Class: PgQuery

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

Defined Under Namespace

Classes: ParseError

Constant Summary collapse

VERSION = 
'0.5.0'

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 25

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 23

def parsetree
  @parsetree
end

#query ⇒ Object (readonly)

Returns the value of attribute query.



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# File 'lib/pg_query/parse.rb', line 22

def query
  @query
end

#warnings ⇒ Object (readonly)

Returns the value of attribute warnings.



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

def warnings
  @warnings
end

Class Method Details

._raw_parse(input) ⇒ Object

#define DEBUG



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# File 'ext/pg_query/pg_query.c', line 36

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

  ctx = AllocSetContextCreate(TopMemoryContext,
                "pg_query_raw_parse",
                ALLOCSET_DEFAULT_MINSIZE,
                ALLOCSET_DEFAULT_INITSIZE,
                ALLOCSET_DEFAULT_MAXSIZE);
  MemoryContextSwitchTo(ctx);
  
#ifndef DEBUG
  // 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]);
#endif
  
  // Parse it!
  PG_TRY();
  {
    List *tree;
    char *str;
    
    str = StringValueCStr(input);
    tree = raw_parser(str);
    
    str = nodeToJSONString(tree);
  
#ifndef DEBUG
    // Save stderr for result
    read(stderr_pipe[0], stderr_buffer, STDERR_BUFFER_LEN);
#endif

    result = rb_ary_new();
    rb_ary_push(result, rb_str_new2(str));
    rb_ary_push(result, rb_str_new2(stderr_buffer));
  
    pfree(str);
  }
  PG_CATCH();
  {
    ErrorData* error_data = CopyErrorData();
    error = new_parse_error(error_data);
    FlushErrorState();
  }
  PG_END_TRY();
  
#ifndef DEBUG
  // Restore stderr, close pipe
  dup2(stderr_global, STDERR_FILENO);
  close(stderr_pipe[0]);
  close(stderr_global);
#endif

  // Return to previous PostgreSQL memory context
  MemoryContextSwitchTo(TopMemoryContext);
  MemoryContextDelete(ctx);
  
  // If we got an error, throw it
  if (!NIL_P(error)) rb_exc_raise(error);
  
  return result;
}

.normalize(input) ⇒ Object 



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# File 'ext/pg_query/pg_query.c', line 408

static VALUE pg_query_normalize(VALUE self, VALUE input)
{
  Check_Type(input, T_STRING);
  
  MemoryContext ctx = NULL;
  VALUE result = Qnil;
  VALUE error = Qnil;
  
  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_str_new2(str);
  
    pfree(str);
  }
  PG_CATCH();
  {
    ErrorData* error_data = CopyErrorData();
    error = new_parse_error(error_data);
    FlushErrorState();
  }
  PG_END_TRY();
  
  MemoryContextSwitchTo(TopMemoryContext);
  MemoryContextDelete(ctx);
  
  // If we got an error, throw it
  if (!NIL_P(error)) rb_exc_raise(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)

  begin
    parsetree = JSON.parse(parsetree, max_nesting: 1000)
  rescue JSON::ParserError => e
    raise ParseError.new("Failed to parse JSON", -1)
  end

  warnings = []
  stderr.each_line do |line|
    next unless line[/^WARNING/]
    warnings << line.strip
  end

  PgQuery.new(query, parsetree, warnings)
end

Instance Method Details

#aliases ⇒ Object 



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# File 'lib/pg_query/parse.rb', line 36

def aliases
  load_tables_and_aliases! if @aliases.nil?
  @aliases
end

#filter_columns ⇒ Object

Returns a list of columns that the query filters by - this excludes the target list, but includes things like JOIN condition and WHERE clause.

Note: This also traverses into sub-selects.



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# File 'lib/pg_query/filter_columns.rb', line 6

def filter_columns
  load_tables_and_aliases! if @aliases.nil?

