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​​Salsa In More Depth (2019.01)

​​#[salsa::query_group(InputsStorage)]

​​pub trait MyQueryGroup {

​​  #[salsa::input] // `set_manifest` is auto-generated

​​  fn manifest(&self) -> Manifest;

​​


​​  #[salsa::input] // `set_source_text` is auto-generated

​​  fn source_text(&self, name: String) -> String;

​​


​​  fn ast(&self, name: String) -> Ast;

​​


​​  fn whole_program_ast(&self) -> Ast;

​​}

​​


​​fn ast(db: &dyn MyQueryGroup, name: String) -> Ast {

​​  let source_text: String = db.source_text(name);

​​  

​​  // do the actual parser on `source_text`

​​  

​​  return ast;

​​}

​​


​​fn whole_program_ast(db: &dyn MyQueryGroup, name: String) -> Ast {

​​  let mut ast = Ast::default();

​​  for source_file in db.manifest() {

​​    let ast_source_file = db.ast(name);

​​    ast.extend(ast_source_file);

​​  }

​​  return ast;

​​}

​​

​​

​​Database storage

• ​​Database has internally a shared storage with:

• ​​revision (R0)

• ​​one struct per query group

• ​​one map per query

• ​​db.set_input_file("a.rs", "fn main() { }")​

• ​​storing into the input_file​ map with the key a.rs​ and the value given

• ​​store the (new) revision R1

• ​​increment the revision (R1)

• ​​db.set_input_file("b.rs", "fn foo() { }")​

• ​​go to revision R2

• ​​setters are &mut self​

• ​​db.type_check()​ // &self​

​​

​​Query storage

• ​​Input query:

• ​​(Key) → (Value, Revision)

​​