@tanstack/db/dist/esm/query/compiler/select.js

A reactive client store for building super fast apps on sync

import { map } from "@tanstack/db-ivm";
import { isExpressionLike, Value, PropRef, ConditionalSelect } from "../ir.js";
import { UnsafeAliasPathError } from "../../errors.js";
import { compileExpression, isCaseWhenConditionTrue } from "./evaluators.js";
function unwrapVal(input) {
  if (input instanceof Value) return input.value;
  return input;
}
const UNSAFE_ALIAS_SEGMENTS = /* @__PURE__ */ new Set([`__proto__`, `prototype`, `constructor`]);
function assertSafeAliasSegments(segments) {
  for (const seg of segments) {
    if (UNSAFE_ALIAS_SEGMENTS.has(seg)) {
      throw new UnsafeAliasPathError(seg);
    }
  }
}
function mergeSourceFields(target, source) {
  for (const key of Reflect.ownKeys(source)) {
    if (!Object.prototype.propertyIsEnumerable.call(source, key)) continue;
    defineSelectField(target, key, unwrapVal(Reflect.get(source, key)));
  }
}
function ownedDestination(result, path, owned) {
  let cursor = result;
  for (const segment of path) {
    const next = Object.hasOwn(cursor, segment) ? Reflect.get(cursor, segment) : void 0;
    if (next != null && typeof next === `object` && owned.has(next)) {
      cursor = next;
      continue;
    }
    const destination = Array.isArray(next) ? new Array(next.length) : {};
    if (Array.isArray(next)) {
      Object.setPrototypeOf(destination, Object.getPrototypeOf(next));
    }
    if (next != null && typeof next === `object`) {
      mergeSourceFields(destination, next);
    }
    owned.add(destination);
    defineSelectField(cursor, segment, destination);
    cursor = destination;
  }
  return cursor;
}
function defineSelectField(target, key, value) {
  Object.defineProperty(
    target,
    key,
    Object.hasOwn(target, key) ? { value } : { value, enumerable: true, configurable: true, writable: true }
  );
}
function processMerge(op, namespacedRow, selectResults, owned) {
  assertSafeAliasSegments(op.targetPath);
  const value = op.source(namespacedRow);
  if (value && typeof value === `object`) {
    mergeSourceFields(
      ownedDestination(selectResults, op.targetPath, owned),
      value
    );
  }
}
function processNonMergeOp(op, namespacedRow, selectResults, owned) {
  const path = op.alias.split(`.`);
  assertSafeAliasSegments(path);
  const target = ownedDestination(selectResults, path.slice(0, -1), owned);
  defineSelectField(
    target,
    path[path.length - 1],
    unwrapVal(op.compiled(namespacedRow))
  );
}
function evaluateSelectObject(namespacedRow, ops) {
  const selectResults = {};
  const owned = new WeakSet([selectResults]);
  for (const op of ops) {
    if (op.kind === `merge`) {
      processMerge(op, namespacedRow, selectResults, owned);
    } else if (op.kind === `field`) {
      processNonMergeOp(op, namespacedRow, selectResults, owned);
    } else {
      assertSafeAliasSegments(op.targetPath);
      const target = ownedDestination(
        selectResults,
        op.targetPath.slice(0, -1),
        owned
      );
      const destination = {};
      owned.add(destination);
      defineSelectField(
        target,
        op.targetPath[op.targetPath.length - 1],
        destination
      );
    }
  }
  return selectResults;
}
function processRow([key, namespacedRow], ops) {
  const selectResults = evaluateSelectObject(namespacedRow, ops);
  return [
    key,
    {
      ...namespacedRow,
      $selected: selectResults
    }
  ];
}
function processSelect(pipeline, select, _allInputs) {
  if (!isNestedSelectObject(select)) {
    const compiled = compileSelectValue(select);
    return pipeline.pipe(
      map(([key, namespacedRow]) => [
        key,
        { ...namespacedRow, $selected: compiled(namespacedRow) }
      ])
    );
  }
  const ops = [];
  addFromObject([], select, ops);
  return pipeline.pipe(map((row) => processRow(row, ops)));
}
function compileSelectObject(obj) {
