => {
+                self.files.remove(&file_id);
+            }
+            Some(text) => {
+                self.files.insert(file_id, Arc::new(text));
+            }
+        }
+    }
+    pub(crate) fn set_file_resolver(&mut self, file_resolver: FileResolverImp) {
+        self.file_resolver = file_resolver
+    }
+    pub(crate) fn query_ctx(&self) -> QueryCtx {
+        QueryCtx { db: self.clone() }
+    }
+}
+
+pub(crate) struct QueryCtx {
+    db: Db
+}
+
+impl QueryCtx {
+    pub(crate) fn get<Q: Get>(&self, params: &Q::Params) -> Q::Output {
+        Q::get(self, params)
+    }
+}
+
+pub(crate) trait Query {
+    const ID: u32;
+    type Params: Hash;
+    type Output;
+}
+
+pub(crate) trait Get: Query {
+    fn get(ctx: &QueryCtx, params: &Self::Params) -> Self::Output;
+}
+
+impl<T: Eval> Get for T {
+    fn get(ctx: &QueryCtx, params: &Self::Params) -> Self::Output {
+        Self::eval(ctx, params)
+    }
+}
+
+pub(crate) trait Eval: Query {
+    fn eval(ctx: &QueryCtx, params: &Self::Params) -> Self::Output;
+}
+
+pub(crate) struct DbFiles {
+    db: Db,
+}
+
+impl DbFiles {
+    pub(crate) fn iter<'a>(&'a self) -> impl Iterator<Item=FileId> + 'a {
+        self.db.files.keys().cloned()
+    }
+    pub(crate) fn file_resolver(&self) -> FileResolverImp {
+        self.db.file_resolver.clone()
+    }
+}
+
+pub(crate) enum Files {}
+impl Query for Files {
+    const ID: u32 = 1;
+    type Params = ();
+    type Output = DbFiles;
+}
+impl Get for Files {
+    fn get(ctx: &QueryCtx, _params: &()) -> DbFiles {
+        DbFiles { db: ctx.db.clone() }
+    }
+}
+
+enum FileText {}
+impl Query for FileText {
+    const ID: u32 = 10;
+    type Params = FileId;
+    type Output = Arc<String>;
+}
+impl Get for FileText {
+    fn get(ctx: &QueryCtx, file_id: &FileId) -> Arc<String> {
+        ctx.db.files[file_id].clone()
+    }
+}
+
+pub(crate) enum FileSyntax {}
+impl Query for FileSyntax {
+    const ID: u32 = 20;
+    type Params = FileId;
+    type Output = File;
+}
+impl Eval for FileSyntax {
+    fn eval(ctx: &QueryCtx, file_id: &FileId) -> File {
+        let text = ctx.get::<FileText>(file_id);
+        File::parse(&text)
+    }
+}