示例#1
0
 /**
  * Ensures that none of the specified expressions performs an update. Otherwise, throws an
  * exception.
  *
  * @param exprs expressions (may be {@code null}, and may contain {@code null} references)
  * @throws QueryException query exception
  */
 protected final void checkNoneUp(final Expr... exprs) throws QueryException {
   if (exprs == null) return;
   checkAllUp(exprs);
   for (final Expr expr : exprs) {
     if (expr != null && expr.has(Flag.UPD)) throw UPNOT_X.get(info, description());
   }
 }
示例#2
0
 @Override
 public int exprSize() {
   int sz = 0;
   for (final Expr e : preExpr) sz += e.exprSize();
   for (final Expr e : specs) sz += e.exprSize();
   return sz;
 }
示例#3
0
文件: Path.java 项目: runeengh/basex
  @Override
  public final Expr compile(final QueryContext qc, final VarScope scp) throws QueryException {
    if (root != null) root = root.compile(qc, scp);
    // no steps
    if (steps.length == 0) return root == null ? new Context(info) : root;

    final Value init = qc.value, cv = initial(qc);
    final boolean doc = cv != null && cv.type == NodeType.DOC;
    qc.value = cv;
    try {
      final int sl = steps.length;
      for (int s = 0; s < sl; s++) {
        Expr e = steps[s];

        // axis step: if input is a document, its type is temporarily generalized
        final boolean as = e instanceof Step;
        if (as && s == 0 && doc) cv.type = NodeType.NOD;

        e = e.compile(qc, scp);
        if (e.isEmpty()) return optPre(qc);
        steps[s] = e;

        // no axis step: invalidate context value
        if (!as) qc.value = null;
      }
    } finally {
      if (doc) cv.type = NodeType.DOC;
      qc.value = init;
    }
    // optimize path
    return optimize(qc, scp);
  }
示例#4
0
文件: Path.java 项目: runeengh/basex
 @Override
 public final boolean has(final Flag flag) {
   // first step or root expression will be used as context
   if (flag == Flag.CTX) return root == null || root.has(flag);
   for (final Expr s : steps) if (s.has(flag)) return true;
   return root != null && root.has(flag);
 }
示例#5
0
文件: Path.java 项目: runeengh/basex
  @Override
  public final Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
    final Value v = initial(qc);
    if (v != null && v.isEmpty() || emptyPath(v)) return optPre(qc);

    // merge descendant steps
    Expr e = mergeSteps(qc);
    if (e == this && v != null && v.type == NodeType.DOC) {
      // check index access
      e = index(qc, v);
      // rewrite descendant to child steps
      if (e == this) e = children(qc, v);
    }
    // recompile path if it has changed
    if (e != this) return e.compile(qc, scp);

    // set atomic type for single attribute steps to speed up predicate tests
    if (root == null && steps.length == 1 && steps[0] instanceof Step) {
      final Step curr = (Step) steps[0];
      if (curr.axis == ATTR && curr.test.kind == Kind.URI_NAME) curr.seqType(SeqType.NOD_ZO);
    }

    // choose best path implementation and set type information
    final Path path = get(info, root, steps);
    path.size = path.size(qc);
    path.seqType = SeqType.get(steps[steps.length - 1].seqType().type, size);
    return path;
  }
示例#6
0
 @Override
 public boolean accept(final ASTVisitor visitor) {
   if (!visitAll(visitor, specs)) return false;
   for (final Expr ng : preExpr) if (!ng.accept(visitor)) return false;
   for (final Var ng : post) if (!visitor.declared(ng)) return false;
   return true;
 }
示例#7
0
文件: Preds.java 项目: dirkk/basex
 @Override
 public boolean has(final Flag flag) {
   for (final Expr pred : preds) {
     if (flag == Flag.FCS && pred.seqType().mayBeNumber() || pred.has(flag)) return true;
   }
   return false;
 }
示例#8
0
文件: Preds.java 项目: dirkk/basex
  /**
   * Checks if the predicates are successful for the specified item.
   *
   * @param it item to be checked
   * @param qc query context
   * @return result of check
   * @throws QueryException query exception
   */
  protected final boolean preds(final Item it, final QueryContext qc) throws QueryException {
    if (preds.length == 0) return true;

