Revamping Expression Context, special operator for XPath, etc.

[leonelsanchesdasilva]

Special thanks to Marco Balestra on this one.

First of all, XPath became a big pain when using <xsl:template> with <xsl:apply-templates> because:

• Both transformations rely on XPath;
• XPath doesn't have a "self and siblings" axis. The default axis is "child", what created a big headache after filtering nodes on <xsl:apply-templates>, since there's not a good way to select the current nesting level appropriately;
• The 0.x version way of solving it was a very kludgy approach manipulating the relative XPath match. Not just it created a good amount of bugs, as its maintainability was chaotic.

To resolve the issues with <xsl:apply-templates> and relative paths, I created this special axis, self-and-siblings. It seems to solve the problems very well so far, but nothing prevents me to remove it if I find a better approach using pure XPath.

At versions 1.1.x, I was using the input to map the output nodes. It was very convenient, but it doesn't work well in occasions that one match needs to revisit a node that already generated the output. For this reason, I decided to expand the Expression Context to accommodate the input and the output, with input nodes holding a reference to its direct output node.

Some tests are skipped because they are incorrect, considering tests in other XSLT libraries. They should be revisited in the future.

Finally, the <xslt:sort> needs to be called explicitly, and it is not executed by default during <xslt:apply-templates> as before. To solve the output positioning, I created a property called siblingPosition, which it is copied to output nodes, preserving the order while writing the output XML.

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	69.75% (-1.1% 🔻)	1393/1997
🟡	Branches	61.46% (-2.14% 🔻)	622/1012
🟡	Functions	68.62% (-1.55% 🔻)	199/290
🟡	Lines	70.06% (-0.97% 🔻)	1308/1867

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	dom/util.ts	92.86% (-7.14% 🔻)	40% (-50% 🔻)	100%	95.45% (-4.55% 🔻)
🔴	dom/xnode.ts	36.4% (-1.92% 🔻)	29.37% (+5.68% 🔼)	48.48% (+0.1% 🔼)	37.44% (-2.17% 🔻)
🟢	dom/functions.ts	83.9% (-0.72% 🔻)	78.31% (-2.41% 🔻)	78.57%	84.07% (+0.14% 🔼)
🟡	... / xml-functions.ts	79.43% (-6.18% 🔻)	67.44% (-8.53% 🔻)	85.71% (-14.29% 🔻)	78.29% (-6.08% 🔻)
🔴	... / standard.ts	48.35% (-2.75% 🔻)	33.9% (-10.17% 🔻)	43.75% (-3.13% 🔻)	48% (-2.86% 🔻)
🟢	... / step-expr.ts	89.06% (+0.26% 🔼)	77.33% (-2.9% 🔻)	100%	87.72% (+0.33% 🔼)
🟢	xpath/xpath.ts	88.86% (-0.24% 🔻)	84.43% (+0.89% 🔼)	91.67% (-1.67% 🔻)	88.41% (-0.26% 🔻)
🟡	xslt/xslt.ts	68.98% (+0.31% 🔼)	60.71% (-0.58% 🔻)	77.78% (-2.99% 🔻)	69.62% (+0.72% 🔼)

Test suite run success

51 tests passing in 14 suites.

Report generated by 🧪jest coverage report action from 12fd8e8