Crate spacetimedb_vm

Abstract Virtual Machine for execution of end-user logic

It optimizes the code & include a more general “query planner”

The execution is split in 3 “phases”:

1- AST formation

Generate the AST (that could be invalid according to the semantics).

This step is outside the [vm] and can be done, for example, by the SQL layer.

Use dsl to build the [expr:Expr] that build the AST.

2- AST validation

Calling eval::optimize verify the code has the correct semantics (ie: It checks types, schemas, functions are valid, etc.), and “desugar” the code in a more optimal form for later execution.

This build expr::ExprOpt that is what could be stored in the database, ie: Is like bytecode.

3- Execution

Run the AST build from expr::ExprOpt. It assumes is correct.

Modules

• dsl
  Utilities for build valid constructs for the vm.
• env
  The different environments that support the runtime/compilation storage of idents, functions, lambdas, etc.
• errors
• eval
• expr
• functions
• iterators
• operator
  Operators are implemented as “alias” of functions that are loaded at the start of the [ProgramVm] creation, ie:
• ops
  Implements the in-built operators & functions loaded by the vm
• program
  Definition for a Program to run code.
• rel_ops
• types
  Define an in-progress type annotation.