xpath.js

ajax patterns 这是关于ajax设计模式方面的原代码

  }
  return c;
}

// The axes of XPath expressions.

var xpathAxis = {
  ANCESTOR_OR_SELF: 'ancestor-or-self',
  ANCESTOR: 'ancestor',
  ATTRIBUTE: 'attribute',
  CHILD: 'child',
  DESCENDANT_OR_SELF: 'descendant-or-self',
  DESCENDANT: 'descendant',
  FOLLOWING_SIBLING: 'following-sibling',
  FOLLOWING: 'following',
  NAMESPACE: 'namespace',
  PARENT: 'parent',
  PRECEDING_SIBLING: 'preceding-sibling',
  PRECEDING: 'preceding',
  SELF: 'self'
};

var xpathAxesRe = [
    xpathAxis.ANCESTOR_OR_SELF,
    xpathAxis.ANCESTOR,
    xpathAxis.ATTRIBUTE,
    xpathAxis.CHILD,
    xpathAxis.DESCENDANT_OR_SELF,
    xpathAxis.DESCENDANT,
    xpathAxis.FOLLOWING_SIBLING,
    xpathAxis.FOLLOWING,
    xpathAxis.NAMESPACE,
    xpathAxis.PARENT,
    xpathAxis.PRECEDING_SIBLING,
    xpathAxis.PRECEDING,
    xpathAxis.SELF
].join('|');


// The tokens of the language. The label property is just used for
// generating debug output. The prec property is the precedence used
// for shift/reduce resolution. Default precedence is 0 as a lookahead
// token and 2 on the stack. TODO(mesch): this is certainly not
// necessary and too complicated. Simplify this!

// NOTE: tabular formatting is the big exception, but here it should
// be OK.

var TOK_PIPE =   { label: "|",   prec:   17, re: new RegExp("^\\|") };
var TOK_DSLASH = { label: "//",  prec:   19, re: new RegExp("^//")  };
var TOK_SLASH =  { label: "/",   prec:   30, re: new RegExp("^/")   };
var TOK_AXIS =   { label: "::",  prec:   20, re: new RegExp("^::")  };
var TOK_COLON =  { label: ":",   prec: 1000, re: new RegExp("^:")  };
var TOK_AXISNAME = { label: "[axis]", re: new RegExp('^(' + xpathAxesRe + ')') };
var TOK_PARENO = { label: "(",   prec:   34, re: new RegExp("^\\(") };
var TOK_PARENC = { label: ")",               re: new RegExp("^\\)") };
var TOK_DDOT =   { label: "..",  prec:   34, re: new RegExp("^\\.\\.") };
var TOK_DOT =    { label: ".",   prec:   34, re: new RegExp("^\\.") };
var TOK_AT =     { label: "@",   prec:   34, re: new RegExp("^@")   };

var TOK_COMMA =  { label: ",",               re: new RegExp("^,") };

var TOK_OR =     { label: "or",  prec:   10, re: new RegExp("^or\\b") };
var TOK_AND =    { label: "and", prec:   11, re: new RegExp("^and\\b") };
var TOK_EQ =     { label: "=",   prec:   12, re: new RegExp("^=")   };
var TOK_NEQ =    { label: "!=",  prec:   12, re: new RegExp("^!=")  };
var TOK_GE =     { label: ">=",  prec:   13, re: new RegExp("^>=")  };
var TOK_GT =     { label: ">",   prec:   13, re: new RegExp("^>")   };
var TOK_LE =     { label: "<=",  prec:   13, re: new RegExp("^<=")  };
var TOK_LT =     { label: "<",   prec:   13, re: new RegExp("^<")   };
var TOK_PLUS =   { label: "+",   prec:   14, re: new RegExp("^\\+"), left: true };
var TOK_MINUS =  { label: "-",   prec:   14, re: new RegExp("^\\-"), left: true };
var TOK_DIV =    { label: "div", prec:   15, re: new RegExp("^div\\b"), left: true };
var TOK_MOD =    { label: "mod", prec:   15, re: new RegExp("^mod\\b"), left: true };

var TOK_BRACKO = { label: "[",   prec:   32, re: new RegExp("^\\[") };
var TOK_BRACKC = { label: "]",               re: new RegExp("^\\]") };
var TOK_DOLLAR = { label: "$",               re: new RegExp("^\\$") };

