Name
xpath_explain, xquery_explain, xpath_text, xpath_lex_analyze, xquery_lex_analyze — compile-time diagnostics for XPath and XQuery expressions
Synopsis
varchar xpath_explain(
|
in xpath varchar); |
varchar xquery_explain(
|
in xquery varchar); |
varchar xpath_text(
|
in xpath varchar); |
any xpath_lex_analyze(
|
in xpath varchar); |
any xquery_lex_analyze(
|
in xquery varchar); |
Description
These BIFs operate on XPath and XQuery source text without actually evaluating it, returning compile-time information useful for tooling.
xpath_explain and xquery_explain
return a textual representation of the optimised execution plan the engine
would use, analogous to SQL explain. The output is
the same form printed by the development-mode debug option
XML_DEBUG_PLAN.
xpath_text normalises the input XPath by parsing it
and re-emitting it as canonical text. Useful for diffing two expressions
modulo formatting.
xpath_lex_analyze and
xquery_lex_analyze run the lexer over the source and
return the token stream as a vector of (token_kind, token_text,
offset) triples. Useful for syntax-highlighting tools and for
diagnosing parse errors at a specific token boundary.