/*
 * Copyright 2016 WebAssembly Community Group participants
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef WABT_WAST_LEXER_H_
#define WABT_WAST_LEXER_H_

#include <cstddef>
#include <cstdio>
#include <memory>

#include "common.h"
#include "lexer-source-line-finder.h"
#include "literal.h"
#include "opcode.h"

namespace wabt {

class ErrorHandler;
class LexerSource;
class WastParser;

struct StringTerminal {
  StringTerminal() = default;
  StringTerminal(const char* data, size_t size) : data(data), size(size) {}

  const char* data;
  size_t size;

  // Helper functions.
  std::string to_string() const { return std::string(data, size); }
  string_view to_string_view() const { return string_view(data, size); }
};

struct LiteralTerminal {
  LiteralTerminal() = default;
  LiteralTerminal(LiteralType type, StringTerminal text)
      : type(type), text(text) {}

  LiteralType type;
  StringTerminal text;
};

enum class TokenType {
  Invalid,
  Reserved,
  Eof,
  Lpar,
  Rpar,
  Nat,
  Int,
  Float,
  Text,
  Var,
  ValueType,
  Anyfunc,
  Mut,
  Nop,
  Drop,
  Block,
  End,
  If,
  Then,
  Else,
  Loop,
  Br,
  BrIf,
  BrTable,
  Try,
  Catch,
  CatchAll,
  Throw,
  Rethrow,
  Call,
  CallIndirect,
  Return,
  GetLocal,
  SetLocal,
  TeeLocal,
  GetGlobal,
  SetGlobal,
  Load,
  Store,
  OffsetEqNat,
  AlignEqNat,
  Const,
  Unary,
  Binary,
  Compare,
  Convert,
  Select,
  Unreachable,
  CurrentMemory,
  GrowMemory,
  Func,
  Start,
  Type,
  Param,
  Result,
  Local,
  Global,
  Table,
  Elem,
  Memory,
  Data,
  Offset,
  Import,
  Export,
  Except,
  Module,
  Bin,
  Quote,
  Register,
  Invoke,
  Get,
  AssertMalformed,
  AssertInvalid,
  AssertUnlinkable,
  AssertReturn,
  AssertReturnCanonicalNan,
  AssertReturnArithmeticNan,
  AssertTrap,
  AssertExhaustion,

  First = Invalid,
  Last = AssertExhaustion,
};

const char* GetTokenTypeName(TokenType);

struct Token {
  Token() : token_type(TokenType::Invalid) {}
  Token(Location, TokenType);
  Token(Location, TokenType, Type);
  Token(Location, TokenType, StringTerminal);
  Token(Location, TokenType, Opcode);
  Token(Location, TokenType, LiteralTerminal);

  Location loc;
  TokenType token_type;

  union {
    StringTerminal text;
    Type type;
    Opcode opcode;
    LiteralTerminal literal;
  };

  std::string to_string() const;
};

class WastLexer {
 public:
  WABT_DISALLOW_COPY_AND_ASSIGN(WastLexer);

  WastLexer(std::unique_ptr<LexerSource> source, const char* filename);
  ~WastLexer();

  // Convenience functions.
  static std::unique_ptr<WastLexer> CreateFileLexer(const char* filename);
  static std::unique_ptr<WastLexer> CreateBufferLexer(const char* filename,
                                                      const void* data,
                                                      size_t size);

  Token GetToken(WastParser* parser);
  Result Fill(size_t need);

  // TODO(binji): Move this out of the lexer.
  LexerSourceLineFinder& line_finder() { return line_finder_; }

 private:
  Location GetLocation();
  LiteralTerminal MakeLiteral(LiteralType);
  StringTerminal GetText(size_t at = 0);

  std::unique_ptr<LexerSource> source_;
  LexerSourceLineFinder line_finder_;
  const char* filename_;
  int line_;
  int comment_nesting_;
  size_t buffer_file_offset_; // File offset of the start of the buffer.
  size_t line_file_offset_;   // File offset of the start of the current line.

  // Lexing data needed by re2c.
  bool eof_;
  char* buffer_;
  size_t buffer_size_;
  char* marker_;
  char* next_pos_;
  char* cursor_;
  char* limit_;
};

}  // namespace wabt

#endif /* WABT_WAST_LEXER_H_ */