Merge pull request #28 from JackDanger/deparse-constraints

Deparse constraints

lib/pg_query/deparse.rb

@@ -357,9 +357,14 @@ def deparse_columndef(node)
 
     def deparse_constraint(node)
       output = []
+      if node['conname']
+        output << 'CONSTRAINT'
+        output << node['conname']
+      end
       # NOT_NULL -> NOT NULL
       output << node['contype'].gsub('_', ' ')
       output << deparse_item(node['raw_expr']) if node['raw_expr']
+      output << '(' + node['keys'].join(', ') + ')' if node['keys']
       output.join(' ')
     end
 
@@ -547,6 +552,10 @@ def deparse_typecast(node)
     end
 
     def deparse_typename(node)
+      # Intervals are tricky and should be handled in a separate method because
+      # they require performing some bitmask operations.
+      return deparse_interval_type(node) if node['names'] == %w(pg_catalog interval)
+
       output = []
       output << 'SETOF' if node['setof']
 
@@ -555,7 +564,6 @@ def deparse_typename(node)
           deparse_item(item)
         end.join(', ')
       end
-
       output << deparse_typename_cast(node['names'], arguments)
 
       output.join(' ')
@@ -589,11 +597,36 @@ def deparse_typename_cast(names, arguments) # rubocop:disable Metrics/Cyclomatic
         'real'
       when 'float8'
         'double'
+      when 'time'
+        'time'
+      when 'timetz'
+        'time with time zone'
+      when 'timestamp'
+        'timestamp'
+      when 'timestamptz'
+        'timestamp with time zone'
       else
         fail format("Can't deparse type: %s", type)
       end
     end
 
+    # Deparses interval type expressions like `interval year to month` or
+    # `interval hour to second(5)`
+    def deparse_interval_type(node)
+      type = ['interval']
+      typmods = node['typmods'].map { |typmod| deparse_item(typmod) }
+      type << DeparseInterval.from_int(typmods.first.to_i).map do |part|
+        # only the `second` type can take an argument.
+        if part == 'second' && typmods.size == 2
+          "second(#{typmods.last})"
+        else
+          part
+        end.downcase
+      end.join(' to ')
+
+      type.join(' ')
+    end
+
     def deparse_nulltest(node)
       output = [deparse_item(node['arg'])]
       if node['nulltesttype'] == 0
@@ -678,4 +711,105 @@ def relpersistence(rangevar)
       end
     end
   end
+  # A type called 'interval hour to minute' is stored in a compressed way by
+  # simplifying 'hour to minute' to a simple integer. This integer is computed
+  # by looking up the arbitrary number (always a power of two) for 'hour' and
+  # the one for 'minute' and XORing them together.
+  #
+  # For example, when parsing "interval hour to minute":
+  #
+  #   HOUR_MASK = 10
+  #   MINUTE_MASK = 11
+  #   mask = (1 << 10) | (1 << 11)
+  #   mask = 1024 | 2048
+  #   mask =     (010000000000
+  #                   xor
+  #               100000000000)
+  #   mask =      110000000000
+  #   mask = 3072
+  #
+  #   Postgres will store this type as 'interval,3072'
+  #   We deparse it by simply reversing that process.
+
+  module DeparseInterval
+    # From src/include/utils/datetime.h
+    # The number is the power of 2 used for the mask.
+    MASKS = {
+      0  => 'RESERV',
+      1  => 'MONTH',
+      2  => 'YEAR',
+      3  => 'DAY',
+      4  => 'JULIAN',
+      5  => 'TZ',
+      6  => 'DTZ',
+      7  => 'DYNTZ',
+      8  => 'IGNORE_DTF',
+      9  => 'AMPM',
+      10 => 'HOUR',
+      11 => 'MINUTE',
+      12 => 'SECOND',
+      13 => 'MILLISECOND',
+      14 => 'MICROSECOND',
+      15 => 'DOY',
+      16 => 'DOW',
+      17 => 'UNITS',
+      18 => 'ADBC',
+      19 => 'AGO',
+      20 => 'ABS_BEFORE',
+      21 => 'ABS_AFTER',
+      22 => 'ISODATE',
+      23 => 'ISOTIME',
+      24 => 'WEEK',
+      25 => 'DECADE',
+      26 => 'CENTURY',
+      27 => 'MILLENNIUM',
+      28 => 'DTZMOD'
+    }
+    KEYS = MASKS.invert
+
+    # Postgres stores the interval 'day second' as 'day hour minute second' so
+    # we need to reconstruct the sql with only the largest and smallest time
+    # values. Since the rules for this are hardcoded in the grammar (and the
+    # above list is not sorted in any sensible way) it makes sense to hardcode
+    # the patterns here, too.
+    #
+    #  This hash takes the form:
+    #
+    #      { (1 << 1) | (1 << 2) => 'year to month' }
+    #
+    #  Which is:
+    #
+    #      { 6 => 'year to month' }
+    #
+    SQL_BY_MASK = {
+      (1 << KEYS['YEAR'])     => %w(year),
+      (1 << KEYS['MONTH'])    => %w(month),
+      (1 << KEYS['DAY'])      => %w(day),
+      (1 << KEYS['HOUR'])     => %w(hour),
+      (1 << KEYS['MINUTE'])   => %w(minute),
+      (1 << KEYS['SECOND'])   => %w(second),
+      (1 << KEYS['YEAR'] |
+         1 << KEYS['MONTH'])  => %w(year month),
+      (1 << KEYS['DAY'] |
+         1 << KEYS['HOUR'])   => %w(day hour),
+      (1 << KEYS['DAY'] |
+         1 << KEYS['HOUR'] |
+         1 << KEYS['MINUTE']) => %w(day minute),
+      (1 << KEYS['DAY'] |
+         1 << KEYS['HOUR'] |
+         1 << KEYS['MINUTE'] |
+         1 << KEYS['SECOND']) => %w(day second),
+      (1 << KEYS['HOUR'] |
+         1 << KEYS['MINUTE']) => %w(hour minute),
+      (1 << KEYS['HOUR'] |
+         1 << KEYS['MINUTE'] |
+         1 << KEYS['SECOND']) => %w(hour second),
+      (1 << KEYS['MINUTE'] |
+         1 << KEYS['SECOND']) => %w(minute second)
+    }
+
+    def self.from_int(int)
+      SQL_BY_MASK[int]
+    end
+  end
 end

