pub fn parse_xpath(src: &str) -> Result<Expr>Expand description
Parse an XPath 1.0 expression string into its AST representation
using the default strict options. See parse_xpath_with to
opt into libxml2-compatible lexing.
Examples found in repository?
examples/probe_parser_rss.rs (line 36)
23fn main() {
24 let path = std::env::args().nth(1).expect("usage: probe_parser_rss <input-path>");
25 let bytes = std::fs::read(&path).expect("read input");
26 let s = std::str::from_utf8(&bytes).expect("UTF-8");
27 let iters: usize = std::env::args().nth(2)
28 .and_then(|s| s.parse().ok()).unwrap_or(1_000_000);
29
30 println!("input: {} bytes, {} iters", s.len(), iters);
31 println!("rss start: {:>8.1} MB", rss_bytes() as f64 / 1_048_576.0);
32
33 let t0 = Instant::now();
34 let mid = iters / 2;
35 for i in 0..iters {
36 let _ = parse_xpath(s);
37 if i == mid {
38 println!("rss mid: {:>8.1} MB (after {} parses, {:.2?})",
39 rss_bytes() as f64 / 1_048_576.0, i, t0.elapsed());
40 }
41 }
42 let dt = t0.elapsed();
43 println!("rss end: {:>8.1} MB (after {} parses, {:.2?}, {:.0} parses/sec)",
44 rss_bytes() as f64 / 1_048_576.0, iters, dt,
45 iters as f64 / dt.as_secs_f64());
46}More examples
examples/profile_xpath_slow_unit.rs (line 72)
59fn main() {
60 let path = std::env::args().nth(1)
61 .expect("usage: profile_xpath_slow_unit <artifact-path>");
62 let bytes = std::fs::read(&path).expect("read artifact");
63 let full = std::str::from_utf8(&bytes).expect("artifact is UTF-8");
64
65 let doc = parse_str(FIXTURE, &ParseOptions::default()).expect("fixture parses");
66 let ctx = XPathContext::new(&doc);
67
68 // Report the predicate-nesting depth of the original artifact so we
69 // can pick a sensible MAX_PREDICATE_NESTING_DEPTH.
70 use sup_xml_core::xpath::ast::max_predicate_nesting;
71 use sup_xml_core::xpath::parse_xpath;
72 match parse_xpath(full) {
73 Ok(e) => println!("# original artifact parses; predicate-nesting depth = {}", max_predicate_nesting(&e)),
74 Err(e) => println!("# original artifact parse-error: {}",
75 e.message.chars().take(80).collect::<String>()),
76 }
77
78 println!("# best-of-3 timing of slow-unit reductions");
79 println!("{:>9} {:>8} {}", "time", "len", "expression → result");
80 println!("{}", "-".repeat(78));
81
82 // ── baseline ──────────────────────────────────────────────────────────
83 time_one(&ctx, "FULL artifact (1018 B)", full);
84
85 // ── strip from the right, halving each time ──────────────────────────
86 time_one(&ctx, "first 512 B", &full[..full.len().min(512)]);
87 time_one(&ctx, "first 256 B", &full[..full.len().min(256)]);
88 time_one(&ctx, "first 128 B", &full[..full.len().min(128)]);
89 time_one(&ctx, "first 64 B", &full[..full.len().min(64)]);
90
91 // ── isolate specific patterns ────────────────────────────────────────
92 time_one(&ctx, "just nested substring chains",
93 "r*substring(/*substring(/*substring(/*substring(/*substring(/*substring(/*substring(//book[author='Hu'])))))))");
94 time_one(&ctx, "deep //*/*/* descent chain",
95 "//*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*");
96 time_one(&ctx, "nested predicates (the worst case)",
97 "//*[//*[//*[//*[//*[//*[//*[.='x']]]]]]]");
98 time_one(&ctx, "nested //*/* in predicate",
99 "//*[/*//*//*//*//*//*//*//*//*//*]");
100 time_one(&ctx, "wildcard arithmetic chain",
101 "//*/*/*/* * * * * * * * * * //*/*/*");
102 time_one(&ctx, "many top-level *",
103 "* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *");
104
105 // ── single-step costs for comparison ─────────────────────────────────
106 time_one(&ctx, "trivial root", "/");
107 time_one(&ctx, "trivial wildcard", "/*");
108 time_one(&ctx, "all elements", "//*");
109 time_one(&ctx, "all elements with trivial predicate", "//*[true()]");
110 time_one(&ctx, "all elements with attribute access", "//*[@id]");
111 time_one(&ctx, "books filtered by author", "//book[author='Hunt']");
112 time_one(&ctx, "substring on string literal", "substring('hello', 2, 3)");
113 time_one(&ctx, "substring on node text", "substring(//title, 2, 3)");
114}