EDITOR: Use ramOverride() to set compiled script RAM (#1446)

To use this, add a line like "ns.ramOverride(2);" as the first statement
in main(). Not only will it take effect at runtime, but it will now
*also* be parsed at compile time, changing the script's static RAM
limit. Since ns.ramOverride is a 0-cost function, the call to it on
startup then becomes a no-op.

This is an often-requested feature, and allows for scripts to set their
usage without it needing to be explicitly mentioned via args or options
when being launched. This also reduces pressure on the static RAM
analysis to be perfect all the time. (But certain limits, such as
"functions names must be unique across namespaces," remain.)

This also adds a tooltip to the RAM calculation, to make this slightly
discoverable.

src/Script/RamCalculations.ts

@@ -15,6 +15,7 @@ import { Script } from "./Script";
 import { Node } from "../NetscriptJSEvaluator";
 import { ScriptFilePath, resolveScriptFilePath } from "../Paths/ScriptFilePath";
 import { ServerName } from "../Types/strings";
+import { roundToTwo } from "../utils/helpers/roundToTwo";
 
 export interface RamUsageEntry {
   type: "ns" | "dom" | "fn" | "misc";
@@ -44,6 +45,11 @@ const specialReferenceIF = "__SPECIAL_referenceIf";
 const specialReferenceFOR = "__SPECIAL_referenceFor";
 const specialReferenceWHILE = "__SPECIAL_referenceWhile";
 
+// This special string is used to signal that RAM is being overriden for a script.
+// It doesn't apply when importing that script.
+// The nature of the name guarantees it can never be conflated with a valid identifier.
+const specialReferenceRAM = ".^SPECIAL_ramOverride";
+
 // The global scope of a script is registered under this key during parsing.
 const memCheckGlobalKey = ".__GLOBAL__";
 
@@ -77,7 +83,7 @@ function parseOnlyRamCalculate(
    * We walk the dependency graph to calculate RAM usage, given that some identifiers
    * reference Netscript functions which have a RAM cost.
    */
-  let dependencyMap: Record<string, string[]> = {};
+  let dependencyMap: Record<string, Set<string>> = {};
 
   // Scripts we've parsed.
   const completedParses = new Set();
@@ -132,6 +138,16 @@ function parseOnlyRamCalculate(
     const ref = unresolvedRefs.shift();
     if (ref === undefined) throw new Error("ref should not be undefined");
 
+    if (ref.endsWith(specialReferenceRAM)) {
+      if (ref !== initialModule + specialReferenceRAM) {
+        // All RAM override tokens that *aren't* for the main module should be discarded.
+        continue;
+      }
+      // This is a RAM override for the main module. We can end ram calculation immediately.
+      const [first] = dependencyMap[ref];
+      const override = Number(first);
+      return { cost: override, entries: [{ type: "misc", name: "override", cost: override }] };
+    }
     // Check if this is one of the special keys, and add the appropriate ram cost if so.
     if (ref === "hacknet" && !resolvedRefs.has("hacknet")) {
       ram += RamCostConstants.HacknetNodes;
@@ -299,6 +315,52 @@ function parseOnlyCalculateDeps(code: string, currentModule: ScriptFilePath, ns1
     key: string;
   }
 
+  function checkRamOverride(node: Node) {
+    // To trigger a syntactic RAM override, the first statement must be a call
+    // to ns.ramOverride() (or something that looks similar).
+    if (!node.body || !node.body.length) return;
+    const statement = node.body[0];
+    if (statement.type !== "ExpressionStatement") return;
+    const expr = statement.expression;
+    if (expr.type !== "CallExpression") return;
+    if (!expr.arguments || expr.arguments.length !== 1) return;
+
+    function findIdentifier(node: Node): Node {
+      for (;;) {
+        // Find the identifier node attached to the call
+        switch (node.type) {
+          case "ParenthesizedExpression":
+          case "ChainExpression":
+            node = node.expression;
+            break;
+          case "MemberExpression":
+            node = node.property;
+            break;
+          default:
+            return node;
+        }
+      }
+    }
+    const idNode = findIdentifier(expr.callee);
+    if (idNode.type !== "Identifier" || idNode.name !== "ramOverride") return;
+
+    // For the time being, we only handle simple literals for the argument.
+    // If needed, this could be extended to simple constant expressions.
+    const literal = expr.arguments[0];
+    if (literal.type !== "Literal") return;
+    const value = literal.value;
+    if (typeof value !== "number") return;
+
+    // Finally, we know the syntax checks out for applying the RAM override.
+    // But the value might be illegal.
+    if (!isFinite(value) || value < RamCostConstants.Base) return;
+
+    // This is an unusual arrangement; the "function name" here is our special
+    // case, and it is "depending on" the stringified value of our ram override
+    // (which is not any kind of identifier).
+    dependencyMap[currentModule + specialReferenceRAM] = new Set([roundToTwo(value).toString()]);
+  }
+
   // If we discover a dependency identifier, state.key is the dependent identifier.
   // walkDeeper is for doing recursive walks of expressions in composites that we handle.
   function commonVisitors(): walk.RecursiveVisitors<State> {
@@ -373,6 +435,9 @@ function parseOnlyCalculateDeps(code: string, currentModule: ScriptFilePath, ns1
           }
         },
         FunctionDeclaration: (node: Node) => {
+          if (node.id?.name === "main") {
+            checkRamOverride(node.body);
+          }
           // node.id will be null when using 'export default'. Add a module name indicating the default export.
           const key = currentModule + "." + (node.id === null ? "__SPECIAL_DEFAULT_EXPORT__" : node.id.name);
           walk.recursive(node, { key: key }, commonVisitors());

src/ScriptEditor/ui/Toolbar.tsx

@@ -8,6 +8,7 @@ import Table from "@mui/material/Table";
 import TableCell from "@mui/material/TableCell";
 import TableRow from "@mui/material/TableRow";
 import TableBody from "@mui/material/TableBody";
+import Tooltip from "@mui/material/Tooltip";
 import Typography from "@mui/material/Typography";
 
 import SettingsIcon from "@mui/icons-material/Settings";
@@ -87,6 +88,13 @@ export function Toolbar({ editor, onSave }: IProps) {
         onThemeChange={onThemeChange}
       />
       <Modal open={ramInfoOpen} onClose={closeRAMInfo}>
+        <Tooltip
+          title={
+            "Static RAM costs of individual functions used by this script. " +
+            "Calling `ns.ramOverride()` with a constant number as the first statement in " +
+            "your script will override the value here, as well."
+          }
+        >
           <Table>
             <TableBody>
               {ramEntries.map(([n, r]) => (
@@ -101,6 +109,7 @@ export function Toolbar({ editor, onSave }: IProps) {
               ))}
             </TableBody>
           </Table>
+        </Tooltip>
       </Modal>
     </>
   );

test/jest/Netscript/RamCalculation.test.ts

@@ -169,4 +169,18 @@ describe("Netscript RAM Calculation/Generation Tests", function () {
       });
     }
   });
+
+  describe("ramOverride checks", () => {
+    test.each([
+      ["ns.ramOverride(5)", 5],
+      ["ramOverride(5)", 5],
+      ["ns.ramOverride(5 * 1024)", baseCost], // Constant expressions are not handled yet
+    ])("%s", (code, expected) => {
+      const fullCode = `export function main(ns) { ${code} }`;
+
+      const result = calculateRamUsage(fullCode, "testfile.js", new Map(), "testserver");
+      expect(result.errorMessage).toBe(undefined);
+      expect(result.cost).toBe(expected);
+    });
+  });
 });