rea/src/domain/javascript/javascriptSemanticObjects.ts

import * as t from "@babel/types";

import type {
  JavaScriptSemanticCallable,
  JavaScriptSemanticObjectOperation,
} from "./javascriptSemanticIr.js";
import {
  semanticCallableIdForNode,
  semanticReadsBeforeWrite,
  semanticStaticPropertyKey,
} from "./javascriptSemanticProjection.js";
import {
  resolveSemanticBindingState,
  type JavaScriptSemanticAnalysisState,
} from "./javascriptSemanticState.js";
import { traverseJavaScriptAst } from "./javascriptSemanticTraversal.js";
import { range } from "./javascriptStaticAnalysisHelpers.js";

/** Recover bounded static property reads, writes, spreads, and destructuring. */
export const collectJavaScriptSemanticObjects = (
  program: t.Program,
  state: JavaScriptSemanticAnalysisState,
  callables: readonly JavaScriptSemanticCallable[],
): JavaScriptSemanticObjectOperation[] => {
  const output: JavaScriptSemanticObjectOperation[] = [];
  const callableIds = new Set(callables.map(({ callableId }) => callableId));
  const callableStack: string[] = [];
  const context: ObjectCollectionContext = { state, output };
  traverseJavaScriptAst(program, {
    enter: (node, parent) => {
      const callableId = semanticCallableIdForNode(node);
      if (callableId !== null && callableIds.has(callableId))
        callableStack.push(callableId);
      const ownerCallableId = callableStack.at(-1) ?? null;
      if (t.isMemberExpression(node) || t.isOptionalMemberExpression(node))
        collectMember(node, parent, ownerCallableId, context);
      else if (
        t.isSpreadElement(node) &&
        parent !== null &&
        t.isObjectExpression(parent)
      )
        addObjectOperation(
          {
            node,
            kind: "spread",
            ownerCallableId,
            objectBindingId: expressionBindingId(node.argument, state),
            targetBindingId: null,
            propertyName: null,
          },
          state,
          output,
        );
      else if (t.isVariableDeclarator(node) && t.isObjectPattern(node.id))
        collectDestructuring(node, ownerCallableId, state, output);
    },
    exit: (node) => {
      const callableId = semanticCallableIdForNode(node);
      if (callableId !== null && callableStack.at(-1) === callableId)
        callableStack.pop();
    },
  });
  return output;
};

interface ObjectCollectionContext {
  readonly state: JavaScriptSemanticAnalysisState;
  readonly output: JavaScriptSemanticObjectOperation[];
}

const collectMember = (
  node: t.MemberExpression | t.OptionalMemberExpression,
  parent: t.Node | null,
  ownerCallableId: string | null,
  context: ObjectCollectionContext,
): void => {
  const { state, output } = context;
  const name = semanticStaticPropertyKey(node.property, node.computed);
  if (name === null) return;
  const write =
    (t.isAssignmentExpression(parent) && parent.left === node) ||
    (t.isUpdateExpression(parent) && parent.argument === node);
  const readsBeforeWrite = write && semanticReadsBeforeWrite(node, parent);
  if (readsBeforeWrite)
    addObjectOperation(
      {
        node,
        kind: "read",
        ownerCallableId,
        objectBindingId: expressionBindingId(node.object, state),
        targetBindingId: null,
        propertyName: name,
      },
      state,
      output,
    );
  addObjectOperation(
    {
      node,
      kind: write ? "write" : "read",
      ownerCallableId,
      objectBindingId: expressionBindingId(node.object, state),
      targetBindingId: null,
      propertyName: name,
    },
    state,
    output,
  );
};

const collectDestructuring = (
  node: t.VariableDeclarator,
  ownerCallableId: string | null,
  state: JavaScriptSemanticAnalysisState,
  output: JavaScriptSemanticObjectOperation[],
): void => {
  if (!t.isObjectPattern(node.id)) return;
  const objectBindingId = expressionBindingId(node.init, state);
  for (const property of node.id.properties) {
    if (!t.isObjectProperty(property)) continue;
    const name = semanticStaticPropertyKey(property.key, property.computed);
    if (name === null) continue;
    const target = bindingIdentifier(property.value);
    addObjectOperation(
      {
        node: property,
        kind: "destructure",
        ownerCallableId,
        objectBindingId,
        targetBindingId:
          target === null
            ? null
            : (resolveSemanticBindingState(state, target, target.name)
                ?.bindingId ?? null),
        propertyName: name,
      },
      state,
      output,
    );
  }
};

interface AddObjectOperationInput {
  readonly node: t.Node;
  readonly kind: JavaScriptSemanticObjectOperation["kind"];
  readonly ownerCallableId: string | null;
  readonly objectBindingId: string | null;
  readonly targetBindingId: string | null;
  readonly propertyName: string | null;
}

const addObjectOperation = (
  input: AddObjectOperationInput,
  state: JavaScriptSemanticAnalysisState,
  output: JavaScriptSemanticObjectOperation[],
): void => {
  output.push({
    objectOperationId: `object:${input.kind}:${String(input.node.start ?? -1)}:${String(input.node.end ?? -1)}`,
    kind: input.kind,
    location: range(input.node),
    ownerCallableId: input.ownerCallableId,
    objectBindingId: input.objectBindingId,
    targetBindingId: input.targetBindingId,
    propertyName: input.propertyName,
    resolution:
      input.kind === "spread"
        ? input.objectBindingId === null
          ? "partial"
          : "complete"
        : input.objectBindingId === null ||
            input.propertyName === null ||
            (input.kind === "destructure" && input.targetBindingId === null)
          ? "partial"
          : "complete",
  });
};

const expressionBindingId = (
  node: t.Node | null | undefined,
  state: JavaScriptSemanticAnalysisState,
): string | null =>
  t.isIdentifier(node)
    ? (resolveSemanticBindingState(state, node, node.name)?.bindingId ?? null)
    : null;

const bindingIdentifier = (node: t.Node): t.Identifier | null => {
  if (t.isIdentifier(node)) return node;
  if (t.isAssignmentPattern(node) && t.isIdentifier(node.left))
    return node.left;
  return null;
};