  const ops = [];
  addFromObject([], obj, ops);
  return (row) => evaluateSelectObject(row, ops);
}
function compileSelectValue(value) {
  if (value == null) {
    return () => value;
  }
  if (isConditionalSelectValue(value)) {
    return compileConditionalSelect(value);
  }
  if (value instanceof Value) {
    return () => value.value;
  }
  if (value.type === `includesSubquery`) {
    return () => null;
  }
  if (isNestedSelectObject(value)) {
    return compileSelectObject(value);
  }
  if (!isExpressionLike(value)) {
    return () => value;
  }
  return compileExpression(value);
}
function compileConditionalSelect(conditional) {
  const branches = conditional.branches.map((branch) => ({
    condition: compileExpression(branch.condition),
    value: compileSelectValue(branch.value)
  }));
  const defaultFn = conditional.defaultValue === void 0 ? void 0 : compileSelectValue(conditional.defaultValue);
  return (row) => {
    for (const branch of branches) {
      if (isCaseWhenConditionTrue(branch.condition(row))) {
        return branch.value(row);
      }
    }
    return defaultFn !== void 0 ? defaultFn(row) : null;
  };
}
function isNestedSelectObject(obj) {
  return obj && typeof obj === `object` && !isExpressionLike(obj);
}
function addFromObject(prefixPath, obj, ops) {
  for (const [key, value] of Object.entries(obj)) {
    if (!key.startsWith(`__SPREAD_SENTINEL__`)) {
      assertSafeAliasSegments(key.split(`.`));
    }
    if (key.startsWith(`__SPREAD_SENTINEL__`)) {
      const rest = key.slice(`__SPREAD_SENTINEL__`.length);
      const splitIndex = rest.lastIndexOf(`__`);
      const pathStr = splitIndex >= 0 ? rest.slice(0, splitIndex) : rest;
      const isRefExpr = value && typeof value === `object` && `type` in value && value.type === `ref`;
      if (pathStr.includes(`.`) || isRefExpr) {
        const targetPath = [...prefixPath];
        const path = pathStr.split(`.`);
        const expr = isRefExpr ? value : new PropRef(path, path[0]);
        const compiled = compileExpression(expr);
        ops.push({ kind: `merge`, targetPath, source: compiled });
      } else {
        const tableAlias = pathStr;
        const targetPath = [...prefixPath];
        ops.push({
          kind: `merge`,
          targetPath,
          source: (row) => row[tableAlias]
        });
      }
      continue;
    }
    const expression = value;
    if (isConditionalSelectValue(expression)) {
      ops.push({
        kind: `field`,
        alias: [...prefixPath, key].join(`.`),
        compiled: compileConditionalSelect(expression)
      });
      continue;
    }
    if (expression && expression.type === `includesSubquery`) {
      ops.push({
        kind: `field`,
        alias: [...prefixPath, key].join(`.`),
        compiled: () => null
      });
      continue;
    }
    if (isNestedSelectObject(expression)) {
      const targetPath = [...prefixPath, ...key.split(`.`)];
      ops.push({ kind: `object`, targetPath });
      addFromObject(targetPath, expression, ops);
      continue;
    }
    if (expression === void 0 || !isExpressionLike(expression)) {
      ops.push({
        kind: `field`,
        alias: [...prefixPath, key].join(`.`),
        compiled: () => expression
      });
      continue;
    }
    if (expression instanceof Value) {
      const val = expression.value;
      ops.push({
        kind: `field`,
        alias: [...prefixPath, key].join(`.`),
        compiled: () => val
      });
    } else {
      ops.push({
        kind: `field`,
        alias: [...prefixPath, key].join(`.`),
        compiled: compileExpression(expression)
      });
    }
  }
}
function isConditionalSelectValue(value) {
  return value instanceof ConditionalSelect || value != null && typeof value === `object` && value.type === `conditionalSelect` && Array.isArray(value.branches);
}
export {
  processSelect
};
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