Enum Pred 

pub enum Pred {
    Cmp {
        field: String,
        op: String,
        value: Value,
    },
    In {
        field: String,
        values: Vec<Value>,
        negated: bool,
    },
    Between {
        field: String,
        low: Value,
        high: Value,
        negated: bool,
    },
    Like {
        field: String,
        pattern: String,
        negated: bool,
        ci: bool,
    },
    Regex {
        field: String,
        pattern: String,
        negated: bool,
        ci: bool,
    },
    IsNull {
        field: String,
        negated: bool,
    },
    And(Vec<Pred>),
    Or(Vec<Pred>),
    Not(Box<Pred>),
}

A boolean predicate tree.

The old representation was Vec<WhereClause> evaluated with .all(), which can only ever express a conjunction of comparisons. A tree is required for OR, for NOT, and for parenthesised grouping — WHERE (a = 1 OR b = 2) AND c != 3 has no encoding as a flat list.

Variants

Cmp

field value, for op in = != > < >= <=

Fields

field: String

op: String

value: Value

In

field [NOT] IN (v1, v2, …)

Fields

field: String

values: Vec<Value>

negated: bool

Between

field [NOT] BETWEEN low AND high — inclusive on both ends, as in SQL.

Fields

field: String

low: Value

high: Value

negated: bool

Like

field [NOT] LIKE “pat” — SQL wildcards: % = any run, _ = any one char. ci is set by ILIKE (case-insensitive).

Fields

field: String

pattern: String

negated: bool

ci: bool

Regex

field ~ "pat" / field !~ "pat" — POSIX regex match, over a DOCUMENTED SUBSET. ci is set by ~* / !~*.

Exists because Postgres catalogue introspection needs it: psql’s \dn filters with nspname !~ '^pg_', and \dt with nspname !~ '^pg_toast'. Without the operator those queries cannot run at all.

The subset is ^, $, ., and literal text — which is everything those queries actually use. A pattern containing any other metacharacter is REFUSED with an error naming it, rather than matched approximately. Approximate regex matching on a catalogue filter would silently include or exclude schemas, and a wrong schema list looks exactly like a correct one.

Deliberately no regex crate: it would add a dependency tree to an engine whose small footprint is a selling point, to serve two anchored prefix patterns.

Fields

field: String

pattern: String

negated: bool

ci: bool

IsNull

field IS [NOT] NULL — true when the field is JSON null OR absent.

Fields

field: String

negated: bool

And(Vec<Pred>)

Or(Vec<Pred>)

Not(Box<Pred>)

Trait Implementations

impl Clone for Pred

fn clone(&self) -> Pred

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Pred

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.