    // set context value and position
    final Value cv = qc.value;
    try {
      if (qc.scoring) {
        double s = 0;
        for (final Expr p : preds) {
          qc.value = it;
          final Item i = p.test(qc, info);
          if (i == null) return false;
          s += i.score();
        }
        it.score(Scoring.avg(s, preds.length));
      } else {
        for (final Expr p : preds) {
          qc.value = it;
          if (p.test(qc, info) == null) return false;
        }
      }
      return true;
    } finally {
      qc.value = cv;
    }
  }
示例#9
0
 /**
  * Ensures that all specified expressions are vacuous or either updating or non-updating.
  * Otherwise, throws an exception.
  *
  * @param exprs expressions to be checked
  * @throws QueryException query exception
  */
 void checkAllUp(final Expr... exprs) throws QueryException {
   // updating state: 0 = initial state, 1 = updating, -1 = non-updating
   int s = 0;
   for (final Expr expr : exprs) {
     expr.checkUp();
     if (expr.isVacuous()) continue;
     final boolean u = expr.has(Flag.UPD);
     if (u && s == -1 || !u && s == 1) throw UPALL.get(info, description());
     s = u ? 1 : -1;
   }
 }
示例#10
0
文件: Preds.java 项目: dirkk/basex
 /**
  * Prepares this expression for iterative evaluation. The expression can be iteratively evaluated
  * if no predicate or only the first is positional.
  *
  * @return result of check
  */
 protected final boolean posIterator() {
   // check if first predicate is numeric
   if (preds.length == 1) {
     Expr p = preds[0];
     if (p instanceof Int) p = Pos.get(((Int) p).itr(), info);
     pos = p instanceof Pos ? (Pos) p : null;
     last = p.isFunction(Function.LAST);
     preds[0] = p;
   }
   return pos != null || last;
 }
示例#11
0
文件: Path.java 项目: nikhi/basex
  @Override
  public Expr optimize(final QueryContext ctx, final VarScope scp) throws QueryException {
    if (root instanceof Context) {
      ctx.compInfo(OPTREMCTX);
      root = null;
    }

    for (final Expr e : steps) {
      // check for empty steps
      if (e.isEmpty()) return optPre(null, ctx);
    }

    return this;
  }
示例#12
0
文件: Path.java 项目: runeengh/basex
 /**
  * Returns the initial context value of a path or {@code null}.
  *
  * @param qc query context (may be @code null)
  * @return root
  */
 private Value initial(final QueryContext qc) {
   // current context value
   final Value v = qc != null ? qc.value : null;
   // no root or context expression: return context
   if (root == null || root instanceof Context) return v;
   // root reference
   if (root instanceof Root) return v != null && v instanceof Item ? Root.root(v) : v;
   // root is value: return root
   if (root.isValue()) return (Value) root;
   // data reference
   final Data d = root.data();
   if (d != null) return new DBNode(d, 0, Data.ELEM);
   // otherwise, return null
   return null;
 }
示例#13
0
文件: Path.java 项目: runeengh/basex
  /**
   * Checks if the path can be rewritten for iterative evaluation.
   *
   * @param root root expression; can be a {@code null} reference
   * @param steps path steps
   * @return result of check
   */
  private static boolean iterative(final Expr root, final Expr... steps) {
    if (root == null || !root.iterable()) return false;

    final int sl = steps.length;
    for (int s = 0; s < sl; ++s) {
      switch (((Step) steps[s]).axis) {
          // reverse axes - don't iterate
        case ANC:
        case ANCORSELF:
        case PREC:
        case PRECSIBL:
          return false;
          // multiple, unsorted results - only iterate at last step,
          // or if last step uses attribute axis
        case DESC:
        case DESCORSELF:
        case FOLL:
        case FOLLSIBL:
          return s + 1 == sl || s + 2 == sl && ((Step) steps[s + 1]).axis == Axis.ATTR;
          // allow iteration for CHILD, ATTR, PARENT and SELF axes
        default:
      }
    }
    return true;
  }
示例#14
0
文件: Path.java 项目: nikhi/basex
  @Override
  public final Expr inline(final QueryContext ctx, final VarScope scp, final Var v, final Expr e)
      throws QueryException {

    final Value oldVal = ctx.value;
    try {
      ctx.value = root(ctx);
      final Expr rt = root == null ? null : root.inline(ctx, scp, v, e);
      if (rt != null) {
        setRoot(ctx, rt);
        ctx.value = oldVal;
        ctx.value = root(ctx);
      }

