src/text_utils.h

// Copyright 2026 Google Inc. All Rights Reserved.
//
// 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.

#pragma once

#include <string>
#include <vector>

#include "string_piece.h"

struct DiskInterface;

/// Remove both leading and trailing whitespace from a StringPiece.
StringPiece StripStringPiece(StringPiece input);

/// Read input text as a StringPiece, and iterate over its lines.
/// Usage is:
/// 1. Create instance.
/// 2. Call GetNextLine() in a loop, until it returns false.
struct TextLineSplitter {
  /// Constructor takes input text as argument.
  TextLineSplitter(StringPiece content);

  /// Get next line of input. On success, set |*line| and return true.
  /// On end of text, return false.
  bool GetNextLine(StringPiece* line);

 private:
  const char* p_ = nullptr;
  const char* limit_ = nullptr;
};

/// Convenience class to read a text file line-by-line.
/// Empty lines are ignored. Usage is:
///
/// 1. Create instance.
/// 2. Call Reset() to read an input file.
/// 3. Call lines() to see the lines read from the input.
///    these do not include line terminators.
///
struct TextFileParser {
  /// Constructor takes a DiskInterface instance.
  TextFileParser(DiskInterface&);

  /// Read the input file and parse it into lines.
  /// On success, returns true and populates lines_ with the lines from the
  /// input file. On failure, returns false and sets error to a description of
  /// the error.
  bool Reset(const char* input_file, std::string* error);

  /// Returns the lines read from the input file.
  /// Always empty if Reset() returned false.
  const std::vector<StringPiece>& lines() const { return lines_; }

  /// Return the content of the input file.
  /// Always empty if Reset() returned false.
  StringPiece content() const { return content_; }

 private:
  DiskInterface& disk_interface_;
  std::string content_;
  std::vector<StringPiece> lines_;
};