var TOK_NCNAME = { label: "[ncname]", re: new RegExp('^[a-z][-\\w]*','i') };

var TOK_ASTERISK = { label: "*", prec: 15, re: new RegExp("^\\*"), left: true };
var TOK_LITERALQ = { label: "[litq]", prec: 20, re: new RegExp("^'[^\\']*'") };
var TOK_LITERALQQ = {
  label: "[litqq]",
  prec: 20,
  re: new RegExp('^"[^\\"]*"')
};

var TOK_NUMBER  = {
  label: "[number]",
  prec: 35,
  re: new RegExp('^\\d+(\\.\\d*)?') };

var TOK_QNAME = {
  label: "[qname]",
  re: new RegExp('^([a-z][-\\w]*:)?[a-z][-\\w]*','i')
};

var TOK_NODEO = {
  label: "[nodetest-start]",
  re: new RegExp('^(processing-instruction|comment|text|node)\\(')
};

// The table of the tokens of our grammar, used by the lexer: first
// column the tag, second column a regexp to recognize it in the
// input, third column the precedence of the token, fourth column a
// factory function for the semantic value of the token.
//
// NOTE: order of this list is important, because the first match
// counts. Cf. DDOT and DOT, and AXIS and COLON.

var xpathTokenRules = [
    TOK_DSLASH,
    TOK_SLASH,
    TOK_DDOT,
    TOK_DOT,
    TOK_AXIS,
    TOK_COLON,
    TOK_AXISNAME,
    TOK_NODEO,
    TOK_PARENO,
    TOK_PARENC,
    TOK_BRACKO,
    TOK_BRACKC,
    TOK_AT,
    TOK_COMMA,
    TOK_OR,
    TOK_AND,
    TOK_NEQ,
    TOK_EQ,
    TOK_GE,
    TOK_GT,
    TOK_LE,
    TOK_LT,
    TOK_PLUS,
    TOK_MINUS,
    TOK_ASTERISK,
    TOK_PIPE,
    TOK_MOD,
    TOK_DIV,
    TOK_LITERALQ,
    TOK_LITERALQQ,
    TOK_NUMBER,
    TOK_QNAME,
    TOK_NCNAME,
    TOK_DOLLAR
];

// All the nonterminals of the grammar. The nonterminal objects are
// identified by object identity; the labels are used in the debug
// output only.
var XPathLocationPath = { label: "LocationPath" };
var XPathRelativeLocationPath = { label: "RelativeLocationPath" };
var XPathAbsoluteLocationPath = { label: "AbsoluteLocationPath" };
var XPathStep = { label: "Step" };
var XPathNodeTest = { label: "NodeTest" };
var XPathPredicate = { label: "Predicate" };
var XPathLiteral = { label: "Literal" };
var XPathExpr = { label: "Expr" };
var XPathPrimaryExpr = { label: "PrimaryExpr" };
var XPathVariableReference = { label: "Variablereference" };
var XPathNumber = { label: "Number" };
var XPathFunctionCall = { label: "FunctionCall" };
var XPathArgumentRemainder = { label: "ArgumentRemainder" };
var XPathPathExpr = { label: "PathExpr" };
var XPathUnionExpr = { label: "UnionExpr" };
var XPathFilterExpr = { label: "FilterExpr" };
var XPathDigits = { label: "Digits" };

var xpathNonTerminals = [
    XPathLocationPath,
    XPathRelativeLocationPath,
    XPathAbsoluteLocationPath,
    XPathStep,
    XPathNodeTest,
    XPathPredicate,
    XPathLiteral,
    XPathExpr,
    XPathPrimaryExpr,
    XPathVariableReference,
    XPathNumber,
    XPathFunctionCall,
    XPathArgumentRemainder,
    XPathPathExpr,
    XPathUnionExpr,
    XPathFilterExpr,
    XPathDigits
];

// Quantifiers that are used in the productions of the grammar.
var Q_01 = { label: "?" };
var Q_MM = { label: "*" };
var Q_1M = { label: "+" };

// Tag for left associativity (right assoc is implied by undefined).
var ASSOC_LEFT = true;

