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// SPDX-Copyright: Copyright (c) Capital One Services, LLC
// SPDX-License-Identifier: Apache-2.0
// Copyright 2020 Capital One Services, 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.
// From https://github.com/google/cel-spec
// Modified in several ways:
// - EBNF to Lark: Rules are all lower case, No terminating ; on rules, Regexes wrapped in //, Replace ::= with :.
// - Strings expanded to include escapes and rewritten to be pure regex.
// - FLOAT_LIT expanded
// - Terminals reordered to reflect priorities better.
// A number of rules used ! annotation to capture tokens.
// These were rewritten to expand into specific, named rules and avoid a need for the Lark "!" construct.
expr : conditionalor ["?" conditionalor ":" expr]
conditionalor : [conditionalor "||"] conditionaland
conditionaland : [conditionaland "&&"] relation
// Original...
// !relation : [relation relop] addition
// !relop : "<" | "<=" | ">=" | ">" | "==" | "!=" | "in"
// Expose operators in the AST.
relation : [relation_lt | relation_le | relation_ge | relation_gt | relation_eq | relation_ne | relation_in] addition
relation_lt : relation "<"
relation_le : relation "<="
relation_gt : relation ">"
relation_ge : relation ">="
relation_eq : relation "=="
relation_ne : relation "!="
relation_in : relation "in"
// Original...
// !addition : [addition ("+" | "-")] multiplication
// Expose operators in the AST.
addition : [addition_add | addition_sub] multiplication
addition_add : addition "+"
addition_sub : addition "-"
// Original...
// !multiplication: [multiplication ("*" | "/" | "%")] unary
// Expose operators in the AST.
multiplication : [multiplication_mul | multiplication_div | multiplication_mod] unary
multiplication_mul : multiplication "*"
multiplication_div : multiplication "/"
multiplication_mod : multiplication "%"
// Original...
// !unary : member
// | "!" "!"* member
// | "-" "-"* member
// Expose operators in the AST
// Option 1: zero or more token nodes; requires some care to handle sequence of operations.
//unary : [unary_not | unary_neg]* member
// Option 2: separate expressions; doesn't maintain type safetly, allows ~!~!~!~!~x syntax which isn't really ideal.
unary : member
| unary_not unary
| unary_neg unary
unary_not : "!"
unary_neg : "-"
// Original...
// !member : primary
// | member "." IDENT ["(" [exprlist] ")"]
// | member "[" expr "]"
// | member "{" [fieldinits] "}"
// Expose constructs in the AST.
member : member_dot | member_dot_arg | member_index | member_object | primary
member_dot : member "." IDENT
member_dot_arg : member "." IDENT "(" [exprlist] ")"
member_index : member "[" expr "]"
member_object : member "{" [fieldinits] "}"
// Original...
// !primary : ["."] IDENT ["(" [exprlist] ")"]
// | "(" expr ")"
// | "[" [exprlist] "]"
// | "{" [mapinits] "}"
// | literal
// Expose constructs in the AST.
primary : literal | dot_ident_arg | dot_ident | ident_arg
| paren_expr | list_lit | map_lit | ident
dot_ident_arg : "." IDENT "(" [exprlist] ")"
dot_ident : "." IDENT
ident_arg : IDENT "(" [exprlist] ")"
ident : IDENT
paren_expr : "(" expr ")"
list_lit : "[" [exprlist] "]"
map_lit : "{" [mapinits] "}"
exprlist : expr ("," expr)*
fieldinits : IDENT ":" expr ("," IDENT ":" expr)*
mapinits : expr ":" expr ("," expr ":" expr)*
// Elevated from Terminals to expose the type name in the AST.
literal : UINT_LIT | FLOAT_LIT | INT_LIT | MLSTRING_LIT | STRING_LIT | BYTES_LIT
| BOOL_LIT | NULL_LIT
// Terminals. Order of some definitions altered to help lark.
// Signs added (see https://github.com/google/cel-spec/issues/126)
INT_LIT : /-?/ /0x/ HEXDIGIT+ | /-?/ DIGIT+
UINT_LIT : INT_LIT /[uU]/
// Original...
// FLOAT_LIT : DIGIT* . DIGIT+ EXPONENT? | DIGIT+ EXPONENT
// Expanded and signs added (see https://github.com/google/cel-spec/issues/126)
FLOAT_LIT : /-?/ DIGIT+ "." DIGIT* EXPONENT? | /-?/ DIGIT* "." DIGIT+ EXPONENT? | /-?/ DIGIT+ EXPONENT
DIGIT : /[0-9]/
HEXDIGIT : /[0-9abcdefABCDEF]/
EXPONENT : /[eE]/ /[+-]?/ DIGIT+
// Rewritten into REGEX; explicitly list the escapes
STRING_LIT : /[rR]?"(?:\\[abfnrtv"'\\]|\\\d{3}|\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4-8}|.)*?"/
| /[rR]?'(?:\\[abfnrtv"'\\]|\\\d{3}|\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}|\\U[0-9a-fA-F]{8}|.)*?'/
MLSTRING_LIT : /[rR]?"""(?:\\[abfnrtv"'\\]|\\\d{3}|\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4-8}|\r\n|\r|\n|.)*?"""/
| /[rR]?'''(?:\\[abfnrtv"'\\]|\\\d{3}|\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}|\\U[0-9a-fA-F]{8}|\r\n|\r|\n|.)*?'''/
BYTES_LIT : /[bB]/ MLSTRING_LIT | /[bB]/ STRING_LIT
// Moved into STRING_LIT and MLSTRING_LIT, no longer needed.
// ESCAPE : /\\[bfnrt"'\\]/
// | /\\x/ HEXDIGIT HEXDIGIT
// | /\\u/ HEXDIGIT HEXDIGIT HEXDIGIT HEXDIGIT
// | /\\[0-3][0-7][0-7]/
// NEWLINE : /\\r\\n/ | /\\r/ | /\\n/
BOOL_LIT : "true" | "false"
NULL_LIT : "null"
IDENT : /[_a-zA-Z][_a-zA-Z0-9]*/
RESERVED.0 : "as" | "break" | "const" | "continue" | "else"
| "for" | "function" | "if" | "import" | "let"
| "loop" | "package" | "namespace" | "return"
| "var" | "void" | "while"
WHITESPACE : /[\t\n\f\r ]+/
COMMENT : /\/\/.*/
%ignore WHITESPACE
%ignore COMMENT
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