Function createSwitchBlock

packages/compiler/src/render3/r3_control_flow.ts:218–357

(
  ast: html.Block,
  visitor: html.Visitor,
  bindingParser: BindingParser,
)

/** Creates a switch block from an HTML AST node. */
export function createSwitchBlock(
  ast: html.Block,
  visitor: html.Visitor,
  bindingParser: BindingParser,
): {node: t.SwitchBlock | null; errors: ParseError[]} {
  const errors = validateSwitchBlock(ast);
  const primaryExpression =
    ast.parameters.length > 0
      ? parseBlockParameterToBinding(ast.parameters[0], bindingParser)
      : bindingParser.parseBinding('', false, ast.sourceSpan, 0);
  const groups: t.SwitchBlockCaseGroup[] = [];
  const unknownBlocks: t.UnknownBlock[] = [];
  let collectedCases: t.SwitchBlockCase[] = [];
  let firstCaseStart: ParseSourceSpan | null = null;
  let exhaustiveCheck: t.SwitchExhaustiveCheck | null = null;

  // Here we assume that all the blocks are valid given that we validated them above.
  for (const node of ast.children) {
    if (!(node instanceof html.Block)) {
      continue;
    }

    if (
      (node.name !== 'case' || node.parameters.length === 0) &&
      node.name !== 'default' &&
      node.name !== 'default never'
    ) {
      unknownBlocks.push(new t.UnknownBlock(node.name, node.sourceSpan, node.nameSpan));
      continue;
    }

    if (exhaustiveCheck !== null) {
      errors.push(
        new ParseError(
          node.sourceSpan,
          '@default block with "never" parameter must be the last case in a switch',
        ),
      );
    }

    const isCase = node.name === 'case';
    let expression: AST | null = null;

    if (isCase) {
      expression = parseBlockParameterToBinding(node.parameters[0], bindingParser);
    } else if (node.name === 'default never') {
      if (node.parameters.length > 0) {
        expression = parseBlockParameterToBinding(node.parameters[0], bindingParser);
      }

      if (
        node.children.length > 0 ||
        (node.endSourceSpan !== null &&
          node.endSourceSpan.start.offset !== node.endSourceSpan.end.offset)
      ) {
        errors.push(
          new ParseError(
            node.sourceSpan,