Class: PgQuery

Inherits:
Object
  • Object
show all
Defined in:
lib/pg_query/parse.rb,
lib/pg_query/version.rb,
lib/pg_query/parse_error.rb

Defined Under Namespace

Classes: ParseError

Constant Summary collapse

VERSION = 
'0.2.0'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query, parsetree, warnings = []) ⇒ PgQuery

Returns a new instance of PgQuery.



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# File 'lib/pg_query/parse.rb', line 26

def initialize(query, parsetree, warnings = [])
  @query = query
  @parsetree = parsetree
  @warnings = warnings
end

Instance Attribute Details

#parsetree ⇒ Object (readonly)

Returns the value of attribute parsetree.



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# File 'lib/pg_query/parse.rb', line 24

def parsetree
  @parsetree
end

#query ⇒ Object (readonly)

Returns the value of attribute query.



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# File 'lib/pg_query/parse.rb', line 23

def query
  @query
end

#warnings ⇒ Object (readonly)

Returns the value of attribute warnings.



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# File 'lib/pg_query/parse.rb', line 25

def warnings
  @warnings
end

Class Method Details

._raw_parse(input) ⇒ Object 



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# File 'ext/pg_query/pg_query.c', line 34

static VALUE pg_query_raw_parse(VALUE self, VALUE input)
{
  Check_Type(input, T_STRING);
  
  MemoryContext ctx = NULL;
  VALUE result;
  ErrorData* error = NULL;
  char stderr_buffer[STDERR_BUFFER_LEN + 1] = {0};
  int stderr_global;
  int stderr_pipe[2];

  ctx = AllocSetContextCreate(TopMemoryContext,
                "pg_query_raw_parse",
                ALLOCSET_DEFAULT_MINSIZE,
                ALLOCSET_DEFAULT_INITSIZE,
                ALLOCSET_DEFAULT_MAXSIZE);
  MemoryContextSwitchTo(ctx);
  
  // Setup pipe for stderr redirection
  if (pipe(stderr_pipe) != 0)
    rb_raise(rb_eIOError, "Failed to open pipe, too many open file descriptors");

  fcntl(stderr_pipe[0], F_SETFL, fcntl(stderr_pipe[0], F_GETFL) | O_NONBLOCK);
  
  // Redirect stderr to the pipe
  stderr_global = dup(STDERR_FILENO);
  dup2(stderr_pipe[1], STDERR_FILENO);
  close(stderr_pipe[1]);
  
  // Parse it!
  PG_TRY();
  {
    List *tree;
    char *str;
    
    str = StringValueCStr(input);
    tree = raw_parser(str);
    
    str = nodeToString(tree);
  
    // Save stderr for result
    read(stderr_pipe[0], stderr_buffer, STDERR_BUFFER_LEN);
  
    result = rb_ary_new();
    rb_ary_push(result, rb_tainted_str_new_cstr(str));
    rb_ary_push(result, rb_str_new2(stderr_buffer));
  
    pfree(str);
  }
  PG_CATCH();
  {
    error = CopyErrorData();
    FlushErrorState();
  }
  PG_END_TRY();
  
  // Restore stderr, close pipe & return to previous PostgreSQL memory context
  dup2(stderr_global, STDERR_FILENO);
  close(stderr_pipe[0]);
  MemoryContextSwitchTo(TopMemoryContext);
  MemoryContextDelete(ctx);
  
  // If we got an error, throw a ParseError exception
  if (error) raise_parse_error(error);
  
  return result;
}

.normalize(input) ⇒ Object 



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# File 'ext/pg_query/pg_query.c', line 370

static VALUE pg_query_normalize(VALUE self, VALUE input)
{
  Check_Type(input, T_STRING);
  
  MemoryContext ctx = NULL;
  VALUE result;
  ErrorData* error = NULL;
  
  ctx = AllocSetContextCreate(TopMemoryContext,
                "pg_query_normalize",
                ALLOCSET_DEFAULT_MINSIZE,
                ALLOCSET_DEFAULT_INITSIZE,
                ALLOCSET_DEFAULT_MAXSIZE);
  MemoryContextSwitchTo(ctx);
  
  PG_TRY();
  {
    List *tree;
    char *str;
    pgssConstLocations jstate;
    int query_len;
    
    /* Parse query */
    str = StringValueCStr(input);
    tree = raw_parser(str);
    
    /* Set up workspace for constant recording */
    jstate.clocations_buf_size = 32;
    jstate.clocations = (pgssLocationLen *)
      palloc(jstate.clocations_buf_size * sizeof(pgssLocationLen));
    jstate.clocations_count = 0;
    
    /* Walk tree and record const locations */
    const_record_walker((Node *) tree, &jstate);
    
    /* Normalize query */
    query_len = (int) strlen(str);
    str = generate_normalized_query(&jstate, str, &query_len, PG_UTF8);
  
    result = rb_tainted_str_new_cstr(str);
  
    pfree(str);
  }
  PG_CATCH();
  {
    error = CopyErrorData();
    FlushErrorState();
  }
  PG_END_TRY();

