Stack system in Massa

• ExecuteSC

  When an account A sends an ExecuteSC operation, the stack at the beginning of that execution is: bottom [ A ] top.

• CallSC

  When an account A sends a CallSC operation to call a function in a smart contract B, the stack at the beginning of the execution of that function is: bottom [ A, B ] top. Note: A and B can be the same.

• Call from one smart contract to another

  When a function F from smart contract C is being executed with the stack [A, B, C] and calls a function on a smart contract D, the stack at the beginning of the execution of D’s function becomes: bottom [A, B, C, D] top. When D’s function finishes, the stack becomes bottom [A, B, C] top and the execution of F resumes.

• Autonomous SC

  A message sent at a moment when the stack was [A, B, C] and calling a target function F of a smart contract D, will yield the following stack at the beginning of the execution of the target function: bottom [C, D] top. Note: C and D can be the same.

• Local execution

  Local executions don’t change the stack, they allow executing foreign code in the current context.

ABIs

In the massa assemblyscript sdk there is an Object called Context. You can import it in your smart-contract code this way:

import { Context } from "@massalabs/massa-as-sdk";

It exposes some useful functions like:

• addressStack() returns the full call stack as a list, bottom to top

• caller() returns the stack element just below the top

• callee() returns the stack element at the top of the stack

• transactionCreator() returns the stack element at the bottom of the stack