Ep.getDispatchLoop = function()

in packages/transform/src/emit.js [241:296]

• 41 lines of code
• 4 McCabe index (conditional complexity)

Ep.getDispatchLoop = function() {
  const self = this;
  const t = util.getTypes();
  let cases = [];
  let current;

  // If we encounter a break, continue, or return statement in a switch
  // case, we can skip the rest of the statements until the next case.
  let alreadyEnded = false;

  self.listing.forEach(function(stmt, i) {
    if (self.marked.hasOwnProperty(i)) {
      cases.push(t.switchCase(
        t.numericLiteral(i),
        current = []));
      alreadyEnded = false;
    }

    if (!alreadyEnded) {
      current.push(stmt);
      if (t.isCompletionStatement(stmt))
        alreadyEnded = true;
    }
  });

  // Now that we know how many statements there will be in this.listing,
  // we can finally resolve this.finalLoc.value.
  this.finalLoc.value = this.listing.length;

  cases.push(
    t.switchCase(this.finalLoc, [
      // Intentionally fall through to the "end" case...
    ]),

    // So that the runtime can jump to the final location without having
    // to know its offset, we provide the "end" case as a synonym.
    t.switchCase(t.stringLiteral("end"), [
      // This will check/clear both context.thrown and context.rval.
      t.returnStatement(
        t.callExpression(this.contextProperty("stop"), [])
      )
    ])
  );

  return t.whileStatement(
    t.numericLiteral(1),
    t.switchStatement(
      t.assignmentExpression(
        "=",
        this.contextProperty("prev"),
        this.contextProperty("next")
      ),
      cases
    )
  );
};