理解emacs align regexp

我已经阅读了align regexp的emacs文档，但仍然难以理解它是如何工作的。我所说的是它的前缀形式C-u m-x align regexp，而不是简单的形式m-x align regexp。我的问题是:

正则表达式的第一个参数必须匹配整行字符串吗？如果正则表达式只匹配字符串的一部分呢？ 为第二个参数圆括号组提供什么，以便在为负时修改“对齐”？正如我在这里所理解的，我需要从1中提供一个捕获的组数计数，对吗？如果是否定的话，那么是否需要证明，如果我想让第3组右对齐，我会提供-3作为输入？ 如果为负，则间距或列的第三个参数量意味着什么？我完全不明白这个参数的作用。 我收集了一些文本示例进行练习。如果有人可以使用下面的文字作为例子，这将是非常有帮助的

从

到

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对于第一种情况，请选择创建表下面的区域，然后尝试C-uM-xalign-regexp\：\-1 y

对于第二种情况，请选择区域并尝试C-uM-xalign-regexp\[0-9]+\-1 y

如您所见，正则表达式不必匹配整个字符串。您对第二个参数的理解似乎是正确的。有关详细信息，请阅读“对齐规则帮助”列表：

---

您在\：：上缺少一个反斜杠。而且，这并不能真正回答问题。重复

class CreateStudents < ActiveRecord::Migration
  def change
    create_table :students, :comment => "学生信息表" do |t|
      t.string :political_status, :comment => "政治面貌"
      t.string :education_level, :comment => "培养层次"
      t.string :enroll_method, :comment => "入学方式"
      t.date :enrolled_at, :comment => "入学时间"
      t.string :charge_type, :comment => "收费类别"
      t.string :enrolled_year, :comment => "学籍年度"
      t.string :enrolled_place, :comment => "生源所在地"
      t.string :bank_card_number, :comment => "银行卡号"
      t.string :bank_account_number,  :comment => "银行账号"
      t.boolean :is_active_duty, :default => false, :comment => "是否现役军人"
      t.boolean :is_equivalent_degree, :default => false, :comment => "是否同等学历"
      t.boolean :is_on_record, :default => true, :comment => "是否在籍"
      t.boolean :is_at_school, :default => true, :comment => "是否在校"
      t.timestamps
    end
  end
end

class CreateStudents < ActiveRecord::Migration
  def change
    create_table :students, :comment => "学生信息表" do |t|
      t.string  :political_status,     :comment => "政治面貌"
      t.string  :education_level,      :comment => "培养层次"
      t.string  :enroll_method,        :comment => "入学方式"
      t.date    :enrolled_at,          :comment => "入学时间"
      t.string  :charge_type,          :comment => "收费类别"
      t.string  :enrolled_year,        :comment => "学籍年度"
      t.string  :enrolled_place,       :comment => "生源所在地"
      t.string  :bank_card_number,     :comment => "银行卡号"
      t.string  :bank_account_number,  :comment => "银行账号"
      t.boolean :is_active_duty,       :default => false,  :comment => "是否现役军人"
      t.boolean :is_equivalent_degree, :default => false,  :comment => "是否同等学历"
      t.boolean :is_on_record,         :default => true,   :comment => "是否在籍"
      t.boolean :is_at_school,         :default => true,   :comment => "是否在校"
      t.timestamps
    end
  end
end

my @primes = (
    1,2,3,5,7,
    11,13,17,19,23,
    29,31,37,41,43,
);

my @primes = (
    1,  2,  3,  5,  7,
    11, 13, 17, 19, 23,
    29, 31, 37, 41, 43,
);

`column'    For alignment rules, if the `column' attribute is set --
        which must be an integer, or a symbol whose value is an
        integer -- it will be used as the column in which to align
        the alignment character.  If the text on a particular line
        happens to overrun that column, a single space character,
        or tab stop (see `align-to-tab-stop') will be added
        between the last text character and the alignment
        character.

`spacing'   Alignment rules may also override the amount of spacing
        that would normally be used by providing a `spacing'
        attribute.  This must be an integer, or a list of integers
        corresponding to the number of parenthesis groups matched
        by the `group' attribute.  If a list of value is used, and
        any of those values is nil, `align-default-spacing' will
        be used for that subgroup.  See `align-default-spacing'
        for more details on spacing, tab stops, and how to
        indicate how much spacing should be used.  If TAB-STOP is
        present, it will override the value of `align-to-tab-stop'
        for that rule.