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Replace unshift() with push() to improve performance #120

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Replace unshift() with push() to improve performance #120

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4e5429a
resolve merge conflict
nosvalds Aug 9, 2021
2fbba83
[120] Move preceding step out to separate function
JLRishe Dec 16, 2023
b4162ab
[120] Move following:: out to separe function and fix functionality
JLRishe Dec 16, 2023
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4 changes: 4 additions & 0 deletions test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -524,6 +524,10 @@ describe('xpath', () => {
assert.equal(first3Nodes.length, 6);

assert.equal(first3Nodes[5].textContent, '３章');

const allButFirst = xpath.parse('/*/book[1]/chapter[1]/following::chapter').select({ node: doc });

assert.equal(allButFirst.length, 7);
});

it('should respect reverse axes', () => {
Expand Down
127 changes: 75 additions & 52 deletions xpath.js
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Expand Up @@ -1271,7 +1271,7 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
if (!s) {
throw new Error('XPath expression unspecified.');
}
if (typeof s !== 'string'){
if (typeof s !== 'string') {
throw new Error('XPath expression must be a string.');
}

Expand Down Expand Up @@ -1312,9 +1312,10 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
var rhs = [];
for (var i = 0; i < num; i++) {
tokenType.pop();
rhs.unshift(tokenValue.pop());
rhs.push(tokenValue.pop());
state.pop();
}
rhs.reverse();
var s_ = state[state.length - 1];
tokenType.push(XPathParser.productions[XPathParser.actionTableNumber[s].charCodeAt(a - 1) - 32][0]);
if (this.reduceActions[XPathParser.actionTableNumber[s].charCodeAt(a - 1) - 32] == undefined) {
Expand Down Expand Up @@ -1900,6 +1901,76 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
return null;
};


var applyFollowingStep = function (step, xpc, nodes) {
var newNodes = [];

// TODO: why?
if (xpc.contextNode === xpc.virtualRoot) {
return newNodes;
}

var st = [];
if (xpc.contextNode.firstChild != null) {
st.push(xpc.contextNode.firstChild);
}

for (var m = xpc.contextNode; m != null && m.nodeType !== NodeTypes.DOCUMENT_NODE && m !== xpc.virtualRoot; m = m.parentNode) {
st.push(m.nextSibling);
}
st.reverse();

do {
for (var m = st.pop(); m != null;) {
if (step.nodeTest.matches(m, xpc)) {
newNodes.push(m);
}
if (m.firstChild != null) {
st.push(m.nextSibling);
m = m.firstChild;
} else {
m = m.nextSibling;
}
}
} while (st.length > 0);

return newNodes;
};

var applyPrecedingStep = function (step, xpc) {
var newNodes = [];
var st;

// TODO: Use getRoot instead of this if-else?
if (xpc.virtualRoot != null) {
st = [xpc.virtualRoot];
} else {
// cannot rely on .ownerDocument because the node may be in a document fragment
st = [findRoot(xpc.contextNode)];
}

outer: while (st.length > 0) {
for (var m = st.pop(); m != null;) {
if (m == xpc.contextNode) {
break outer;
}
if (step.nodeTest.matches(m, xpc)) {
newNodes.push(m);
}
if (m.firstChild != null) {
st.push(m.nextSibling);
m = m.firstChild;
} else {
m = m.nextSibling;
}
}
}

newNodes.reverse();

return newNodes;
};

PathExpr.applyStep = function (step, xpc, node) {
if (!node) {
throw new Error('Context node not found when evaluating XPath step: ' + step);
Expand Down Expand Up @@ -2006,32 +2077,7 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
break;

case Step.FOLLOWING:
if (xpc.contextNode === xpc.virtualRoot) {
break;
}
var st = [];
if (xpc.contextNode.firstChild != null) {
st.unshift(xpc.contextNode.firstChild);
} else {
st.unshift(xpc.contextNode.nextSibling);
}
for (var m = xpc.contextNode.parentNode; m != null && m.nodeType != NodeTypes.DOCUMENT_NODE && m !== xpc.virtualRoot; m = m.parentNode) {
st.unshift(m.nextSibling);
}
do {
for (var m = st.pop(); m != null;) {
if (step.nodeTest.matches(m, xpc)) {
newNodes.push(m);
}
if (m.firstChild != null) {
st.push(m.nextSibling);
m = m.firstChild;
} else {
m = m.nextSibling;
}
}
} while (st.length > 0);
break;
return applyFollowingStep(step, xpc);

case Step.FOLLOWINGSIBLING:
if (xpc.contextNode === xpc.virtualRoot) {
Expand Down Expand Up @@ -2089,30 +2135,7 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
break;

case Step.PRECEDING:
var st;
if (xpc.virtualRoot != null) {
st = [xpc.virtualRoot];
} else {
// cannot rely on .ownerDocument because the node may be in a document fragment
st = [findRoot(xpc.contextNode)];
}
outer: while (st.length > 0) {
for (var m = st.pop(); m != null;) {
if (m == xpc.contextNode) {
break outer;
}
if (step.nodeTest.matches(m, xpc)) {
newNodes.unshift(m);
}
if (m.firstChild != null) {
st.push(m.nextSibling);
m = m.firstChild;
} else {
m = m.nextSibling;
}
}
}
break;
return applyPrecedingStep(step, xpc);

case Step.PRECEDINGSIBLING:
if (xpc.contextNode === xpc.virtualRoot) {
Expand Down