messagefilter

Overview ¶

Package messagefilter is a small smart-filter expression engine for Kafka messages (task MSG-24). It compiles a predicate expression into a Filter that can be evaluated against api.Message values.

Grammar (recursive descent, no external deps):

expr       := orExpr
orExpr     := andExpr ( ("OR"|"or"|"||") andExpr )*
andExpr    := comparison ( ("AND"|"and"|"&&") comparison )*
comparison := "(" expr ")" | field OP operand
field      := key | value | partition | offset | header.NAME | headers.NAME
OP         := contains | == | != | > | < | >= | <=
operand    := "quoted" | 'quoted' | number | bareword