/**
* Checks if the specified step will never yield results.
*
* @param rt root value
* @param s index of step
* @return {@code true} if steps will never yield results
*/
private boolean emptyPath(final Value rt, final int s) {
final Step step = axisStep(s);
if (step == null) return false;
final Axis axis = step.axis;
if (s == 0) {
// first location step:
if (root instanceof CAttr) {
// @.../child:: / @.../descendant::
if (axis == CHILD || axis == DESC) return true;
} else if (root instanceof Root
|| root instanceof CDoc
|| rt != null && rt.type == NodeType.DOC) {
if (axis == SELF || axis == ANCORSELF) {
if (step.test != Test.NOD && step.test != Test.DOC) return true;
} else if (axis == CHILD || axis == DESC) {
if (step.test == Test.DOC || step.test == Test.ATT) return true;
} else if (axis == DESCORSELF) {
if (step.test == Test.ATT) return true;
} else {
return true;
}
}
} else {
// remaining steps:
final Step last = axisStep(s - 1);
if (last == null) return false;
// .../self:: / .../descendant-or-self::
if (axis == SELF || axis == DESCORSELF) {
if (step.test == Test.NOD) return false;
// @.../..., text()/...
if (last.axis == ATTR && step.test.type != NodeType.ATT
|| last.test == Test.TXT && step.test != Test.TXT) return true;
if (axis == DESCORSELF) return false;
// .../self::
final QNm name = step.test.name, lastName = last.test.name;
if (lastName == null
|| name == null
|| lastName.local().length == 0
|| name.local().length == 0) return false;
// ...X/...Y
return !name.eq(lastName);
}
// .../following-sibling:: / .../preceding-sibling::
if (axis == FOLLSIBL || axis == PRECSIBL) return last.axis == ATTR;
// .../descendant:: / .../child:: / .../attribute::
if (axis == DESC || axis == CHILD || axis == ATTR)
return last.axis == ATTR
|| last.test == Test.TXT
|| last.test == Test.COM
|| last.test == Test.PI
|| axis == ATTR && step.test == Test.NSP;
// .../parent:: / .../ancestor::
if (axis == PARENT || axis == ANC) return last.test == Test.DOC;
}
return false;
}
/**
* Returns an index to the specified function, or {@code -1}.
*
* @param name name of the function
* @param args optional arguments
* @return function instance
*/
private int indexOf(final QNm name, final Expr[] args) {
for (int id = 0; id < funcs.length; ++id) {
if (name.eq(funcs[id].name) && args.length == funcs[id].args.length) return id;
}
return -1;
}
/**
* Checks if the location path contains steps that will never yield results.
*
* @param stps step array
* @param ctx query context
*/
void voidStep(final Expr[] stps, final QueryContext ctx) {
for (int l = 0; l < stps.length; ++l) {
final Step s = axisStep(l);
if (s == null) continue;
final Axis sa = s.axis;
if (l == 0) {
if (root instanceof CAttr) {
// @.../child:: / @.../descendant::
if (sa == CHILD || sa == DESC) {
ctx.compInfo(WARNDESC, root);
return;
}
} else if (root instanceof Root
|| root instanceof Value && ((Value) root).type == NodeType.DOC
|| root instanceof CDoc) {
if (sa != CHILD
&& sa != DESC
&& sa != DESCORSELF
&& (sa != SELF && sa != ANCORSELF || s.test != Test.NOD && s.test != Test.DOC)) {
ctx.compInfo(WARNDOC, root, sa);
return;
}
}
} else {
final Step ls = axisStep(l - 1);
if (ls == null) continue;
final Axis lsa = ls.axis;
boolean warning = true;
if (sa == SELF || sa == DESCORSELF) {
// .../self:: / .../descendant-or-self::
if (s.test == Test.NOD) continue;
// @.../..., text()/...
warning =
lsa == ATTR && s.test.type != NodeType.ATT
|| ls.test == Test.TXT && s.test != Test.TXT;
if (!warning) {
if (sa == DESCORSELF) continue;
// .../self::
final QNm n0 = ls.test.name;
final QNm n1 = s.test.name;
if (n0 == null || n1 == null || n0.local().length == 0 || n1.local().length == 0)
continue;
// ...X/...Y
warning = !n1.eq(n0);
}
} else if (sa == FOLLSIBL || sa == PRECSIBL) {
// .../following-sibling:: / .../preceding-sibling::
warning = lsa == ATTR;
} else if (sa == DESC || sa == CHILD || sa == ATTR) {
// .../descendant:: / .../child:: / .../attribute::
warning =
lsa == ATTR
|| ls.test == Test.TXT
|| ls.test == Test.COM
|| ls.test == Test.PI
|| sa == ATTR && s.test == Test.NSP;
} else if (sa == PARENT || sa == ANC) {
// .../parent:: / .../ancestor::
warning = ls.test == Test.DOC;
}
if (warning) {
ctx.compInfo(WARNSELF, s);
return;
}
}
}
}