module SQLPP

select := 'SELECT' optional_distinct

optional_projections
optional_froms
optional_wheres
optional_groups
optional_orders
optional_limit
optional_offset

optional_distinct := ''

| 'DISTINCT'

optional_projections := ''

| list

optional_froms := ''

| 'FROM' froms

optional_wheres := ''

| 'WHERE' expr1

optional_groups := ''

| 'GROUP' 'BY' list

optional_orders := ''

| 'ORDER' 'BY' sort_keys

optional_limit := ''

| 'LIMIT' expr4

optional_offset := ''

| 'OFFSET' expr4

sort_keys := sort_key

| sort_key ',' sort_keys

sort_key := expr1

| expr1 sort_options

sort_options := sort_option

| sort_option ' ' sort_options

sort_option := 'ASC' | 'DESC' | 'NULLS FIRST' | 'NULLS LAST'

froms := from

| from ',' froms

from := entity

| entity optional_join_expr

optional_join_expr := ''

| 'LEFT' 'JOIN' from 'ON' expr
| 'INNER' 'JOIN' from 'ON' expr
| 'OUTER' 'JOIN' from 'ON' expr
| 'FULL' 'OUTER' 'JOIN' from 'ON' expr

entity := '(' from ')'

| id
| select_stmt

expr1 := expr2

| expr2 op expr1

op := 'AND' | 'OR' | 'IS' | 'IS NOT'

expr2 := expr3 optional_op

optional_op := ''

| 'NOT' optional_op
| 'BETWEEN' expr3 AND expr3
| 'NOT IN' '(' list ')'
| 'IN' '(' list ')'
| bop expr3

bop := '<' | '<=' | '<>' | '=' | '>=' | '>'

expr3 := expr4

| expr4 op2 expr3
| unary expr3

op2 := '+' | '-' | '*' | '/'

unary := '+' | '-' | 'NOT' | 'DISTINCT'

expr4 := lit

| id
| id '.' id
| id '(' args ')'
| 'CASE' case_stmt 'END'
| '(' expr1 ')'
| expr4 '[' expr1 ']'
| expr4 '::' expr4

list := expr1

| expr1 ',' list