Class: SyntaxTree::Database::AttrQuery

Inherits:
Object
  • Object
show all
Defined in:
lib/syntax_tree/database.rb

Overview

Query for the attributes of a node, optionally also filtering by type.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(type, attrs) ⇒ AttrQuery

Returns a new instance of AttrQuery.



102
103
104
105
 
# File 'lib/syntax_tree/database.rb', line 102

def initialize(type, attrs)
  @type = type
  @attrs = attrs
end

Instance Attribute Details

#attrs ⇒ Object (readonly)

Returns the value of attribute attrs.



100
101
102
 
# File 'lib/syntax_tree/database.rb', line 100

def attrs
  @attrs
end

#type ⇒ Object (readonly)

Returns the value of attribute type.



100
101
102
 
# File 'lib/syntax_tree/database.rb', line 100

def type
  @type
end

Instance Method Details

#each(database, &block) ⇒ Object 



107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
 
# File 'lib/syntax_tree/database.rb', line 107

def each(database, &block)
  joins = []
  binds = []

  attrs.each do |name, query|
    ids = query.each(database).map { |row| row[0] }
    joins << <<~SQL
      JOIN edges AS #{name}
      ON #{name}.from_id = nodes.id
      AND #{name}.name = ?
      AND #{name}.to_id IN (#{(["?"] * ids.size).join(", ")})
    SQL

    binds.push(name).concat(ids)
  end

  sql = +"SELECT nodes.* FROM nodes, edges #{joins.join(" ")}"

  if type
    sql << " WHERE nodes.type = ?"
    binds << type
  end

  sql << " GROUP BY nodes.id"
  database.execute(sql, binds).each(&block)
end