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Merge pull request #30 from JackDanger/deparse-module
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Deparsing ALTER TABLE
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@lfittl
lfittl committed Aug 25, 2015
2 parents 84c0c03 + 80a7c60 commit ae54ca4
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Showing 5 changed files with 424 additions and 130 deletions.
5 changes: 5 additions & 0 deletions .rubocop.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -40,3 +40,8 @@ Metrics/BlockNesting:

Metrics/PerceivedComplexity:
Enabled: false

# extend self preserves private methods,
# module_function buggily removes them.
Style/ModuleFunction:
Enabled: false
228 changes: 107 additions & 121 deletions lib/pg_query/deparse.rb
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Original file line number Diff line number Diff line change
@@ -1,22 +1,28 @@
require_relative 'deparse/interval'
require_relative 'deparse/alter_table'
class PgQuery
# Reconstruct all of the parsed queries into their original form
def deparse(tree = @parsetree)
tree.map do |item|
self.class.deparse(item)
Deparse.from(item)
end.join('; ')
end

class << self
# rubocop:disable Metrics/ModuleLength
module Deparse
extend self

# Given one element of the PgQuery#parsetree reconstruct it back into the
# original query.
def deparse(item)
def from(item)
deparse_item(item)
end

private

def deparse_item(item, context = nil) # rubocop:disable Metrics/CyclomaticComplexity
return if item.nil?
return item if item.is_a?(Fixnum)

type = item.keys[0]
node = item.values[0]
Expand All @@ -33,9 +39,13 @@ def deparse_item(item, context = nil) # rubocop:disable Metrics/CyclomaticComple
when 'AEXPR OR'
deparse_aexpr_or(node)
when 'AEXPR'
deparse_aexpr(node)
deparse_aexpr(node, context)
when 'ALIAS'
deparse_alias(node)
when 'ALTER TABLE'
deparse_alter_table(node)
when 'ALTER TABLE CMD'
deparse_alter_table_cmd(node)
when 'A_ARRAYEXPR'
deparse_a_arrayexp(node)
when 'A_CONST'
Expand Down Expand Up @@ -68,6 +78,8 @@ def deparse_item(item, context = nil) # rubocop:disable Metrics/CyclomaticComple
deparse_defelem(node)
when 'DELETE FROM'
deparse_delete_from(node)
when 'DROP'
deparse_drop(node)
when 'FUNCCALL'
deparse_funccall(node)
when 'FUNCTIONPARAMETER'
Expand All @@ -86,6 +98,8 @@ def deparse_item(item, context = nil) # rubocop:disable Metrics/CyclomaticComple
deparse_rangesubselect(node)
when 'RANGEVAR'
deparse_rangevar(node)
when 'RENAMESTMT'
deparse_renamestmt(node)
when 'RESTARGET'
deparse_restarget(node, context)
when 'ROW'
Expand Down Expand Up @@ -125,6 +139,19 @@ def deparse_rangevar(node)
output.join(' ')
end

def deparse_renamestmt(node)
output = []

if node['renameType'] == 26 # table
output << 'ALTER TABLE'
output << deparse_item(node['relation'])
output << 'RENAME TO'
output << node['newname']
end

output.join(' ')
end

def deparse_columnref(node)
node['fields'].map do |field|
field.is_a?(String) ? field : deparse_item(field)
Expand Down Expand Up @@ -166,6 +193,33 @@ def deparse_alias(node)
end
end

def deparse_alter_table(node)
output = []
output << 'ALTER TABLE'

output << deparse_item(node['relation'])

output << node['cmds'].map do |item|
deparse_item(item)
end.join(', ')

output.join(' ')
end

def deparse_alter_table_cmd(node)
command, options = AlterTable.commands(node)

output = []
output << command if command
output << 'IF EXISTS' if node['missing_ok']
output << node['name']
output << options if options
output << deparse_item(node['def']) if node['def']
output << 'CASCADE' if node['behavior'] == 1

output.compact.join(' ')
end

def deparse_paramref(node)
if node['number'] == 0
'?'
Expand Down Expand Up @@ -194,7 +248,8 @@ def deparse_funccall(node)
# COUNT(*)
args << '*' if node['agg_star']

output << format('%s(%s)', node['funcname'].join('.'), args.join(', '))
name = (node['funcname'] - ['pg_catalog']).join('.')
output << format('%s(%s)', name, args.join(', '))
output << format('OVER (%s)', deparse_item(node['over'])) if node['over']

output.join(' ')
Expand Down Expand Up @@ -241,11 +296,16 @@ def deparse_range_function(node)
output.join(' ')
end

def deparse_aexpr(node)
def deparse_aexpr(node, context = false)
output = []
output << deparse_item(node['lexpr'])
output << deparse_item(node['rexpr'])
output.join(' ' + node['name'][0] + ' ')
output << deparse_item(node['lexpr'], context || true)
output << deparse_item(node['rexpr'], context || true)
output = output.join(' ' + node['name'][0] + ' ')
if context
# This is a nested expression, add parentheses.
output = '(' + output + ')'
end
output
end

def deparse_aexpr_and(node)
Expand Down Expand Up @@ -347,12 +407,16 @@ def deparse_case(node)
def deparse_columndef(node)
output = [node['colname']]
output << deparse_item(node['typeName'])
if node['raw_default']
output << 'USING'
output << deparse_item(node['raw_default'])
end
if node['constraints']
output += node['constraints'].map do |item|
deparse_item(item)
end
end
output.join(' ')
output.compact.join(' ')
end

def deparse_constraint(node)
Expand All @@ -363,8 +427,15 @@ def deparse_constraint(node)
end
# NOT_NULL -> NOT NULL
output << node['contype'].gsub('_', ' ')
output << deparse_item(node['raw_expr']) if node['raw_expr']

if node['raw_expr']
expression = deparse_item(node['raw_expr'])
# Unless it's simple, put parentheses around it
expression = '(' + expression + ')' if node['raw_expr'].keys == ['AEXPR']
output << expression
end
output << '(' + node['keys'].join(', ') + ')' if node['keys']
output << "USING INDEX #{node['indexname']}" if node['indexname']
output.join(' ')
end

Expand Down Expand Up @@ -614,15 +685,18 @@ def deparse_typename_cast(names, arguments) # rubocop:disable Metrics/Cyclomatic
# `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 ')

if node['typmods']
typmods = node['typmods'].map { |typmod| deparse_item(typmod) }
type << Interval.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 ')
end

type.join(' ')
end
Expand Down Expand Up @@ -701,6 +775,19 @@ def deparse_delete_from(node)
output.join(' ')
end

def deparse_drop(node)
output = ['DROP']
output << 'TABLE' if node['removeType'] == 26
output << 'CONCURRENTLY' if node['concurrent']
output << 'IF EXISTS' if node['missing_ok']

output << node['objects'].join(', ')

output << 'CASCADE' if node['behavior'] == 1

output.join(' ')
end

# The PG parser adds several pieces of view data onto the RANGEVAR
# that need to be printed before deparse_rangevar is called.
def relpersistence(rangevar)
Expand All @@ -711,105 +798,4 @@ 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
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