XSLT 2.0: Transform notation in plain text to svg - regex

Question

I am new to transformations between different formats. My goal is to transfer a notation from a toolkit which is in a plain text format to svg. An easy example would be that I have an orange ellipse and the notation would be like this (x and y is the coordinate system so 0 and 0 means the ellipse is in the middle):
GRAPHREP
PEN color:$000000 w:2pt
FILL color:$ff7f00
ELLIPSE x:0pt y:0pt rx:114pt ry:70pt
and my desired output would be an svg code something like this(the cx and cy coordinate are randomly selected for the example):
<svg width="400" height="400" xmlns="http://www.w3.org/2000/svg" xmlns:svg="http://www.w3.org/2000/svg">
<g>
<ellipse fill="#ff7f00" stroke="#000000" stroke-width="2" stroke-dasharray="null" stroke-linejoin="null" stroke-linecap="null" cx="250" cy="250" id="svg_1" rx="114" ry="70"/>
</g>
</svg>
I found these two threads Parse text file with XSLT and XSL transform on text to XML with unparsed-text: need more depth
where they transform plain text to xml with XSLT 2.0 and the unparsed-text() function and regex. In my example how would it be possible to get the commands like ELLIPSE(is a
regex which recognizes the all uppercase words possible?) and the parameters(is it possible to get with Xpath from plain text anyhow?)? Is a good implementation doable in XSLT 2.0 or should I
look for another method? Any help would be appreciated!