// The productions of the grammar. Columns of the table:
//
// - target nonterminal,
// - pattern,
// - precedence,
// - semantic value factory
//
// The semantic value factory is a function that receives parse tree
// nodes from the stack frames of the matched symbols as arguments and
// returns an a node of the parse tree. The node is stored in the top
// stack frame along with the target object of the rule. The node in
// the parse tree is an expression object that has an evaluate() method
// and thus evaluates XPath expressions.
//
// The precedence is used to decide between reducing and shifting by
// comparing the precendence of the rule that is candidate for
// reducing with the precedence of the look ahead token. Precedence of
// -1 means that the precedence of the tokens in the pattern is used
// instead. TODO: It shouldn't be necessary to explicitly assign
// precedences to rules.

var xpathGrammarRules =
  [
   [ XPathLocationPath, [ XPathRelativeLocationPath ], 18,
     passExpr ],
   [ XPathLocationPath, [ XPathAbsoluteLocationPath ], 18,
     passExpr ],

   [ XPathAbsoluteLocationPath, [ TOK_SLASH, XPathRelativeLocationPath ], 18, 
     makeLocationExpr1 ],
   [ XPathAbsoluteLocationPath, [ TOK_DSLASH, XPathRelativeLocationPath ], 18,
     makeLocationExpr2 ],

   [ XPathAbsoluteLocationPath, [ TOK_SLASH ], 0,
     makeLocationExpr3 ],
   [ XPathAbsoluteLocationPath, [ TOK_DSLASH ], 0,
     makeLocationExpr4 ],

   [ XPathRelativeLocationPath, [ XPathStep ], 31,
     makeLocationExpr5 ],
   [ XPathRelativeLocationPath,
     [ XPathRelativeLocationPath, TOK_SLASH, XPathStep ], 31,
     makeLocationExpr6 ],
   [ XPathRelativeLocationPath,
     [ XPathRelativeLocationPath, TOK_DSLASH, XPathStep ], 31,
     makeLocationExpr7 ],

   [ XPathStep, [ TOK_DOT ], 33,
     makeStepExpr1 ],
   [ XPathStep, [ TOK_DDOT ], 33,
     makeStepExpr2 ],
   [ XPathStep,
     [ TOK_AXISNAME, TOK_AXIS, XPathNodeTest ], 33,
     makeStepExpr3 ],
   [ XPathStep, [ TOK_AT, XPathNodeTest ], 33,
     makeStepExpr4 ],
   [ XPathStep, [ XPathNodeTest ], 33,
     makeStepExpr5 ],
   [ XPathStep, [ XPathStep, XPathPredicate ], 33,
     makeStepExpr6 ],

   [ XPathNodeTest, [ TOK_ASTERISK ], 33,
     makeNodeTestExpr1 ],
   [ XPathNodeTest, [ TOK_NCNAME, TOK_COLON, TOK_ASTERISK ], 33,
     makeNodeTestExpr2 ],
   [ XPathNodeTest, [ TOK_QNAME ], 33,
     makeNodeTestExpr3 ],
   [ XPathNodeTest, [ TOK_NODEO, TOK_PARENC ], 33,
     makeNodeTestExpr4 ],
   [ XPathNodeTest, [ TOK_NODEO, XPathLiteral, TOK_PARENC ], 33,
     makeNodeTestExpr5 ],

   [ XPathPredicate, [ TOK_BRACKO, XPathExpr, TOK_BRACKC ], 33,
     makePredicateExpr ],

   [ XPathPrimaryExpr, [ XPathVariableReference ], 33,
     passExpr ],
   [ XPathPrimaryExpr, [ TOK_PARENO, XPathExpr, TOK_PARENC ], 33,
     makePrimaryExpr ],
   [ XPathPrimaryExpr, [ XPathLiteral ], 30,
     passExpr ],
   [ XPathPrimaryExpr, [ XPathNumber ], 30,
     passExpr ],
   [ XPathPrimaryExpr, [ XPathFunctionCall ], 30,
     passExpr ],

   [ XPathFunctionCall, [ TOK_QNAME, TOK_PARENO, TOK_PARENC ], -1,
     makeFunctionCallExpr1 ],
   [ XPathFunctionCall,
     [ TOK_QNAME, TOK_PARENO, XPathExpr, XPathArgumentRemainder, Q_MM,
       TOK_PARENC ], -1,
     makeFunctionCallExpr2 ],
   [ XPathArgumentRemainder, [ TOK_COMMA, XPathExpr ], -1,
     makeArgumentExpr ],

