Rewite indentation engine

doc/indentation_logic/.gitignore

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+/pages

doc/indentation_logic/Makefile

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+pages.pdf: pages/page_000.pdf
+	pdfunite pages/page_*.pdf pages.pdf
+
+pages/page_000.pdf: pages/page_000.svg
+	for i in pages/page_*.svg ; do inkscape --export-pdf=pages/"$$( basename "$${i}" .svg )".pdf "$${i}" ; done
+
+pages/page_000.svg: src/pages.svg src/split_pages.kts
+	kotlinc-jvm -script src/split_pages.kts src/pages.svg
+
+clean:
+	rm -rf pages.pdf pages

doc/indentation_logic/src/split_pages.kts

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+/**
+ * Write each layer of Inkscape SVG file into separate SVG files.
+ */
+import java.io.File
+import javax.xml.parsers.DocumentBuilderFactory
+import javax.xml.transform.TransformerFactory
+import javax.xml.transform.dom.DOMSource
+import javax.xml.transform.stream.StreamResult
+import org.w3c.dom.Element
+
+val INKSCAPE_NS = "http://www.inkscape.org/namespaces/inkscape"
+
+if (args.size < 1) {
+    System.err.println("Usage: kotlinc-jvm -script split_pages.kts pages.svg")
+    System.exit(-1)
+}
+
+val transformer = TransformerFactory.newInstance().newTransformer()
+
+val inputFile = File(args[0])
+val document = DocumentBuilderFactory
+    .newDefaultInstance()
+    .also { it.setNamespaceAware(true) }
+    .newDocumentBuilder()
+    .parse(inputFile)
+
+val svgElement = document.documentElement
+val childNodes = svgElement.childNodes
+val layers = 0.until(childNodes.length)
+    .map { childNodes.item(it) }
+    .filter { child ->
+        child is Element &&
+            child.localName == "g" &&
+            child.getAttributeNS(INKSCAPE_NS, "groupmode") == "layer"
+    }
+
+for (layer in layers) {
+    svgElement.removeChild(layer)
+}
+
+val outputDirectory = File("pages")
+
+outputDirectory.mkdirs()
+
+for ((index, layer) in layers.withIndex()) {
+    svgElement.appendChild(layer)
+
+    // Assuming `style="display:none"`
+    layer.attributes.removeNamedItem("style")
+
+    val outputFile = File(outputDirectory, "page_%03d.svg".format(index))
+
+    transformer.transform(DOMSource(document), StreamResult(outputFile))
+
+    svgElement.removeChild(layer)
+}