SQLite

/*
** Return SQLITE_ERROR if the maximum depth of the expression tree passed 
** as the only argument is more than nMaxDepth.
*/
static int fts3ExprCheckDepth(Fts3Expr *p, int nMaxDepth){
  int rc = SQLITE_OK;
  if( p ){
    if( nMaxDepth<0 ){ 
      rc = SQLITE_ERROR;
    }else{
      rc = fts3ExprCheckDepth(p->pLeft, nMaxDepth-1);
      if( rc==SQLITE_OK ){
        rc = fts3ExprCheckDepth(p->pRight, nMaxDepth-1);
      }
    }

  do_test 3.$i {
    test_fts3expr2 "[random_and_query $i 1] OR [random_and_query $i 1]"
  } [list OR [balanced_and_tree $i] [balanced_and_tree $i]]
}

# Try trees of AND nodes with leaves that are themselves trees of OR nodes.
#
for {set i 2} {$i < 64} {incr i 4} {
  do_test 3.$i {
    test_fts3expr2 [random_andor_query $i]
  } [balanced_andor_tree $i]
}

# These exceed the depth limit. 
#
for {set i 65} {$i < 70} {incr i} {
  do_test 3.$i {
    list [catch {test_fts3expr2 [random_andor_query $i]} msg] $msg
  } {1 {Error parsing expression}}
}

# This also exceeds the depth limit. 
#

do_test 4.1.1 {
  set q "1"
  for {set i 2} {$i < 5000} {incr i} {
    append q " AND $i"
  }
  list [catch {test_fts3expr2 $q} msg] $msg
} {1 {Error parsing expression}}
do_test 4.1.2 {
  set q "1"
  for {set i 2} {$i < 4000} {incr i} {
    append q " AND $i"
  }
  catch {test_fts3expr2 $q}
} {0}

proc create_toggle_tree {nDepth} {
  if {$nDepth == 0} { return xxx }
  set nNew [expr $nDepth-1]
  if {$nDepth % 2} {
    return "([create_toggle_tree $nNew]) OR ([create_toggle_tree $nNew])"
  }