1 files changed, 231 insertions, 0 deletions
diff --git a/node_modules/postcss-merge-rules/src/lib/ensureCompatibility.js b/node_modules/postcss-merge-rules/src/lib/ensureCompatibility.js
new file mode 100644
index 00000000..e8f60f09
--- /dev/null
+++ b/node_modules/postcss-merge-rules/src/lib/ensureCompatibility.js
@@ -0,0 +1,231 @@
+'use strict';
+const { isSupported } = require('caniuse-api');
+const selectorParser = require('postcss-selector-parser');
+
+const simpleSelectorRe = /^#?[-._a-z0-9 ]+$/i;
+
+const cssSel2 = 'css-sel2';
+const cssSel3 = 'css-sel3';
+const cssGencontent = 'css-gencontent';
+const cssFirstLetter = 'css-first-letter';
+const cssFirstLine = 'css-first-line';
+const cssInOutOfRange = 'css-in-out-of-range';
+const formValidation = 'form-validation';
+
+const vendorPrefix =
+  /-(ah|apple|atsc|epub|hp|khtml|moz|ms|o|rim|ro|tc|wap|webkit|xv)-/;
+
+const level2Sel = new Set(['=', '~=', '|=']);
+const level3Sel = new Set(['^=', '$=', '*=']);
+
+/**
+ * @param {string} selector
+ * @return {RegExpMatchArray | null}
+ */
+function filterPrefixes(selector) {
+  return selector.match(vendorPrefix);
+}
+
+/**
+ * Internet Explorer use :-ms-input-placeholder.
+ * Microsoft Edge use ::-ms-input-placeholder.
+ *
+ * @type {(selector: string) => number}
+ */
+const findMsInputPlaceholder = (selector) =>
+  ~selector.search(/-ms-input-placeholder/i);
+
+/**
+ * @param {string[]} selectorsA
+ * @param {string[]} selectorsB
+ * @return {boolean}
+ */
+function sameVendor(selectorsA, selectorsB) {
+  /** @type {(selectors: string[]) => string} */
+  let same = (selectors) => selectors.map(filterPrefixes).join();
+  /** @type {(selectors: string[]) => string | undefined} */
+  let findMsVendor = (selectors) => selectors.find(findMsInputPlaceholder);
+  return (
+    same(selectorsA) === same(selectorsB) &&
+    !(findMsVendor(selectorsA) && findMsVendor(selectorsB))
+  );
+}
+
+/**
+ * @param {string} selector
+ * @return {boolean}
+ */
+function noVendor(selector) {
+  return !vendorPrefix.test(selector);
+}
+
+const pseudoElements = {
+  ':active': cssSel2,
+  ':after': cssGencontent,
+  ':any-link': 'css-any-link',
+  ':before': cssGencontent,
+  ':checked': cssSel3,
+  ':default': 'css-default-pseudo',
+  ':dir': 'css-dir-pseudo',
+  ':disabled': cssSel3,
+  ':empty': cssSel3,
+  ':enabled': cssSel3,
+  ':first-child': cssSel2,
+  ':first-letter': cssFirstLetter,
+  ':first-line': cssFirstLine,
+  ':first-of-type': cssSel3,
+  ':focus': cssSel2,
+  ':focus-within': 'css-focus-within',
+  ':focus-visible': 'css-focus-visible',
+  ':has': 'css-has',
+  ':hover': cssSel2,
+  ':in-range': cssInOutOfRange,
+  ':indeterminate': 'css-indeterminate-pseudo',
+  ':invalid': formValidation,
+  ':is': 'css-matches-pseudo',
+  ':lang': cssSel2,
+  ':last-child': cssSel3,
+  ':last-of-type': cssSel3,
+  ':link': cssSel2,
+  ':matches': 'css-matches-pseudo',
+  ':not': cssSel3,
+  ':nth-child': cssSel3,
+  ':nth-last-child': cssSel3,
+  ':nth-last-of-type': cssSel3,
+  ':nth-of-type': cssSel3,
+  ':only-child': cssSel3,
+  ':only-of-type': cssSel3,
+  ':optional': 'css-optional-pseudo',
+  ':out-of-range': cssInOutOfRange,
+  ':placeholder-shown': 'css-placeholder-shown',
+  ':required': formValidation,
+  ':root': cssSel3,
+  ':target': cssSel3,
+  '::after': cssGencontent,
+  '::backdrop': 'dialog',
+  '::before': cssGencontent,
+  '::first-letter': cssFirstLetter,
+  '::first-line': cssFirstLine,
+  '::marker': 'css-marker-pseudo',
+  '::placeholder': 'css-placeholder',
