Method ResolveAsType

postgres/parser/sem/tree/constant.go:570–630

ResolveAsType implements the Constant interface.

(
	ctx context.Context, semaCtx *SemaContext, typ *types.T,
)

// ResolveAsType implements the Constant interface.
func (expr *StrVal) ResolveAsType(
	ctx context.Context, semaCtx *SemaContext, typ *types.T,
) (TypedExpr, error) {
	if expr.scannedAsBytes {
		// We're looking at typing a byte literal constant into some value type.
		switch typ.Family() {
		case types.BytesFamily:
			expr.resBytes = DBytes(expr.s)
			return &expr.resBytes, nil
		case types.EnumFamily:
			return MakeDEnumFromPhysicalRepresentation(typ, []byte(expr.s))
		case types.UuidFamily:
			return ParseDUuidFromBytes([]byte(expr.s))
		case types.StringFamily:
			// bpchar types truncate trailing whitespace.
			if typ.Oid() == oid.T_bpchar {
				expr.resString = DString(strings.TrimRight(expr.s, " "))
				return &expr.resString, nil
			}
			expr.resString = DString(expr.s)
			return &expr.resString, nil
		}
		return nil, errors.AssertionFailedf("attempt to type byte array literal to %T", typ)
	}

	// Typing a string literal constant into some value type.
	switch typ.Family() {
	case types.StringFamily:
		if typ.Oid() == oid.T_name {
			expr.resString = DString(expr.s)
			return NewDNameFromDString(&expr.resString), nil
		}
		// bpchar types truncate trailing whitespace.
		if typ.Oid() == oid.T_bpchar {
			expr.resString = DString(strings.TrimRight(expr.s, " "))
			return &expr.resString, nil
		}
		expr.resString = DString(expr.s)
		return &expr.resString, nil

	case types.BytesFamily:
		return ParseDByte(expr.s)

	default:
		val, dependsOnContext, err := ParseAndRequireString(typ, expr.s, dummyParseTimeContext{})
		if err != nil {
			return nil, err
		}
		if !dependsOnContext {
			return val, nil
		}
		// Interpreting a string as one of these types may depend on the timezone or
		// the current time; the value won't be safe to reuse later. So in this case
		// we return a CastExpr and let the conversion happen at evaluation time. We
		// still want to error out if the conversion is not possible though (this is
		// used when resolving overloads).
		expr.resString = DString(expr.s)
		c := NewTypedCastExpr(&expr.resString, typ)