C. Scott Ananian has uploaded a new change for review. (
https://gerrit.wikimedia.org/r/386021 )
Change subject: Add DOMUtils.hasNChildren() for quickly testing # of child nodes
......................................................................
Add DOMUtils.hasNChildren() for quickly testing # of child nodes
When testing whether a node has a small number of children (for example,
0, 1, or 2) we can avoid paying the O(# children) cost of potentially
creating a backing array for Node#childNodes by simply walking a
short distance down the linked list of children.
Change-Id: I16eca1e5c088a94acfb64177a9ce8545eb487401
---
M lib/html2wt/DOMHandlers.js
M lib/utils/DOMUtils.js
M lib/wt2html/pp/handlers/cleanup.js
M tests/mocha/parse.js
4 files changed, 22 insertions(+), 8 deletions(-)
git pull ssh://gerrit.wikimedia.org:29418/mediawiki/services/parsoid
refs/changes/21/386021/1
diff --git a/lib/html2wt/DOMHandlers.js b/lib/html2wt/DOMHandlers.js
index 9ac2547..f1731b7 100644
--- a/lib/html2wt/DOMHandlers.js
+++ b/lib/html2wt/DOMHandlers.js
@@ -1166,7 +1166,7 @@
return
nativeExt.serialHandler.handle(node, state, wrapperUnmodified);
} else if
(/(?:^|\s)mw:(?:Image|Video|Audio)(\/(Frame|Frameless|Thumb))?/.test(type)) {
return
state.serializer.figureHandler(node);
- } else if (/(?:^|\s)mw\:Entity/.test(type) &&
node.childNodes.length === 1) {
+ } else if (/(?:^|\s)mw\:Entity/.test(type) &&
DU.hasNChildren(node, 1)) {
// handle a new mw:Entity (not handled
by selser) by
// serializing its children
if (dp.src !== undefined && contentSrc
=== dp.srcContent) {
@@ -1183,7 +1183,7 @@
if (dp.src !== undefined) {
return emitPlaceholderSrc(node,
state);
} else if (/(^|\s)mw:Placeholder(\s|$)/
&&
- node.childNodes.length === 1 &&
+ DU.hasNChildren(node, 1) &&
DU.isText(node.firstChild) &&
// See the DisplaySpace hack in
the urltext rule
// in the tokenizer.
@@ -1286,7 +1286,7 @@
} else {
// Trigger separator
if (state.sep.constraints &&
state.sep.constraints.min === 2 &&
-
node.parentNode.childNodes.length === 1) {
+
DU.hasNChildren(node.parentNode, 1)) {
// p/br pair
// Hackhack ;)
diff --git a/lib/utils/DOMUtils.js b/lib/utils/DOMUtils.js
index dc221ce..0cfa41c 100644
--- a/lib/utils/DOMUtils.js
+++ b/lib/utils/DOMUtils.js
@@ -90,6 +90,20 @@
},
/**
+ * Test the number of children this node has without using
+ * `Node#childNodes.length`. This walks the sibling list and so
+ * takes O(`nchildren`) time -- so `nchildren` is expected to be small
+ * (say: 0, 1, or 2).
+ */
+ hasNChildren: function(node, nchildren) {
+ for (var child = node.firstChild; child; child =
child.nextSibling) {
+ if (nchildren <= 0) { return false; }
+ nchildren -= 1;
+ }
+ return true;
+ },
+
+ /**
* Is 'node' a block node that is also visible in wikitext?
* An example of an invisible block node is a `<p>`-tag that
* Parsoid generated, or a `<ul>`, `<ol>` tag.
diff --git a/lib/wt2html/pp/handlers/cleanup.js
b/lib/wt2html/pp/handlers/cleanup.js
index d761aba..a546282 100644
--- a/lib/wt2html/pp/handlers/cleanup.js
+++ b/lib/wt2html/pp/handlers/cleanup.js
@@ -87,7 +87,7 @@
// template/extension content OR nodes with templated-attributes
!DU.hasParsoidAboutId(node) && (
(!node.hasChildNodes()) || (
- node.childNodes.length === 1 &&
!DU.isElt(node.firstChild) &&
+ DU.hasNChildren(node, 1) &&
!DU.isElt(node.firstChild) &&
/^\s*$/.test(node.textContent)
)
)) {
diff --git a/tests/mocha/parse.js b/tests/mocha/parse.js
index de145c2..7f7f8bc 100644
--- a/tests/mocha/parse.js
+++ b/tests/mocha/parse.js
@@ -33,12 +33,12 @@
doc.outerHTML.startsWith('<!DOCTYPE
html><html').should.equal(true);
doc.outerHTML.endsWith('</body></html>').should.equal(true);
// verify that body has only one <html> tag,
one <body> tag, etc.
- doc.childNodes.length.should.equal(2);//
<!DOCTYPE> and <html>
+ DU.hasNChildren(doc, 2).should.equal(true); //
<!DOCTYPE> and <html>
doc.firstChild.nodeName.should.equal('html');
doc.lastChild.nodeName.should.equal('HTML');
// <html> children should be <head> and <body>
var html = doc.documentElement;
- html.childNodes.length.should.equal(2);
+ DU.hasNChildren(html, 2).should.equal(true);
html.firstChild.nodeName.should.equal('HEAD');
html.lastChild.nodeName.should.equal('BODY');
// <body> should have one child, <p>
@@ -58,12 +58,12 @@
doc.outerHTML.startsWith('<!DOCTYPE
html><html').should.equal(true);
doc.outerHTML.endsWith('</body></html>').should.equal(true);
// verify that body has only one <html> tag,
one <body> tag, etc.
- doc.childNodes.length.should.equal(2);//
<!DOCTYPE> and <html>
+ DU.hasNChildren(doc, 2).should.equal(true); //
<!DOCTYPE> and <html>
doc.firstChild.nodeName.should.equal('html');
doc.lastChild.nodeName.should.equal('HTML');
// <html> children should be <head> and <body>
var html = doc.documentElement;
- html.childNodes.length.should.equal(2);
+ DU.hasNChildren(html, 2).should.equal(true);
html.firstChild.nodeName.should.equal('HEAD');
html.lastChild.nodeName.should.equal('BODY');
// <body> should have one child, <table>
--
To view, visit https://gerrit.wikimedia.org/r/386021
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I16eca1e5c088a94acfb64177a9ce8545eb487401
Gerrit-PatchSet: 1
Gerrit-Project: mediawiki/services/parsoid
Gerrit-Branch: master
Gerrit-Owner: C. Scott Ananian <canan...@wikimedia.org>
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