  # Get condition items from the parsetree
  statements = @parsetree.dup
  condition_items = []
  filter_columns = []
  loop do
    if statement = statements.shift
      if statement["SELECT"]
        if statement["SELECT"]["op"] == 0
          if statement["SELECT"]["fromClause"]
            # FROM subselects
            statement["SELECT"]["fromClause"].each do |item|
              statements << item["RANGESUBSELECT"]["subquery"] if item["RANGESUBSELECT"]
            end

            # JOIN ON conditions
            condition_items += conditions_from_join_clauses(statement["SELECT"]["fromClause"])
          end

          # WHERE clause
          condition_items << statement["SELECT"]["whereClause"] if statement["SELECT"]["whereClause"]
        elsif statement["SELECT"]["op"] == 1
          statements << statement["SELECT"]["larg"] if statement["SELECT"]["larg"]
          statements << statement["SELECT"]["rarg"] if statement["SELECT"]["rarg"]
        end
      elsif statement["UPDATE"]
        condition_items << statement["UPDATE"]["whereClause"] if statement["UPDATE"]["whereClause"]
      elsif statement["DELETE FROM"]
        condition_items << statement["DELETE FROM"]["whereClause"] if statement["DELETE FROM"]["whereClause"]
      end
    end

    # Process both JOIN and WHERE conditions here
    if next_item = condition_items.shift
      if next_item.keys[0].start_with?("AEXPR") || next_item["ANY"]
        ["lexpr", "rexpr"].each do |side|
          next unless expr = next_item.values[0][side]
          next unless expr.is_a?(Hash)
          condition_items << expr
        end
      elsif next_item["ROW"]
        condition_items += next_item["ROW"]["args"]
      elsif next_item["COLUMNREF"]
        column, table = next_item["COLUMNREF"]["fields"].reverse
        filter_columns << [@aliases[table] || table, column]
      elsif next_item["NULLTEST"]
        condition_items << next_item["NULLTEST"]["arg"]
      elsif next_item["FUNCCALL"]
        # FIXME: This should actually be extracted as a funccall and be compared with those indices
        condition_items += next_item["FUNCCALL"]["args"] if next_item["FUNCCALL"]["args"]
      elsif next_item["SUBLINK"]
        condition_items << next_item["SUBLINK"]["testexpr"]
        statements << next_item["SUBLINK"]["subselect"]
      end
    end

    break if statements.empty? && condition_items.empty?
  end

  filter_columns.uniq
end

#fingerprint ⇒ Object 



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

def fingerprint
  normalized_parsetree = deep_dup(parsetree)
  exprs = normalized_parsetree.dup
  loop do
    expr = exprs.shift

    if expr.is_a?(Hash)
      expr.each do |k,v|
        if v.is_a?(Hash) && ["A_CONST", "ALIAS", "PARAMREF"].include?(v.keys[0])
          # Remove constants, aliases and param references from tree
          expr[k] = nil
        elsif k == "location"
          # Remove location info in order to ignore whitespace and target list ordering
          expr.delete(k)
        elsif !v.nil?
          # Remove SELECT target list names & ignore order
          if k == "targetList" && v.is_a?(Array)
            v.each {|v| v["RESTARGET"]["name"] = nil if v["RESTARGET"] } # Remove names
            v.sort_by! {|v| v.to_s }
            expr[k] = v
          end

          # Ignore INSERT cols order
          if k == "cols" && v.is_a?(Array)
            v.sort_by! {|v| v.to_s }
            expr[k] = v
          end

          # Process sub-expressions
          exprs << v
        end
      end
    elsif expr.is_a?(Array)
      exprs += expr
    end

    break if exprs.empty?
  end

  Digest::SHA1.hexdigest(normalized_parsetree.to_s)
end

#param_refs ⇒ Object 



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# File 'lib/pg_query/param_refs.rb', line 2

def param_refs
  results = []
  exprs = parsetree.dup
  loop do
    expr = exprs.shift

    if expr.is_a?(Hash)
      expr.each do |k,v|
        if v.is_a?(Hash)
          if v["PARAMREF"]
            length = 1 # FIXME: Not true when we have actual paramrefs
            results << {"location" => v["PARAMREF"]["location"], "length" => length}
            next
          elsif (p = v["TYPECAST"]["arg"]["PARAMREF"] rescue false) && (t = v["TYPECAST"]["typeName"]["TYPENAME"] rescue false)
            location = p["location"]
            typeloc = t["location"]
            typename = t["names"].join(".")
            length = 1 # FIXME: Not true when we have actual paramrefs
            if typeloc < location
              length += location - typeloc
              location = typeloc
            end
            results << {"location" => location, "length" => length, "typename" => typename}
            next
          end
        end

        exprs << v if !v.nil?
      end
    elsif expr.is_a?(Array)
      exprs += expr
    end

    break if exprs.empty?
  end
  results.sort_by! {|r| r["location"] }
  results
end

#tables ⇒ Object 



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# File 'lib/pg_query/parse.rb', line 31

def tables
  load_tables_and_aliases! if @tables.nil?
  @tables
end