// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
grammar CEL;
// Grammar Rules
// =============
start
: e=expr EOF
;
expr
: e=conditionalOr (op='?' e1=conditionalOr ':' e2=expr)?
;
conditionalOr
: e=conditionalAnd (ops+='||' e1+=conditionalAnd)*
;
conditionalAnd
: e=relation (ops+='&&' e1+=relation)*
;
relation
: calc
| relation op=('<'|'<='|'>='|'>'|'=='|'!='|'in') relation
;
calc
: unary
| calc op=('*'|'/'|'%') calc
| calc op=('+'|'-') calc
;
unary
: member # MemberExpr
| (ops+='!')+ member # LogicalNot
| (ops+='-')+ member # Negate
;
member
: primary # PrimaryExpr
| member op='.' (opt='?')? id=IDENTIFIER # Select
| member op='.' id=IDENTIFIER open='(' args=exprList? ')' # MemberCall
| member op='[' (opt='?')? index=expr ']' # Index
;
primary
: leadingDot='.'? id=IDENTIFIER (op='(' args=exprList? ')')? # IdentOrGlobalCall
| '(' e=expr ')' # Nested
| op='[' elems=listInit? ','? ']' # CreateList
| op='{' entries=mapInitializerList? ','? '}' # CreateStruct
| leadingDot='.'? ids+=IDENTIFIER (ops+='.' ids+=IDENTIFIER)*
op='{' entries=fieldInitializerList? ','? '}' # CreateMessage
| literal # ConstantLiteral
;
exprList
: e+=expr (',' e+=expr)*
;
listInit
: elems+=optExpr (',' elems+=optExpr)*
;
fieldInitializerList
: fields+=optField cols+=':' values+=expr (',' fields+=optField cols+=':' values+=expr)*
;
optField
: (opt='?')? IDENTIFIER
;
mapInitializerList
: keys+=optExpr cols+=':' values+=expr (',' keys+=optExpr cols+=':' values+=expr)*
;
optExpr
: (opt='?')? e=expr
;
literal
: sign=MINUS? tok=NUM_INT # Int
| tok=NUM_UINT # Uint
| sign=MINUS? tok=NUM_FLOAT # Double
| tok=STRING # String
| tok=BYTES # Bytes
| tok=CEL_TRUE # BoolTrue
| tok=CEL_FALSE # BoolFalse
| tok=NUL # Null
;
// Lexer Rules
// ===========
EQUALS : '==';
NOT_EQUALS : '!=';
IN: 'in';
LESS : '<';
LESS_EQUALS : '<=';
GREATER_EQUALS : '>=';
GREATER : '>';
LOGICAL_AND : '&&';
LOGICAL_OR : '||';
LBRACKET : '[';
RPRACKET : ']';
LBRACE : '{';
RBRACE : '}';
LPAREN : '(';
RPAREN : ')';
DOT : '.';
COMMA : ',';
MINUS : '-';
EXCLAM : '!';
QUESTIONMARK : '?';
COLON : ':';
PLUS : '+';
STAR : '*';
SLASH : '/';
PERCENT : '%';
CEL_TRUE : 'true';
CEL_FALSE : 'false';
NUL : 'null';
fragment BACKSLASH : '\\';
fragment LETTER : 'A'..'Z' | 'a'..'z' ;
fragment DIGIT : '0'..'9' ;
fragment EXPONENT : ('e' | 'E') ( '+' | '-' )? DIGIT+ ;
fragment HEXDIGIT : ('0'..'9'|'a'..'f'|'A'..'F') ;
fragment RAW : 'r' | 'R';
fragment ESC_SEQ
: ESC_CHAR_SEQ
| ESC_BYTE_SEQ
| ESC_UNI_SEQ
| ESC_OCT_SEQ
;
fragment ESC_CHAR_SEQ
: BACKSLASH ('a'|'b'|'f'|'n'|'r'|'t'|'v'|'"'|'\''|'\\'|'?'|'`')
;
fragment ESC_OCT_SEQ
: BACKSLASH ('0'..'3') ('0'..'7') ('0'..'7')
;
fragment ESC_BYTE_SEQ
: BACKSLASH ( 'x' | 'X' ) HEXDIGIT HEXDIGIT
;
fragment ESC_UNI_SEQ
: BACKSLASH 'u' HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT
| BACKSLASH 'U' HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT
;
WHITESPACE : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+ -> channel(HIDDEN) ;
COMMENT : '//' (~'\n')* -> channel(HIDDEN) ;
NUM_FLOAT
: ( DIGIT+ ('.' DIGIT+) EXPONENT?
| DIGIT+ EXPONENT
| '.' DIGIT+ EXPONENT?
)
;
NUM_INT
: ( DIGIT+ | '0x' HEXDIGIT+ );
NUM_UINT
: DIGIT+ ( 'u' | 'U' )
| '0x' HEXDIGIT+ ( 'u' | 'U' )
;
STRING
: '"' (ESC_SEQ | ~('\\'|'"'|'\n'|'\r'))* '"'
| '\'' (ESC_SEQ | ~('\\'|'\''|'\n'|'\r'))* '\''
| '"""' (ESC_SEQ | ~('\\'))*? '"""'
| '\'\'\'' (ESC_SEQ | ~('\\'))*? '\'\'\''
| RAW '"' ~('"'|'\n'|'\r')* '"'
| RAW '\'' ~('\''|'\n'|'\r')* '\''
| RAW '"""' .*? '"""'
| RAW '\'\'\'' .*? '\'\'\''
;
BYTES : ('b' | 'B') STRING;
IDENTIFIER : (LETTER | '_') ( LETTER | DIGIT | '_')*;