      boolean change = rt != null;
      for (int i = 0; i < steps.length; i++) {
        final Expr nw = steps[i].inline(ctx, scp, v, e);
        if (nw != null) {
          steps[i] = nw;
          change = true;
        }
      }
      return change ? optimize(ctx, scp) : null;
    } finally {
      ctx.value = oldVal;
    }
  }
示例#15
0
文件: Path.java 项目: runeengh/basex
  /**
   * Merges expensive descendant-or-self::node() steps.
   *
   * @param qc query context
   * @return original or new expression
   */
  private Expr mergeSteps(final QueryContext qc) {
    boolean opt = false;
    final int sl = steps.length;
    final ExprList stps = new ExprList(sl);
    for (int s = 0; s < sl; s++) {
      final Expr step = steps[s];
      // check for simple descendants-or-self step with succeeding step
      if (s < sl - 1 && step instanceof Step) {
        final Step curr = (Step) step;
        if (curr.simple(DESCORSELF, false)) {
          // check succeeding step
          final Expr next = steps[s + 1];
          // descendant-or-self::node()/child::X -> descendant::X
          if (simpleChild(next)) {
            ((Step) next).axis = DESC;
            opt = true;
            continue;
          }
          // descendant-or-self::node()/(X, Y) -> (descendant::X | descendant::Y)
          Expr e = mergeList(next);
          if (e != null) {
            steps[s + 1] = e;
            opt = true;
            continue;
          }
          // //(X, Y)[text()] -> (/descendant::X | /descendant::Y)[text()]
          if (next instanceof Filter && !next.has(Flag.FCS)) {
            final Filter f = (Filter) next;
            e = mergeList(f.root);
            if (e != null) {
              f.root = e;
              opt = true;
              continue;
            }
          }
        }
      }
      stps.add(step);
    }

    if (opt) {
      qc.compInfo(OPTDESC);
      return get(info, root, stps.finish());
    }
    return this;
  }
示例#16
0
文件: Preds.java 项目: dirkk/basex
  /**
   * Merges a single predicate with the root expression and returns the resulting expression, or
   * returns a self reference if the expression cannot be merged. This function is e.g. called by
   * {@link Where#optimize}.
   *
   * @param qc query context
   * @param scp variable scope
   * @param root root expression
   * @return expression
   * @throws QueryException query exception
   */
  public Expr merge(final Expr root, final QueryContext qc, final VarScope scp)
      throws QueryException {

    // only one predicate can be rewritten; root expression must yield nodes
    if (preds.length != 1 || !(root.seqType().type instanceof NodeType)) return this;

    final Expr pred = preds[0];
    // a[.] -> a
    if (pred instanceof Context) return root;

    if (!pred.seqType().mayBeNumber()) {
      // a[b] -> a/b
      if (pred instanceof Path) return Path.get(info, root, pred).optimize(qc, scp);

      if (pred instanceof CmpG) {
        final CmpG cmp = (CmpG) pred;
        final Expr expr1 = cmp.exprs[0], expr2 = cmp.exprs[1];
        // only first operand can depend on context
        if (!expr2.has(Flag.CTX)) {
          Expr path = null;
          // a[. = 'x'] -> a = 'x'
          if (expr1 instanceof Context) path = root;
          // a[text() = 'x'] -> a/text() = 'x'
          if (expr1 instanceof Path) path = Path.get(info, root, expr1).optimize(qc, scp);
          if (path != null) return new CmpG(path, expr2, cmp.op, cmp.coll, cmp.sc, cmp.info);
        }
      }

