Class: Seaquel::ExpressionConverter

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/seaquel/expression_converter.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(quoter) ⇒ ExpressionConverter

Returns a new instance of ExpressionConverter.



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# File 'lib/seaquel/expression_converter.rb', line 9

def initialize quoter
  @quoter = quoter
end

Instance Attribute Details

#quoter ⇒ Object (readonly)

Returns the value of attribute quoter.



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# File 'lib/seaquel/expression_converter.rb', line 7

def quoter
  @quoter
end

Instance Method Details

#sql(node) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 152

def sql node
  # p [:sql, node]
  case node
    when nil
      bit('NULL')
    when Array
      sql_bits = node.map { |el| sql(el).at(0) }
      bit("(" + sql_bits.join(', ') + ")")
    when String
      bit(quote_string(node))
    when Fixnum
      bit(quote_number(node))
    when true,false
      node ? bit('TRUE') : bit('FALSE')
  else
    node.visit(self)
  end
end

#visit_alias(name, to) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 61

def visit_alias name, to
  prec = precedence(:as)
  bit("#{sql(to).at(prec)} AS \"#{name}\"")
end

#visit_assign(left, right) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 22

def visit_assign left, right
  if left.kind_of? AST::Column
    bit(
      [left.as_column_reference(quoter), '=', sql(right).at(0)].join)
  else
    bit(
      [sql(left).at(0), '=', sql(right).at(0)].join)
  end
end

#visit_binding(pos) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 139

def visit_binding pos
  bit("$#{pos}")
end

#visit_binop(op, left, right) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 66

def visit_binop op, left, right
  prec = precedence(op)

  if right.nil?
    op = :is if op==:eq
    op = :isnot if op==:noteq
  end

  if op==:in && right.kind_of?(Range)
    raise "Ranges excluding the right side are not permitted in Seaquel." \
      if right.exclude_end?

    return bit([
      sql(left).at(0), 
      'BETWEEN', 
      right.begin, 
      'AND', 
      right.end].join(' '))
  end

  if binops.has_key?(op)
    symbol = binops[op]

    return bit(
      [sql(left).at(prec), symbol, sql(right).at(prec)].join, 
      prec)
  end

  raise "No such operation (#{op.inspect})."
end

#visit_column(col) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 135

def visit_column col
  bit(col.as_full_reference(quoter))
end

#visit_column_list(elements) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 44

def visit_column_list elements
  # Column lists only contain columns.
  bit(elements.map { |e| e.as_column_reference(quoter) }.join(', '))
end

#visit_funcall(name, args) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 143

def visit_funcall name, args
  arglist = args.map { |arg| sql(arg).toplevel }.join(', ')
  bit("#{name}(#{arglist})")
end

#visit_joinop(op, exps) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 97

def visit_joinop op, exps
  # Shortcut if we join one element only. 
  if exps.size == 1
    el = exps.first
    return sql(el)
  end

  prec = precedence(op)
  parts = exps.map { |e| sql(e).at(prec) }

  sql = case op
    when :and
      parts.join(' AND ')
    when :or
      parts.join(' OR ')
  else
    raise "AF: JoinOp called for #{op.inspect}, but has no branch for it."
  end

  bit(sql, prec)
end

#visit_list(elements) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 40

def visit_list elements
  bit(elements.map { |e| sql(e).at(0) }.join(', '))
end

#visit_literal(literal) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 36

def visit_literal literal
  bit(literal)
end

#visit_new_statement(*args) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 32

def visit_new_statement *args
  ::Seaquel::Generator.new(self).compact_sql
end

#visit_node(node) ⇒ Object

Gets called whenever the expression contains a statement-type AST::Node.



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# File 'lib/seaquel/expression_converter.rb', line 15

def visit_node node
  bit(node.to_sql, 0)
end

#visit_order(order, expr) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 148

def visit_order order, expr
  bit("#{sql(expr).at(0)} #{order.upcase}")
end

#visit_table(table) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 49

def visit_table table
  bit(table.quote(quoter))
end

#visit_table_alias(table, name) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 53

def visit_table_alias table, name
  bit([
    sql(table).at(0), 
    "AS", 
    quoter.identifier(name)
    ].join(' '))
end

#visit_unary(op, exp) ⇒ Object 



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# File 'lib/seaquel/expression_converter.rb', line 119

def visit_unary op, exp
  raise "No such unary operation #{op.inspect}." \
    unless unaryops.has_key?(op)

  symbol, prefix = unaryops[op]
  prec = precedences[op]

  parts = []

  parts << symbol if prefix 
  parts << sql(exp).at(0)
  parts << symbol unless prefix 

  bit(parts.join, prec)
end