Some refactoring separated from #8825 for easier review.
# Important Notes
**ID types**
The new *synchronization IDs* will replace `ExprId` for `Ast` references in frontend logic. `ExprId` (now called `ExternalId`) is now used only for module serialization and engine communication. The graph database will maintain an index that is used to translate at the boundaries. For now, this translation is implemented as a type cast, as the IDs have the same values until the next PR.
- `AstId`: Identifies an `Ast` node.
- `NodeId`: A subtype of `AstId`.
- `ExternalId`: UUID used for serialization and engine communication.
**Other changes**:
- Immediate validation of `Owned` usage.
- Eliminate `Ast.RawCode`.
- Prepare to remove `IdMap` from yjsModel.
Further AST integration and API refinement before introducing the new synchronization mechanism.
closes#8609
# Important Notes
API changes:
- Renamed `Ast.parseExpression` / `Ast.parse` to better reflect their usage:
- `Ast.parse` returns a block or a single expression, depending on its input; this is convenient for expressions expected to be single-line.
- `Ast.parseBlock` always treats its input as a block; this is suitable for parsing a file.
- `astExtended` is no longer needed to access span information. `Ast.span` provides access to the value when appropriate (the project's committed modules have spans; uncommitted changes or other parsed expressions don't).
- `SourceRange` is now used everywhere in place of `ContentRange`--the two types had the same definition.
Features:
- Fix CodeEditor viewing.
Implementation improvements:
- Updated widget update handlers (#8545) implementation to Ast API.
- Integrated `imports` more thoroughly with new AST APIs.
- More tests.
- The module is edited by changing the AST, not the text representation.
- `IdMap`s no longer need to be maintained in parallel with the module content; they are snapshots produced as needed from the ASTs.
- Simplistic synchronization is in place until #8237: Edits are never merged; if two edits are started from the same state, one will be overwritten.
Introduce new AST type; use it to replace current uses of AstExtended; for now edits and synchronization are implemented on the old mechanisms (text edits / RelativeRange id map).
# Important Notes
- Edit-related code is commented out until the next PR because it is incompatible with the transitional IdMap-based synchronization.
Fixes#8252
As we use proper alias analysis, we no longer display connections to overshadowed identifiers.
# Important Notes
I've changed the meaning of edge's "source" - now it's expression ID of the constituted identifier, not the node ID. This will allow proper handling nodes like `[x, y] = Main.get_point` once the engine will support them.
