【源码日记】type cast

The SQL

select xmin::text::int8;

grammar

a_expr: a_expr TYPECAST Typename { $$ = makeTypeCast($1, $3, @2); }

static Node *
makeTypeCast(Node *arg, TypeName *typename, int location)
{
	TypeCast *n = makeNode(TypeCast);
	n->arg = arg;
	n->typeName = typename;
	n->location = location;
	return (Node *) n;
}

transformer

transformExprRecurse

case T_TypeCast:
			result = transformTypeCast(pstate, (TypeCast *) expr);
			break;

result = coerce_to_target_type(pstate, expr, inputType,
							   targetType, targetTypmod,
							   COERCION_EXPLICIT,
							   COERCE_EXPLICIT_CAST,
							   location);

pstate could be NULL.