  MemoryContextSwitchTo(TopMemoryContext);
  MemoryContextDelete(ctx);
  
  // If we got an error, throw a ParseError exception
  if (error) raise_parse_error(error);
  
  return result;
}

.parse(query) ⇒ Object 



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# File 'lib/pg_query/parse.rb', line 4

def self.parse(query)
  parsetree, stderr = _raw_parse(query)
  
  parsetree = [] if parsetree == '<>'
  
  if !parsetree.nil? && !parsetree.empty?
    parsetree = parsetree_to_json(parsetree)
    parsetree = JSON.parse(parsetree, max_nesting: 1000)
  end
  
  warnings = []
  stderr.each_line do |line|
    next unless line[/^WARNING/]
    warnings << line.strip
  end
  
  PgQuery.new(query, parsetree, warnings)
end

.parsetree_to_json(str) ⇒ Object 



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# File 'lib/pg_query/parse.rb', line 33

def self.parsetree_to_json(str)
  str.strip!
  control_chars = '(){}: '
  location = nil # :hashname, :key, :value
  structure_stack = [] # :hash, :array (when delimiter opens we push, when delimiter closes we pop)
  open_string = false
  escaped_string = false
  next_char_is_escaped = false
  double_hash_close_in = 0 # This is used to ask for an additional closing delimiter (added when x = 1 and we reach a closing delimiter)
  out = ""

  i = 0
  loop do
    break if i > str.size-1
  
    c = str[i]
    last_location = location
    char_is_escaped = next_char_is_escaped
    next_char_is_escaped = false
    if control_chars.include?(c) && !char_is_escaped && (!open_string || !escaped_string)
      # Space is not always a control character, skip in those cases
      if c == ' ' && last_location == :hashname && str[i+1] != ':'
        out += c
        i += 1
        next
      end
      
      # Keep empty nodes as empty hashes (e.g. nodes that can't be output)
      if c == '{' && str[i+1] == '}'
        out += "{}"
        out += ", " if i+2 < str.size && !'})'.include?(str[i+2])
        i += 2 # Skip {}
        next
      end
    
      location = nil # All control characters reset location
    
      # This should never happen, but if it does, catch it
      if open_string
        out += '"' unless escaped_string
        open_string = false
        escaped_string = false
      end
    
      # Write out JSON control characters
      if last_location == :hashname
        out += ': {'
      elsif last_location == :key
        out += ': '
      end
    
      case c
      when '('
        out += '['
      when ')'
        out += ']'
      when '{'
        out += '{'
      when '}'
        out += '}}'
      when ':'
        # No JSON equivalent
      end
      
      # Handle double hash closes (required for out-of-place nodes like ANY)
      case c
      when '{'  
        if double_hash_close_in > 0
          double_hash_close_in += 1
        end
      when '}'
        if double_hash_close_in == 1
          out += '}}'
          double_hash_close_in = 0
        elsif double_hash_close_in > 1
          double_hash_close_in -= 1
        end
      end
    
      # Write out delimiter if needed
      if (last_location == :value || '})'.include?(c)) && i+1 < str.size && !'})'.include?(str[i+1])
        out += ', '
      end
    
      # Determine new location
      case c
      when '{'
        structure_stack << :hash
        location = :hashname
      when '('
        structure_stack << :array
        location = :value if !control_chars.include?(str[i+1])
      when '}', ')'
        structure_stack.pop
      when ':'
        location = :key
      when ' '
        location = :value if [:value, :key].include?(last_location) && !control_chars.include?(str[i+1])
      end
    else
      if char_is_escaped
        case c
        when '"'
          out += "\\\""
        when '\\'
          out += "\\\\"
        else
          out += c
        end
      elsif str[i] == '<' && str[i+1] == '>' && control_chars.include?(str[i+2])
        # Make <> into null values
        i += 1
        out += "null"
      elsif c == '\\'
        next_char_is_escaped = true # For next round
        # Ignore all other cases
      elsif c[/[A-Z]/] && !open_string && last_location != :value && last_location != :hashname && structure_stack.last == :hash
        # We were not expecting a node name here, but this can happen (e.g. with ANY), try to construct into valid expression
        location = :hashname
        double_hash_close_in = 1
        open_string = true
        out += '"lexpr": {"'
        out += c
      elsif control_chars.include?(str[i-1]) && !open_string && !'0123456789'.include?(c)
        open_string = true
        escaped_string = true if c == '"'
        out += '"' unless escaped_string
        out += c
        c = nil # To avoid close string taking care of us...
      else
        out += c
      end
    
      # Close string if next element is control character
      if open_string && !char_is_escaped && c != '\\' &&
         ((last_location == :hashname && ((str[i+1] == '}') || (str[i+1] == ' ' && str[i+2] == ':') || (str[i+1] == ' ' && str[i+2] == ' ' && str[i+3] == ':'))) ||
          (last_location != :hashname && !escaped_string && control_chars.include?(str[i+1])) || 
          (escaped_string && c == '"'))
        out += '"' unless escaped_string
        open_string = false
        escaped_string = false
      end
    end

    i += 1
  end
  out
end