      if (pred instanceof FTContains) {
        final FTContains cmp = (FTContains) pred;
        final FTExpr ftexpr = cmp.ftexpr;
        // only first operand can depend on context
        if (!ftexpr.has(Flag.CTX)) {
          final Expr expr = cmp.expr;
          Expr path = null;
          // a[. contains text 'x'] -> a contains text 'x'
          if (expr instanceof Context) path = root;
          // [text() contains text 'x'] -> a/text() contains text 'x'
          if (expr instanceof Path) path = Path.get(info, root, expr).optimize(qc, scp);
          if (path != null) return new FTContains(path, ftexpr, cmp.info);
        }
      }
    }
    return this;
  }
示例#17
0
文件: Preds.java 项目: dirkk/basex
 @Override
 public Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
   // number of predicates may change in loop
   for (int p = 0; p < preds.length; p++) {
     final Expr pred = preds[p];
     if (pred instanceof CmpG || pred instanceof CmpV) {
       final Cmp cmp = (Cmp) pred;
       if (cmp.exprs[0].isFunction(Function.POSITION)) {
         final Expr e2 = cmp.exprs[1];
         final SeqType st2 = e2.seqType();
         // position() = last() -> last()
         // position() = $n (numeric) -> $n
         if (e2.isFunction(Function.LAST) || st2.one() && st2.type.isNumber()) {
           if (cmp instanceof CmpG && ((CmpG) cmp).op == OpG.EQ
               || cmp instanceof CmpV && ((CmpV) cmp).op == OpV.EQ) {
             qc.compInfo(OPTWRITE, pred);
             preds[p] = e2;
           }
         }
       }
     } else if (pred instanceof And) {
       if (!pred.has(Flag.FCS)) {
         // replace AND expression with predicates (don't swap position tests)
         qc.compInfo(OPTPRED, pred);
         final Expr[] and = ((Arr) pred).exprs;
         final int m = and.length - 1;
         final ExprList el = new ExprList(preds.length + m);
         for (final Expr e : Arrays.asList(preds).subList(0, p)) el.add(e);
         for (final Expr a : and) {
           // wrap test with boolean() if the result is numeric
           el.add(Function.BOOLEAN.get(null, info, a).optimizeEbv(qc, scp));
         }
         for (final Expr e : Arrays.asList(preds).subList(p + 1, preds.length)) el.add(e);
         preds = el.finish();
       }
     } else if (pred instanceof ANum) {
       final ANum it = (ANum) pred;
       final long i = it.itr();
       if (i == it.dbl()) {
         preds[p] = Pos.get(i, info);
       } else {
         qc.compInfo(OPTREMOVE, this, pred);
         return Empty.SEQ;
       }
     } else if (pred.isValue()) {
       if (pred.ebv(qc, info).bool(info)) {
         qc.compInfo(OPTREMOVE, this, pred);
         preds = Array.delete(preds, p--);
       } else {
         // handle statically known predicates
         qc.compInfo(OPTREMOVE, this, pred);
         return Empty.SEQ;
       }
     }
   }
   return this;
 }
示例#18
0
文件: Path.java 项目: nikhi/basex
  @Override
  public final Expr compile(final QueryContext ctx, final VarScope scp) throws QueryException {
    if (root != null) setRoot(ctx, root.compile(ctx, scp));

    final Value v = ctx.value;
    try {
      ctx.value = root(ctx);
      return compilePath(ctx, scp);
    } finally {
      ctx.value = v;
    }
  }
示例#19
0
文件: Path.java 项目: nikhi/basex
 /**
  * Returns the root of the current context or {@code null}.
  *
  * @param ctx query context
  * @return root
  */
 final Value root(final QueryContext ctx) {
   final Value v = ctx != null ? ctx.value : null;
   // no root specified: return context, if it does not reference a document
   // as e.g. happens in //a(b|c)
   if (root == null) return v == null || v.type != NodeType.DOC ? v : null;
   // root is value: return root
   if (root.isValue()) return (Value) root;
   // no root reference, no context: return null
   if (!(root instanceof Root) || v == null) return null;
   // return context sequence or root of current context
   return v.size() == 1 ? Root.root(v) : v;
 }
示例#20
0
文件: Path.java 项目: runeengh/basex
 @Override
 public boolean accept(final ASTVisitor visitor) {
   if (root == null) {
     if (!visitor.lock(DBLocking.CTX)) return false;
   } else if (!root.accept(visitor)) {
     return false;
   }
   visitor.enterFocus();
   if (!visitAll(visitor, steps)) return false;
   visitor.exitFocus();
   return true;
 }
示例#21
0
文件: Path.java 项目: runeengh/basex
 @Override
 public Data data() {
   if (root != null) {
     // data reference
     final Data data = root.data();
     if (data != null) {
       final int sl = steps.length;
       for (int s = 0; s < sl; s++) {
         if (axisStep(s) == null) return null;
       }
       return data;
     }
   }
   return null;
 }
示例#22
0
文件: List.java 项目: ngrstad/basex
  @Override
  public Expr compile(final QueryContext ctx) throws QueryException {
    for (int e = 0; e < expr.length; e++) expr[e] = expr[e].compile(ctx);

    // compute number of results
    size = 0;
    for (final Expr e : expr) {
      final long c = e.size();
      if (c == -1) {
        size = c;
        break;
      }
      size += c;
    }

