#
#  The grammar for a Select statement
#

start: 
  defaults
  select
;

defaults:
  # empty
  |
  'set' 'default' 'property' propertyList 'semi-colon' defaults
;

select:
  selectClause fromClause whereClause 'semi-colon'
;

propertyList:
  'left parenthesis' 'right parenthesis'
  |
  'left parenthesis' property propertyListContinues 'right parenthesis'
;

propertyListContinues:
  # empty 
  | 'comma' property propertyListContinues 
;

property:
  'identifier' propertyContinues 
;

propertyContinues:
  requiredProperty | optionalProperty 
;
  
requiredProperty:
  'exclamation mark' literal
;

optionalProperty:
  'colon' literal
;

literal:
  'identifier'
  | 
  'timeInterval' 
  | 
  'integer' 
  | 
  'string'
  | 
  'constant' 'left parenthesis' 'identifier' 'comma' literal 'right parenthesis'
;

selectClause: 
  'select' 
  generalizedAttributeList
;

generalizedAttributeList:
  '*' 
  | 
  generalizedAttribute 
  attributeList
;

attributeList:
  #empty
  | 
  'comma' generalizedAttribute attributeList
;

generalizedAttribute:
  attribute 
  | 
  aggregate 
;

aggregate: 
  'aggregate' 'left parenthesis' attribute 'right parenthesis'
;

attribute:
   fullDescriptorExpression 
;

fromClause:
  #empty
  | 
  'from' table tableList
;

tableList:
  #empty
  | 
  'comma' table tableList
;

table:
  valueSpecification 'identifier'
;

valueSpecification:
  propertyValue 
  | 
  coalescedValue
  | 
  node
  | 
  path
;

propertyValue:
  'property' 'left parenthesis' 'identifier' 'comma' path 'right parenthesis'
;

coalescedValue:
  'coalesce' 'left parenthesis' 'identifier' 'comma' path 'right parenthesis'
;

path:
  fullDescriptorExpression
  |
  collapsedPath
  | 
  slicedPath
  | 
  matchedPath
  | 
  'roots'
;

fullDescriptorExpression:
  descriptorExpression
;

collapsedPath:
  'collapse' 'left parenthesis' path 'right parenthesis'
;

slicedPath:
  'slice' 'left parenthesis' regionSpecification 'comma' path 'right parenthesis'
;

matchedPath:
  'match' 'left parenthesis' path  'comma' descriptorExpression 'right parenthesis'
;

node:
  'nodes' 'left parenthesis' path 'right parenthesis'
;

descriptorExpression:
  descriptor
  | 
  'left parenthesis' descriptorExpression 'right parenthesis' 
  |
  descriptorExpression 'period' descriptorExpression
  |
  descriptorExpression '*' 
  |
  descriptorExpression 'question mark' 
  |
  descriptorExpression '+' 
;
  
regionSpecification:
  'identifier'
  |
  propertyList
;

descriptor:
  'identifier'
  |
  propertyList
;

whereClause:
  #empty
  | 
  'where' predicate 
;

predicate:
  'not' predicate
  | 
  'left parenthesis' predicate 'right parenthesis' 
  | 
  predicate 'and' predicate 
  | 
  predicate 'or' predicate 
  |   
  'null' 'left parenthesis' path 'right parenthesis'
  |   
  'nonnull' 'left parenthesis' path 'right parenthesis'
  | 
  expression 'comparison' expression 
;

expression: 
  'integer'
  |   
  'string'
  |   
  'timeInterval'
  | 
  'constant' 'left parenthesis' 'identifier' 'comma' literal 'right parenthesis'
  |   
  fullDescriptorExpression 
  |   
  expression '+' expression 
  |   
  expression '-' expression       
  |   
  expression '*' expression      
  |   
  expression '/' expression     
  |   
  '-' expression 
;