datahike.pg.sql.cast — org.replikativ/pg-datahike 0.1.60

One implementation of CAST(<value> AS <type>).

The same cast semantics used to be written out four times — in sql.clj's table-free literal fast path, in expr.clj's translate-cast, in stmt.clj's apply-sql-cast, and in coerce.clj's INSERT path — each a case/cond over types/cast-category that had drifted from the others. Which copy ran depended on the SHAPE of the expression, not on its meaning, so the same cast could behave three ways:

29::bit(4) → literal fast path → correct (-44)::bit(12) → translate-cast → passed through as -44 '101'::bit(3)::int → nested, another path → read the digits as decimal 101, not 5

Issue #12 hit exactly this for '1'::boolean, and issue #19 hit it again for bit. Adding a branch to one copy fixes one shape.

This namespace holds the value-level semantics — (value, type) → value. Callers keep their own surrounding logic (when to fold at translate time, how to bind a runtime var, how to read a JSqlParser AST node); they just stop reimplementing what a cast MEANS.

parse-timestamp is injected rather than required because the parser lives in expr.clj, which requires this namespace's dependencies — taking it as an argument keeps this namespace a leaf and avoids a load cycle.

cast-scalar clj

(cast-scalar v
             type-str
             {:keys [explicit? parse-timestamp resolve-regclass
                     prefer-local-datetime?]
              :or {explicit? true}})

Apply a SQL cast of v to the target named by type-str.

Options: :explicit? — an explicit CAST reshapes silently; an assignment raises instead (matters for bit width coercion). :parse-timestamp — fn String → java.util.Date, from expr.clj. :resolve-regclass— fn String → oid, for ::regclass. :prefer-local-datetime? — return a LocalDateTime (microsecond precision) rather than a Date for a timestamp cast. See the :timestamp branch.

Returns v unchanged for a target this doesn't classify, which is what every call site did before and keeps unknown types passing through rather than erroring.

cast-to-bit clj

(cast-to-bit v type-str explicit?)

int / text / bit → bit(n) or bit varying(n).

An integer source keeps the RIGHTMOST n bits and sign-extends on the left (varbit.c:1550), which is why (-44)::bit(12) is 111111010100 and not the digits of -44.