//===-- DILLexerTests.cpp --------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "lldb/ValueObject/DILLexer.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Testing/Support/Error.h"
#include "gtest/gtest.h"
#include <string>

using llvm::StringRef;

using namespace lldb_private::dil;

llvm::Expected<std::vector<std::pair<Token::Kind, std::string>>>
ExtractTokenData(llvm::StringRef input_expr) {

  llvm::Expected<DILLexer> maybe_lexer = DILLexer::Create(input_expr);
  if (!maybe_lexer)
    return maybe_lexer.takeError();
  DILLexer lexer(*maybe_lexer);

  std::vector<std::pair<Token::Kind, std::string>> data;
  do {
    Token tok = lexer.GetCurrentToken();
    data.push_back(std::make_pair(tok.GetKind(), tok.GetSpelling()));
    lexer.Advance();
  } while (data.back().first != Token::eof);
  // Don't return the eof token.
  data.pop_back();
  return data;
}

TEST(DILLexerTests, SimpleTest) {
  StringRef input_expr("simple_var");
  llvm::Expected<DILLexer> maybe_lexer = DILLexer::Create(input_expr);
  ASSERT_THAT_EXPECTED(maybe_lexer, llvm::Succeeded());
  DILLexer lexer(*maybe_lexer);
  Token token = lexer.GetCurrentToken();

  EXPECT_EQ(token.GetKind(), Token::identifier);
  EXPECT_EQ(token.GetSpelling(), "simple_var");
  lexer.Advance();
  token = lexer.GetCurrentToken();
  EXPECT_EQ(token.GetKind(), Token::eof);
}

TEST(DILLexerTests, TokenKindTest) {
  Token token = Token(Token::identifier, "ident", 0);

  EXPECT_TRUE(token.Is(Token::identifier));
  EXPECT_FALSE(token.Is(Token::l_paren));
  EXPECT_TRUE(token.IsOneOf(Token::eof, Token::identifier));
  EXPECT_FALSE(token.IsOneOf(Token::l_paren, Token::r_paren, Token::coloncolon,
                             Token::eof));
}

TEST(DILLexerTests, LookAheadTest) {
  StringRef input_expr("(anonymous namespace)::some_var");
  llvm::Expected<DILLexer> maybe_lexer = DILLexer::Create(input_expr);
  ASSERT_THAT_EXPECTED(maybe_lexer, llvm::Succeeded());
  DILLexer lexer(*maybe_lexer);
  Token token = lexer.GetCurrentToken();

  // Current token is '('; check the next 4 tokens, to make
  // sure they are the identifier 'anonymous', the identifier 'namespace'
  // ')' and '::', in that order.
  EXPECT_EQ(token.GetKind(), Token::l_paren);
  EXPECT_EQ(lexer.LookAhead(1).GetKind(), Token::identifier);
  EXPECT_EQ(lexer.LookAhead(1).GetSpelling(), "anonymous");
  EXPECT_EQ(lexer.LookAhead(2).GetKind(), Token::identifier);
  EXPECT_EQ(lexer.LookAhead(2).GetSpelling(), "namespace");
  EXPECT_EQ(lexer.LookAhead(3).GetKind(), Token::r_paren);
  EXPECT_EQ(lexer.LookAhead(4).GetKind(), Token::coloncolon);

  // Our current index should still be 0, as we only looked ahead; we are still
  // officially on the '('.
  EXPECT_EQ(lexer.GetCurrentTokenIdx(), 0u);

  // Accept the 'lookahead', so our current token is '::', which has the index
  // 4 in our vector of tokens (which starts at zero).
  lexer.Advance(4);
  token = lexer.GetCurrentToken();
  EXPECT_EQ(token.GetKind(), Token::coloncolon);
  EXPECT_EQ(lexer.GetCurrentTokenIdx(), 4u);

  lexer.Advance();
  token = lexer.GetCurrentToken();
  EXPECT_EQ(token.GetKind(), Token::identifier);
  EXPECT_EQ(token.GetSpelling(), "some_var");
  EXPECT_EQ(lexer.GetCurrentTokenIdx(), 5u);
  EXPECT_EQ(token.GetLocation(), strlen("(anonymous namespace)::"));

  lexer.Advance();
  token = lexer.GetCurrentToken();
  EXPECT_EQ(token.GetKind(), Token::eof);
}

TEST(DILLexerTests, MultiTokenLexTest) {
  EXPECT_THAT_EXPECTED(
      ExtractTokenData("This string has (several ) ::identifiers"),
      llvm::HasValue(testing::ElementsAre(
          testing::Pair(Token::identifier, "This"),
          testing::Pair(Token::identifier, "string"),
          testing::Pair(Token::identifier, "has"),
          testing::Pair(Token::l_paren, "("),
          testing::Pair(Token::identifier, "several"),
          testing::Pair(Token::r_paren, ")"),
          testing::Pair(Token::coloncolon, "::"),
          testing::Pair(Token::identifier, "identifiers"))));
}

TEST(DILLexerTests, IdentifiersTest) {
  // These strings should lex into identifier tokens.
  std::vector<std::string> valid_identifiers = {
      "$My_name1", "$pc",  "abcd", "_", "_a",     "_a_",      "$",
      "a_b",       "this", "self", "a", "MyName", "namespace"};

  // The lexer can lex these strings, but they should not be identifiers.
  std::vector<std::string> invalid_identifiers = {"", "::", "(", ")"};

  // The lexer is expected to fail attempting to lex these strings (it cannot
  // create valid tokens out of them).
  std::vector<std::string> invalid_tok_strings = {"234", "2a", "2", "1MyName"};

  // Verify that all of the valid identifiers come out as identifier tokens.
  for (auto &str : valid_identifiers) {
    SCOPED_TRACE(str);
    EXPECT_THAT_EXPECTED(ExtractTokenData(str),
                         llvm::HasValue(testing::ElementsAre(
                             testing::Pair(Token::identifier, str))));
  }

  // Verify that the lexer fails on invalid token strings.
  for (auto &str : invalid_tok_strings) {
    SCOPED_TRACE(str);
    auto maybe_lexer = DILLexer::Create(str);
    EXPECT_THAT_EXPECTED(maybe_lexer, llvm::Failed());
  }

  // Verify that none of the invalid identifiers come out as identifier tokens.
  for (auto &str : invalid_identifiers) {
    SCOPED_TRACE(str);
    llvm::Expected<DILLexer> maybe_lexer = DILLexer::Create(str);
    EXPECT_THAT_EXPECTED(maybe_lexer, llvm::Succeeded());
    DILLexer lexer(*maybe_lexer);
    Token token = lexer.GetCurrentToken();
    EXPECT_TRUE(token.IsNot(Token::identifier));
    EXPECT_TRUE(token.IsOneOf(Token::eof, Token::coloncolon, Token::l_paren,
                              Token::r_paren));
  }
}