   [ XPathUnionExpr, [ XPathPathExpr ], 20,
     passExpr ],
   [ XPathUnionExpr, [ XPathUnionExpr, TOK_PIPE, XPathPathExpr ], 20,
     makeUnionExpr ],

   [ XPathPathExpr, [ XPathLocationPath ], 20, 
     passExpr ], 
   [ XPathPathExpr, [ XPathFilterExpr ], 19, 
     passExpr ], 
   [ XPathPathExpr, 
     [ XPathFilterExpr, TOK_SLASH, XPathRelativeLocationPath ], 20,
     makePathExpr1 ],
   [ XPathPathExpr,
     [ XPathFilterExpr, TOK_DSLASH, XPathRelativeLocationPath ], 20,
     makePathExpr2 ],

   [ XPathFilterExpr, [ XPathPrimaryExpr, XPathPredicate, Q_MM ], 20,
     makeFilterExpr ], 

   [ XPathExpr, [ XPathPrimaryExpr ], 16,
     passExpr ],
   [ XPathExpr, [ XPathUnionExpr ], 16,
     passExpr ],

   [ XPathExpr, [ TOK_MINUS, XPathExpr ], -1,
     makeUnaryMinusExpr ],

   [ XPathExpr, [ XPathExpr, TOK_OR, XPathExpr ], -1,
     makeBinaryExpr ],
   [ XPathExpr, [ XPathExpr, TOK_AND, XPathExpr ], -1,
     makeBinaryExpr ],

   [ XPathExpr, [ XPathExpr, TOK_EQ, XPathExpr ], -1,
     makeBinaryExpr ],
   [ XPathExpr, [ XPathExpr, TOK_NEQ, XPathExpr ], -1,
     makeBinaryExpr ],

   [ XPathExpr, [ XPathExpr, TOK_LT, XPathExpr ], -1,
     makeBinaryExpr ],
   [ XPathExpr, [ XPathExpr, TOK_LE, XPathExpr ], -1,
     makeBinaryExpr ],
   [ XPathExpr, [ XPathExpr, TOK_GT, XPathExpr ], -1,
     makeBinaryExpr ],
   [ XPathExpr, [ XPathExpr, TOK_GE, XPathExpr ], -1,
     makeBinaryExpr ],

   [ XPathExpr, [ XPathExpr, TOK_PLUS, XPathExpr ], -1,
     makeBinaryExpr, ASSOC_LEFT ],
   [ XPathExpr, [ XPathExpr, TOK_MINUS, XPathExpr ], -1,
     makeBinaryExpr, ASSOC_LEFT ],

   [ XPathExpr, [ XPathExpr, TOK_ASTERISK, XPathExpr ], -1,
     makeBinaryExpr, ASSOC_LEFT ],
   [ XPathExpr, [ XPathExpr, TOK_DIV, XPathExpr ], -1,
     makeBinaryExpr, ASSOC_LEFT ],
   [ XPathExpr, [ XPathExpr, TOK_MOD, XPathExpr ], -1,
     makeBinaryExpr, ASSOC_LEFT ],

   [ XPathLiteral, [ TOK_LITERALQ ], -1,
     makeLiteralExpr ],
   [ XPathLiteral, [ TOK_LITERALQQ ], -1,
     makeLiteralExpr ],

   [ XPathNumber, [ TOK_NUMBER ], -1,
     makeNumberExpr ],

   [ XPathVariableReference, [ TOK_DOLLAR, TOK_QNAME ], 200,
     makeVariableReference ]
   ];

// That function computes some optimizations of the above data
// structures and will be called right here. It merely takes the
// counter variables out of the global scope.

var xpathRules = [];

function xpathParseInit() {
  if (xpathRules.length) {
    return;
  }

  // Some simple optimizations for the xpath expression parser: sort
  // grammar rules descending by length, so that the longest match is
  // first found.

  xpathGrammarRules.sort(function(a,b) {
    var la = a[1].length;
    var lb = b[1].length;
    if (la < lb) {
      return 1;
    } else if (la > lb) {
      return -1;
    } else {
      return 0;
    }
  });

  var k = 1;
  for (var i = 0; i < xpathNonTerminals.length; ++i) {
    xpathNonTerminals[i].key = k++;
  }

  for (i = 0; i < xpathTokenRules.length; ++i) {
    xpathTokenRules[i].key = k++;
  }

