Class: SQLPP::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/sqlpp/parser.rb

Defined Under Namespace

Classes: Exception, TrailingTokens, UnexpectedToken

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/sqlpp/parser.rb', line 104

def initialize(string)
  @tokenizer = SQLPP::Tokenizer.new(string)
end

Class Method Details

.parse(string) ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 99

def self.parse(string)
  parser = new(string)
  parser.parse
end

Instance Method Details

#_eat(type_or_types, pattern = nil) ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 488

def _eat(type_or_types, pattern=nil)
  _next if _peek(type_or_types, pattern)
end

#_ensure_stream_empty! ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 523

def _ensure_stream_empty!
  unless _peek(:eof)
    raise TrailingTokens, _next.inspect
  end
end

#_expect(type_or_types, pattern = nil) ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 509

def _expect(type_or_types, pattern=nil)
  token = _next

  if !_match(token, type_or_types, pattern)
    raise UnexpectedToken, "expected #{type_or_types.inspect}(#{pattern.inspect}), got #{token.inspect}"
  end

  token
end

#_match(token, type_or_types, pattern = nil) ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 499

def _match(token, type_or_types, pattern=nil)
  types = type_or_types.is_a?(Array) ? type_or_types : [ type_or_types ]

  if types.include?(token.type) && (pattern.nil? || pattern === token.text)
    token
  else
    nil
  end
end

#_next ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 519

def _next
  @tokenizer.next
end

#_parse_atom ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 397

def _parse_atom
  if (lit = _eat(:lit))
    AST::Atom.new(:lit, lit.text)

  elsif (key = _eat(:key, :case))
    _parse_case

  elsif _eat(:punct, "(")
    expr = _parse_expr1
    _eat :space
    _expect(:punct, ")")
    AST::Parens.new(expr)

  elsif _eat(:key, :null)
    AST::Atom.new(:lit, "NULL")

  elsif _eat(:punct, "*")
    AST::Atom.new(:lit, "*")

  else
    id = _expect(:id)

    if _eat(:punct, "(")
      args = _parse_list
      _expect(:punct, ")")
      AST::Atom.new(:func, id.text, args)
    elsif _eat(:punct, '.')
      id2 = _eat(:id) || _eat(:punct, '*')

      if !id2
        raise UnexpectedToken, "expected id or *, got #{_peek.inspect}"
      end

      AST::Atom.new(:attr, id.text, id2.text)
    else
      AST::Atom.new(:attr, id.text)
    end
  end
end

#_parse_case ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 437

def _parse_case
  _expect :space

  kase = AST::Atom.new(:case)
  unless _peek(:key, :when)
    kase.left = _parse_expr1
    _eat :space
  end

  cases = []
  while _eat(:key, :when)
    condition = _parse_expr1
    _eat :space
    _expect :key, :then
    result = _parse_expr1
    cases << [condition, result]
    _eat :space
  end

  if _eat(:key, :else)
    cases << _parse_expr1
    _eat :space
  end

  _expect :key, :end

  kase.right = cases
  kase
end

#_parse_entity ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 283

def _parse_entity
  _eat :space

  entity = if _eat(:punct, '(')
      from = _parse_from
      _eat :space
      _expect :punct, ')'
      AST::Parens.new(from)

    elsif _peek(:key, :select)
      _parse_select

    else
      id = _expect(:id)
      AST::Atom.new(:attr, id.text)
    end

  _eat :space
  if _eat(:key, :as)
    _eat :space
    id = _expect(:id)
    AST::As.new(id.text, entity)
  elsif (id = _eat(:id))
    AST::Alias.new(id.text, entity)
  else
    entity
  end
end

#_parse_expr1 ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 312

def _parse_expr1
  _eat :space

  left = _parse_expr2
  _eat :space

  if (op = _eat(:key, /^(and|or|is)$/i))
    op = op.text

    if op == :is
      _eat :space
      op2 = _eat(:key, :not)
      op = "#{op} #{op2.text}" if op2
    end

    right = _parse_expr1

    AST::Expr.new(left, op, right)
  else
    left
  end
end

#_parse_expr2 ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 335

def _parse_expr2
  _eat :space

  left = _parse_expr3
  _eat :space

  if (op = _eat(:key, :between))
    op = op.text

    _eat :space
    lo = _parse_expr3

    _eat :space
    _expect :key, :and

    _eat :space
    hi = _parse_expr3

    right = AST::Atom.new(:range, lo, hi)

  elsif (op = _eat(:key, :in))
    op = op.text

    _eat :space
    _expect :punct, "("

    right = AST::Atom.new(:list, _parse_list)
    _eat :space
    _expect :punct, ")"

  elsif (op = _eat(:punct, /<=|<>|>=|=|<|>/) || _eat(:key, /^i?like$/))
    op = op.text
    right = _parse_expr3
  end

  if right
    AST::Expr.new(left, op, right)
  else
    left
  end
end

#_parse_expr3 ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 377

def _parse_expr3
  _eat :space

  if (op = (_eat(:punct, /[-+]/) || _eat(:key, /^(not|distinct)$/)))
    _eat :space
    AST::Unary.new(op.text, _parse_expr3)

  else
    atom = _parse_atom
    _eat :space

    if (op = _eat(:punct, /[-+*\/]/))
      _eat :space
      AST::Expr.new(atom, op.text, _parse_expr3)
    else
      atom
    end
  end
end

