Module eval 

Expression evaluator. Given a parsed Expr, a Row, and the row’s column schema, produce a Value. v0.4 implements:

• literals
• column lookups (bare and qualified t.col)
• unary minus / NOT
• binary arithmetic, comparison, AND, OR
• numeric widening (Int → BigInt → Float) at evaluation time
• SQL three-valued logic for NULL:
  • any arithmetic / comparison op with a NULL operand → NULL
  • TRUE OR NULL → TRUE, FALSE OR NULL → NULL,
  • FALSE AND NULL → FALSE, TRUE AND NULL → NULL,
  • NOT NULL → NULL

v0.4 deliberately does not implement: function calls, string concatenation, IS NULL / IS NOT NULL, BETWEEN, IN, etc. Those come later.

Structs

EvalContext

Resolution context for evaluating a single row. table_alias is the alias (or table name) callers should accept as the qualifier on a column ref — e.g. FROM users AS u makes u.name valid and rejects other.name.

Enums

EvalError

Functions

cast_to_vector

Parse a Value::Text("[1.0, 2.0, 3.0]") into a Value::Vector(..). Mirrors pgvector’s '[..]'::vector cast. NULL casts as NULL.

cast_value

PG-style expr::TYPE coercion. NULL always casts as NULL.

days_from_civil

Inverse of civil_from_days — converts (year, month, day) to days since 1970-01-01. Out-of-range months / days saturate.

eval_expr

format_bytea_hex

v7.10.4 — render a BYTEA payload in PG’s hex output format (\x prefix, lowercase hex pairs). Public so the wire layer can emit the canonical bytea-as-text representation.

format_date

Render a Date (days since epoch) as YYYY-MM-DD. Negative values for pre-1970 dates render with a leading - on the year.

format_interval

Render an Interval { months, micros } in a PG-ish shape. The output mirrors psql’s text format: years/months from the months part, days/HH:MM:SS[.frac] from the microsecond part. Empty parts are omitted; an all-zero interval renders as 0.

format_numeric

Render a Numeric { scaled, scale } as its decimal text form. Negative scaled prepends - to the absolute value’s digits; the integer / fractional split is by character count, padding the fractional side with leading zeros to exactly scale chars.

format_timestamp

Render a Timestamp (microseconds since epoch) as YYYY-MM-DD HH:MM:SS[.fff...]. Trailing-zero fractional digits are dropped; a whole-second value has no fractional part.

parse_date_literal

Parse YYYY-MM-DD into a Date (days since Unix epoch). Returns None on shape / numeric failure; the engine surfaces that as a TypeMismatch with the original text included.

parse_timestamp_literal

Parse YYYY-MM-DD[ HH:MM:SS[.ffffff]] into a Timestamp (microseconds since Unix epoch). The time portion is optional; missing → midnight. The fractional portion accepts 1–6 digits and pads with zeros to microseconds.