Answer 1

Below is an example of how you can load the text file using unparsed-text(), and parse the content using xsl:analyze-text to produce an intermediate XML document, and then transform that XML using a "push"-style stylesheet.
It shows an example of how to support ELLIPSE, CIRCLE and RECTANGLE text conversion. You may need to customize it a bit, but should give you an idea of what is possible. With the addition of regex and unparsed-text(), XSLT 2.0 and 3.0 makes all sorts of text transformations possible that would have been extremely cumbersome or difficult in XSLT 1.0.
With a file called "drawing.txt" with the following content:
GRAPHREP
PEN color:$000000 w:2pt
FILL color:$ff7f00
ELLIPSE x:0pt y:0pt rx:114pt ry:70pt
GRAPHREP
PEN color:$000000 w:2pt
FILL color:$ff7f00
CIRCLE x:0pt y:0pt rx:114pt ry:70pt
GRAPHREP
PEN color:$000000 w:2pt
FILL color:$ff7f00
RECTANGLE x:0pt y:0pt width:114pt height:70pt
Executing the following XSLT in the same directory:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:local="local"
exclude-result-prefixes="xs"
version="2.0"
xmlns:svg="http://www.w3.org/2000/svg">
<xsl:output indent="yes"/>
<!--matches sequences of UPPER-CASE letters -->
<xsl:variable name="label-pattern" select="'[A-Z]+'"/>
<!--matches the "attributes" in the line i.e. w:2pt,
has two capture groups (1) => attribute name, (2) => attribute value -->
<xsl:variable name="attribute-pattern" select="'\s?(\S+):(\S+)'"/>
<!--matches a line of data for the drawing text,
has two capture groups (1) => label, (2) attribute data-->
<xsl:variable name="line-pattern" select="concat('(', $label-pattern, ')\s(.*)\n?')"/>
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* | node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="/">
<svg width="400" height="400">
<g>
<!-- Find the text patterns indicating the shape -->
<xsl:analyze-string select="unparsed-text('drawing.txt')"
regex="{concat('(', $label-pattern, ')\n((', $line-pattern, ')+)\n?')}">
<xsl:matching-substring>
<!--Convert text to XML -->
<xsl:variable name="drawing-markup" as="element()">
<!--Create an element for this group, using first matched pattern as the element name
(i.e. GRAPHREP => <GRAPHREP>) -->
<xsl:element name="{regex-group(1)}">
<!--split the second matched group for this shape into lines by breaking on newline-->
<xsl:variable name="lines" select="tokenize(regex-group(2), '\n')"/>
<xsl:for-each select="$lines">
<!--for each line, run through this process to create an element with attributes
(e.g. FILL color:$frf7f00 => <FILL color=""/>
-->
<xsl:analyze-string select="." regex="{$line-pattern}">
<xsl:matching-substring>
<!--create an element using the UPPER-CASE label starting the line -->
<xsl:element name="{regex-group(1)}">
<!-- capture each of the attributes -->
<xsl:analyze-string select="regex-group(2)" regex="\s?(\S+):(\S+)">
<xsl:matching-substring>
<!--convert foo:bar into attribute foo="bar",
translate $ => #
and remove the letters 'p' and 't' by translating into nothing"-->
<xsl:attribute name="{regex-group(1)}" select="translate(regex-group(2), '$pt', '#')"/>
</xsl:matching-substring>
<xsl:non-matching-substring/>
</xsl:analyze-string>
</xsl:element>
</xsl:matching-substring>
<xsl:non-matching-substring/>
</xsl:analyze-string>
</xsl:for-each>
</xsl:element>
</xsl:variable>
<!--Uncomment the copy-of below if you want to see the intermediate XML $drawing-markup-->
<!--<xsl:copy-of select="$drawing-markup"/>-->
<!-- Transform XML into SVG -->
<xsl:apply-templates select="$drawing-markup"/>
</xsl:matching-substring>
<xsl:non-matching-substring/>
</xsl:analyze-string>
</g>
</svg>
</xsl:template>
<!--==========================================-->
<!-- Templates to convert the $drawing-markup -->
<!--==========================================-->
<!--for supported shapes, create the element using
lower-case value, and change rectangle to rect
for the svg element name-->
<xsl:template match="GRAPHREP[ELLIPSE | CIRCLE | RECTANGLE]">
<xsl:element name="{replace(lower-case(local-name(ELLIPSE | CIRCLE | RECTANGLE)), 'rectangle', 'rect', 'i')}">
<xsl:attribute name="id" select="concat('id_', generate-id())"/>
<xsl:apply-templates />
</xsl:element>
</xsl:template>
<xsl:template match="ELLIPSE | CIRCLE | RECTANGLE"/>
<!-- Just process the content of GRAPHREP.
If there are multiple shapes and you want a new
<svg><g></g></svg> for each shape,
then move it from the template for "/" into this template-->
<xsl:template match="GRAPHREP/*">
<xsl:apply-templates select="#*"/>
</xsl:template>
<xsl:template match="PEN" priority="1">
<!--TODO: test if these attributes exist, if they do, do not create these defaults.
Hard-coding for now, to match desired output, since I don't know what the text
attributes would be, but could wrap each with <xsl:if test="not(#dasharray)">-->
<xsl:attribute name="stroke-dasharray" select="'null'"/>
<xsl:attribute name="stroke-linjoin" select="'null'"/>
<xsl:attribute name="stroke-linecap" select="'null'"/>
<xsl:apply-templates select="#*"/>
</xsl:template>
<!-- conterts #color => #stroke -->
<xsl:template match="PEN/#color">
<xsl:attribute name="stroke" select="."/>
</xsl:template>
<!--converts #w => #stroke-width -->
<xsl:template match="PEN/#w">
<xsl:attribute name="stroke-width" select="."/>
</xsl:template>
<!--converts #color => #fill and replaces $ with # -->
<xsl:template match="FILL/#color">
<xsl:attribute name="fill" select="translate(., '$', '#')"/>
</xsl:template>
<!-- converts #x => #cx with hard-coded values.
May want to use value from text, but matching your example-->
<xsl:template match="ELLIPSE/#x | ELLIPSE/#y">
<!--not sure if there was a relationship between ELLIPSE x:0pt y:0pt, and why 0pt would be 250,
but just an example...-->
<xsl:attribute name="c{name()}" select="250"/>
</xsl:template>
</xsl:stylesheet>
Produces the following SVG output:
<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns:local="local"
xmlns:svg="http://www.w3.org/2000/svg"
width="400"
height="400">
<g>
<ellipse id="id_d2e0"
stroke-dasharray="null"
stroke-linjoin="null"
stroke-linecap="null"
stroke="#000000"
stroke-width="2"
fill="#ff7f00"
cx="250"
cy="250"
rx="114"
ry="70"/>
<circle id="id_d3e0"
stroke-dasharray="null"
stroke-linjoin="null"
stroke-linecap="null"
stroke="#000000"
stroke-width="2"
fill="#ff7f00"
x="0"
y="0"
rx="114"
ry="70"/>
<rect id="id_d4e0"
stroke-dasharray="null"
stroke-linjoin="null"
stroke-linecap="null"
stroke="#000000"
stroke-width="2"
fill="#ff7f00"
x="0"
y="0"
width="114"
height="70"/>
</g>
</svg>