  Log.write('XPath parse INIT: ' + k + ' rules');

  // Another slight optimization: sort the rules into bins according
  // to the last element (observing quantifiers), so we can restrict
  // the match against the stack to the subest of rules that match the
  // top of the stack.
  //
  // TODO(mesch): What we actually want is to compute states as in
  // bison, so that we don't have to do any explicit and iterated
  // match against the stack.

  function push_(array, position, element) {
    if (!array[position]) {
      array[position] = [];
    }
    array[position].push(element);
  }

  for (i = 0; i < xpathGrammarRules.length; ++i) {
    var rule = xpathGrammarRules[i];
    var pattern = rule[1];

    for (var j = pattern.length - 1; j >= 0; --j) {
      if (pattern[j] == Q_1M) {
        push_(xpathRules, pattern[j-1].key, rule);
        break;
        
      } else if (pattern[j] == Q_MM || pattern[j] == Q_01) {
        push_(xpathRules, pattern[j-1].key, rule);
        --j;

      } else {
        push_(xpathRules, pattern[j].key, rule);
        break;
      }
    }
  }

  Log.write('XPath parse INIT: ' + xpathRules.length + ' rule bins');
  
  var sum = 0;
  mapExec(xpathRules, function(i) {
    if (i) {
      sum += i.length;
    }
  });
  
  Log.write('XPath parse INIT: ' + (sum / xpathRules.length) + ' average bin size');
}

// Local utility functions that are used by the lexer or parser.

function xpathCollectDescendants(nodelist, node) {
  for (var n = node.firstChild; n; n = n.nextSibling) {
    nodelist.push(n);
    arguments.callee(nodelist, n);
  }
}

function xpathCollectDescendantsReverse(nodelist, node) {
  for (var n = node.lastChild; n; n = n.previousSibling) {
    nodelist.push(n);
    arguments.callee(nodelist, n);
  }
}


// The entry point for the library: match an expression against a DOM
// node. Returns an XPath value.
function xpathDomEval(expr, node) {
  var expr1 = xpathParse(expr);
  var ret = expr1.evaluate(new ExprContext(node));
  return ret;
}

// Utility function to sort a list of nodes. Used by xsltSort() and
// nxslSelect().
function xpathSort(input, sort) {
  if (sort.length == 0) {
    return;
  }

  var sortlist = [];

  for (var i = 0; i < input.nodelist.length; ++i) {
    var node = input.nodelist[i];
    var sortitem = { node: node, key: [] };
    var context = input.clone(node, 0, [ node ]);
    
    for (var j = 0; j < sort.length; ++j) {
      var s = sort[j];
      var value = s.expr.evaluate(context);

      var evalue;
      if (s.type == 'text') {
        evalue = value.stringValue();
      } else if (s.type == 'number') {
        evalue = value.numberValue();
      }
      sortitem.key.push({ value: evalue, order: s.order });
    }

    // Make the sort stable by adding a lowest priority sort by
    // id. This is very convenient and furthermore required by the
    // spec ([XSLT] - Section 10 Sorting).
    sortitem.key.push({ value: i, order: 'ascending' });

    sortlist.push(sortitem);
  }

  sortlist.sort(xpathSortByKey);

  var nodes = [];
  for (var i = 0; i < sortlist.length; ++i) {
    nodes.push(sortlist[i].node);
  }
  input.nodelist = nodes;
  input.setNode(nodes[0], 0);
}


// Sorts by all order criteria defined. According to the JavaScript
// spec ([ECMA] Section 11.8.5), the compare operators compare strings
// as strings and numbers as numbers.
//
// NOTE: In browsers which do not follow the spec, this breaks only in
// the case that numbers should be sorted as strings, which is very
// uncommon.

function xpathSortByKey(v1, v2) {
  // NOTE: Sort key vectors of different length never occur in
  // xsltSort.

  for (var i = 0; i < v1.key.length; ++i) {
    var o = v1.key[i].order == 'descending' ? -1 : 1;
    if (v1.key[i].value > v2.key[i].value) {
      return +1 * o;
    } else if (v1.key[i].value < v2.key[i].value) {
      return -1 * o;
    }
  }

  return 0;
}