+  '::selection': 'css-selection',
+  ':valid': formValidation,
+  ':visited': cssSel2,
+};
+
+/**
+ * @param {string} selector
+ * @return {boolean}
+ */
+function isCssMixin(selector) {
+  return selector[selector.length - 1] === ':';
+}
+
+/**
+ * @param {string} selector
+ * @return {boolean}
+ */
+function isHostPseudoClass(selector) {
+  return selector.includes(':host');
+}
+
+const isSupportedCache = new Map();
+
+// Move to util in future
+/**
+ * @param {string} feature
+ * @param {string[] | undefined} browsers
+ */
+function isSupportedCached(feature, browsers) {
+  const key = JSON.stringify({ feature, browsers });
+  let result = isSupportedCache.get(key);
+
+  if (!result) {
+    result = isSupported(feature, /** @type {string[]} */ (browsers));
+    isSupportedCache.set(key, result);
+  }
+
+  return result;
+}
+
+/**
+ * @param {string[]} selectors
+ * @param{string[]=} browsers
+ * @param{Map<string,boolean>=} compatibilityCache
+ * @return {boolean}
+ */
+function ensureCompatibility(selectors, browsers, compatibilityCache) {
+  // Should not merge mixins
+  if (selectors.some(isCssMixin)) {
+    return false;
+  }
+
+  // Should not merge :host selector https://github.com/angular/angular-cli/issues/18672
+  if (selectors.some(isHostPseudoClass)) {
+    return false;
+  }
+  return selectors.every((selector) => {
+    if (simpleSelectorRe.test(selector)) {
+      return true;
+    }
+    if (compatibilityCache && compatibilityCache.has(selector)) {
+      return compatibilityCache.get(selector);
+    }
+    let compatible = true;
+    selectorParser((ast) => {
+      ast.walk((node) => {
+        const { type, value } = node;
+        if (type === 'pseudo') {
+          const entry =
+            pseudoElements[/** @type {keyof pseudoElements} */ (value)];
+          if (!entry && noVendor(value)) {
+            compatible = false;
+          }
+          if (entry && compatible) {
+            compatible = isSupportedCached(entry, browsers);
+          }
+        }
+        if (type === 'combinator') {
+          if (value.includes('~')) {
+            compatible = isSupportedCached(cssSel3, browsers);
+          }
+          if (value.includes('>') || value.includes('+')) {
+            compatible = isSupportedCached(cssSel2, browsers);
+          }
+        }
+        if (type === 'attribute' && node.attribute) {
+          // [foo]
+          if (!node.operator) {
+            compatible = isSupportedCached(cssSel2, browsers);
+          }
+          if (value) {
+            // [foo="bar"], [foo~="bar"], [foo|="bar"]
+            if (level2Sel.has(/** @type {string} */ (node.operator))) {
+              compatible = isSupportedCached(cssSel2, browsers);
+            }
+            // [foo^="bar"], [foo$="bar"], [foo*="bar"]
+            if (level3Sel.has(/** @type {string} */ (node.operator))) {
+              compatible = isSupportedCached(cssSel3, browsers);
+            }
+          }
+
+          // [foo="bar" i]
+          if (node.insensitive) {
+            compatible = isSupportedCached('css-case-insensitive', browsers);
+          }
+        }
+        if (!compatible) {
+          // If this node was not compatible,
+          // break out early from walking the rest
+          return false;
+        }
+      });
+    }).processSync(selector);
+    if (compatibilityCache) {
+      compatibilityCache.set(selector, compatible);
+    }
+    return compatible;
+  });
+}
+
+module.exports = { sameVendor, noVendor, pseudoElements, ensureCompatibility };