#_parse_from ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 249

def _parse_from
  entity = _parse_entity

  loop do
    _eat :space

    if (which = _eat(:key, /^(inner|cross|left|right|full|outer)$/))
      type = which.text.to_s

      if type == "full" || type == "left" || type == "right"
        _eat :space
        _expect :key, :outer
        type << " outer"
      end

      _eat :space
      _expect :key, :join

      entity = AST::Join.new(type.downcase, entity, _parse_from)

      _eat :space
      if _eat(:key, :on)
        _eat :space
        entity.on = _parse_expr1
      end

    else
      break
    end
  end

  entity
end

#_parse_list ⇒ Object

list := ”

| expr
| expr ',' args



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# File 'lib/sqlpp/parser.rb', line 470

def _parse_list
  _eat :space
  args = []

  loop do
    args << _parse_expr1

    _eat :space
    if _eat(:punct, ",")
      _eat :space
    else
      break
    end
  end

  args
end

#_parse_select ⇒ Object

— internal use —



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# File 'lib/sqlpp/parser.rb', line 142

def _parse_select
  _expect :key, :select
  select = AST::Select.new

  _eat :space
  if _eat(:key, :distinct)
    select.distinct = true
    _eat :space
  end

  if !_peek(:key, /^(from|where)$/) && !_peek(:eof)
    list = []

    loop do
      expr = _parse_expr1
      _eat :space
      if _peek(:key, :as)
        _next
        _eat :space
        name = _expect(:id)
        expr = AST::As.new(name.text, expr)
      end
      list.push expr
      break unless _eat(:punct, ",")
    end
    _eat :space

    select.projections = list
  end

  if _eat(:key, :from)
    list = []

    loop do
      _eat :space
      list << _parse_from
      _eat :space
      break unless _eat(:punct, ',')
    end
    _eat :space

    select.froms = list
  end

  if _eat(:key, :where)
    select.wheres = _parse_expr1
    _eat :space
  end

  if _eat(:key, :group)
    _eat :space
    _expect :key, :by
    _eat :space
    select.groups = _parse_list
  end

  if _eat(:key, :order)
    _eat :space
    _expect :key, :by
    _eat :space

    list = []
    loop do
      key = AST::SortKey.new(_parse_expr1, [])
      list << key

      _eat :space

      if (dir = _eat(:key, /^(asc|desc)$/))
        _eat :space
        key.options << dir.text
      end

      if (opt = _eat(:key, :nulls))
        opt = opt.text.to_s
        _eat :space
        sort = _eat(:key, /^(first|last)$/)
        opt << " " << sort.text.to_s if sort
        key.options << opt
      end

      _eat :space
      break unless _eat(:punct, ",")
    end

    select.orders = list
  end

  if _eat(:key, :limit)
    _eat :space
    atom = _parse_atom
    _eat :space

    select.limit = AST::Limit.new(atom)
  end

  if _eat(:key, :offset)
    _eat :space
    atom = _parse_atom
    _eat :space

    select.offset = AST::Offset.new(atom)
  end

  select
end

#_peek(type_or_types, pattern = nil) ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 492

def _peek(type_or_types, pattern=nil)
  token = _next
  _match(token, type_or_types, pattern)
ensure
  @tokenizer.push(token)
end

#parse ⇒ Object

Raises:



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# File 'lib/sqlpp/parser.rb', line 108

def parse
  _eat :space

  token = _peek(:key)
  raise UnexpectedToken, token.inspect unless token

  case token.text
    when :select then parse_select
    else raise UnexpectedToken, token.inspect
  end
end

#parse_expression ⇒ Object

— exposed for testing purposes —



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# File 'lib/sqlpp/parser.rb', line 122

def parse_expression
  _parse_expr1
ensure
  _ensure_stream_empty!
end

#parse_from ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 128

def parse_from
  _parse_from
ensure
  _ensure_stream_empty!
end

#parse_select ⇒ Object 



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# File 'lib/sqlpp/parser.rb', line 134

def parse_select
  _parse_select
ensure
  _ensure_stream_empty!
end