spec/lib/deparse_spec.rb

@@ -322,6 +322,25 @@
         it { is_expected.to eq oneline_query }
       end
 
+      context 'with common types' do
+        let(:query) do
+          """
+            CREATE TABLE distributors (
+                name       varchar(40) DEFAULT 'Luso Films',
+                len        interval hour to second(3),
+                name       varchar(40) DEFAULT 'Luso Films',
+                did        int DEFAULT nextval('distributors_serial'),
+                stamp      timestamp DEFAULT pg_catalog.now() NOT NULL,
+                stamptz    timestamp with time zone,
+                time       time NOT NULL,
+                timetz     time with time zone,
+                CONSTRAINT name_len PRIMARY KEY (name, len)
+            );
+          """
+        end
+        it { is_expected.to eq oneline_query }
+      end
+
       context 'with alternate typecasts' do
         let(:query) do
           """
@@ -479,4 +498,33 @@
       it { is_expected.to eq oneline_query }
     end
   end
+
+  describe PgQuery::DeparseInterval do
+    describe '.from_int' do
+      it 'unpacks the parts of the interval' do
+        # Supported combinations taken directly from gram.y
+        {
+          # the SQL form    => what PG stores
+          %w(year)          => %w(YEAR),
+          %w(month)         => %w(MONTH),
+          %w(day)           => %w(DAY),
+          %w(hour)          => %w(HOUR),
+          %w(minute)        => %w(MINUTE),
+          %w(second)        => %w(SECOND),
+          %w(year month)    => %w(YEAR MONTH),
+          %w(day hour)      => %w(DAY HOUR),
+          %w(day minute)    => %w(DAY HOUR MINUTE),
+          %w(day second)    => %w(DAY HOUR MINUTE SECOND),
+          %w(hour minute)   => %w(HOUR MINUTE),
+          %w(hour second)   => %w(HOUR MINUTE SECOND),
+          %w(minute second) => %w(MINUTE SECOND)
+        }.each do |sql_parts, storage_parts|
+          number = storage_parts.reduce(0) do |num, part|
+            num | (1 << described_class::KEYS[part])
+          end
+          expect(described_class.from_int(number).sort).to eq(sql_parts.sort)
+        end
+      end
+    end
+  end
 end