text: //===--- ParseRegex.cpp - Regular expression literal parsing --------------===//
  //
  // This source file is part of the Swift.org open source project
  //
  // Copyright (c) 2021 Apple Inc. and the Swift project authors
  // Licensed under Apache License v2.0 with Runtime Library Exception
  //
  // See https://swift.org/LICENSE.txt for license information
  // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
  //
  //===----------------------------------------------------------------------===//
  //
  // Regular expression literal parsing
  //
  //===----------------------------------------------------------------------===//
  
  #include "swift/Parse/Parser.h"
  #include "swift/AST/DiagnosticsParse.h"
  #include "swift/Parse/ParsedSyntaxRecorder.h"
  #include "swift/Parse/SyntaxParsingContext.h"
  #include "swift/Syntax/SyntaxKind.h"
  
  // Regex parser delivered via libSwift
  #include "swift/Parse/ExperimentalRegexBridging.h"
  static ParseRegexStrawperson parseRegexStrawperson = nullptr;
  void Parser_registerParseRegexStrawperson(ParseRegexStrawperson fn) {
    parseRegexStrawperson = fn;
  }
  // Exposes the presence of the regex parsing function to the lexer.
  bool Parser_hasParseRegexStrawperson() {
    return parseRegexStrawperson != nullptr;
  }
  
  using namespace swift;
  using namespace swift::syntax;
  
  ParserResult<Expr> Parser::parseExprRegexLiteral() {
    assert(Tok.is(tok::regex_literal));
    assert(parseRegexStrawperson);
  
    SyntaxParsingContext LocalContext(SyntaxContext,
                                      SyntaxKind::RegexLiteralExpr);
    // Strip off delimiters.
    auto rawText = Tok.getText();
    assert(rawText.front() == '\'' && rawText.back() == '\'');
    auto regexText = rawText.slice(1, rawText.size() - 1);
  
    // Let the Swift library parse the contents, returning an error, or null if
    // successful.
    // TODO: We need to be able to pass back a source location to emit the error
    // at.
    auto *errorStr = parseRegexStrawperson(regexText.str().c_str());
    if (errorStr)
      diagnose(Tok, diag::regex_literal_parsing_error, errorStr);
  
    auto loc = consumeToken();
    return makeParserResult(
        RegexLiteralExpr::createParsed(Context, loc, regexText));
  }
  