A top-level variable evaluates with every previously evaluated global
in scope, so referencing an earlier top-level param works, directly or
via call-template; same-name globals resolve by import precedence with
the last fold winning, so a later sibling import beats an earlier one;
the stylesheet fold uniformly favors later contributions, matching the
post-order precedence model; and the XPath compiler accepts NCName:*
name tests, matching any name in the prefix's namespace at the -0.25
default priority, so @ped:* outranks @*. Xalan baseline 144 -> 134
(variable 10 -> 5, conflictres 8 -> 5).
Compile and evaluate full XPath 1.0 expressions, not just location paths.
Add the four-type Value (node-set, boolean, number, string) with the spec's
coercion rules and canonical number formatting, a recursive-descent parser
for the operator grammar (or/and, equality, relational, additive,
multiplicative, unary minus, union) whose grammatical position disambiguates
* and the operator keywords, function calls, variable references, and filter
expressions. Predicates are now arbitrary expressions (a numeric predicate
is a position test). Comparison follows the node-set quantification rules.
Query gains value/number/string/boolean accessors and a $variable binding
map; the core functions last, position, count, not, true, false, boolean,
number, and string ship with it.
Closes#42
