如何获取文件中指定行列位置的单词？

Got it, let's work through this problem together. You need to build a get_word function that finds the word containing the character at a given line and column position in a file. Here's how to fill in the missing part of your code, with explanations for each step:

Step-by-Step Explanation #

Once you've located the target line, the key is to find the boundaries of the word that includes the specified column:

1. Convert the 1-based column number to 0-based (since Ruby strings use 0-indexing).
2. Handle edge cases where the column is out of bounds (e.g., column number is larger than the line length).
3. Find the left boundary of the word: move left from the target character until you hit a non-letter character.
4. Find the right boundary: move right until you hit a non-letter character.
5. Extract and return the substring between these boundaries.

We'll use Unicode-aware letter matching (\p{Letter}) to handle accented characters like Á or ñ correctly, and specify UTF-8 encoding to avoid issues with non-ASCII text.

Complete Code #

def get_word(file, position)
  target_line_num = position.line_number
  target_col = position.column_number

  # Iterate through each line with UTF-8 encoding to handle accented characters
  File.each_line(file, encoding: 'UTF-8').with_index do |line, line_idx|
    current_line = line_idx + 1 # Convert 0-based index to 1-based line number
    next unless current_line == target_line_num

    # Remove trailing newline so it doesn't count as a character in the column count
    line_chars = line.chomp.chars
    char_index = target_col - 1 # Convert 1-based column to 0-based index

    # Return nil if column is out of bounds
    return nil if char_index < 0 || char_index >= line_chars.length

    # Find left boundary of the word (first letter of the word)
    left_boundary = char_index
    while left_boundary >= 0 && line_chars[left_boundary] =~ /\p{Letter}/
      left_boundary -= 1
    end
    left_boundary += 1

    # Find right boundary of the word (last letter of the word)
    right_boundary = char_index
    while right_boundary < line_chars.length && line_chars[right_boundary] =~ /\p{Letter}/
      right_boundary += 1
    end
    right_boundary -= 1

    # Join the characters between boundaries to get the word
    return line_chars[left_boundary..right_boundary].join
  end

  # Return nil if the target line doesn't exist in the file
  nil
end

Testing with Your Example #

For your message.md file:

Dear people:
My name is [Ángeliño](#angelino).
Bye!

• get_word("message.md", Position.new(1, 9)) returns "people" (the 9th column is the second 'p' in "people", and the function correctly captures the entire word).
• get_word("message.md", Position.new(2, 13)) returns "Ángeliño" (the 13th column is the Á, and the function handles the accented characters properly).

Key Notes #

• Unicode Support: Using \p{Letter} ensures we match all alphabetic characters across languages, not just ASCII letters.
• Encoding: Specifying encoding: 'UTF-8' when reading the file prevents garbled text for non-ASCII characters.
• Edge Cases: The function returns nil if the target line doesn't exist or the column is out of bounds, making it robust against invalid inputs.

内容的提问来源于stack exchange，提问作者user7450793