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backend/node_modules/svgo/plugins/minifyStyles.js

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+'use strict';
+
+/**
+ * @typedef {import('../lib/types').XastElement} XastElement
+ * @typedef {import('../lib/types').XastParent} XastParent
+ */
+
+const csso = require('csso');
+const { detachNodeFromParent } = require('../lib/xast');
+const { hasScripts } = require('../lib/svgo/tools');
+
+exports.name = 'minifyStyles';
+exports.description = 'minifies styles and removes unused styles';
+
+/**
+ * Minifies styles (<style> element + style attribute) using CSSO.
+ *
+ * @author strarsis <strarsis@gmail.com>
+ * @type {import('./plugins-types').Plugin<'minifyStyles'>}
+ */
+exports.fn = (_root, { usage, ...params }) => {
+  /** @type {Map<XastElement, XastParent>} */
+  const styleElements = new Map();
+
+  /** @type {XastElement[]} */
+  const elementsWithStyleAttributes = [];
+
+  /** @type {Set<string>} */
+  const tagsUsage = new Set();
+
+  /** @type {Set<string>} */
+  const idsUsage = new Set();
+
+  /** @type {Set<string>} */
+  const classesUsage = new Set();
+
+  let enableTagsUsage = true;
+  let enableIdsUsage = true;
+  let enableClassesUsage = true;
+
+  /**
+   * Force to use usage data even if it unsafe. For example, the document
+   * contains scripts or in attributes..
+   */
+  let forceUsageDeoptimized = false;
+
+  if (typeof usage === 'boolean') {
+    enableTagsUsage = usage;
+    enableIdsUsage = usage;
+    enableClassesUsage = usage;
+  } else if (usage) {
+    enableTagsUsage = usage.tags == null ? true : usage.tags;
+    enableIdsUsage = usage.ids == null ? true : usage.ids;
+    enableClassesUsage = usage.classes == null ? true : usage.classes;
+    forceUsageDeoptimized = usage.force == null ? false : usage.force;
+  }
+
+  let deoptimized = false;
+
+  return {
+    element: {
+      enter: (node, parentNode) => {
+        // detect deoptimisations
+        if (hasScripts(node)) {
+          deoptimized = true;
+        }
+
+        // collect tags, ids and classes usage
+        tagsUsage.add(node.name);
+        if (node.attributes.id != null) {
+          idsUsage.add(node.attributes.id);
+        }
+        if (node.attributes.class != null) {
+          for (const className of node.attributes.class.split(/\s+/)) {
+            classesUsage.add(className);
+          }
+        }
+        // collect style elements or elements with style attribute
+        if (node.name === 'style' && node.children.length !== 0) {
+          styleElements.set(node, parentNode);
+        } else if (node.attributes.style != null) {
+          elementsWithStyleAttributes.push(node);
+        }
+      },
+    },
+
+    root: {
+      exit: () => {
+        /** @type {csso.Usage} */
+        const cssoUsage = {};
+        if (!deoptimized || forceUsageDeoptimized) {
+          if (enableTagsUsage) {
+            cssoUsage.tags = Array.from(tagsUsage);
+          }
+          if (enableIdsUsage) {
+            cssoUsage.ids = Array.from(idsUsage);
+          }
+          if (enableClassesUsage) {
+            cssoUsage.classes = Array.from(classesUsage);
+          }
+        }
+        // minify style elements
+        for (const [styleNode, styleNodeParent] of styleElements.entries()) {
+          if (
+            styleNode.children[0].type === 'text' ||
+            styleNode.children[0].type === 'cdata'
+          ) {
+            const cssText = styleNode.children[0].value;
+            const minified = csso.minify(cssText, {
+              ...params,
+              usage: cssoUsage,
+            }).css;
+
+            if (minified.length === 0) {
+              detachNodeFromParent(styleNode, styleNodeParent);
+              continue;
+            }
+
+            // preserve cdata if necessary
+            // TODO split cdata -> text optimisation into separate plugin
+            if (cssText.indexOf('>') >= 0 || cssText.indexOf('<') >= 0) {
+              styleNode.children[0].type = 'cdata';
+              styleNode.children[0].value = minified;
+            } else {
+              styleNode.children[0].type = 'text';
+              styleNode.children[0].value = minified;
+            }
+          }
+        }
+        // minify style attributes
+        for (const node of elementsWithStyleAttributes) {
+          // style attribute
+          const elemStyle = node.attributes.style;
+          node.attributes.style = csso.minifyBlock(elemStyle, {
+            ...params,
+          }).css;
+        }
+      },
+    },
+  };
+};