    // evaluate sequence type
    type = SeqType.EMP;
    Value[] val = new Value[expr.length];
    for (int v = 0; v < expr.length; v++) {
      final Expr e = expr[v];
      // check if all expressions are values
      if (val != null) {
        if (e.isValue()) val[v] = (Value) e;
        else val = null;
      }
      // skip expression that will not add any results
      if (e.isEmpty()) continue;
      // evaluate sequence type
      final SeqType et = e.type();
      type =
          type == SeqType.EMP
              ? et
              : SeqType.get(
                  et.type == type.type ? et.type : AtomType.ITEM,
                  et.mayBeZero() && type.mayBeZero() ? Occ.ZERO_MORE : Occ.ONE_MORE);
    }

    // return cached integer sequence, cached values or self reference
    Expr e = this;
    final int s = (int) size;
    if (val != null && size <= Integer.MAX_VALUE) {
      if (type.type == AtomType.STR) e = StrSeq.get(val, s);
      else if (type.type == AtomType.BLN) e = BlnSeq.get(val, s);
      else if (type.type == AtomType.FLT) e = FltSeq.get(val, s);
      else if (type.type == AtomType.DBL) e = DblSeq.get(val, s);
      else if (type.type == AtomType.DEC) e = DecSeq.get(val, s);
      else if (type.type == AtomType.BYT) e = BytSeq.get(val, s);
      else if (type.type.instanceOf(AtomType.ITR)) e = IntSeq.get(val, s, type.type);
      else {
        final ValueBuilder vb = new ValueBuilder(s);
        for (final Value v : val) vb.add(v);
        e = vb.value();
      }
    }
    return optPre(e, ctx);
  }
示例#23
0
文件: Path.java 项目: runeengh/basex
  @Override
  public final Expr inline(final QueryContext qc, final VarScope scp, final Var var, final Expr ex)
      throws QueryException {

    boolean changed = false;
    if (root != null) {
      final Expr rt = root.inline(qc, scp, var, ex);
      if (rt != null) {
        root = rt;
        changed = true;
      }
    }

    final int sl = steps.length;
    for (int s = 0; s < sl; s++) {
      final Expr nw = steps[s].inline(qc, scp, var, ex);
      if (nw != null) {
        steps[s] = nw;
        changed = true;
      }
    }
    return changed ? optimize(qc, scp) : null;
  }
示例#24
0
 /**
  * Checks if the specified expression yields a QName. Returns the item or throws an exception.
  *
  * @param ex expression to be evaluated
  * @param qc query context
  * @param empty allow empty result
  * @return QNm item
  * @throws QueryException query exception
  */
 protected final QNm toQNm(final Expr ex, final QueryContext qc, final boolean empty)
     throws QueryException {
   return toQNm(ex.atomItem(qc, info), empty);
 }
示例#25
0
 @Override
 public GroupBy compile(final QueryContext qc, final VarScope sc) throws QueryException {
   for (final Expr e : preExpr) e.compile(qc, sc);
   for (final Spec b : specs) b.compile(qc, sc);
   return optimize(qc, sc);
 }
示例#26
0
文件: List.java 项目: ngrstad/basex
 @Override
 public boolean isVacuous() {
   for (final Expr e : expr) if (!e.isVacuous()) return false;
   return true;
 }
示例#27
0
文件: Path.java 项目: runeengh/basex
 @Override
 public final int exprSize() {
   int sz = 1;
   for (final Expr e : steps) sz += e.exprSize();
   return root == null ? sz : sz + root.exprSize();
 }
示例#28
0
文件: Path.java 项目: runeengh/basex
 @Override
 public VarUsage count(final Var var) {
   final VarUsage inRoot = root == null ? VarUsage.NEVER : root.count(var);
   return VarUsage.sum(var, steps) == VarUsage.NEVER ? inRoot : VarUsage.MORE_THAN_ONCE;
 }
示例#29
0
文件: Path.java 项目: runeengh/basex
 @Override
 public final boolean removable(final Var var) {
   for (final Expr step : steps) if (step.uses(var)) return false;
   return root == null || root.removable(var);
 }
示例#30
0
 /**
  * Checks if the specified expression yields an item of the specified atomic type. Returns the
  * item or throws an exception.
  *
  * @param ex expression to be evaluated
  * @param qc query context
  * @param type type to be checked
  * @return item
  * @throws QueryException query exception
  */
 protected Item checkAtomic(final Expr ex, final QueryContext qc, final Type type)
     throws QueryException {
   return checkType(ex.atomItem(qc, info), type);
 }