@babel/plugin-transform-typescript/lib/enum.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = transpileEnum;

var _assert = _interopRequireDefault(require("assert"));

var _core = require("@babel/core");

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function transpileEnum(path, t) {
  const {
    node
  } = path;

  if (node.const) {
    throw path.buildCodeFrameError("'const' enums are not supported.");
  }

  if (node.declare) {
    path.remove();
    return;
  }

  const name = node.id.name;
  const fill = enumFill(path, t, node.id);

  switch (path.parent.type) {
    case "BlockStatement":
    case "ExportNamedDeclaration":
    case "Program":
      {
        path.insertAfter(fill);

        if (seen(path.parentPath)) {
          path.remove();
        } else {
          const isGlobal = t.isProgram(path.parent);
          path.scope.registerDeclaration(path.replaceWith(makeVar(node.id, t, isGlobal ? "var" : "let"))[0]);
        }

        break;
      }

    default:
      throw new Error(`Unexpected enum parent '${path.parent.type}`);
  }

  function seen(parentPath) {
    if (parentPath.isExportDeclaration()) {
      return seen(parentPath.parentPath);
    }

    if (parentPath.getData(name)) {
      return true;
    } else {
      parentPath.setData(name, true);
      return false;
    }
  }
}

function makeVar(id, t, kind) {
  return t.variableDeclaration(kind, [t.variableDeclarator(id)]);
}

const buildEnumWrapper = (0, _core.template)(`
  (function (ID) {
    ASSIGNMENTS;
  })(ID || (ID = {}));
`);
const buildStringAssignment = (0, _core.template)(`
  ENUM["NAME"] = VALUE;
`);
const buildNumericAssignment = (0, _core.template)(`
  ENUM[ENUM["NAME"] = VALUE] = "NAME";
`);

const buildEnumMember = (isString, options) => (isString ? buildStringAssignment : buildNumericAssignment)(options);

function enumFill(path, t, id) {
  const x = translateEnumValues(path, t);
  const assignments = x.map(([memberName, memberValue]) => buildEnumMember(t.isStringLiteral(memberValue), {
    ENUM: t.cloneNode(id),
    NAME: memberName,
    VALUE: memberValue
  }));
  return buildEnumWrapper({
    ID: t.cloneNode(id),
    ASSIGNMENTS: assignments
  });
}

function translateEnumValues(path, t) {
  const seen = Object.create(null);
  let prev = -1;
  return path.node.members.map(member => {
    const name = t.isIdentifier(member.id) ? member.id.name : member.id.value;
    const initializer = member.initializer;
    let value;

    if (initializer) {
      const constValue = evaluate(initializer, seen);

      if (constValue !== undefined) {
        seen[name] = constValue;

        if (typeof constValue === "number") {
          value = t.numericLiteral(constValue);
          prev = constValue;
        } else {
          (0, _assert.default)(typeof constValue === "string");
          value = t.stringLiteral(constValue);
          prev = undefined;
        }
      } else {
        value = initializer;
        prev = undefined;
      }
    } else {
      if (prev !== undefined) {
        prev++;
        value = t.numericLiteral(prev);
        seen[name] = prev;
      } else {
        throw path.buildCodeFrameError("Enum member must have initializer.");
      }
    }

    return [name, value];
  });
}

function evaluate(expr, seen) {
  return evalConstant(expr);

  function evalConstant(expr) {
    switch (expr.type) {
      case "StringLiteral":
        return expr.value;

      case "UnaryExpression":
        return evalUnaryExpression(expr);

      case "BinaryExpression":
        return evalBinaryExpression(expr);

      case "NumericLiteral":
        return expr.value;

      case "ParenthesizedExpression":
        return evalConstant(expr.expression);

      case "Identifier":
        return seen[expr.name];

      case "TemplateLiteral":
        if (expr.quasis.length === 1) {
          return expr.quasis[0].value.cooked;
        }

      default:
        return undefined;
    }
  }

  function evalUnaryExpression({
    argument,
    operator
  }) {
    const value = evalConstant(argument);

    if (value === undefined) {
      return undefined;
    }

    switch (operator) {
      case "+":
        return value;

      case "-":
        return -value;

      case "~":
        return ~value;

      default:
        return undefined;
    }
  }

  function evalBinaryExpression(expr) {
    const left = evalConstant(expr.left);

    if (left === undefined) {
      return undefined;
    }

    const right = evalConstant(expr.right);

    if (right === undefined) {
      return undefined;
    }

    switch (expr.operator) {
      case "|":
        return left | right;

      case "&":
        return left & right;

      case ">>":
        return left >> right;

      case ">>>":
        return left >>> right;

      case "<<":
        return left << right;

      case "^":
        return left ^ right;

      case "*":
        return left * right;

      case "/":
        return left / right;

      case "+":
        return left + right;

      case "-":
        return left - right;

      case "%":
        return left % right;

      default:
        return undefined;
    }
  }
}