demo_grammar.ebnf

/* Lexical Part */

_letter : 'a'-'z' | 'A'-'Z' ;

_digit : '0'-'9' ;

_idchar : _letter | _digit | '_' ;

id : (_letter | '_') {_idchar} ;

!whitespace : ' ' | '\t' | '\n' | '\r' ;

/* Syntax Part */

<< import "github.com/couchbaselabs/gojsonsm/parser/ast" >>

RootExpression : Expression ;

True : "true"           << ast.NewBoolValue(true) >> ;

False : "false"         << ast.NewBoolValue(false) >>;

String :
      "\"" id "\""      << ast.NewStringValue($1) >>
    | "'" id "'"        << ast.NewStringValue($1) >>
;

FieldRef :
      id                << ast.NewFieldRef($0) >>
    | FieldRef "." id   << ast.AppendToFieldRef($0, $2) >>
;

Literal :
      String
    | True
    | False
;

Value :
      FieldRef
    | Literal
;

ComparisonExpr :
      Value "!=" Value   << ast.NewComparisonExpr("!=", $0, $2) >>
    | Value "==" Value   << ast.NewComparisonExpr("==", $0, $2) >>
    | Value ">" Value   << ast.NewComparisonExpr(">", $0, $2) >>
    | Value ">=" Value   << ast.NewComparisonExpr(">=", $0, $2) >>
    | Value "<" Value   << ast.NewComparisonExpr("<", $0, $2) >>
    | Value "<=" Value   << ast.NewComparisonExpr("<=", $0, $2) >>
;

AndExpr :
      Expression "&&" Expression    << ast.NewPredicateExpr("&&", $0, $2) >>
    | AndExpr "&&" Expression       << ast.AppendToPredicateExpr("&&", $0, $2) >>
;

OrExpr :
      Expression "&&" Expression    << ast.NewPredicateExpr("||", $0, $2) >>
    | OrExpr "&&" Expression       << ast.AppendToPredicateExpr("||", $0, $2) >>
;

GroupExpr :
      "(" Expression ")"            << $1, nil >>
;

NotExpr :
      "!" GroupExpr     << ast.NewNotExpr($1) >>
;

Expression :
      ComparisonExpr
    | NotExpr
    | GroupExpr
    | AndExpr
    | OrExpr
;