Native OCaml Rego/OPA policy engine
Resolve all shift/reduce conflicts in Rego parser
4 conflicts, all inherent to Rego's grammar where postfix operators
(call, bracket-ref) are ambiguous with rule/statement boundaries:
- LPAREN/LBRACK after term_expr in rule heads: resolved by giving
the infix_expr->term_expr reduction %prec below_LPAREN
- SEMICOLON after literal_stmt in queries: resolved by giving
the single-statement reduction %prec below_SEMI
- LBRACK after contains_key: resolved by giving the bare
CONTAINS rule %prec below_LPAREN
+8
-3
+8
-3
lib/parser.mly
+8
-3
lib/parser.mly
···
43
43
%nonassoc EQEQ BANGEQ LT GT LE GE
44
44
%left PLUS MINUS
45
45
%left STAR SLASH PERCENT
46
+
(* Dummy token for reducing term_expr → infix_expr at lower precedence
47
+
than LPAREN/LBRACK postfix operators, resolving the shift/reduce
48
+
conflicts in rule heads and contains_key. *)
49
+
%nonassoc below_LPAREN below_SEMI
50
+
%nonassoc LPAREN LBRACK SEMICOLON
46
51
47
52
%start <Ast.rego_module> rego_module
48
53
%start <Ast.expr> expr_only
···
97
102
{ RuleDefault (sp, r, [], op, v) }
98
103
| r=ref_expr CONTAINS k=contains_key IF b=rule_body
99
104
{ RuleSpec (sp, RuleHeadSet (sp, r, Some k), [b]) }
100
-
| r=ref_expr CONTAINS k=contains_key
105
+
| r=ref_expr CONTAINS k=contains_key %prec below_LPAREN
101
106
{ RuleSpec (sp, RuleHeadSet (sp, r, Some k), []) }
102
107
| r=ref_expr LPAREN a=separated_list(COMMA, expr) RPAREN
103
108
op=assign_op v=expr IF b=rule_body es=else_chain
···
139
144
(* ── Query ─────────────────────────────────────────────────────────────── *)
140
145
141
146
query_stmts:
142
-
| s=literal_stmt { [s] }
147
+
| s=literal_stmt { [s] } %prec below_SEMI
143
148
| s=literal_stmt SEMICOLON { [s] }
144
149
| s=literal_stmt SEMICOLON rest=query_stmts { s :: rest }
145
150
;
···
185
190
;
186
191
187
192
infix_expr:
188
-
| t=term_expr { t }
193
+
| t=term_expr { t } %prec below_LPAREN
189
194
| l=infix_expr PLUS r=infix_expr { ArithExpr (sp, Add, l, r) }
190
195
| l=infix_expr MINUS r=infix_expr { ArithExpr (sp, Sub, l, r) }
191
196
| l=infix_expr STAR r=infix_expr { ArithExpr (sp, Mul, l, r) }