Struct XPathOptions 

pub struct XPathOptions {
    pub libxml2_compatible: bool,
    pub xpath_2_0: bool,
    pub max_eval_steps: u64,
}

Knobs for the XPath 1.0 lexer + evaluator. Default is strict XPath 1.0 spec conformance; flipping libxml2_compatible relaxes three points where libxml2 historically deviates from the spec:

1. Number literals with exponents — XPath 1.0 § 3.5 forbids 1e10 / 1.5e-3 style exponent notation in number literals; libxml2 accepts them. In compat mode we accept too.
2. number('-') — XPath 1.0 § 4.4 says the result is NaN when the argument is not a lexical number; libxml2 returns -0. In compat mode we return -0.
3. string() of large numbers — XPath 1.0 § 4.2 mandates decimal-only output; libxml2 emits 1.23456789012346e+19 in scientific form for very large / very small magnitudes. In compat mode we emit libxml2’s scientific form.

Default: false (strict — recommended). Set to true only when porting from libxml2-flavoured XPath corpora or pipelines.

Fields

libxml2_compatible: bool

xpath_2_0: bool

Enable XPath 2.0 syntax additions that XPath 1.0 forbids:

• if (cond) then a else b conditional expression
• for $v in seq return body (with comma-chained bindings)
• (more 2.0 grammar will land here as it grows)

Off by default — XPath 1.0 is the spec contract callers depend on. The XSLT compiler flips this on when the stylesheet declares version="2.0" (or higher).

max_eval_steps: u64

Per-evaluation step ceiling — the cap on charged eval steps that bounds adversarial nested-predicate complexity (the //*[//*[…]] O(N^k) shape). When exceeded, evaluation aborts with an error rather than hanging. Defaults to eval::DEFAULT_MAX_EVAL_STEPS (20M) — comfortable for ordinary and generated XPath. Lower it (e.g. 1–2M) when evaluating untrusted expressions to tighten the worst-case CPU bound; raise it for trusted, legitimately-expensive generated XPath. A value of 0 makes every evaluation fail on its first step.

Trait Implementations

impl Clone for XPathOptions

fn clone(&self) -> XPathOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for XPathOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for XPathOptions

fn default() -> XPathOptions

Returns the “default value” for a type.